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Report E

UR

22784 E

N

CERTIFICATION REPORT

The certification of the mass fractions of As, Br, Cd, Cl, Cr, Hg, Pb, S and Sb and the assignment of

indicative values for Sn and Zn in two polyethylene reference materials

Certified Reference Materials ERM®-EC680k and

ERM®-EC681k

The mission of IRMM is to promote a common and reliable European measurement system in support of EU policies. European Commission Directorate-General Joint Research Centre Institute for Reference Materials and Measurements Contact information CRM Sales European Commission Directorate-General Joint Research Centre Institute for Reference Materials and Measurements Retieseweg 111 B-2440 Geel • Belgium Email: [email protected] Tel.: +32 (0)14 571 705 Fax: +32 (0)14 590 406 http://www.irmm.jrc.be http://www.jrc.ec.europa.eu http://www.erm-crm.org Legal Notice Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use which might be made of the following information. EUR Report 22784 EN ISSN 1018-5593 ISBN 978-92-79-06027-4 Luxembourg: Office for Official Publications of the European Communities © European Communities, 2007 Reproduction is authorised provided the source is acknowledged Printed in Belgium

Report EUR 22784 EN

CERTIFICATION REPORT

The certification of the mass fraction of, As, Br, Cd, Cl, Cr, Hg, Pb, S and Sb and the assignment of indicative

values for Sn and Zn in two polyethylene reference materials

Certified Reference Materials ERM®-EC680k and

ERM®-EC681k

T. Linsinger, A. Liebich, E. Przyk, A. Lamberty

European Commission, Joint Research Centre Institute for Reference Materials and Measurements (IRMM)

Geel (BE)

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SUMMARY This report describes the preparation and certification of the polymer certified reference materials (CRM) ERM-EC680k and ERM-EC681k. They replace the exhausted predecessors, ERM-EC680 and ERM-EC681. The CRMs have been certified by the European Commission, Directorate General Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Geel, Belgium.

The CRM was prepared from a low-density polyethylene (LDPE) granulate spiked with inorganic pigments (As2O3, Green 36, ZnS/CdS, Green 7, Cr2O3, PbCrO4/PbSO4, HgS, Sb2O3, SnO2).

Certification of the CRM included testing of the homogeneity and stability of the material as well as the characterisation using an intercomparison approach.

The new CRMs have been certified for their content of As, Br, Cd, Cl, Cr, Hg, Pb, S, Sb and indicative values have been established for Sn and Zn. Additional information about acid digestible Cr is given.

These CRMs are intended for use in quality assurance of measurements of elements in polymers and related matrices.

The following values were assigned:

Certified and indicative values. Assigned uncertainties are expanded uncertainties estimated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) with a coverage factor k = 2.78 for Cr and k = 2 for all other elements, corresponding to a level of confidence of about 95 %.

ERM-EC680k ERM-EC681k As 4.1 ± 0.5 mg/kg 29.1 ± 1.8 mg/kg Br 96 ± 4 mg/kg 0.77 ± 0.04 g/kg Cd 19.6 ± 1.4 mg/kg 137 ± 4 mg/kg Cl 102.2 ± 3.0 mg/kg 0.80 ± 0.05 g/kg Cr 20.2 ± 1.1 mg/kg 100 ± 5 mg/kg Hg 4.64 ± 0.20 mg/kg 23.7 ± 0.8 mg/kg Pb 13.6 ± 0.5 mg/kg 98 ± 6 mg/kg S 76 ± 4 mg/kg 0.63 ± 0.04 g/kg Sb 10.1 ± 1.6 mg/kg 99 ± 6 mg/kg

Indicative values

ERM-EC680k ERM-EC681k Sn 15.3 ± 2.8 mg/kg 86 ± 6 mg/kg Zn 137 ± 20 mg/kg 1.25 ± 0.07 g/kg

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3

TABLE OF CONTENTS

Summary .................................................................................................................................1

Table of contents....................................................................................................................3

Glossary ..................................................................................................................................4

1 Introduction.....................................................................................................................5

2 Time table of the project ................................................................................................5

3 Participants .....................................................................................................................6

4 Processing ......................................................................................................................7

5 Homogeneity...................................................................................................................8 5.1 Between-unit homogeneity .......................................................................................8 5.2 Minimum sample intake..........................................................................................11

6 Stability..........................................................................................................................13 6.1 Stability of the previous materials ...........................................................................13 6.2 Tests on the current materials ................................................................................14 6.3 Uncertainty of stability.............................................................................................16

7 Characterisation ...........................................................................................................19 7.1 Technical evaluation...............................................................................................19 7.2 Statistical evaluation...............................................................................................22

8 Assigned Values and their uncertainties ...................................................................24 8.1 Certified values.......................................................................................................25 8.2 Indicative values .....................................................................................................26 8.3 Additional material information ...............................................................................26

9 Metrological Traceability and commutability.............................................................27 9.1 Metrological Traceability .........................................................................................27 9.2 Commutability .........................................................................................................27

10 Instructions for use ..................................................................................................28 10.1 Storage conditions..................................................................................................28 10.2 Safety and protection of the environment ...............................................................28 10.3 Use of the certified values ......................................................................................28

11 Acknowledgements..................................................................................................28

12 Annexes.....................................................................................................................28

13 References ................................................................................................................29

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GLOSSARY AAS Atomic absorption spectrometry AFS Atomic fluorescence spectrometry ANOVA Analysis of variance CRM Certified reference material CVAAS Cold vapour AAS CVAFS Cold vapour AFS DMA Direct mercury analyser ETAAS Electrothermal AAS HG Hydride generation HPA High pressure asher IC Ion chromatography ICP Inductively coupled plasma ICP-AES Inductively coupled plasma atomic emission spectrometry ICP-MS Inductively coupled plasma mass spectrometry ID -TIMS Thermal ionization mass spectrometry using isotope dilution INAA Instrumental neutron activation analysis IPAA Instrumental photon activation analysis IR Infrared spectrometry k Coverage factor k0NAA Neutron activation analysis using the k0-method for quantification MSamong Mean square among bottles from an ANOVA MSwithin Mean square within a bottle from an ANOVA NAA Neutron activation analysis RoHS Directive 2002/95/EC (restriction of the use of certain hazardous substances in

electric and electronic equipment) RSD Relative standard deviation rel Relative (as subscript) sbb Between-unit variability swb Standard deviation within bottle SF Sectorfield SI Système International d'Unités (International System of Units) SS-ZAAS Solid sampling Zeeman AAS ubb Uncertainty related to a possible between-bottle heterogeneity u*

bb Heterogeneity that could be hidden by method repeatability uc Combined uncertainty of the certified value uchar Uncertainty of the characterisation UCRM Expanded uncertainty of a certified value ults Uncertainty of long-term stability usts Uncertainty of short-term stability WDXRF Wavelength-dispersive X-ray fluorescence spectrometry XRF X-ray fluorescence spectrometry

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1 INTRODUCTION Most countries have adopted legislation to monitor the mass fraction of elements in consumer products in order to protect human and animal health. From an environmental perspective, the flow of heavy metals to the environment should be monitored well to avoid adverse health effects due to excessive load. To this end, the European Union has passed legislation to limit the load of certain elements in various products, amongst them Directive 94/62/EC (packaging directive), Directive 2002/95/EC (restriction of the use of certain hazardous substances in electric and electronic equipment RoHS) and Directive 2000/53/EC (end of live vehicles).

• Directive 94/62/EC concerns plastics packaging and packaging material and regulates the amounts of metals (Cd, Cr, Hg and Pb) in plastics used for packaging. Article 11 of this directive states that the maximum element content should be decreased in three consecutive steps, namely to 600 mg/kg before June 30, 1998, to 250 mg/kg before June 30, 1999 and to 100 mg/kg before June 30, 2001.

• Directive 2002/95/EC aims at reducing the amount of hazardous substances in electric and electronic equipment. Use of Pb, Hg, Cr(VI), Cd and polybrominated flame retardants is prohibited unless not alternatives exist for certain applications. Commission Decision 2005/618/EC sets a limit of maximum 0.1 g/kg in homogeneous materials for Pb, Hg, Cr(VI) and 0.1 g/kg for Cd.

• Similarly, Directive 2000/53/EC aims at reducing the amount of hazardous substances entering the environment from old vehicles. Council Decision 2005/673/EC sets a limit of maximum 0.1 g/kg in homogeneous materials for Pb, Hg, Cr(VI) and 0.1 g/kg for Cd.

In support of these directives, two sets of certified reference materials (CRMs) have been produced by the European Commission, namely a set of four polyethylene (PE) materials (on behalf of the German Verband der Automobilindustrie e.V. (VDA), Frankfurt) [1] and two additional PE materials, BCR-680 and BCR-681 [2]. BCR-680 and BCR-681 were re-labelled as ERM-EC680 and ERM-EC681 in 2004. Due to the high need for these materials, stocks of ERM-EC680 and ERM-EC681 were exhausted in 2006 and new batches were produced. This report describes the production of the two replacement batches ERM-EC680k and ERM-EC681k.

2 TIME TABLE OF THE PROJECT Processing...............................................March 2006 – June 2006 Homogeneity study..................................July 2006 – September 2006 Stability study ..........................................July 2006 – October 2006 Characterisation study.............................August 2006 – December 2006

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3 PARTICIPANTS Processing DSM Resolve, Geleen (NL) EC-JRC, Institute for Reference Materials and Measurements (IRMM), Geel (BE) Homogeneity study Vlaamse Instelling voor Technologisch Onderzoek (VITO), Mol (BE) European Commission, Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Geel (BE) All measurements were performed by wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) except for Hg in EC680k, for which a direct-mercury analyser was used.

Stability study Vlaamse Instelling voor Technologisch Onderzoek (VITO), Mol (BE) European Commission, Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Geel (BE) All measurements were performed by wavelength-dispersive X-ray fluorescence spectrometry (WDXRF) except for Hg in EC680k, for which a direct-mercury analyser was used.

Characterisation measurements Bundesanstalt für Materialforschung und –prüfung (BAM), Berlin (DE) (accredited for the

measurements performed according to ISO 17025 DAP-PL-2614.14)

DSM Resolve, Geleen (NL)

GSF, Neuherberg (DE)

Institut Jozef Stefan, Ljubljana (SI)

Solvias, Basel (CH)

Studiecentrum voor Kernenergie (SCK), Mol (BE)

Umweltbundesamt, Vienna (AT) (accredited for the measurements performed according to ISO 17025 BMWA-92.714/0191-I/12/2005, PSID 200)

Vlaamse Instelling voor Technologisch Onderzoek (VITO), Mol (BE)

Methods used included methods without sample preparation (XRF, NAA) as well as digestion methods (acid, oxygen) with different quantification steps (ICP methods, IC with conductivity detection, AAS, XRF).

Project Management and evaluation European Commission, Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Geel (BE)

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4 PROCESSING A survey among customers was conducted to come up with potential improvements of the previous material. Amongst ideas of a different format (e.g. plates), the additional certification of the mass fraction of Sb and Sn was mentioned. Therefore, Sb and Sn were added to the range of elements.

Preparation of the batches was performed by DSM Resolve, Geleen (NL). Low-density polyethylene (LDPE) was used as base material without addition of plasticisers and softeners. The target elements had to be added as LDPE itself does not contain them. Most frequent use of the target elements is as colourant, i.e. in the form of pigments. Therefore, inorganic pigments were added to achieve the target contents for the various elements. Due to the nature of the production process, these pigments cannot be present in the initial polymerisation process but have to be blended into the final LDPE granulate.

Pigments were ground to particle sizes < 1 µm if necessary. For each material, a master batch of a higher element concentration was produced by mixing with PE powder in a nail mill and subsequent extrusion. The granulate obtained was mixed, blended with blank LDPE to yield the desired element concentrations and extruded. The granulate from this step was mixed again and extruded a second time. Pigments used and the desired target element mass fractions are listed in Table 1.

Table 1: Pigments used and element target concentrations.

Element target mass fractions [mg/kg]

Element Pigments

ERM-EC680k ERM-EC681k As As2O3 5 30 Br Cl/Br phthalocyanine (Green 36) 100 800 Cd ZnS/CdS 20 140

Cl Cl-phthalocyanine (Green 7), Cl/Br phthalocyanine (Green 36) 100 800

Cr Cr2O3 (Green 17), PbCrO4/PbSO4 (Yellow 34) 20 100 Hg HgS 5 25 Pb PbCrO4/PbSO4 (Yellow 34) 15 100 S ZnS/CdS, PbCrO4/PbSO4 (Yellow 34) 80 700 Sb Sb2O3 10 100 Sn SnO2 20 100

The same pigments and target concentration levels as for the previous batches were used. However, the coding was reversed: while ERM-EC680 was previously the high level material, ERM-EC680k is the low level material. This is clearly indicated on the label.

About 300 kg of each batch were produced and delivered to IRMM. Material was filled into drums of about 100 kg (maximum capacity of the mixer) and homogenised in a turbula mixer. One hundred grams were filled into amber glass jars, which were numbered according to the filling sequence. The relationship between drums and sample numbers is given in Table 2.

Table 2: Drums and sample numbers. For ERM-EC681k, samples were labelled 53-2812, i.e. samples 1-52 do not exist.

Bottle numbers ERM-EC680k

Bottle numbers ERM-EC681k

Drum 1 1-1030 53-988 Drum 2 1031-2056 989-1911 Drum 3 2057-3026 1912-2812

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5 HOMOGENEITY

5.1 BETWEEN-UNIT HOMOGENEITY Thirty units of each batch were selected using a random stratified sampling scheme and analysed by VITO (ERM-EC680k) and IRMM (ERM-EC681k) for all elements. Three plates (diameter about 4 cm; height about 5 mm) were pressed from each bottle and the plates were analysed in a randomised manner to be able to separate potential analytical drift from a trend in the filling sequence.

The methods used were WDXRF for all elements except Hg in ERM-EC680k, where a direct mercury analyser (combustion with subsequent quantification by AAS) was used.

5.1.1 Descriptive evaluation Grubbs-tests were performed to detect potentially outlying individual results as well as outlying bottle averages.

For ERM-EC680k, outlying individual values were found for Pb, Cl, S and Sb. The ones for Pb and Sb were only significant on a 95 %, but not on a 99 % confidence level whereas the ones for Cl and S were also significant on a 99 % level. Four outlying bottle averages (one for As and Br and two for Cl) were found, all significant at 95 %, but not at 99 % confidence levels. Bottle 1222 was found an outlier both for As and Br, whereas the two outlying averages for Cl came from bottles 316 and 1520.

For ERM-EC681k, one outlying result each was found for Br and Cl. These outlying results made the bottle average an outlier as well. Both measurements concerned the same result, namely measurement number 36 of bottle number 2136. Measurement number 36 was also an outlying result for S. Additionally, measurement number 16 (bottle 1523) was an outlier for S as well. The other measurements of the other plates from the same bottle did not confirm the deviating result for this bottle, so the outliers are most likely statistical artefacts.

As no technical reason for the outlier could be found and outlying bottle averages were not significant at 99 % confidence levels, all data were retained for statistical analysis.

Regression analyses were performed to evaluate potential trends in the analytical sequence as well as trends in the filling sequence.

In ERM-EC680k, the apparent mass fractions of Br and Sn increased with increasing bottle numbers. These trends were significant on a 95 % confidence level, but not on a 99 % confidence level. The same was true for Cd in EC681k. All data were retained. Uncertainty of homogeneity is very low (see below), despite the fact that any potential trend is reflected in this uncertainty.

For EC681k, some trends in the analytical sequence were visible, pointing at instability of the analytical system. These were again only significant on a 95 %, but not on a 99 % confidence level and no drift correction was applied.

It was furthermore checked whether the individual data and bottle averages follow a normal distribution using normal probability plots and whether the individual data are unimodally distributed using histograms.

For ERM-EC680k and ERM-EC681k, most individual results and sample means follow normal distributions. Sample means are unimodally distributed for all elements. A special case is Pb in EC681k: as can be seen in Annex A, individual results fall clearly into three groups with Pb mass fractions around 96.5, 101 and 107 mg/kg respectively. This grouping is not visible in the sample means. Fifteen plates were measured again, yielding a similar pattern, but with different plates. It was therefore concluded that this grouping is due to some instrumental artefact and not due to some real variation in the Pb mass fractions. All values were therefore retained as the higher variation between the individual measurement results

9

is reflected in the estimate of the uncertainty of homogeneity. Retention of the values therefore does not result in an underestimation of potential heterogeneity.

