Elemental, My Dear Watson

Elemental, My Dear Elemental, My Dear WatsonWatson

Paul MiddlesteadUniversity of Ottawa, G.G. Hatch Laboratory

For 19th Continuous Flow Conference, Calgary, 2013

This talk is for new usersThis talk is for new users We will touch the basics on Elemental analysersWe will touch the basics on Elemental analysers A mix bag of tricks and advicesA mix bag of tricks and advices Refer to manufacturer’s instruction manualsRefer to manufacturer’s instruction manuals

Only endorsed products are: Only endorsed products are: Rickards RedRickards Red and and Rickards WhiteRickards White

Who/what is this Who/what is this talk for?talk for?

Meet my familyMeet my family

Combustion

EA

NCHS

TC/EA

Pyrolysis

HO

Largecapacity

S only TOC Stableisotopes

15000C12000C

Leco is the most popular manufacturer of elemental Leco is the most popular manufacturer of elemental analysers. Every department has one or two of those analysers. Every department has one or two of those accumulating dust.accumulating dust.

Static combustion using oxygen: not suitable for IRMSStatic combustion using oxygen: not suitable for IRMS

Meet Grand PaMeet Grand Pa

•Elemental Analyser as an…instrument•Schematics•Autosamplers•Flash combustion•Chemicals & Configurations•Gas Chromatography•Thermal Conductivity Detector•Typical run

•Common problems•EA-IRMS

Let’s touch onLet’s touch on

Simultaneous determination of Nitrogen, Carbon, Simultaneous determination of Nitrogen, Carbon, Hydrogen, Sulfur, OxygenHydrogen, Sulfur, Oxygen

Measuring range: 100 ppm to 100%Measuring range: 100 ppm to 100% Sample size: 0.1 to 1000 mg / 0.1 to 25 ulSample size: 0.1 to 1000 mg / 0.1 to 25 ul Detection limit: 10 ppmDetection limit: 10 ppm Accuracy: 0.3% - 0.02% absoluteAccuracy: 0.3% - 0.02% absolute

EA as an …. instrumentEA as an …. instrument

CE instruments (Carlo Erba) models 1108, CE instruments (Carlo Erba) models 1108, 1110, NA 1500, NA 2100, Flash 1112 1110, NA 1500, NA 2100, Flash 1112

Costech Model ECS4010Costech Model ECS4010 Elementar cube familyElementar cube family Eurovector models EuroEa3028-HT, Eurovector models EuroEa3028-HT,

Ea3024-IRMS, pyrolysis modelEa3024-IRMS, pyrolysis model Sercon-Integra Sercon-Integra TC\EA ThermoTC\EA Thermo ……

Manufacturers, models Manufacturers, models blablablablablabla

EA : Bulk analysis of NCHS/OEA : Bulk analysis of NCHS/O

Organic compoundsOrganic compounds PharmaceuticalsPharmaceuticals OrganometallicsOrganometallics PetrochemicalsPetrochemicals Gasoline & fuelsGasoline & fuels GraphiteGraphite Carbides & nitridesCarbides & nitrides

Metals & alloysMetals & alloys PolymersPolymers ExplosivesExplosives HydrocarbonsHydrocarbons SoilsSoils Coal & cokeCoal & coke LiquidsLiquids

In short, you can combust your grandmother!

Ref gas 1

Elemental Analyser

(CNS)(OH)

Interface Isotope Ratio Mass Spectrometer

HeRef gas 2 2 m

Typical EA setup with IRMSTypical EA setup with IRMS

EA pictureEA picture

Elemental Analyser SchematicElemental Analyser Schematic

TCD

CombustionChemicals1020C

ReductionChemicals650C

Gas chromatographyColumn in oven

Thermal Conduc-tivity Detector

Autosampler

N2

H2O

CO2

SO2

HeO2

WaterTrap EA line

out

Found the problem with Found the problem with the previous slide?the previous slide?