The result of the descriptive evaluation is given in Table 3 and Table 4.

Table 3: Results of the descriptive evaluation of the homogeneity results of ERM-EC680k. None of the trends is significant on a 99 % confidence level. Only the outliers for S and Cd

are significant on a 99 % confidence level. For the individual values with indication of outliers, see Annex A.

Outliers Significant trends (95 % confidence)

Distribution of individual results

Distribution of bottle means

Individual

values Bottle

average Analytical sequence

Filling sequence Normal Unimodal Normal Unimodal

As no 1 no no yes yes approx. yes

Br no 1 no yes approx. hint of bimodal approx. yes

Cd no no no no yes yes yes yes Cl 1 2 no no no yes no yes Cr no no no no yes yes yes yes Hg no no no no yes yes yes yes Pb 2 no no no yes yes yes yes S 1 no no no no yes no yes Sb 1 no no no no yes no yes Sn no no no yes yes yes yes yes

Table 4: Result of the descriptive evaluation for the homogeneity results of ERM-EC681k. None of the trends is significant on a 99 % confidence level. Only the outlier for the individual value for Br is significant on a 99 % confidence level. For the individual values with indication

of outliers see Annex A.

Outliers Significant trends (95 % confidence)

Distribution of individual results

Distribution of bottle means

Individual values

Bottle average

Analytical sequence

Filling sequence Normal Unimodal Normal Unimodal

As no no no no yes yes yes yes Br 1 1 no no no yes no yes Cd no no yes yes yes yes yes yes Cl 1 1 no no no yes no yes Cr no no no no yes yes yes yes Hg no no yes no yes yes yes yes Pb no no no no no no no approx. S 2 no yes no no yes yes yes Sb no no no no yes yes no yes Sn no no no no yes yes yes yes

5.1.2 Between-drum homogeneity Samples were produced in three batches due to restraints in the maximum mixing capacity. Therefore the equivalence of the three batches was checked. Mean values for all elements were grouped by the batch and differences were evaluated using one-way analysis of variance (ANOVA) with the batch number as grouping variable.

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For ERM-EC680k, the differences between drums were significant for Br on a 95 %, but not on a 99 % confidence level and were therefore regarded as statistical artefact. No significant difference between drums was found for any of the other elements on a 95 % confidence level. For Br, the difference between the highest and the lowest drum average was 1.50 %.

For ERM-EC681k, differences between batch averages were significantly different on a 95 % significance level for Br and Cr. The differences between the highest and the lowest average were 0.34 % for Br and 0.24 % for Cr.

The uncertainty of variation between drums, udrum, was estimated assuming a rectangular distribution of results between the highest and lowest drum average. In line with the Guide to the Expression of Uncertainty in Measurement (GUM) [3], uncertainty was estimated as half-width of this difference divided by √3. This gives uncertainty contributions of 0.43 % for Br in ERM-EC680k and 0.10 % and 0.07 %, respectively, for Br and Cr, respectively, in ERM-EC681k.

5.1.3 Variation between bottles Key requirement for any reference material is equivalence between the various units. In this respect, it is not relevant whether the variation between units is significant compared to the analytical variation, but whether this variation is significant to the certified uncertainty. Consequently, ISO Guide 35 demands RM producers to quantify the between bottle variation.

This quantification is most easily done by ANOVA, which can separate the between-bottle variation (sbb) from the within-bottle variation (swb). The latter is equivalent to the analytical variation if the individual subsamples are representative for the whole bottle. Evaluation by ANOVA is only possible if data follow unimodal distributions.

One has to bear in mind that sbb and swb are estimates of the true standard deviations and therefore subject to random fluctuations. This can result in negative estimates for the between-bottle variation, whereas the natural lower limit is naturally zero. In this case, u*

bb, the maximum heterogeneity that could be hidden by method repeatability, was calculated as described by Linsinger et al. [4]. u*

bb is comparable to the limit of detection of an analytical method, yielding the maximum amount of a substance that might be undetected by any given analytical test.

Because all individual values and sample means followed unimodal distributions, results could be evaluated using ANOVA. Standard deviations within units (swb) and between units (sbb) as well as u*

bb were calculated. The results of these evaluations are shown in Table 5 and Table 6.

Table 5: Results of the homogeneity test for ERM-EC680k. n.c.= cannot be calculated as MSamong < MSwithin.

swb sbb u*bb Average

[mg/kg] [mg/kg] [%] [mg/kg] [%] [mg/kg] [%] As 4.25 0.613 14.4 0.173 4.08 0.151 3.56 Br 108.1 4.72 4.36 n.c. n.c. 1.16 1.08 Cd 18.9 2.01 10.6 n.c. n.c. 0.495 2.62 Cl 100.3 4.54 4.53 0.961 0.958 1.12 1.12 Cr 23.7 0.328 1.38 0.0824 0.347 0.0809 0.341 Hg 4.60 0.287 6.25 n.c. n.c. 0.0716 1.56 Pb 14.6 0.575 3.93 n.c. n.c. 0.142 0.970 S 116.3 2.46 2.12 n.c. n.c. 0.608 0.523

Sb 2.48 0.712 28.7 n.c. n.c. 0.176 7.08 Sn 10.5 0.574 5.46 0.386 3.67 0.142 1.35

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Table 6: Results of the homogeneity test for ERM-EC681k. n.c.= cannot be calculated as MSamong < MSwithin

swb sbb u*bb Average

[mg/kg] [mg/kg] [%] [mg/kg] [%] [mg/kg] [%] As 28.9 1.462 5.06 n.c. n.c. 0.361 1.25 Br 862.3 3.097 0.36 1.731 0.20 0.764 0.09 Cd 140.3 1.967 1.40 0.608 0.43 0.485 0.35 Cl 832.1 2.429 0.29 0.419 0.05 0.599 0.07 Cr 123.3 0.491 0.40 n.c. n.c. 0.121 0.10 Hg 20.7 0.483 2.33 n.c. n.c. 0.119 0.58 Pb 104.6 3.709 3.55 n.c. n.c. 0.915 0.87 S 1111.9 4.254 0.38 2.011 0.18 1.050 0.09

Sb 94.9 2.150 2.27 0.872 0.92 0.530 0.56 Sn 101.8 2.793 2.75 n.c. n.c. 0.689 0.68

As can be seen in Table 5 and, the estimates for sbb or ubb* are above the between-drum

variation, confirming expectations that the between-drum variation is already included in the variation between units. The between-drum variation therefore does not have to be added to the between-bottle variation.

5.2 MINIMUM SAMPLE INTAKE The minimum sample intake defines the minimum amount of sample that is representative for the whole unit. Samples above the minimum sample intake therefore guarantee the certified value, which is not true for subsamples smaller than the minimum sample intake: intrinsic microhomogeneity may result in deviations from the certified value for such very small samples. Minimum sample intake was estimated using two approaches, namely conducting measurements with solid-sampling atomic absorption spectrometry (SS-AAS) and its assessment from the characterisation study.

Cd, Pb and Cr were measured by SS-AAS. In this method, minute sample amounts (0.43 to 4.3 mg) are analysed by direct atomisation. The assumption is that at these small sample intakes, analytical variation becomes negligible compared to variation due to microheterogeneity. The observed standard deviation can therefore be used to estimate a minimum sample amount necessary for a given measurement repeatability as described by Pauwels et al [5]. Fifty measurements were performed for each element and the minimum sample intakes necessary for a repeatability of 5 % are given in Table 7. It should be emphasised that these are conservative estimates, as the variation has not been corrected for the intrinsic analytical variability.

For all other elements, the minimum sample intakes were estimated from the characterisation studies: a sample intake is automatically sufficient if a laboratory achieved satisfactory repeatability with a given sample intake. The lowest sample intake that resulted in satisfactory repeatability was therefore used as minimum sample intake.

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Table 7: Minimum sample intakes. Sample intakes for Cd, Cr and Pb from SS-AAS for a repeatability of 5 %, for all other elements from the characterisation study. Two values are

given for elements for which different minimum sample intakes have been used.

ERM-EC680k[mg]

ERM-EC681k[mg]

As 100 Br 150 Cd 28 2 Cl 150 Cr 13 22 Hg 70 20 Pb 77 75 S 150

Sb 100 Sn 150

As shown above, minimum subsamples for all elements were 150 mg or below. Data for Cd, Cr, Hg and Pb suggest that the material can be used for microanalytical techniques for some elements. While this may also be true for the other elements, no positive proof for this is available. Sample intakes of 150 mg, approximately 7 granules, are therefore representative for both materials and all analytes. This sample intake is suitable for all digestion based methods.

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6 STABILITY Possibilities to reduce the time needed for the initial stability study were sought in order to decrease time until release,

Where possible, the same pigments were used for the preparation of the new material as for the old material, the only difference being that BaCrO4 was replaced by Cr2O3, which is also very stable against radiation and heat. Two new stable pigments have been used, namely SnO2 and Sb2O3.

All materials, ERM-EC680/ERM-EC681 and ERM-EC680k/ERM-681k consist of polyethylene. High-density polyethylene is used in the first case whereas low density polyethylene is used for the new batch. However, both materials show similar resistance to oxidative degradation.

As the pigments as well as the matrix are very similar, stability of the new batch can be inferred from stability of the previous batch.

Stability could therefore be inferred from two sources, namely stability of the EC680 and EC681 and stability tests on EC680k and EC681k. Extreme conditions were chosen for testing the current materials in order to have good confidence on their stability.

6.1 STABILITY OF THE PREVIOUS MATERIALS In November 2005, measurements were performed on EC680 and EC681 in the frame of IRMM's stability monitoring program. k0NAA was chosen as analytical method for this test as it can determine multiple elements simultaneously with high accuracy. Twelve subsamples of about 350 mg were taken from one bottle of each material. Irradiations lasted 9 hours for the determination of long-lived isotopes (As, Br, Cd, Cr and Hg) and 900 seconds for the determination of Cl. The results are compared to the certified values in Table 8.

Additional confirmation of stability comes from the results of the characterisation study of the current material: participants received one unit each of EC680 and EC681 as quality control sample. As these samples are used for quality control purpose, stability is a prerequisite and the results cannot be used for a rigorous stability test. However, as the laboratories used validated methods, results still give additional indication of stability.

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Table 8: Comparison of the certified values of EC680 and EC681 with the results of the stability test 2005 and the results obtained during the characterisation study for the new

batches. Error ranges are expanded uncertainties (k=2) for the certified values 1999, single standard deviations of the results for the stability test 2005 and single standard deviation of

the laboratory means accepted for the characterisation for the characterisation 2006. Element Certified value 1999

[mg/kg] Stability test 2005

[mg/kg] Characterisation 2006

[mg/kg] As 30.9 ± 0.7 31.0 ± 0.4 31.0 ± 1.0 Br 808 ± 19 796 ± 5.5 772 ± 38 Cd 140.8 ± 2.5 139 ± 3.8 138.0 ± 5.5 Cl 810 ± 16 802 ± 12 767 ± 81 Cr 114.6 ± 2.6 112.0 ± 0.6 111.0 ± 1.8 Hg 25.6 ± 1.0 24.8 ± 0.4 25.11 ± 1.1 Pb 107.6 ± 2.8 105.3 ± 3.2 E

RM

-EC

680

S 670 ± 70 not tested 622 ± 60 As 3.93 ± 0.15 3.71 ± 0.04 3.79 ± 0.25 Br 98 ± 5 94.6 ± 0.76 92.8 ± 5.4 Cd 21.7 ± 0.7 21.4 ± 0.3 21.1 ± 1.3 Cl 92.9 ± 2.8 87.0 ± 1.3 96.5 ± 10.3 Cr 17.7 ± 0.6 17.1 ± 0.2 17.3 ± 0.7 Hg 4.50 ± 0.15 4.40 ± 0.09 4.46 ± 0.18 Pb 13.8 ±0.7 12.1 ± 3.6 E

RM

-EC

681

S 78 ± 17 not tested 71.1 ± 5.91 As can be seen in Table 8, all results from 2005 with the exception of As and Cl in ERM-EC681 agree with the certified values. Furthermore, all averages obtained during characterisation study 2006 agreed with the certified values, confirming stability.

6.2 TESTS ON THE CURRENT MATERIALS Stability of the new materials was tested under stress conditions to confirm the assumption of equal behaviour of the old and the new batches in a short time. The main potential degradation factors were thought to be temperature-dependent, thus testing at elevated temperature was performed. Also the influence of UV radiation was investigated as polyethylene is known to be sensitive to UV-irradiation.

Samples were stored for 0, 2 and 4 months at +60 °C and 4 months at +18 °C in an isochronous study [6]. Samples were shifted to -20 °C after the respective times at +60 °C and 18 °C. In this way, the degradation status of the materials is maintained. At the end of the study, all materials can be analysed in one run under repeatability conditions, thus minimising analytical variation. After 4 months, samples were analysed by WDXRF (4 bottles per time point; three measurements per bottle).

In addition, samples were put on flat Petri dishes and irradiated for 544 hours by a low-pressure Hg UV-lamp (254 nm; 30 W; max 15 cm distance to the lamp) in a laminar flow hood to avoid contamination. The samples were spread in a single layer of granules and were mixed approximately every 24 hours. After irradiation, samples were analysed in triplicate together with the samples from the isochronous study. On visual inspection, no significant change in colour was visible as shown in Figure 1.

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Figure 1: Comparison of ERM-EC680k and ERM-EC681k following 0 and 544 hours of UV

irradiation.

Data obtained by WDXRF were screened for outlying values. Some outlying individual values were found (Grubbs-test at 95 % and 99 % confidence level). These were retained as no technical reason for exclusion was found. Moreover, tentative removal of the outliers did not significantly influence the outcome of the subsequent analysis, therefore outliers were retained. Subsequently the regression lines for samples stored at 60 °C were calculated and tested for significance. If found not significant, the uncertainty of stability during dispatch was calculated for 1 week (usts) as uncertainty of the slope of a regression line with a slope of 0 multiplied with the time (1 week) using the equation below [7].

( )t

xx

susts ⋅−

=∑ 2

Equation 1

with usts being the uncertainty of short-term stability, s the standard deviation of results, x and x the time points and average time of the study, respectively and t the duration for which the uncertainty is evaluated (1 week). In addition, the results for the irradiated sample and the samples stored at +18 °C were compared to the result obtained on the samples stored at +4 °C throughout using a t-test. The results of these evaluations are shown in Table 9 and Table 10, graphs of the study are given in Annex B.

Table 9: Results of stability test EC680k. Test temperature+ 60 °C; reference temperature 4 °C.

60 °C Difference with t = 0 (4 °C) significant?

Average ± s [mg/kg]

Slope ± s [mg/kg/month]

Slope significant

usts for t = 1 week [%]

18 °C Irradiated

As 4.5 ± 0.6 -0.07 ± 0.06 no 0.34 no no Br 107.8 ± 3.6 -0.12 ± 0.36 no 0.08 no no Cd 19.0 ± 1.8 -0.14 ± 0.18 no 0.23 no no Cl 105.7 ± 9.0 0.35 ± 0.88 no 0.21 no no

Cr 24.5 ± 0.4 0.02 ± 0.03 no 0.04 yes (95 %), no (99%) no

Hg 4.0 ± 0.4 0.04 ± 0.12 no 0.27 no no Pb 14.2 ± 0.5 -0.01 ± 0.05 no 0.08 no no S 86.3 ± 6.3 -0.27 ± 0.62 no 0.18 no no

Sb 2.2 ± 0.7 0.06 ± 0.06 no 0.72 no no Sn 10.5 ± 0.6 0.07 ± 0.05 no 0.13 no no

16

Table 10: Results of stability test EC681k. Test temperature +60 °C; reference temperature +4 °C

60 °C Difference with t = 0 (4 °C) significant?

Average ± s [µg/kg]

Slope ± s [mg/kg/month]

Slope significant

usts for t = 1 week [%]

18 °C Irradiated

As 28.3 ± 1.7 -0.30 ± 0.18 no 0.16 no no Br 861.5 ± 2.2 0.27 ± 0.23 no 0.01 no no Cd 140.8 ± 2.1 -0.13 ± 0.21 no 0.04 no no

Cl 826.7 ± 2.7 -0.56 ± 0.26 yes (95 %), no (99 % ) 0.01 yes (95 %),

no (99 %) yes (99 %)

Cr 123.5 ± 0.6 0.03 ± 0.06 no 0.01 no no

Hg 20.6 ± 0.5 -0.04 +- 0.05 no 0.06 no yes (95 %), no (99 %)

Pb 104.4 ± 4.0 0.08 ± 0.41 no 0.10 no no

S 1101.7 ± 3.2 -0.75 ± 0.31 yes (95% ), no (99 % ) 0.01 no no

Sb 96.0 ± 2.9 -0.25 ± 0.30 no 0.08 no no Sn 103.3 ± 3.0 -0.23 ± 0.31 no 0.08 yes (99 %) yes (99 %)

None of the slopes of the regression lines was significantly different from zero on a 95 % confidence level for ERM-EC 680k. For ERM-EC681k, two slopes were found significant at a 95 %, but not at a 99 % confidence level. The significance of the slope for Cl depends on retaining an individual value that is actually flagged as outlier on a 99 % confidence level – removal makes the slope not significant, which casts some doubts on the validity of the significance of this slope. Because in total 20 studies were evaluated, one significant slope on a 95 % confidence level can be expected on statistical grounds. It was therefore concluded that the two significant slopes were most likely statistical artefacts. In any case, uncertainty of stability for these two analytes is also higher (see section 6.3), so that even if the slope was indeed real, shelf lives of more than 40 months are obtained for these two analytes. The observed slopes therefore do not indicate significant degradation.

Mass fractions of samples stored at +18 °C and of irradiated samples were not significantly (99 % confidence) different from samples stored at +4 °C in the case of ERM-EC680k. The apparent change for Cr at 18 °C is contradicted by the stability at 60 °C and was therefore regarded as statistical artefact. Some significant differences exist for ERM-EC681k, especially for irradiated samples. This indicates some changes during irradiation, which are presumably hidden by the higher relative standard deviation of the measurements for ERM-EC680k. The indication of changes during irradiation is also confirmed by the appearance of the platelets prepared for XRF: boundaries between grains are clearly visible for irradiated samples, possibly caused by surface oxidation.

The tests of ERM-EC680k and ERM-EC681k at +60 °C therefore confirm the assumption that the stability of the new batches is equivalent to the stability of the old batches.

6.3 UNCERTAINTY OF STABILITY Tests of the current material gave no indication of degradation. Uncertainty of stability (ults) was evaluated from the previous batches as follows:

22 biasutt

u confstudy

shelflts += Equation 2

with tshelf the chosen shelf life, tstudy the duration of the stability study, uconf the uncertainty of the confirmation of stability and bias the observed bias in the confirmation of result. This approach of combining bias has been shown not to underestimate uncertainties [8] while

17

retaining symmetric uncertainties. Bias is only included if the bias is indeed significant, i.e. if 2*uconf < bias.

tshelf is the arbitrarily chosen shelf life for which stability can be guaranteed and is closely related to the further stability monitoring: stability must be confirmed before tshelf ends. An initial shelf life of 2 years was chosen for EC680k and EC681k.

The factor tshelf/tstudy derived from the fact that the square root of equation 2 gives the potential degradation of the complete duration of the study. Assuming as first approximation linear degradation as proposed in [7], potential degradation for e.g. half of the time is half as severe.

uconf , the confirmation of stability comprises uncertainty of the certified values and the measurement uncertainty and was estimated as

2

2

⎟⎟⎠

⎞⎜⎜⎝

⎛+=

meas

measCRMconf n

suu Equation 3

with uCRM the standard uncertainty of the certified values (U/2), nmeas and smeas the number of results and their standard deviation of the stability tests.

The uncertainty components and the uncertainty of stability are listed in Table 11.

Table 11: Estimation of ults for ERM-EC680k and ERM-EC681k. tshelf = 2 years; tstudy = 6 years; ults in % is based on the certified value; * significant bias; # bias included in ults.

ults Element uCRM [mg/kg]

smeas/√n [mg/kg]

uconf [mg/kg]

Bias [mg/kg] [mg/kg] [%]

As 0.35 0.14 0.38 0.10 0.13 0.41 Br 9.5 2.2 9.8 -12.0 3.3 0.40 Cd 1.25 1.6 1.99 -1.80 0.66 0.47 Cl 8.0 4.8 9.3 -8.0 3.1 0.38 Cr 1.3 0.2 1.3 -2.6 0.4 0.38

ER

M-E

C68

0k

Hg 0.50 0.16 0.53 -0.80 0.18 0.68 As 0.075 0.016 0.077 -0.220* 0.078 1.98# Br 2.5 0.3 2.5 -3.4 0.8 0.86 Cd 0.35 0.12 0.37 -0.30 0.12 0.57 Cl 1.4 0.5 1.5 -5.9* 2.0 2.18# Cr 0.30 0.09 0.31 -0.60 0.10 0.59

ER

M-E

C68

1k

Hg 0.075 0.037 0.084 -0.100 0.028 0.62

No completely independent data for Pb and S are available. However, the pigments containing Pb and S are chemically very stable and no degradation is expected. In addition, agreement of the results obtained during the characterisation study for the previous batches of the material also indicates stability. As conservative estimates, ults for Pb and S were therefore set equal to the largest relative uncertainty for each material. The same reasoning was used for Sb and Sn. These uncertainties are given in Table 12.

18

Table 12: ults for Pb, S, Sb and Sn in ERM-EC680k and ERM-EC681k. Uncertainties of stability were set equal to the highest uncertainty obtained for any of the other elements in

the respective material (see Table 11). Material Element ults [%]

Pb 0.68 S 0.68

Sb 0.68

ERM-EC680k

Sn 0.68 Pb 2.18 S 2.18

Sb 2.18

ERM-EC681k

Sn 2.18

19

7 CHARACTERISATION The participants received two bottles of each material and were requested to provide 3 independent results from each bottle. Measurements had to be spread over two days.

Characterisation of the material was based on intercomparison between expert laboratories for randomisation of individual laboratory bias.

Methods used included methods without sample preparation (XRF, NAA) as well as digestion methods (acid, oxygen) with different quantification steps (ICP methods, IC with conductivity detection, AAS, XRF). Quantification was based on completely different principles: neutron capture, atomic emission by thermal excitation, atomic emission after ionisation by X-rays, mass spectrometry after different ionisation techniques, atomic absorption as well as chromatographic separation. It is unlikely that all these results are biased in the same way.

Tables and graphs showing the submitted values are given in Annex D.

As a quality control measure, the participants also received a bottle of the previous batches ERM-EC680 and ERM-EC681. One digestion (if applicable) had to be performed for each of these samples and the digest had to be analysed in triplicate. The results for this sample are not reported here but have been used to support the evaluation of results to identify and substantiate outliers.

7.1 TECHNICAL EVALUATION The methods used in the characterisation study are described in Annex C. Individual results of the participants, grouped per element and material are displayed in tabular and graphical form in Annex D.

All laboratories had received samples of the previous materials (EC680 and EC681) as quality control samples. It was checked whether the data set result on the original material agreed with the certified values within the stated uncertainties. In addition, a meeting was held in which the results of the participants were discussed.

This meeting identified several inexplicable deviations for the two WDXRF datasets. In some cases, such unexplainable deviations had been observed by one laboratory also in other intercomparisons. These deviations were not of a systematic nature, i.e. in some cases the result of one dataset was above, in other cases below the other results. While these deviations were usually not large in absolute terms and well within what can be expected from the method, they were significant in comparison with the agreement among the other datasets. It was therefore concluded that WDXRF, while in general a valid method, did not show the accuracy required for the certification of the two reference materials. The results from WDXRF therefore confirm the applicability of the materials for WDXRF, but were not used for the calculation of the certified values. Therefore, "all results" should read as "all results with the exception of WDXRF" in the subsequent text.

The detailed outcome of the technical discussion is given below.

7.1.1 Arsenic All results agree within their stated uncertainties and the datasets for the previous materials agree with the certified values. Therefore, all datasets were accepted for characterisation.

Results from WDXRF agree with the other values, thus confirming both applicability of the method as well as the assigned values within the accuracy of the method.

20

7.1.2 Bromine Results from titration, IC, ICP-AES using two different digestion techniques, k0NAA, INAA and IPAA agree with each other within the stated uncertainties. Result for the previous materials agree with the certified values. There is therefore no reason to expect any bias.

However, the Br-concentration of EC680k is close to the limit of quantification for the titration method, resulting in a large uncertainty. While this dataset confirms the values of the other methods, it was excluded from the calculation of the certified value due to its high uncertainty.

The result for WDXRF is a little above the other values, indicating the general applicability of the method as well as confirming the assigned value within the accuracy of the method.

7.1.3 Cadmium For EC680k, 15 datasets agree within their stated uncertainties. Three datasets seem to be on the low side, but fall within a normal distribution. The results were therefore retained.

For EC681k, results of 14 datasets agree within their stated uncertainty and most results on the previous material agree with the certified values. The result of one dataset, obtained by ETAAS, is significantly above the certified value. The laboratory reported that the standard deviation of this dataset was significantly above what would be normally expected from the method. As the value for this dataset was above the certified value in the old material by about the same amount and as the precision was also significantly worse than that of the other laboratories, the value was excluded from the calculation of the certified value.

Laboratory 16 observed significant differences between the Cd mass fractions of the two bottles. This observation was not confirmed by any of the other laboratories, not even by the laboratories that had received bottle numbers close to those analysed by laboratory 16. This observation is therefore most likely an analytical artefact.


7.1.4 Chlorine The 6 (EC680k) and 7 (EC681k) datasets, respectively, agree within their stated uncertainties and the results for the previous material agree with the certified value. The laboratory concerned reported that the method for dataset 21 (HPA-ICP-AES) was close to the limit of quantification for EC680, resulting in a large uncertainty. While this dataset confirms the values of the other methods, it was excluded from the calculation of the certified value due to the high uncertainty.


7.1.5 Chromium A clear pattern is visible for Cr with instrumental methods giving significantly higher results than methods based on acid digestion. This is due to the presence of Cr2O3, which is very difficult to dissolve in acids. While one laboratory reported complete dissolution of pure Cr2O3 in a mixture of HClO4/H2O2, the presence of the polymer, maybe by consumption of the acid, apparently makes complete digestion with acids impossible.

Laboratory 18 achieved complete digestion, but only after filtration of the undissolved residue, ashing of the filter and fusion melting of the ash.

Laboratory 22 used very harsh digestion conditions and reported increasing Cr-results with decreasing sample intake. At a sample intake of 30 mg a result close to the ones from instrumental methods was obtained for EC680k. However, the higher amount of Cr2O3 to be

21

digested resulted in less complete digestion in the higher level material EC681k. A uniform sample intake of 200 mg was used for the ICP-MS set of results (code 22), which explains the lower values for the same digestion method. All other datasets obtained by acid digestion achieved varying digestion efficiencies, depending on the sample intake, digestion medium and digestion conditions.

It was therefore concluded that the value of 4 datasets obtained by 3 instrumental methods (INAA, IPAA and twice k0NAA) together with the value obtained by ID-TIMS after fusion melting was the best estimate of the true value. These values agree with each other and also agree with the nominal content. A certified value can be assigned as results from one primary method (ID-TIMS) and a candidate primary method (k0NAA) are confirmed by two other independent methods.

Both datasets obtained by WDXRF are about 25 % above the results from the other instrumental methods as well as above the nominal values, indicating some unresolved measurement bias. No explanation for these high results could be given by the participants.

7.1.6 Mercury The results agree within their stated uncertainties and the datasets for the previous materials agree with the certified values. Therefore, all datasets were accepted for characterisation.

The dataset obtained by WDXRF is below those obtained by the other methods for EC680k, but is in agreement with some of the other datasets for EC681k. This confirms the general applicability of the method and the assessment that the accuracy is lower than for the other methods.

7.1.7 Lead Results from ETAAS, ICP-MS, ICP-AES, ID-TIMS and IPAA agree within their stated uncertainties and the datasets for the previous materials agree with the certified values. However, IPAA is not very sensitive for Pb. The concentrations are close to the limits of quantification, resulting in large uncertainties. While this dataset confirms the values of the other methods, it was excluded from the calculation of the certified value due to the high uncertainty.

The dataset obtained by WDXRF is in agreement with the results obtained by other methods for EC680k while being 10 % above the other results for EC681k. This is in agreement with some of the other datasets, thus confirming both applicability of the method as well as the assigned values within the accuracy of the method.

7.1.8 Sulfur Results from ICP-AES, IC and ID-TIMS agree within their stated uncertainties and the laboratories' results for the previous materials agree with the certified values. Therefore, all datasets were accepted for characterisation.

The method using combustion-IR resulted in extensive soot formation. Therefore, no complete dataset could be delivered and the dataset was therefore not used for certification, but it confirms the certified value.

One result from WDXRF agrees with the values whereas one WDXRF-dataset gives values significantly above the other laboratories and the nominal value.

7.1.9 Antimony Most results agree with one another at reasonably low uncertainties. The only exception is the result of Laboratory 23 for EC681k, which is significantly below the other values. However, no explanation could be given for this deviation. The result was therefore retained.

22

Results from WDXRF are 22 % (EC680k) and 12 % (EC681k) below the other datasets, respectively, but in agreement with other datasets confirming both applicability of the method as well as the assigned values within the accuracy of the method.

7.1.10 Tin The two datasets from k0NAA agree with the datasets obtained by WDXRF while results for digestion based methods are below these. The reason is, as for Cr, that the pigment used (SnO2) is hardly digestible by acid mixtures. As for Cr, laboratory 21 achieved complete digestion with small sample intakes for EC680k, due to the smaller amount of SnO2 present, while only incomplete digestion was achieved for EC681k. The higher sample intake used for dataset 23 explains the lower values obtained in this dataset although the same digestion method had been used.

The low number of methods ruled out certification of the Sn content, but indicative values can be assigned. As indicative values require less accuracy, results obtained by WDXRF can be included in the value assignment. Indicative values for Sn are therefore based on results by WDXRF, k0NAA and, in the case of EC680k, ICP-AES dataset 22.

7.1.11 Zinc Zn was not intended for certification. However, three datasets for Zn analysed by instrumental methods were submitted. These results, obtained by k0NAA and IPAA agree with each other. No certified values can be assigned as neither homogeneity data nor stability data are available. In addition, the number of results and method variability is rather low for assigning certified values. Indicative values are therefore assigned based on the available results.

7.2 STATISTICAL EVALUATION The datasets accepted on technical grounds were tested for outlying means using the Grubbs and Nalimov procedures, for outlying standard deviations using the Cochran test, (both at a 99 % confidence level) as well as for normality of dataset means using the normal probability plot. Standard deviation within (swithin) and between (sbetween) laboratories were calculated using one-way ANOVA. The results of these evaluations are shown in Table 13 and Table 14.

Table 13: Statistical evaluation of the technically accepted datasets for ERM-EC680k; p: number of accepted sets of results; s: standard deviation of dataset means; averages and

standard deviations in mg/kg.

Outliers Statistical parameters Element p Means Variances

Normally distributed Average s sbetween swithin

As 10 no no yes 4.133 0.391 0.358 0.286 Br 7 no yes yes 96.36 3.92 3.17 5.65 Cd 15 no yes yes 19.57 1.70 1.69 0.80 Cl 5 no yes approx. 102.21 1.90 n.c. 5.24 Cr 5 no no yes 20.19 0.85 0.84 0.62 Hg 9 no no no 4.643 0.186 0.162 0.196 Pb 12 no no yes 13.56 0.46 0.45 0.49 S 6 yes yes no 75.90 4.12 3.93 3.02

Sb 11 no yes yes 10.08 0.77 0.74 0.50 Sn 5 no yes no 15.33 2.77 2.73 1.14 Zn 3 too few data 136.7 2.5 2.3 2.6

23

Table 14: Statistical evaluation of the technically accepted datasets for ERM-EC681k; p: number of accepted sets of results; s: standard deviation of dataset means; averages and

standard deviations in mg/kg. Outliers Statistical parameters Element p

Means Variances Normally

distributed Average s sbetween swithin As 12 no yes yes 29.08 1.87 1.72 1.37 Br 8 no no yes 773.6 37.9 36.9 21.0 Cd 14 no no approx. 136.74 6.0 5.9 2.9 Cl 6 no yes yes 795.0 38.8 37.3 26.2 Cr 5 no no yes 100.1 3.0 3.1 1.4 Hg 9 no yes yes 23.73 1.02 0.93 0.77 Pb 11 no yes no 98.01 3.82 3.53 2.62 S 7 no yes yes 630.2 36.1 35.0 21.8

Sb 11 no y no 99.39 4.79 4.60 3.04 Sn 4 no no approx. 86.36 3.30 2.66 4.79 Zn 3 too few data 1252 11 9 14

The statistical evaluation confirmed the assumption of normal distribution of averages for most elements and hardly any outlying averages were found.