A beer if you do…A beer if you do…(5 seconds)(5 seconds)

Elemental Analyser SchematicElemental Analyser Schematic

TCD

CombustionChemicals1020C

ReductionChemicals700C

Gas chromatographyColumn in oven

ThermocoupleDetector

Autosampler

N2

H2O

CO2

SO2

HeO2

WaterTrap EA line

out

A cold A cold Rickard’s RedRickard’s Red for me please.for me please.

1.1. Sample/Std is weighed and wrapped in tin Sample/Std is weighed and wrapped in tin foil, placed in culture tray/autosamplerfoil, placed in culture tray/autosampler

2.2. Sample drops is flash-combusted in OSample drops is flash-combusted in O22 in in He stream, causing rapid cracking and He stream, causing rapid cracking and oxidation of gases stoichiometrically oxidation of gases stoichiometrically equivalent to their elemental components, equivalent to their elemental components, some gas oxides need to be reduced some gas oxides need to be reduced before obtaining final products (Nbefore obtaining final products (N22, CO, CO22, , HH22O, SOO, SO22) i.e. oxidation and reducing ) i.e. oxidation and reducing reactions involvedreactions involved

Typical Analysis Procedure for EATypical Analysis Procedure for EA

Typical Analysis Procedure for Typical Analysis Procedure for EAEA

3. Separation of gases by gas chromatography or chemical column traps

4. Detection by thermal conductivity detector (TCD) or IRMS.

5. Curve made from weighing certified stds (for isotope and/or quantitative measurements)

Some torture tools…Some torture tools…

Well well, got culture?Well well, got culture?

SSuuppeerr ssiizzee mmee

MAIS C’EST MAIS C’EST IMPOSSIBLE!IMPOSSIBLE!

C’EST FANTASTIQUE!C’EST FANTASTIQUE!

Filters? Careful!

Not flat pleaseNot flat please

AutosamplersAutosamplers (AS128) (AS128)

Autosamplers (AS200)Autosamplers (AS200)

Zero BlankZero Blank

Zero Blank modifiedZero Blank modified

Special tools requiredSpecial tools required

ECS 4010

Take 20 minutes to study the Take 20 minutes to study the gas schematics of your gas schematics of your

instrumentinstrument

Take 20 minutes to study the Take 20 minutes to study the gas schematics of your gas schematics of your

instrumentinstrument

Be good to yourselfBe good to yourself

Loop concept (a)Loop concept (a)

OXYGENOUT

He99.996

SAMPLE LOOP10 , 5 , 3 ML

O2

99.998

TO AUTOSAMPLERHe only

Loop concept (b)Loop concept (b)

HeHe

SAMPLE LOOP10 , 5 , 3 ML

O2

TO AUTOSAMPLERTO AUTOSAMPLERHe + OHe + O22 + He + He

OXYGENOXYGENOUTOUT

Sample droppingSample dropping

0 10 30 40

START

Sample drops

Combustion starts Injected O2Flash should occurwithin 2-3 secondsof being dropped

20

seconds

• PLATINUMPLATINUM: Absorbs much of the heat of the : Absorbs much of the heat of the reactor before passing it on to the sample, slowing reactor before passing it on to the sample, slowing down reactiondown reaction

• ALUMINIUMALUMINIUM: Supplies good oxidation flash and : Supplies good oxidation flash and prime sample ignition but does not melt or mix prime sample ignition but does not melt or mix with the sample thus does not promote inner with the sample thus does not promote inner oxidationoxidation

• SILVERSILVER: Melts at 960: Melts at 96000C, does not take part in the C, does not take part in the combustion, retains trace of carbon when in combustion, retains trace of carbon when in molten statemolten state

• TINTIN: Inexpensive & takes active part in process. : Inexpensive & takes active part in process. Melts at 235Melts at 23500C with very low enthalpy, intermixes C with very low enthalpy, intermixes with organic and inorganic substances, expedites with organic and inorganic substances, expedites the final oxidation reactionthe final oxidation reaction

Why you Tin man?Why you Tin man?