ERM-EC680k While the distribution of the means for Hg in EC680k seems to violate the assumption of normal distribution, the individual values are clearly normally distributed. Calculation of an overall mean is therefore justifiable. The result of dataset 21 is an outlier for S in EC680k, which results in an overall deviation of means from a normal distribution. However, as the result agrees within the uncertainty with the other values and the uncertainty is about the same as for other datasets, the value was retained. The results for Sn are similar, with the results from dataset 13 deviating from the normal distribution. In addition, several datasets showed outlying variances. These results were retained as it was concluded that variation in repeatability was not extraordinary and did not reflect lack of technical proficiency.

ERM-EC681k For Pb, one result each on the high and the low end violate the assumption of normal distribution, but do not skew the distribution too much to forbid the use of an average. In the case of Sb, one result on the low end deviates from the assumption of normal distribution, but was nevertheless retained as the result agrees within the uncertainty. Retaining the values was also supported by skewness and kurtosis tests which indicated normal distributions.

After the technical evaluation it was decided that the unweighted mean of laboratory means would, despite some potential deviation from the normal distribution and heterogeneity of variances, give the best estimation of the true element content in the materials.

24

8 ASSIGNED VALUES AND THEIR UNCERTAINTIES The unweighted means of the means of the accepted datasets as shown in Table 13 and Table 14 were used as assigned values for all elements.

The certified uncertainty consists of uncertainties related to characterisation (uchar), between-bottle heterogeneity (ubb), degradation during long-term storage (ults) and transport to the customer (usts)[9].

• uchar was estimated as the standard error of the mean of laboratory means, i.e. s/√p with s and p taken from Table 13 and Table 14.

• ubb was estimated as standard deviation between-units (sbb) or the maximum heterogeneity potentially hidden by method repeatability (u*

bb) as defined in Table 5 and Table 6. The higher of these two values was taken as a conservative estimate of potential heterogeneity. The largest uncertainty contribution of all elements was taken as conservative estimate for Zn.

• ults was estimated from stability tests on the previous batch and were taken from Table 11 and Table 12. The largest uncertainty contribution of all elements was taken as conservative estimate for Zn.

• usts was regarded negligible (i.e. assumed zero), as the stability tests did not show any degradation at 60 °C and only minor changes upon irradiation with UV. The potential degradation during transport is therefore negligible.

These uncertainties were regarded as uncorrelated and combined quadratically to estimate the uncertainty of the certified value (uCRM) as shown below.

2222stsltsbbcharCRM uuuuu +++=

The various uncertainty contributions and the combined uncertainty are shown in Table 15 and Table 16.

Table 15: Uncertainty budget for ERM-EC680k uchar

[%] ubb [%]

ults [%]

usts [%]

uCRM [%]

As 2.99 4.08 0.41 5.08 Br 1.54 1.08 0.40 1.92 Cd 2.24 2.62 0.47 3.48 Cl 0.83 1.12 0.38 1.44 Cr 1.88 0.35 0.38 1.95 Hg 1.34 1.56 0.68 2.16 Pb 0.97 0.97 0.68 1.53 S 2.21 0.52 0.68 2.37

Sb 2.30 7.08 0.68 7.48 Sn 8.08 3.67 0.68 8.90 Zn 1.07 7.08 0.68

negligible

7.19

25

Table 16: Uncertainty budget for ERM-EC681k uchar

[%] ubb [%]

ults [%]

usts [%]

uCRM [%]

As 1.85 1.25 1.98 2.99 Br 1.73 0.20 0.86 1.94 Cd 1.17 0.43 0.57 1.37 Cl 1.99 0.07 2.18 2.95 Cr 1.35 0.10 0.59 1.48 Hg 1.43 0.58 0.62 1.66 Pb 1.18 0.87 2.18 2.62 S 2.16 0.18 2.18 3.08

Sb 1.45 0.92 2.18 2.78 Sn 1.91 0.68 2.18 2.98 Zn 0.49 1.25 2.18

negligible

2.56

Expanded uncertainties are calculated from the combined uncertainty by multiplication with a coverage factor k. This coverage factor was taken as 2 for all elements except Cr, where uchar has a low number of degrees of freedom and is the main contribution to the uncertainty. The coverage factor for Cr was taken as double-sided t-value for a confidence interval of 95 % for the degrees of freedom from the characterisation study. This gave a coverage factor for Cr of 2.78 (4 degrees of freedom).

Relative expanded uncertainties were multiplied with the mean of accepted dataset means to obtain absolute uncertainties. Based on these calculations and rounding uncertainties always up, the following values were assigned.

8.1 CERTIFIED VALUES

Table 17: Certified values for ERM-EC680k Mass fraction

[mg/kg] Expanded uncertainty

[mg/kg] Coverage factor

As 4.1 0.5 2 Br 96 4 2 Cd 19.6 1.4 2 Cl 102.2 3.0 2 Cr 20.2 1.1 2.78 Hg 4.64 0.20 2 Pb 13.6 0.5 2 S 76 4 2

Sb 10.1 1.6 2

26

Table 18: Certified values for ERM-EC681k Mass fraction Expanded uncertainty Unit Coverage factor

As 29.1 1.8 mg/kg 2 Br 0.77 0.04 g/kg 2 Cd 137 4 mg/kg 2 Cl 0.80 0.05 g/kg 2 Cr 100 5 mg/kg 2.78 Hg 23.7 0.8 mg/kg 2 Pb 98 6 mg/kg 2 S 0.63 0.04 g/kg 2

Sb 99 6 mg/kg 2

8.2 INDICATIVE VALUES Table 19: Indicative values for ERM-EC680k

Mass fraction [mg/kg]

Expanded uncertainty [mg/kg]

Coverage factor

Sn 15.3 2.8 2

Zn 137 20 2

Table 20: Indicative values for ERM-EC681k Mass fraction Expanded uncertainty Unit Coverage factor

Sn 86 6 mg/kg 2 Zn 1.25 0.07 g/kg 2

8.3 ADDITIONAL MATERIAL INFORMATION Table 21 :Additional material information for acid digestible Cr. The amount of acid digestible Cr depends on the sample intake as well as on digestion conditions (acid mix; temperature,

pressure) which can be found in Annex C. Mass fraction

[mg/kg] EC680k 3-16 EC681k 20-60

27

9 METROLOGICAL TRACEABILITY AND COMMUTABILITY

9.1 METROLOGICAL TRACEABILITY The participating laboratories used a number of different methods for the sample preparation. Methods of final determination were based on different method principles, thus eliminating any possibility of method dependent results.

Different calibrants have been used which have been cross-checked against other calibrants and/or certified reference materials thus ensuring traceability of the final quantification result.

Absence of method bias was confirmed by the inclusion of samples of the previous batch as quality control samples, which ensures traceability of the final results over the complete analytical process.

The results are therefore traceable to the SI.

9.2 COMMUTABILITY Commutable CRMs must exhibit the same analytical behaviour for given methods as a normal laboratory sample. The laboratories participating in the characterisation study have been selected such as to provide a large variety of analytical methods, regarding digestion, calibration and detection. The good agreement between the results obtained shows the commutability of the material.

28

10 INSTRUCTIONS FOR USE

10.1 STORAGE CONDITIONS The material shall be stored below 18 °C in the dark.

10.2 SAFETY AND PROTECTION OF THE ENVIRONMENT The usual laboratory safety measures apply.

10.3 USE OF THE CERTIFIED VALUES The main purpose of the materials is to assess method performance, i.e. for checking accuracy of analytical results. As any reference material, it can also be used for control charts or validation studies.

Comparing an analytical result with the certified value

A result is unbiased if the combined uncertainty of measurement and certified value covers the difference between the certified value and the measurement result. (see also ERM Application Note 1; www.erm-crm.org [10]).

Use in quality control charts

The materials can be used for quality control charts. Different CRM-units will give the same result as heterogeneity was included in the uncertainties of the certified values.

Use as a calibrant

It is not recommended to use these matrix materials as calibrants. If used nevertheless, the uncertainty of the certified value shall be taken into account in the final estimation of measurement uncertainty.

11 ACKNOWLEDGEMENTS The authors would like to thank W. Broothaerts and H. Emteborg (IRMM, BE) for the reviewing of the certification report, as well as the experts of the Certification Advisory Panel ‘Elements and inorganic ions’, O. F. X. Donard (CNRS/Université de Pau et des pays de l’Adour, FR), L. Jorhem (Livsmedelsverket, SE) and H. Muntau (Ranco, IT) for their constructive comments.

12 ANNEXES Annex A: Results of the homogeneity studies

Annex B: Results of the stability studies

Annex C: Summary of methods used

Annex D: Results of characterisation measurements

29

13 REFERENCES

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2 A. Lamberty, W. Van Borm, Ph. Quevauviller (2001) The certification of mass fraction of As, Br, Cd, Cl, Cr, Hg, Pb and S in two polyethylene CRMs ERM-EC680 and -EC681, EUR 19450EN, ISBN 92-894-0874-X, Luxembourg, 2001

3 International Organization for Standardization (ISO), ISO Guide to the Expression of Uncertainty in Measurements, ISO, Geneva, Switzerland, 1995

4 T.P.J. Linsinger, J. Pauwels J, A.M.H. van der Veen, H. Schimmel, A. Lamberty (2001) Homogeneity and stability of reference materials, Accred Qual Assur 6: 20-25

5 J. Pauwels, C. Vandecasteele (1993): Determination of the minimum sample mass of a solid CRM to be used in chemical analysis, Fres. J. Anal. Chem 345:121-123

6 A.Lamberty, H.Schimmel, J. Pauwels (1998) The study of the stability of reference materials by isochronous measurements, Fres J Anal Chem 360: 359-361

7 T.P.J. Linsinger, J. Pauwels, A. Lamberty, H. Schimmel, A.M.H. van der Veen, L. Siekmann (2001) Estimating the Uncertainty of Stability for Matrix CRMs, Fres. J. Anal. Chem 370: 183-188

8 S.D. Phillips, K.R. Eberhardt (1997) Guidelines for expression of uncertainty of measurement results containing uncorrected bias, J Res NIST 102: 577-585

9 J. Pauwels, A. van der Veen, A. Lamberty, H. Schimmel (2000) Evaluation of uncertainty of reference materials, Accred. Qual. Assur. 5: 95-90

10 T. Linsinger, (2005), ERM application Note 1, www.erm-crm.org

ANNEX A: Results of the homogeneity studies

30

ERM-EC680k, As Mass fractions in mg/kg

Replicate 1 Replicate 2 Replicate 3 Bottle number Sequence

number Result Sequence


number Result

4 10 4.9 52 3.3 61 4.2 184 53 5.5 33 3.8 28 3.7 259 89 3.7 27 4.9 80 3.8 316 83 4.4 85 4.0 13 4.4 395 51 3.3 12 4.6 17 3.9 572 76 3.7 81 3.6 63 3.3 591 16 3.9 77 4.4 43 4.0 708 87 3.6 41 3.4 20 5.9 839 84 4.8 15 4.4 71 4.0 936 86 5.3 49 4.7 69 4.3 1003 5 4.3 30 3.8 56 3.8 1074 45 3.9 4 4.0 14 4.8 1222* 68 6.1 36 4.8 62 5.4 1282 47 3.6 60 4.8 40 4.4 1402 55 3.7 6 4.5 54 4.8 1520 64 4.1 3 3.3 73 3.5 1582 59 4.2 25 4.3 44 5.2 1753 22 5.1 2 4.6 65 4.2 1857 58 3.7 78 3.5 79 3.4 1997 39 3.7 90 4.3 42 3.4 2072 18 4.5 19 3.7 67 5.0 2164 11 5.1 66 3.6 37 4.1 2267 74 4.0 7 4.3 1 4.4 2399 23 4.3 50 4.1 75 4.3 2484 8 5.3 32 3.9 26 4.9 2527 29 3.6 31 4.0 57 4.1 2664 9 4.6 35 4.8 46 3.3 2777 24 5.3 70 4.9 38 4.2 2885 34 5.2 82 3.3 21 4.7 2809 72 4.2 48 3.5 88 4.5 * Outlying average on a 95 % confidence level


31

ERM-EC680k, Br Mass fractions in mg/kg




number Result

4 10 101.6 52 109.4 61 109.8 184 53 109.1 33 102.4 28 101.7 259 89 102.7 27 109.5 80 110.0 316 83 103.4 85 103.1 13 112.9 395 51 103.7 12 109.6 17 112.7 572 76 109.8 81 108.0 63 102.2 591 16 103.1 77 110.8 43 101.8 708 87 108.6 41 104.6 20 108.6 839 84 113.9 15 109.7 71 104.9 936 86 111.1 49 105.9 69 103.5 1003 5 101.2 30 112.2 56 110.7 1074 45 103.7 4 103.7 14 114.9 1222* 68 116.9 36 106.3 62 115.9 1282 47 114.9 60 103.3 40 113.3 1402 55 103.4 6 104.2 54 113.3 1520 64 110.8 3 103.1 73 110.6 1582 59 104.0 25 112.5 44 110.4 1753 22 105.1 2 113.4 65 104.6 1857 58 112.3 78 103.6 79 109.7 1997 39 112.5 90 104.1 42 103.3 2072 18 106.4 19 106.9 67 115.1 2164 11 106.6 66 113.3 37 104.3 2267 74 105.5 7 115.4 1 104.3 2399 23 105.6 50 112.8 75 107.3 2484 8 114.5 32 108.3 26 106.7 2527 29 105.7 31 105.8 57 111.5 2664 9 105.4 35 114.7 46 107.1 2777 24 112.4 70 111.6 38 106.8 2885 34 112.5 82 107 21 104.5 2809 72 111.3 48 104 88 106.1 * Outlying average on a 95 % confidence level


32

ERM-EC680k, Cd Mass fractions in mg/kg




number Result

4 10 17.7 52 21.4 61 18.3 184 53 18.3 33 21.2 28 18.4 259 89 15.8 27 20.9 80 22.8 316 83 19.4 85 17.1 13 17.6 395 51 16.1 12 18.9 17 21.6 572 76 19.6 81 19.5 63 15.8 591 16 19.2 77 21.8 43 17.9 708 87 22.5 41 15.9 20 17.9 839 84 17.1 15 20.2 71 17.7 936 86 21.5 49 19.9 69 18.6 1003 5 17.0 30 18.8 56 17.4 1074 45 17.5 4 16.5 14 20.1 1222 68 22.8 36 17.8 62 21.4 1282 47 17.9 60 19.7 40 16.6 1402 55 17.4 6 16.2 54 20.5 1520 64 20.7 3 21.3 73 22.3 1582 59 18.5 25 20.5 44 19.4 1753 22 17.1 2 19.4 65 17.3 1857 58 21.9 78 20.3 79 19.5 1997 39 19.5 90 14.3 42 15.7 2072 18 19.3 19 18.3 67 20.2 2164 11 18.6 66 20.9 37 18.5 2267 74 17.6 7 20.8 1 19.1 2399 23 16.8 50 24.3 75 18.9 2484 8 21.0 32 18.3 26 19.8 2527 29 21.9 31 17.8 57 17.7 2664 9 19.3 35 19.4 46 16.8 2777 24 16.5 70 18.7 38 21.1 2885 34 17.1 82 17.6 21 18.5 2809 72 18.7 48 18.0 88 16.6 * Outlier on a 95 % level; + Outlier on a 99 % level;


33

ERM-EC680k, Cl Mass fractions in mg/kg




number Result

4 10 100.1 52 96.4 61 100.3 184 53 100 33 96.2 28 96.3 259 89 92.6 27 100.5 80 98.5 316* 83 98.6 85 95.8 13 128.7*+ 395 51 100.2 12 100.2 17 103.2 572 76 97.3 81 100 63 98.8 591 16 96 77 98.9 43 97.1 708 87 93.8 41 95.4 20 99.5 839 84 100.4 15 99 71 96.8 936 86 100.5 49 102.4 69 98 1003 5 94.5 30 98.3 56 98.8 1074 45 96 4 99.8 14 98.3 1222 68 98.6 36 96.1 62 97.6 1282 47 98.7 60 96.4 40 106 1402 55 101 6 97.7 54 100.3 1520* 64 108.1 3 108.6 73 101.2 1582 59 112.1 25 101.2 44 100.7 1753 22 103.3 2 96.9 65 97.6 1857 58 104.3 78 99.4 79 104.3 1997 39 99.9 90 101.9 42 100.5 2072 18 107.3 19 97.6 67 98.5 2164 11 97 66 98 37 102 2267 74 98.7 7 99.2 1 101.4 2399 23 101.5 50 100.3 75 96.8 2484 8 98.1 32 96.3 26 100.6 2527 29 105.5 31 102.1 57 98.2 2664 9 98.3 35 111.2 46 104.1 2777 24 98 70 99.1 38 103.2 2885 34 104.6 82 101 21 104.6 2809 72 102.3 48 102.3 88 100.5 * Outlier on a 95 % level; + Outlier on a 99 % level;


34

ERM-EC680k, Cr Mass fractions in mg/kg




number Result

4 10 23.9 52 24 61 23.6 184 53 24.3 33 24.1 28 23.1 259 89 23.8 27 23.6 80 23.8 316 83 23.2 85 23.2 13 23.9 395 51 24.2 12 23.5 17 23.9 572 76 24.1 81 23.8 63 23.6 591 16 23.6 77 23.7 43 23.7 708 87 23.1 41 23.5 20 23.4 839 84 23.5 15 23.7 71 24.3 936 86 23.9 49 24 69 23.6 1003 5 23.9 30 23.9 56 24 1074 45 23.3 4 23.9 14 23.9 1222 68 23.8 36 24.3 62 24.2 1282 47 23.5 60 23.9 40 23.7 1402 55 23.9 6 24.1 54 23.6 1520 64 23.5 3 23.4 73 23.8 1582 59 23.4 25 23.5 44 23.7 1753 22 23.7 2 23.6 65 23.2 1857 58 24.2 78 23.4 79 24 1997 39 23.4 90 24.1 42 23.5 2072 18 24.2 19 23.4 67 23 2164 11 23.4 66 24 37 23.1 2267 74 24 7 24.2 1 23.6 2399 23 24.2 50 23.4 75 23.7 2484 8 24.3 32 23.9 26 24.1 2527 29 23.5 31 24.1 57 23.5 2664 9 23.7 35 23.5 46 23.2 2777 24 23.9 70 23.7 38 24.2 2885 34 24.4 82 24.2 21 23.9 2809 72 23.6 48 24.1 88 23.2


35

ERM-EC680k, Hg Mass fractions in mg/kg




number Result

4 11 4.437 57 4.44 66 4.46 184 58 4.515 36 4.544 30 4.377 259 85 4.538 29 4.036 87 5.135 316 90 4.591 6 4.702 14 4.381 395 55 4.27 13 5.028 18 4.833 572 82 4.475 88 4.707 68 4.857 591 17 4.601 83 4.809 47 4.492 708 56 4.341 44 4.66 22 4.903 839 20 4.378 16 4.517 77 4.268 936 31 4.501 53 4.513 75 4.854 1003 5 4.671 33 4.478 61 4.385 1074 49 5.126 4 4.576 15 4.511 1222 74 4.139 39 4.646 67 4.479 1282 51 4.374 65 4.647 43 4.675 1402 60 4.564 7 5.128 59 4.348 1520 69 4.182 3 4.739 79 4.347 1582 64 4.751 27 4.961 48 4.358 1753 24 4.838 2 4.685 71 4.525 1857 63 4.615 84 4.405 86 4.34 1997 42 5.229 45 4.515 46 4.421 2072 19 4.662 21 4.574 73 4.575 2164 12 72 4.956 40 4.701 2267 80 4.394 8 4.496 1 5.074 2399 25 4.41 54 4.324 81 4.886 2484 9 4.933 35 4.18 28 4.603 2527 32 4.382 34 4.763 62 4.6 2664 10 4.916 38 4.967 50 4.328 2777 26 4.483 76 5.165 41 4.349 2885 37 5.104 89 4.609 23 4.355 2809 78 4.375 52 4.816 70 4.532


36

ERM-EC680k, Pb Mass fractions in mg/kg




number Result

4 10 14.5 52 14.3 61 15.6 184 53 14.0 33 14.7 28 14.5 259 89 15.0 27 14.7 80 13.8 316 83 14.2 85 15.6 13 14.1 395 51 14.0 12 14.5 17 14.9 572 76 13.5 81 14.9 63 14.5 591 16 15.0 77 14.1 43 14.7 708 87 14.4 41 15.2 20 15.4 839 84 14.5 15 15.4 71 14.3 936 86 14.0 49 14.0 69 13.8 1003 5 16.5* 30 13.9 56 13.9 1074 45 14.3 4 15.3 14 14.2 1222 68 14.7 36 15.7 62 14.9 1282 47 14.6 60 14.9 40 14.7 1402 55 14.7 6 14.4 54* 12.6 1520 64 15.1 3 15.2 73 15.4 1582 59 14.9 25 14.4 44 15.1 1753 22 15.1 2 14.5 65 14.9 1857 58 14.1 78 14.9 79 14.5 1997 39 15.0 90 15.4 42 15.1 2072 18 14.2 19 14.9 67 14.5 2164 11 14.3 66 13.9 37 14.7 2267 74 14.7 7 14.8 1 15.1 2399 23 14.3 50 15.1 75 14.4 2484 8 13.8 32 14.8 26 14.5 2527 29 14.2 31 13.8 57 14.7 2664 9 14.9 35 15.1 46 14.5 2777 24 13.8 70 14.5 38 15.0 2885 34 14.8 82 15.3 21 15.1 2809 72 15.2 48 13.9 88 14.2 * Outlier on a 95 % level


37

ERM-EC680K, S Mass fractions in mg/kg




number Result

4 10 116.8 52 117.2 61 118.3 184 53 119.1 33 113.6 28 114 259 89 118.5 27 118.1 80 115.8 316 83 112.6 85 118.3 13 117.7 395 51 116.8 12 119.1 17 120.0 572 76 115.9 81 115.6 63 113.1 591 16 114.5 77 115.1 43 113.5 708 87 118.3 41 116.5 20 117.6 839 84 118.9 15 114.3 71 113.8 936 86 120.7 49 117.4 69 112.7 1003 5 116.4 30 121.2 56 115.8 1074 45 113.3 4 116.5 14 114.3 1222 68 114.2 36 115.2 62 113 1282 47 117.5 60 113.5 40 119.2 1402 55 115.7 6 117.0 54 119.0 1520 64 119.8 3 119.4 73 114.4 1582 59 117.5 25 115.7 44 115.5 1753 22 117.2 2 116.8 65 115.2 1857 58 118.0 78 112.4 79 116.0 1997 39 115.6 90 126.2*+ 42 118.1 2072 18 117.6 19 115.6 67 114.9 2164 11 116.1 66 115.2 37 114.4 2267 74 112.6 7 118.2 1 119.0 2399 23 118.6 50 114.1 75 113.4 2484 8 117.9 32 114.4 26 114.3 2527 29 117.6 31 115.3 57 117.1 2664 9 116.1 35 117.3 46 115.9 2777 24 114.9 70 113.4 38 114.9 2885 34 117.2 82 113 21 115.5 2809 72 113.6 48 115.3 88 122.3 *: Outlier on a 95 % confidence level; + Outlier on a 99 % level;


38

ERM-EC6380k, Sb Mass fractions in mg/kg




number Result

4 10 1.7 52 1.4 61 2.4 184 53 2.2 33 1.7 28 1.5 259 89 2.3 27 1.4 80 2.7 316 83 2.9 85 1.9 13 3.4 395 51 2.2 12 3.7 17 1.5 572 76 3.1 81 2.9 63 2.3 591 16 4.7* 77 2.5 43 2.9 708 87 1.5 41 2.5 20 1.7 839 84 1.5 15 2.8 71 3.0 936 86 2.4 49 3.1 69 2.1 1003 5 3.1 30 3.3 56 1.9 1074 45 2.1 4 2.8 14 3.7 1222 68 2.7 36 1.9 62 2.8 1282 47 2.4 60 1.5 40 3.3 1402 55 3.6 6 2.7 54 1.2 1520 64 1.8 3 1.9 73 2.3 1582 59 2.4 25 2.5 44 1.8 1753 22 2.0 2 2.5 65 2.0 1857 58 2.2 78 1.1 79 2.5 1997 39 2.8 90 3.5 42 2.1 2072 18 1.9 19 2.5 67 3.1 2164 11 2.9 66 2.9 37 1.4 2267 74 2.5 7 2.3 1 3.7 2399 23 2.2 50 2.3 75 2.3 2484 8 2.9 32 2.6 26 2.5 2527 29 2.9 31 1.9 57 2.0 2664 9 2.3 35 2.5 46 3.6 2777 24 3.7 70 2.8 38 2.6 2885 34 2.9 82 2.7 21 2.3 2809 72 2.4 48 4.4 88 1.9 *: Outlier on a 95 % confidence level;


39

ERM-EC680k, Sn Mass fractions in mg/kg




number Result

4 10 10.1 52 9.4 61 10.5 184 53 9.2 33 9.3 28 10 259 89 10.8 27 10.4 80 10.8 316 83 11.2 85 10.3 13 10.9 395 51 10.2 12 10.1 17 10.3 572 76 10.7 81 10.9 63 9.9 591 16 10.2 77 10 43 10 708 87 10.5 41 10.4 20 10.7 839 84 9.8 15 10.4 71 9.9 936 86 11.2 49 10.2 69 11.2 1003 5 11.4 30 10 56 11 1074 45 10.4 4 9 14 10.9 1222 68 10.7 36 11.2 62 11.3 1282 47 10 60 10.1 40 9.3 1402 55 10.9 6 10.3 54 10.8 1520 64 10.6 3 9.9 73 10.5 1582 59 11.7 25 11.5 44 10.7 1753 22 10 2 9.8 65 9.5 1857 58 10.1 78 10.8 79 10.2 1997 39 9.2 90 10.7 42 10.3 2072 18 11.1 19 10.9 67 11.4 2164 11 10.9 66 10.1 37 9.1 2267 74 10.1 7 11.4 1 10.8 2399 23 9.9 50 11.4 75 11.3 2484 8 11.8 32 11.7 26 10.4 2527 29 9.9 31 9.7 57 9.9 2664 9 10.5 35 11.7 46 10 2777 24 9.8 70 10.9 38 12.2 2885 34 11.7 82 11.7 21 10.8 2809 72 10.2 48 10.7 88 10.9


40

ERM-EC681k, As Mass fractions in mg/kg




number Result

81 42 29.5 68 30.3 4 28.6 164 62 26.7 87 26.2 9 28.9 296 18 30.7 5 28.6 19 28.0 331 15 28.4 73 29.4 43 31.3 489 3 27.6 66 29.3 34 29.1 563 31 27.0 44 29.2 29 30.3 677 85 29.4 35 29.3 25 27.4 712 2 30.8 24 27.4 45 33.3 862 30 27.4 63 31.1 21 27.7 946 59 27.5 78 28.7 57 27.6 1014 61 29.6 28 28.9 72 29.4 1052 7 29.0 23 29.6 65 26.8 1189 89 30.2 71 27.8 79 29.8 1228 69 27.1 10 30.4 77 29.9 1334 40 28.1 80 28.6 50 29.8 1449 39 31.6 83 28.6 6 26.8 1523 52 31.9 16 30.3 46 27.7 1643 67 29.3 37 29.3 60 29.6 1703 8 27.1 54 30.2 13 25.9 1800 82 30 76 26.3 27 28.6 1935 75 29.2 33 28.4 47 29.6 2062 12 30.1 20 29.7 17 29.3 2136 26 27.5 36 27.4 74 30.5 2258 56 29.8 58 27.5 38 30.0 2359 22 28.1 1 27.9 49 30.1 2399 32 29.0 48 27.7 55 27.7 2526 70 28.2 41 27.6 88 28.7 2653 53 27.5 11 28.5 90 29.7 2664 14 28.1 81 29.5 51 30.5 2809 84 29.0 64 31.3 86 29.5


41

ERM-EC681k, Br Replicate 1 Replicate 2 Replicate 3 Bottle

number Sequence number

Result Sequence number

Result Sequence number

Result

81 42 862 68 865 4 859 164 62 855 87 858 9 867 296 18 866 5 866 19 865 331 15 864 73 866 43 866 489 3 864 66 862 34 865 563 31 862 44 862 29 854 677 85 860 35 864 25 865 712 2 862 24 863 45 861 862 30 865 63 864 21 861 946 59 865 78 862 57 859 1014 61 862 28 859 72 863 1052 7 867 23 865 65 864 1189 89 865 71 867 79 863 1228 69 866 10 865 77 866 1334 40 862 80 863 50 860 1449 39 861 83 865 6 866 1523 52 866 16 865 46 863 1643 67 863 37 864 60 867 1703 8 862 54 861 13 864 1800 82 860 76 866 27 859 1935 75 860 33 862 47 861 2062 12 859 20 862 17 861 2136+ 26 862 36*+ 841 74 856 2258 56 863 58 861 38 861 2359 22 863 1 867 49 860 2399 32 861 48 861 55 861 2526 70 865 41 860 88 862 2653 53 859 11 862 90 861 2664 14 864 81 860 51 863 2809 84 861 64 863 86 860

*: Outlier on a 95 % confidence level; + Outlier on a 99 % level


42

ERM-EC681k, Cd Mass fractions in mg/kg




number Result

81 42 140.0 68 143.0 4 144.9 164 62 139.7 87 140.4 9 143.6 296 18 142.2 5 141.2 19 139.9 331 15 139.6 73 138.0 43 140.7 489 3 141.3 66 144.3 34 142.5 563 31 142.6 44 143.9 29 140.0 677 85 136.4 35 138.3 25 145.1 712 2 138.0 24 140.5 45 142.2 862 30 140.6 63 141.9 21 141.6 946 59 139.4 78 137.9 57 142.2 1014 61 139.7 28 142.8 72 140.8 1052 7 141.3 23 141.8 65 140.8 1189 89 141.0 71 141.0 79 138.7 1228 69 137.2 10 139.4 77 138.6 1334 40 138.6 80 141.4 50 140.1 1449 39 140.3 83 141.9 6 140.2 1523 52 136.1 16 140.5 46 138.8 1643 67 142.3 37 140.1 60 139.3 1703 8 143.6 54 140.8 13 140.2 1800 82 137.6 76 138.6 27 139.5 1935 75 138.3 33 137.9 47 137.6 2062 12 137.6 20 138.3 17 142.6 2136+ 26 142.7 36 136.1 74 136.7 2258 56 141.3 58 139.6 38 138.1 2359 22 141.0 1 143.1 49 138.8 2399 32 143.3 48 140.9 55 137.8 2526 70 139.3 41 138.2 88 141.8 2653 53 138.1 11 138.9 90 138.4 2664 14 139.6 81 140.9 51 142.2 2809 84 139.1 64 143.1 86 141.3


43

M-EC681k, Cl Mass fractions in mg/kg




number Result

81 42 832 68 833 4 831 164 62 829 87 835 9 829 296 18 830 5 837 19 832 331 15 833 73 830 43 833 489 3 831 66 831 34 830 563 31 831 44 831 29 829 677 85 837 35 836 25 834 712 2 832 24 832 45 832 862 30 834 63 834 21 832 946 59 832 78 833 57 832 1014 61 831 28 834 72 836 1052 7 834 23 834 65 833 1189 89 834 71 834 79 830 1228 69 831 10 833 77 833 1334 40 833 80 834 50 833 1449 39 834 83 832 6 835 1523 52 830 16 832 46 837 1643 67 837 37 831 60 830 1703 8 830 54 830 13 830 1800 82 834 76 828 27 830 1935 75 834 33 834 47 830 2062 12 833 20 835 17 830 2136* 26 833 36 821*+ 74 829 2258 56 830 58 833 38 834 2359 22 828 1 835 49 830 2399 32 834 48 829 55 831 2526 70 834 41 829 88 832 2653 53 833 11 835 90 829 2664 14 832 81 831 51 831 2809 84 833 64 834 86 832 *: Outlier on a 95 % confidence level; + Outlier on a 99 % level


44

ERM-EC681k, Cr Mass fractions in mg/kg




number Result

81 42 123.3 68 123.5 4 122.7 164 62 122.3 87 123.7 9 123.0 296 18 123.8 5 122.1 19 123.3 331 15 123.5 73 123.3 43 123.2 489 3 122.8 66 123.1 34 123.7 563 31 123.0 44 123.5 29 123.1 677 85 123.3 35 123.2 25 123.7 712 2 123.3 24 123.8 45 123.6 862 30 123.6 63 123.1 21 123.1 946 59 122.9 78 124.1 57 123.2 1014 61 123.4 28 123.0 72 123.1 1052 7 122.9 23 122.7 65 123.3 1189 89 122.8 71 122.7 79 123.3 1228 69 122.4 10 123.8 77 123.7 1334 40 123.0 80 123.0 50 123.6 1449 39 123.4 83 123.0 6 122.4 1523 52 123.1 16 123.3 46 123.0 1643 67 123.6 37 122.9 60 123.2 1703 8 122.6 54 124.1 13 122.3 1800 82 123.1 76 123.4 27 123.0 1935 75 123.8 33 122.8 47 123.0 2062 12 122.9 20 123.2 17 123.8 2136+ 26 124.0 36 123.4 74 122.5 2258 56 122.8 58 123.8 38 124.2 2359 22 122.8 1 124.4 49 123.4 2399 32 123.8 48 123.5 55 124.1 2526 70 123.5 41 122.8 88 123.5 2653 53 123.6 11 123.8 90 123.5 2664 14 123.1 81 122.8 51 122.9 2809 84 123.5 64 123.2 86 123.5


45

ERM-EC681k, Hg Mass fractions in mg/kg




number Result

81 42 21.1 68 20.0 4 21.0 164 62 20.5 87 20.5 9 20.4 296 18 21.0 5 20.7 19 19.9 331 15 20.2 73 21.1 43 20.8 489 3 20.9 66 20.5 34 21.3 563 31 21.3 44 20.6 29 19.6 677 85 20.2 35 20.2 25 20.0 712 2 20.3 24 20.3 45 20.4 862 30 21.1 63 20.0 21 20.1 946 59 20.3 78 21.0 57 21.4 1014 61 21.3 28 20.9 72 21.0 1052 7 21.0 23 20.8 65 21.0 1189 89 20.5 71 21.3 79 20.6 1228 69 21.3 10 21.1 77 21.4 1334 40 20.7 80 20.6 50 20.1 1449 39 20.2 83 21.6 6 20.1 1523 52 21.1 16 20.7 46 20.5 1643 67 19.8 37 20.7 60 20.3 1703 8 20.3 54 21.0 13 20.8 1800 82 20.7 76 20.9 27 20.4 1935 75 21.0 33 20.1 47 21.7 2062 12 20.5 20 20.8 17 20.3 2136+ 26 21.7 36 20.7 74 20.5 2258 56 20.2 58 21.3 38 20.5 2359 22 20.3 1 20.7 49 20.4 2399 32 20.6 48 20.7 55 21.0 2526 70 20.3 41 20.4 88 21.6 2653 53 20.7 11 20.4 90 21.4 2664 14 20.8 81 21.2 51 20.1 2809 84 21.0 64 20.1 86 21.1


46

ERM-EC681k, Pb Mass fractions in mg/kg




number Result

81 42 106 68 102 4 102 164 62 101 87 96 9 107 296 18 108 5 107 19 97 331 15 107 73 107 43 101 489 3 101 66 107 34 108 563 31 107 44 101 29 96 677 85 106 35 96 25 107 712 2 108 24 101 45 107 862 30 107 63 107 21 107 946 59 107 78 106 57 107 1014 61 102 28 106 72 107 1052 7 98 23 102 65 101 1189 89 107 71 107 79 107 1228 69 108 10 107 77 106 1334 40 107 80 101 50 106 1449 39 106 83 106 6 106 1523 52 107 16 102 46 106 1643 67 97 37 107 60 97 1703 8 106 54 107 13 106 1800 82 106 76 106 27 106 1935 75 108 33 107 47 106 2062 12 106 20 107 17 97 2136+ 26 101 36 106 74 96 2258 56 101 58 108 38 108 2359 22 108 1 108 49 106 2399 32 102 48 107 55 106 2526 70 108 41 108 88 97 2653 53 97 11 106 90 107 2664 14 107 81 100 51 107 2809 84 107 64 107 86 108


47

ERM-EC681k, S Mass fractions in mg/kg




number Result

81 42 1114 68 1111 4 1116 164 62 1112 87 1114 9 1118 296 18 1112 5 1112 19 1109 331 15 1120 73 1110 43 1113 489 3 1115 66 1109 34 1112 563 31 1116 44 1113 29 1113 677 85 1111 35 1111 25 1114 712 2 1113 24 1113 45 1115 862 30 1116 63 1110 21 1110 946 59 1112 78 1111 57 1108 1014 61 1105 28 1113 72 1100 1052 7 1121 23 1115 65 1113 1189 89 1116 71 1109 79 1107 1228 69 1110 10 1114 77 1112 1334 40 1111 80 1111 50 1115 1449 39 1109 83 1113 6 1118 1523 52 1110 16*+ 1130 46 1111 1643 67 1114 37 1110 60 1108 1703 8 1116 54 1107 13 1117 1800 82 1122 76 1114 27 1120 1935 75 1115 33 1116 47 1115 2062 12 1112 20 1109 17 1110 2136 26 1113 36* 1096 74 1105 2258 56 1112 58 1109 38 1111 2359 22 1106 1 1114 49 1108 2399 32 1105 48 1107 55 1108 2526 70 1111 41 1104 88 1111 2653 53 1102 11 1111 90 1112 2664 14 1118 81 1116 51 1109 2809 84 1114 64 1111 86 1111 *: Outlier on a 95 % confidence level; + Outlier on a 99 % level


48

ERM-EC681k, Sb Mass fractions in mg/kg




number Result

81 42 94 68 95 4 98 164 62 96 87 98 9 93 296 18 96 5 97 19 95 331 15 95 73 94 43 91 489 3 96 66 93 34 98 563 31 96 44 94 29 91 677 85 96 35 96 25 96 712 2 93 24 96 45 94 862 30 95 63 95 21 95 946 59 94 78 97 57 91 1014 61 98 28 98 72 92 1052 7 97 23 95 65 96 1189 89 100 71 96 79 97 1228 69 93 10 93 77 95 1334 40 95 80 95 50 96 1449 39 95 83 97 6 95 1523 52 97 16 96 46 100 1643 67 98 37 96 60 98 1703 8 93 54 91 13 90 1800 82 96 76 95 27 93 1935 75 94 33 96 47 92 2062 12 96 20 97 17 94 2136+ 26 95 36 96 74 94 2258 56 96 58 90 38 100 2359 22 95 1 94 49 96 2399 32 92 48 92 55 91 2526 70 95 41 93 88 96 2653 53 93 11 92 90 94 2664 14 95 81 92 51 100 2809 84 89 64 95 86 96


49

ERM-EC681k, Sn Mass fractions in mg/kg




number Result

81 42 96 68 103 4 106 164 62 103 87 102 9 100 296 18 105 5 99 19 99 331 15 101 73 96 43 107 489 3 100 66 100 34 102 563 31 100 44 105 29 105 677 85 100 35 100 25 102 712 2 104 24 101 45 100 862 30 102 63 105 21 104 946 59 102 78 102 57 95 1014 61 106 28 101 72 100 1052 7 99 23 104 65 102 1189 89 103 71 104 79 100 1228 69 105 10 101 77 105 1334 40 100 80 98 50 103 1449 39 102 83 103 6 100 1523 52 100 16 103 46 102 1643 67 99 37 102 60 108 1703 8 101 54 102 13 105 1800 82 104 76 103 27 98 1935 75 100 33 100 47 98 2062 12 102 20 103 17 102 2136+ 26 105 36 100 74 105 2258 56 103 58 102 38 108 2359 22 103 1 103 49 100 2399 32 98 48 107 55 99 2526 70 102 41 100 88 99 2653 53 102 11 103 90 103 2664 14 100 81 99 51 96 2809 84 103 64 101 86 103

ANNEX B: Results of the stability studies

50

Error bars are single standard deviations

Stability EC680k

0

2

4

6

8

10

12

0 months60 °C

2 months60 °C

4 months60 °C

4 months18 °C

irradiated

mas

s fr

actio

n [m

g/kg

]

AsHgSbSn

Stability EC680k

10

12

14

16

18

20

22

24

26

0 months60 °C

2 months60 °C

4 months60 °C

4 months18 °C

irradiated

mas

s fr

actio

n [m

g/kg

]

CrPbCd

Stability EC680k

70

75

80

85

90

95

100

105

110

115

120

0 months60 °C

2 months60 °C

4 months60 °C

4 months18 °C

irradiated

mas

s fr

actio

n [m

g/kg

]

BrSCl

ANNEX B: Results of the stability studies

51

Error bars are single standard deviations. Error bars are too small to be seen for S, Cl and Br.

Stability EC681k

15

17

19

21

23

25

27

29

31

33

0 months60 °C

2 months60 °C

4 months60 °C

4 months18 °C

irradiated

mas

s fr

actio

n [m

g/kg

]

AsHg

Stability EC681k

80

90

100

110

120

130

140

150

0 months60 °C

2 months60 °C

4 months60 °C

4 months18 °C

irradiated

mas

s fr

actio

n [m

g/kg

]

SbCrPbCdSn

Stability EC681k

700

750

800

850

900

950

1000

1050

1100

1150

1200

0 months60 °C

2 months60 °C

4 months60 °C

4 months18 °C

irradiated

mas

s fr

actio

n [m

g/kg

]

SClBr

ANNEX C: Methods for the Characterisation Study

52

The following datasets come from the same laboratory: Dataset 1, 2, 24; dataset 4, 5, 22, 23, 25; dataset 6, 7, 8, 9, 10, 11, 12, 13, 21; dataset 15, 16; dataset 18, 19, 20

Data-set

Method Elements Sample mass [mg]

Sample preparation Calibration Instrumentation and measurement method

1 ETAAS (Cd, Pb),

CVAAS (Hg)

Cd, Pb, Hg

150 Closed microwave 200-220 °C 75 bar 65 min 5 mL HNO3 + 2 mL H2O2

Baker plasma standard; concentration traceable to SI via NIST 3108, 3133 and 3128 (Cd, Hg and Pb standard solution)

Cd, Pb: ETAAS Analyst AA800 (Perkin Elmer); lines 228.8 nm (Cd), 283.3 nm (Pb) Hg: CVAAS FIMS 400 (Perkin Elmer) 400; line 253.7 nm

2 ICP-MS

ICP-AES

As, Cd, Cr, Pb, Sb

S

150 Closed microwave 200-220 °C 75 bar 65 min 5 mL HNO3 + 2 mL H2O2

Baker plasma standard; concentration traceable to SI via NIST 3103a, 3108, 3112a, 3128, 3102a and 3128 (single element standard solutions)

ICP-MS ELAN DRC II; masses 75 (As), 111, 112, 114 (Cd), 52, 53 (Cr), 206, 207, 208 (Pb), 121, 123 (Sb) resolution 1 amu internal standard In

3 ICP-AES (Cd, Cr)

ICP-AES (Pb, Sb EC681k)

ICP-MS (As, Sn)

ICP-MS (Pb, Sb EC681k)

CVAAS (Hg)

As, Cd, Cr, Hg, Pb, Sb, Sn

530 Closed microwave 170 – 280 °C 80 bar 25 min 15 mL HNO3 + 1 mL HF

Single element standards CPI international;

concentration by CPI against NIST SRMs; no independent verification

ICP-AES Optima 3000 (Perkin Elmer; lines 214.440, 226.502 (Cd), 205.552, 267.696, 357.878 (Cr)

ICP MS Elan 6000 (Perkin Elmer); masses 75 (As), 206, 207 (Pb), 121, 123 (Sb), 118, 120 (Sn);resolution 0.8 amu; internal standard Rh

CVAAS Analyst 200/400 (Perkin Elmer); line 253.6 nm; D2 background correction


53

Data-set



4 WDXRF As, Br, Cd, Cl, Cr, Hg, Pb, S, Sb, Sn

3000 Milling under cooling with liquid nitrogen; milled sample filled directly into sample cups

Liquid standard solution

Mass absorption coefficient determined by measuring scattered x-ray radiation.

WDXRF SRS 200 (Siemens) Tube: Mo (Pb, As, Br, Cr) Cr (Sb, Sn, Cd, Cl, S) Atmosphere: air (Pb, As, Br, Cr) He (Sb, Sn, Cd, Cl, S) Voltage: 45-55 kV Current: 50-55 mA Collimator: 0.15 (Pb, As, Br, Cr) 0.4 (Sn, Cl, S, Cd, Sb) Detector: LiF100 (Pb, As, Br, Cr) Ge (Cl, S); Flow counter Lines: As Kα, Br Kα, Cd Kα, Cl Kα, Cr Kα, Pb Lβ, S Kα, Sb Lβ, Sn Lα counting time : 40 s

5 titr Br, Cl 80 Combustion at 1000 °C in a continous oxygen stream in a platinum boat; combustion gases are absorbed in an aqueous solution of sodium disulfite.

Organic substances used for titer determination

potentiometric titration with 0.001 N silver nitrate in a acetone/water solution

6 IC Br, Cl, S 2000 (680k),

500 (681k)

Combustion in an oxygen bomb (10 bar O2); Combustion gases trapped in ultra pure water

Pure standard solutions; concentrations to SI via NIST SRMs (NaBr, NaCl and Na2SO4 in water)

Ion chromatography Resin: strong basic low capacity anion exchanger Conductivity detection with a suppressor device

7 IR S 700 (680k)

300 (681k)

Sample was covered with about 1 g WO3; combustion in an oven at 1350 °C in a pure oxygen environment of 3 bar

ERM-EC680; ERM-EC681 (trace elements in plastics)

Traceability to SI ensured by using CRMs for calibration

Combustion-S determination apparatus Truspec S (Leco)

Method based on Leco-procedure and ISO 609: Solid mineral fuels – determination of carbon and hydrogen – high temperature digestion methodf


54

Data-set



8 CVAFS Hg 250 High pressure asher 240 °C 100 bar 90 min 4 mL HNO3 + 1 mL HCl

Hg standard solution

Concentration traceable to SI via NIST SRM 3133 (Hg standard)

CVAFS Line 253.7 nm Method according to EN1483:1997 (water determination- determination of Hg)

9 DMA Hg 70 (EC680k)

20 (EC681k)

Thermal decomposition in the presence of oxygen; 2 steps: 200 °C for 200 s (decomposition of the matrix) and 800 °C for 180 s vaporised Hg caught at a gold trap; Hg releasedby heating

T

23 reference materials with mercury levels ranging from 0.03 to 8.6 mg/kg Hg

Measuring range 0.05 to 600 ng Hg absolute; sample mass is adapted to this range

All results from the same calibration (instrument is only calibrated once per year)

Direct Mercury Analyser DMA-80 (Milestone) line: 253.65 nm

Method according to EPA 7473: Mercury in solids and solutions by thermal decomposition, amalgamation and atomic absorption spectrophotometry

10 ICP-AES Br, Cl, S 2100 (EC680k)

460 (EC681k)

Combustion in an oxygen bomb (10 bar O2); Combustion gases trapped in ultra pure water

Pure standard solutions; concentrations to SI via NIST SRMs (NaBr, NaCl and Na2SO4 in water)

ICP-AES Lines 154.0 nm (Br), 134.7 nm (Cl), 180.7 nm (S

Method according to EN ISO 11885:1997 (Water quality - Determination of 33 elements by inductively coupled plasma atomic emission spectroscopy)


55

Data-set



11 ICP-AES As, Cd, Cr, Pb, Sb, Sn

250 High pressure asher 240 °C 100 bar 90 min 4 mL HNO3 + 1 mL HCl

Pure standard solutions Merck and Spex;

Concentrations traceable to SI via NIST SRMs 3103a, 3108, 3112a, 3128, 3102a, 3161 (pure standard solutions of As, Cd, Cr, Pb, Sb, Sn)

ICP-AES Lines 188.979, 193.696 (confirmation) (As); 214, 228.802 (confirmation) (Cd), 205.552, 206.149 (confirmation) (Cr), 220.353, 216.999 (confirmation) (Pb), 206.833, 217.581 (confirmation) (Sb), 189.933, 283.999 (confirmation) (Sn) Internal standard Rh 233

Method according to EN ISO 11885:1997 (Water quality - Determination of 33 elements by inductively coupled plasma atomic emission spectroscopy)

12 ICP-SF-MS As, Cd, Cr, Pb, Sb, Sn

250 High pressure asher 240 °C 100 bar 90 min 4 mL HNO3 + 1 mL HCl

Pure standard solutions Merck and Spex;

Concentrations traceable to SI via NIST SRMs 3103a, 3108, 3112a, 3128, 3102a, 3161 (pure standard solutions of As, Cd, Cr, Pb, Sb, Sn)

HR-ICP-MS (Thermo Finnigan) masses 75 (As), 111, 112, 114 (Cd), 52, (Cr), 206+207+ 208 (Pb), 121 (Sb), 120 (Sn) Resolution 10000 (As), 4000 (others) amu Internal standard Rh

13 WDXRF As, Br, Cd, Cl, Cr, Hg, Pb, S, Sb, Sn

3000 Hot pressed pellets (230 °C, 100 kN, 3 min melt, 3 min cooldown)

ERM-EC680 and ERM-EC681

Sb, Sn: precalibrated lines with CH2 matrix

WDXRF SRS3000 (Bruker) Tube:Rh Atmosphere: vacuum Voltage: < 60 kV Current: < 100 mA Collimator: 0.15 Cu 0.2 mm filter for Cd Detector: NaI; flow counter Lines: As Kβ, Br Kα, Cd Kα, Cl Kα, Cr Kα, Hg Lα, Pb Lβ, S Kα, Sb Lβ, Sn Lα Counting time: 60 s (Br) 1200 s (all others)


56

Data-set



14 k0NAA As, Br, Cd, Cl, Cr, Hg, Sb, Sn

300 (As, Br, Cd, Cr, Hg, Sb)

600 (Cl)

No preparation IRMM-530 flux monitors (99.9 % Al, 0.1 % Au)

Validated using BCR 176 Incineration Ash (Sb), Tomato Paste CCQM sample (Sn)

Irradiation: 15 min (short lived); 40 min (long lived) with a flux of 3 *1011 neutrons/(cm2 s) Decay time 30-900 s (Cl), 2-5 days (As, Br), 4-5 days (Cd), 15-25 days (Cr, Hb, Sb) Measuring time 24 h Lines (keV): 559.1 (As), 554.3, 619.1, 776.5, 1044, 1317.5 (Br), 527.9, 336.2 (Cd), 1642.7, 2167.4 (Cl), 320.1 (Cr), 279.2 (Hg), 564.2, 1691 (Sb)

15 ICP-AES As, Cd, Cr, Pb, S, Sn

500 Closed microwave 240 °C 60 bar 300 min Two digestion runs: 5 mL HNO3 + 1 mL HF+ 1mL H2O2 add 5 mL H3BO3

Certified SPEX multielement standards

Traceability ensured by checking against certified single element standards

ICP-AES Spectro Ciros Vision (Spectro) lines 189.042 (As); 214.438 (Cd),267.716 (Cr), 184.95 (Hg), 220.353 (Pb), 180.731 (S), 206.833 (Sb), 189.991, (Sn)

16 ICP-SF-MS As, Cd, Hg, Pb, Sb, Sn

100 Closed microwave 240 °C 60 bar 300 min Two digestion runs: 5 mL HNO3 + 1 mL HF+ 1mL H2O2 add 5 mL H3BO3

Certified single standards from CPI As, Cd, Hg, Pb) or SPEX (Sb, Sn) checked against multi-element standard (As, Hg, Sb, Sn) or NIST SRM 3181 (Cd), 3128 (Pb)

ICP-MS Element 1 (Thermo Finnigan); Masses: 75 (As), 114 (Cd), 202 (Hg), 208 (Pb), 121 (Sb), 120 (Sn) Resolution: 7500 (As), 300 (Cd, Hg, Pb, Sb, Sn) Internal standards Ir, Rh


57

Data-set



17 k0NAA As, Cd, Cl, Cr, Hg, Sb, Sn

150 none IRMM-530 flux monitors (99.9 % Al, 0.1 % Au), Zn (99.99 %), Zr (99.8)

validated using NIST 2704 Buffalo River Sediment for Sn and Sb

irradiation: 5 min (short lived); 1000 min (long lived) with a flux of 1 *1012 neutrons/(cm2 s) decay time 7 min (Cl), 8 days (As, Br, Cd), 20 days (Cr, Hg, Sb, Sn) measuring time 6.5 min (Cl), 5 h (As, Br, Cd), 10 h (Cr, Hg, Sb, Sn) lines (keV): 559.1 (As), 776.5 (Br), 336.2 (Cd), 2167.4 (Cl), 320.1 (Cr), 279.2 (Hg), 602.7 (Sb), 391.7 (Sn113)


58

Data-set



18 ID-TIMS Cd, Pb

S

Cr

135 (EC680k),

490 (EC681k)

200

130-500

Closed microwave (Cd, Pb ) 220 °C 60 min 80 bar 6 ml HNO3 + 3 ml H2O2 followed by analyte/matrix separation (Pb: Pb selective extraction resin; Cd: anion chromatography)

HPA (S): 300 °C 4 h 120 bar 5 mL HNO3 + 1 mL H2O2

Two steps: after microwave digestion (as for Cd, Pb)) insoluble residue (Cr2O3) was separated by filtration, the filter was ashed in a platinium crucible and the residue was decomposed by melting with 0,3 - 0,5g of Na2CO3 and 0,02 -0,03g of KNO3; decomposed residue was dissolved in diluted nitric acid and added to the solution of the first step. Cr was separated as chromate from the matrix by anion exchange chromatography

AG1-X8

113Cd, 207Pb: concentration established by back-spiking;

Traceability via primary BAM Cd-1 and Pb-1

Spike via back-spiking; more details in W. Pritzkow, J. Vogl, R. Köppen, M. Ostermann; Determination of sulfur isotope abundance ratios for SI-traceable low sulfur concentration measurements in fossil fuels by ID-TIMS, Int. J. Mass, Spectrom. 242 (2005) 309-318.

53Cr: concentration by back-spiking

TIMS ("Sector 54"); Re-filament in multi-collector configuration

Masses: 112/113 (Cd), 208/207 (Pb), 52/53 (Cr)


59

Data-set



19 INAA As, Br, Cd, Cl, Cr, Hg, Sb

80-150 None. Plastic vials (Br, Cl) or quartz vials were used

Standard solutions prepared out of high purity materials, KCl and KBrO3 for Br and Cl, elemental As, Cd, Cr Hg and Sb for the others.

Irradiation: 10 min (Br, Cl) or 6 d (others) with a flux of 2.1 *1012 neutrons/(cm2 s) (Br, Cl) or 6.6 *1012 neutrons/(cm2 s) (others) Decay time 10-23 min (Cl), 6-23 h (Br), 5 days (As, Cd, Cr, Hg, Sb) Measuring time 20 min (Cl), 1.5-2 h (Br), 3.5 h (As, Cr, Sb), 5h (Cd, Hg) Lines (keV): 559 (As), 554 + 777 (Br), 336+528 (Cd), 1643+2168 (Cl), 320 (Cr), 279 (Hg), 564 (Sb)

20 IPAA As, Br, Cd, Cl, Cr, Pb, Sb

900 None Synthetic multielement calibration material (polymer matrix); Nickel foil flux monitors

Irradiation time: 60 min (EC681k), 90 min (EC680k) Decay time 1-3 d Measuring time 80 h Lines (keV): 559 (As), 520 (Br), 527 (Cd), 320 (Cr), 279 (Pb), 564 (Sb)

21 ICP-AES Br, Cl, S 250 High pressure asher (HPA)

2 step digestion acc. Naozuka et al., J. Anal. At. Spectrom., 2003, 18, 917.

240 °C 90 min 4 mL HNO3 + 5.5 mL H2O2 + 1 mL 1 M AgNO3

S was determined from the solution; precipitate was dissolved in NH3

Commercial Merck standards verified against NIST SRMs

ICP-AES

Lines: 154 nm (Br), 134.7 nm (Cl), 180.7 nm (S)

Quantification according to EN ISO 11885:1997 (Water quality - Determination of 33 elements by inductively coupled plasma atomic emission spectroscopy )


60

Data-set



22 ICP-AES As, Cd, Cr, Pb, Sb, Sn

60-120 (depending on amount of Sn)

MLS / Milestone ultraCLAVE

250 °C 45 min 135 bar 4 mL HNO3 + 0.2 mL HClO4

Certified standards from AkkuStandard Inc. verified against NIST SRM3103a (As), SRM3108 (Cd), SRM3112a (Cr), SRM3128 (Pb), 3102a (Sb), SRM3161 (Sn)

ICP-AES lines 396.152 (As); 214.438 (Cd), 205.560 (Cr), 220.353 (Pb), 217.582 (Sb), 189.9331, (Sn)

int. Standard Sc.

23 ICP-MS Cd, Pb, Sb, Sn

200 mg MLS / Milestone ultraCLAVE

250 °C 45 min 135 bar 4 mL HNO3 + 0.2 mL HClO4

Merck standards verified against NIST SRM3108 (Cd), SRM3112a (Cr), SRM3128 (Pb), 3102a (Sb), SRM3161 (Sn)

ICP-MS

Masses 111 (Cd), 52 (Cr), 206, 207, 208 (Pb), 121 (Sb), 120 (Sn) resolution 0.7 amu internal standard Ho 165 (Pb), Y 89 (others)

24 Cr Aqua regia leaching

25 HGAAS

CVAAS

ETAAS

As

Hg

Cd, Pb

35 (EC681k)

45 (EC680k)

Carius tube

260 °C 6 h 0.5 mL HNO3 + 0.1 mL HCl

Merck standards verified against NIST SRM3103a (As), SRM682 (Cd, Hg, Pb)

Zeeman-AAS

Wavelengths 193.7 nm (As), 228.8 nm (Cd), 253.7 nm (Hg), 283.3 nm (Pb)

ANNEX D: Results of the Characterisation Study

61

Arsenic

Shaded datasets are confirmatory results and were not used for the calculation of the certified value. Error bars in the graphs are expanded uncertainties as reported by the laboratories.

ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 25-ETAAS 3.305 17.2 0.284 14-k0NAA 3.958 4.5 0.150 17-k0NAA 4.120 7.3 0.120 19-INAA 4.232 3.2 0.461 20-IPAA 4.523 2.5 0.057 16-SF-ICP-MS 4.777 21 0.251 12-SF-ICP-MS 3.972 18 0.202 3-ICP-MS 4.175 11.9 0.322 10-ICP-AES 3.967 16 0.427 2-ICP-AES 4.300 12 0.261 4-WDXRF 4.233 9.5 0.207 13-WDXRF 4.133 21 0.816

ERM-EC681k

Dataset

Mean [mg/kg]

U (k=2) [%]

s [mg/kg]

25-ETAAS 25.77 2.1 1.04 14-k0NAA 28.18 4.6 0.85 17-k0NAA 28.15 7.1 0.26 19-INAA 28.82 2.8 0.52 20-IPAA 30.32 3.3 1.57 12-SF-ICP-MS 27.71 6.0 1.01 16-SF-ICP-MS 31.38 3.2 1.09 3-ICP-MS 28.85 10.7 1.66 2-ICP-AES 29.02 12.0 0.93 11-ICP-AES 30.85 5.1 0.81 22-ICP-AES 27.50 22.9 3.17 15-ICP-AES 32.42 14.6 0.58 4-WDXRF 29.33 3.4 0.52 13-WDXRF 31.85 4.4 1.31

EC680k-As

0

1

2

3

4

5

6

7

25-E

TAA

S

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

16-S

F-IC

P-M

S

12-S

F-IC

P-M

S

3-IC

P-M

S

10-IC

P-A

ES

2-IC

P-A

ES

4-W

DX

RF

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]

EC681k-As

0

5

10

15

20

25

30

35

40

25-E

TAA

S

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

12-S

F-IC

P-M

S

16-S

F-IC

P-M

S

3-IC

P-M

S

2-IC

P-A

ES

11-IC

P-A

ES

22-IC

P-A

ES

15-IC

P-A

ES

4-W

DX

RF

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]


62

Bromine


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 6-IC 90.33 11.0 3.72 14-k0NAA 96.69 2.8 0.67 17-k0NAA 100.13 5.4 0.69 19-INAA 101.58 2.7 3.81 20-IPAA 97.75 2.9 1.41 21-ICP-AES 93.25 25.0 10.23 10-ICP-AES 94.79 15.7 9.33 5-titr. 94.00 50.0 27.23 13-WDXRF 112.73 1.1 1.06

ERM-EC681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 5-titr 784.7 6.4 26.2 6-IC 763.0 10.0 23.4 14-k0NAA 779.3 4.6 8.6 17-k0NAA 803.6 5.5 5.7 19-INAA 815.0 2.6 25.4 20-IPAA 805.7 5.2 15.0 21-ICP-AES 710.8 15.0 25.2 10-ICP-AES 726.5 13.0 26.4 13-WDXRF 883.0 2.1 18.2

EC680k-Br

0

20

40

60

80

100

120

140

160

6-IC

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

21-IC

P-A

ES

10-IC

P-A

ES

5-tit

r.

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]

EC681k-Br

500550600650700

750800850900950

5-tit

r

6-IC

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

21-IC

P-A

ES

10-IC

P-A

ES

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]


63

Cadmium


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 1-ETAAS 19.73 8.0 0.280 25-ETAAS 22.92 20.0 2.291 14-k0NAA 19.47 5.6 0.168 17-k0NAA 20.57 8.7 0.103 19-INAA 20.32 3.8 0.694 20-IPAA 21.58 4.2 0.454 18-ID-TIMS 19.83 0.4 0.099 12-SF-ICP-MS 18.64 3.7 0.319 16-SF-ICP-MS 17.22 6.2 0.747 3-ICP-AES 21.43 8.6 0.752 23-ICP-MS 17.08 4.8 0.407 22-ICP-AES 19.47 2.6 0.266 2-ICP-AES 18.92 5.0 0.293 11-ICP-AES 19.52 4.1 0.516 15-ICP-AES 16.90 11.8 1.190 4-WDXRF 18.63 5.3 0.524 13-WDXRF 21.83 11.0 2.311

ERM-EC681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 1-ETAAS 138.8 8.0 4.1 14-k0NAA 137.7 5.1 3.5 17-k0NAA 140.5 8.5 2.5 19-INAA 142.0 2.9 2.3 20-IPAA 145.0 5.8 4.0 18-ID-TIMS 139.2 0.2 0.2 12-SF-ICP-MS 131.4 4.9 1.5 16-SF-ICP-MS 128.0 0.8 5.6 23-ICP-MS 132.4 3.6 2.4 3-ICP-AES 143.0 1.4 3.5 2-ICP-AES 138.0 5.0 1.4 11-ICP-AES 137.9 2.3 1.3 15-ICP-AES 123.3 1.6 2.8 22-ICP-AES 137.2 1.2 0.8 4-WDXRF 132.8 2.7 1.8 13-WDXRF 149.2 2.4 3.6

EC680k-Cd

1012141618202224262830

1-E

TAA

S

25-E

TAA

S

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

18-ID

-TIM

S

12-S

F-IC

P-M

S

16-S

F-IC

P-M

S

3-IC

P-A

ES

23-IC

P-M

S

22-IC

P-A

ES

2-IC

P-A

ES

11-IC

P-A

ES

15-IC

P-A

ES

4-W

DX

RF

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]

EC681k-Cd

100

110

120

130

140

150

160

1-E

TAA

S

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

18-ID

-TIM

S

12-S

F-IC

P-M

S

16-S

F-IC

P-M

S

23-IC

P-M

S

3-IC

P-A

ES

2-IC

P-A

ES

11-IC

P-A

ES

15-IC

P-A

ES

22-IC

P-A

ES

4-W

DX

RF

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]


64

Chlorine


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 6-IC 99.2 8.6 4.8 14-k0NAA 102.5 4.9 2.3 17-k0NAA 103.0 6.4 2.6 19-INAA 104.3 2.7 3.1 10-ICP-AES 102.0 13.4 9.6 21-ICP-AES 102.3 41.0 27.2 4-WDXRF 109.4 2.5 1.4 13-WDXRF 100.4 8.0 7.5 5-titr 125.7 23.9 16.0

ERM-EC681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 5-titr 833.5 3.6 16.1 6-IC 746.2 9.2 22.9 14-k0NAA 810.6 4.9 11.4 17-k0NAA 807.4 5.7 14.0 19-INAA 825.6 2.7 24.9 10-ICP-AES 746.6 14.3 49.0 4-WDXRF 853.5 2.3 10.2 13-WDXRF 833.8 0.8 6.1 21-ICP-AES 603.3 41.4 102.1

EC680k-Cl

40

60

80

100

120

140

160

180

6-IC

14-k

0NA

A

17-k

0NA

A

19-IN

AA

10-IC

P-A

ES

21-IC

P-A

ES

4-W

DX

RF

13-W

DX

RF

5-tit

r

mas

s fr

actio

n [m

g/kg

]

EC681k-Cl

300

400

500

600

700

800

900

1000

5-tit

r

6-IC

14-k

0NA

A

17-k

0NA

A

19-IN

AA

10-IC

P-A

ES

4-W

DX

RF

13-W

DX

RF

21-IC

P-A

ES

mas

s fr

actio

n [m

g/kg

]


65

Chromium


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg]14-k0NAA 19.55 4.7 0.169 17-k0NAA 19.18 4.7 0.542 18-ID-TIMS 21.32 2.3 1.042 19-INAA 20.27 3.1 0.595 20-IPAA 20.63 3.2 0.301 Results with incomplete digestion 2-ICP-AES 13.467 5.838 3-ICP-MS 4.633 2.140 11-ICP-AES 3.001 0.152 12-SF-ICP-MS 2.936 0.065 15-ICP-AES 9.932 2.226 18-ID-TIMS without fusion 4.027 0.254 22-ICP-AES 16.167 1.291 23-ICP-MS 3.482 0.367 24-aq.reg. 7.014 3.316

ERM-EC681k

Dataset Mean [ mg/kg]

U (k=2) [%]

s [mg/kg]

14-k0NAA 96.50 5.2 1.22 17-k0NAA 98.20 4.4 1.09 19-INAA 99.49 2.8 0.90 20-IPAA 101.99 5.8 1.56 18-ID-TIMS 104.11 0.9 1.03 Results with incomplete digestion 12-SF-ICP-MS 20.36 0.45 3-ICP-MS 36.75 17.32 23-ICP-MS 21.88 0.82 2-ICP-AES 58.80 28.00 11-ICP-AES 21.33 0.55 15-ICP-AES 31.35 4.27 22-ICP-AES 82.53 3.84 24-aq. reg 25.24 4.89 18-ID-TIMS without fusion 20.66 0.12

EC680k-Cr

16

17

18

19

20

21

22

23

14-k

0NA

A

17-k

0NA

A

18-ID

-TIM

S

19-IN

AA

20-IP

AA

mas

s fr

actio

n [m

g/kg

]

EC681k-Cr

80

85

90

95

100

105

110

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

18-ID

-TIM

S

mas

s fr

actio

n [m

g/kg

]


66

Mercury


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 1-CVAAS 4.900 10 0.110 3-CVAAS 4.558 4.7 0.173 25-CVAAS 4.825 8.6 0.210 14-k0NAA 4.537 4.6 0.103 17-k0NAA 4.460 5.6 0.190 19-INAA 4.667 3.3 0.301 16-SF-ICP-MS 4.460 7.4 0.275 8-AFS 4.899 8.3 0.202 9-DMA 4.480 4.2 0.135 13-WDXRF 3.267 12.86 0.393

ERM-EC681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 1-CVAAS 24.03 10.0 1.48 3-CVAAS 23.58 5.1 0.68 25-CVAAS 25.63 2.4 0.31 14-k0NAA 22.87 4.8 0.66 17-k0NAA 23.60 5.1 0.42 19-INAA 24.43 2.7 0.37 16-SF-ICP-MS 23.10 1.4 1.11 8-AFS 24.38 2.3 0.31 9-DMA 22.23 10.6 0.84 13-WDXRF 20.28 3.5 0.67

EC680k-Hg

2

2.5

3

3.5

4

4.5

5

5.5

6

1-C

VA

AS

3-C

VA

AS

25-C

VA

AS

14-k

0NA

A

17-k

0NA

A

19-IN

AA

16-S

F-IC

P-M

S

8-A

FS

9-D

MA

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]

EC681k-Hg

15

17

19

21

23

25

27

29

1-C

VA

AS

3-C

VA

AS

25-C

VA

AS

14-k

0NA

A

17-k

0NA

A

19-IN

AA

16-S

F-IC

P-M

S

8-A

FS

9-D

MA

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]


67

Lead


ERM-EC680k

Dataset Mean

[mg/kg]U (k=2)

[%] s

[mg/kg] 1-ETAAS 13.33 8.0 0.15 25-ETAAS 14.15 3.8 0.27 18-ID-TIMS 13.54 0.9 0.11 12-SF-ICP-MS 13.30 4.2 0.30 16-SF-ICP-MS 13.88 5.0 0.67 3-ICP-MS 14.36 10.0 0.81 23-ICP-MS 13.03 4.3 0.28 2-ICP-AES 13.38 10.0 0.13 11-ICP-AES 13.67 3.1 0.28 15-ICP-AES 12.75 13.1 0.67 22-ICP-AES 13.85 4.3 0.29 20-IPAA 16.13 30.0 2.38 13-WDXRF 13.33 8.0 0.15

ERM-EC681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 1-ETAAS 97.52 8.0 3.0525-ETAAS 105.92 12.6 6.6618-ID-TIMS 98.34 0.5 0.1812-SF-ICP-MS 97.19 4.4 1.6716-SF-ICP-MS 97.27 0.7 1.2523-ICP-MS 96.67 3.9 1.883-ICP-AES 98.73 1.8 2.532-ICP-AES 96.37 10.0 1.9111-ICP-AES 99.95 3.1 1.3315-ICP-AES 89.78 1.9 1.3722-ICP-AES 100.37 2.0 1.01 13-WDXRF 20-IPAA 109.55 1.4 1.45

EC680k-Pb

10

12

14

16

18

20

22

1-E

TAA

S

25-E

TAA

S

18-ID

-TIM

S

12-S

F-IC

P-M

S

16-S

F-IC

P-M

S

3-IC

P-M

S

23-IC

P-M

S

2-IC

P-A

ES

11-IC

P-A

ES

15-IC

P-A

ES

22-IC

P-A

ES

20-IP

AA

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]

EC681k-Pb

80

90

100

110

120

130

140

1-E

TAA

S

25-E

TAA

S

18-ID

-TIM

S

12-S

F-IC

P-M

S

16-S

F-IC

P-M

S

23-IC

P-M

S

3-IC

P-A

ES

2-IC

P-A

ES

11-IC

P-A

ES

15-IC

P-A

ES

22-IC

P-A

ES

13-W

DX

RF

20-IP

AA

mas

s fr

actio

n [m

g/kg

]


68

Sulfur


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 18-ID-TIMS 75.59 0.3 0.34 2-ICP-AES 72.68 20.0 1.02 10-ICP-AES 73.29 6.6 2.04 15-ICP-AES 83.98 13.2 1.12 21-ICP-AES 74.67 11.8 2.29 6-IC 75.17 21.0 6.56

4-WDXRF 74.33 4.0 1.51 13-WDXRF 101.05 6.9 6.64

7-IR 75.67 10.0 2.57

ERM-EC681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 18-ID-TIMS 669.3 0.4 1.4 2-ICP-AES 663.6 9.0 15.7 10-ICP-AES 575.6 22.2 9.9 15-ICP-AES 619.8 1.8 9.5 21-ICP-AES 663.7 5.7 16.1 6-IC 602.5 15.0 34.2 7-IR 616.7 6.5 38.2 4-WDXRF 663.6 0.9 15.7 13-WDXRF 997.9 0.8 8.1

EC681k-S

0

200

400

600

800

1000

1200

18-ID

-TIM

S

2-IC

P-A

ES

10-IC

P-A

ES

15-IC

P-A

ES

21-IC

P-A

ES

6-IC

7-IR

4-W

DX

RF

13-W

DX

RF

mas

s fr

actio

n [m

g/kg

]

EC680k-S

50

60

70

80

90

100

110

120

18-ID

-TIM

S

2-IC

P-A

ES

10-IC

P-A

ES

15-IC

P-A

ES

21-IC

P-A

ES

6-IC

4-W

DX

RF

13-W

DX

RF

7-IR

mas

s fr

actio

n [m

g/kg

]


69

Antimony


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 14-k0NAA 9.442 4.2 0.095 17-k0NAA 9.788 6.5 0.054 19-INAA 9.915 2.7 0.248 20-IPAA 11.000 7.0 0.385 12-SF-ICP-MS 9.932 8.3 0.287 16-SF-ICP-MS 11.417 6.1 0.371 3-ICP-MS 10.800 17.0 0.972 23-ICP-MS 8.633 9.8 0.423 2-ICP-AES 9.750 7.0 0.105 11-ICP-AES 9.973 4.4 0.313 22-ICP-AES 10.183 9.8 0.475 4-WDXRF 7.733 14.0 0.547

ERM-EC681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 14-k0NAA 95.59 4.3 1.26 17-k0NAA 98.98 6.5 1.15 19-INAA 99.73 2.7 0.91 20-IPAA 103.45 4.8 2.60 12-SF-ICP-MS 101.71 8.6 3.12 16-SF-ICP-MS 103.25 1.9 5.36 23-ICP-MS 87.40 10.5 4.58 3-ICP-AES 103.43 1.9 2.27 2-ICP-AES 101.17 7.0 1.46 11-ICP-AES 96.56 6.9 5.35 22-ICP-AES 101.98 1.9 0.95 4-WDXRF 87.28 1.7 0.76

EC681k-Sb

707580859095

100105110115

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

12-S

F-IC

P-M

S

16-S

F-IC

P-M

S

23-IC

P-M

S

3-IC

P-A

ES

2-IC

P-A

ES

11-IC

P-A

ES

22-IC

P-A

ES

4-W

DX

RF

mas

s fr

actio

n [m

g/kg

]

EC680k-Sb

6

7

8

9

10

11

12

13

14-k

0NA

A

17-k

0NA

A

19-IN

AA

20-IP

AA

12-S

F-IC

P-M

S

16-S

F-IC

P-M

S

3-IC

P-M

S

23-IC

P-M

S

2-IC

P-A

ES

11-IC

P-A

ES

22-IC

P-A

ES

4-W

DX

RF

mas

s fr

actio

n [m

g/kg

]


70

Tin


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 4-WDXRF 17.50 2.3 0.23 13-WDXRF 10.65 48.8 0.50 14-k0NAA 17.06 34.0 1.87 17-k0NAA 16.33 20.0 0.68 22-ICP-AES 15.10 20.0 1.49 Results with incomplete digestion 12-SF-ICP-MS 0.17 0.053 23-ICP-MS 1.21 0.361

ERM-681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 4-WDXRF 84.72 3.4 1.4513-WDXRF 83.55 44.8 0.7314-k0NAA 91.06 35.0 7.2517-k0NAA 86.22 13.2 6.04Results with incomplete digestion 12-SF-ICP-MS 0.47 0.08 16-SF-ICP-MS 3.64 0.48 23-ICP-MS 6.25 3.28 22-ICP-AES 53.45 7.26

EC681k-Sn

0

20

40

60

80

100

120

1404-

WD

XR

F

13-W

DX

RF

14-k

0NA

A

17-k

0NA

A

mas

s fr

actio

n [m

g/kg

]

EC680k-Sn

0

5

10

15

20

25

4-W

DX

RF

13-W

DX

RF

14-k

0NA

A

17-k

0NA

A

22-IC

P-

AE

S

mas

s fr

actio

n [m

g/kg

]


71

Zinc


ERM-EC680k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 14-k0NAA 137.6 4.7 1.617-k0NAA 133.8 4.7 2.220-IPAA 138.7 5.2 3.7

ERM-681k

Dataset Mean

[mg/kg] U (k=2)

[%] s

[mg/kg] 14-k0NAA 1254 4.6 2117-k0NAA 1260 4.7 1220-IPAA 1240 0.8 5

EC681k-Zn

1,1201,1401,1601,1801,2001,2201,2401,2601,2801,3001,3201,340

14-k

0NA

A

17-k

0NA

A

20-IP

AA

mas

s fr

actio

n [m

g/kg

]

EC680k-Zn

115

120

125

130

135

140

145

150

14-k

0NA

A

17-k

0NA

A

20-IP

AA

mas

s fr

actio

n [m

g/kg

]

European Commission EUR 22784 EN – DG Joint Research Centre, Institute for Reference Materials and Measurements – The certification of the mass fraction of As, Br, Cd, Cl, Cr, Hg, Pb, S and Sb and the assignment of indicative values for Sn and Zn in two polyethylene reference materials, ERM®-EC680k and ERM®-EC681k Authors: T. Linsinger, A. Liebich, E. Przyk, A. Lamberty Luxembourg: Office for Official Publications of the European Communities 2007 – 71 pp. – 21.0 x 29.7 cm EUR - Scientific and Technical Research series; ISSN 1018-5593 ISBN 978-92-79-06027-4 Abstract This report describes the preparation and certification of the polymer certified reference materials (CRM) ERM-EC680k and ERM-EC681k. They replace the exhausted predecessors, ERM-EC680 and ERM-EC681. The CRMs have been certified by the European Commission, Directorate General Joint Research Centre, Institute for Reference Materials and Measurements (IRMM), Geel, Belgium. The CRM was prepared from a low-density polyethylene (LDPE) granulate spiked with inorganic pigments (As2O3, Green 36, ZnS/CdS, Green 7, Cr2O3, PbCrO4/PbSO4, HgS, Sb2O3, SnO2). Certification of the CRM included testing of the homogeneity and stability of the material as well as the characterisation using an intercomparison approach. The new CRMs have been certified for their content of As, Br, Cd, Cl, Cr, Hg, Pb, S, Sb and indicative values have been established for Sn and Zn. Additional information about acid digestible Cr is given. These CRMs are intended for use in quality assurance of measurements of elements in polymers and related matrices. The following values were assigned: Certified and indicative values. Assigned uncertainties are expanded uncertainties estimated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) with a coverage factor k = 2.78 for Cr and k = 2 for all other elements, corresponding to a level of confidence of about 95 %.

ERM-EC680k ERM-EC681k As 4.1 ± 0.5 mg/kg 29.1 ± 1.8 mg/kg Br 96 ± 4 mg/kg 0.77 ± 0.04 g/kg Cd 19.6 ± 1.4 mg/kg 137 ± 4 mg/kg Cl 102.2 ± 3.0 mg/kg 0.80 ± 0.05 g/kg Cr 20.2 ± 1.1 mg/kg 100 ± 5 mg/kg Hg 4.64 ± 0.20 mg/kg 23.7 ± 0.8 mg/kg Pb 13.6 ± 0.5 mg/kg 98 ± 6 mg/kg S 76 ± 4 mg/kg 0.63 ± 0.04 g/kg Sb 10.1 ± 1.6 mg/kg 99 ± 6 mg/kg

Indicative values

ERM-EC680k ERM-EC681k Sn 15.3 ± 2.8 mg/kg 86 ± 6 mg/kg Zn 137 ± 20 mg/kg 1.25 ± 0.07 g/kg

The mission of the Joint Research Centre is to provide customer-driven scientific and technical support for the conception, development, implementation and monitoring of European Union policies. As a service of the European Commission, the JRC functions as a reference centre of science and technology for the Community. Close to the policy-making process, it serves the common interest of the Member States, while being independent of special interests, whether private or national.

LA-N

A-22784

-EN

-C

Documents

CERTIFICATION REPORT reference materials ERM - …publications.jrc.ec.europa.eu/repository/bitstream/JRC37540/7540...CERTIFICATION REPORT The certification of the mass fractions of