Increases local temperature from 1020Increases local temperature from 102000C to C to 1700-18001700-180000C, accelerating combustionC, accelerating combustion

Cancels the endothermic effects of tin Cancels the endothermic effects of tin melting (0.14 calories required for melting melting (0.14 calories required for melting vs 11.96 calories given off during flash)vs 11.96 calories given off during flash)

Equalizes the thermal degradation of any Equalizes the thermal degradation of any substancesubstance

Uses available oxygen immediately and Uses available oxygen immediately and requires lessrequires less

Dynamic Flash CombustionDynamic Flash CombustionOxidation of TIN gives a tremendous enthalpy reactionOxidation of TIN gives a tremendous enthalpy reaction

Sn + O2 SnO2 + 142 000 cal2350C 1700-1800C

Ensures that sample oxidation is performed in Ensures that sample oxidation is performed in gaseous phase (95%) rather than in the gaseous phase (95%) rather than in the catalytic reactionscatalytic reactions

Breaks down any matrix without combustion Breaks down any matrix without combustion aidaid

Converts the sample into a homogenous, Converts the sample into a homogenous, quantitative combustion gas mixture quantitative combustion gas mixture (unfractionated)(unfractionated)

Provides a gaseous plug for the entry into the Provides a gaseous plug for the entry into the GC columnGC column

Forms tin oxide, an oxidation catalystForms tin oxide, an oxidation catalyst Provides visual indication of the reactionProvides visual indication of the reaction

Dynamic Flash CombustionDynamic Flash CombustionOxidation of TIN gives a tremendous enthalpy reactionOxidation of TIN gives a tremendous enthalpy reaction

CC CO CO2 2 COCO22

Let’s get crackingLet’s get cracking

HH HH22OO HH22OO

SS SO SO2 2 + SO+ SO33 SOSO22

Combustion tube

Reduction tube

NN N N2 2 + NxOx+ NxOx N N22

Chemicals and Chemicals and ConfigurationsConfigurations

• System should be optimized for element(s) to be analyzed

• One-tube system: both oxidant catalyst and reducing chemicals in one tube; usually used if S is to be analyzed

• Two-tube system: one tube for oxidant, one tube for reducing chemicals; usually used for N, NC or NCH

• Chemical traps: Mg Perchlorate or Anhydrone will trap H2O, and Carbosorb will trap CO2 (and SO2)

ConfigurationConfigurationCNCN

ConfigurationConfigurationSS

Small is Small is beautifulbeautiful

Using grinding tools and diluted Nitric acid, one can re-use Using grinding tools and diluted Nitric acid, one can re-use combustion and reduction tubescombustion and reduction tubes

More torture toolsMore torture tools

Gas chromatographic columns will separate different Gas chromatographic columns will separate different components according to their polarity and molecular components according to their polarity and molecular size.size.

Factors influencing the quality of the chromatography: Factors influencing the quality of the chromatography: column length, size of packing, tube diameter, column length, size of packing, tube diameter, stationary stationary phase type, flow rate, temperature.phase type, flow rate, temperature.

Packed column:Packed column: packed polymer beads, different sizes packed polymer beads, different sizes available. High capacity , low resolution.available. High capacity , low resolution.

Capillary column:Capillary column: small capillary with polymeric film on small capillary with polymeric film on inner wall. High resolution, low capacity. inner wall. High resolution, low capacity.

Deactivated fused silica is free of adsorption problems Deactivated fused silica is free of adsorption problems encountered with most packings or capillaries columns.encountered with most packings or capillaries columns.

Gas ChromatographyGas Chromatography

Gas Separation/ GCGas Separation/ GC

He + N2 , CO2 , H2O , SO2 + He

He + SO2 + H2O + CO2 + N2 + He

INCREASING POLARITYOF GASES

What after we separate?What after we separate?

He + SO2 + H2O + CO2 + N2 + He

DETECTOR

TIME

DE

TE

CT

OR N2

CO2

SO2

H20

Gas Separation / Purge & Gas Separation / Purge & TrapTrap

TCD

SO2 H2O CO2

Thermal conductivity detector (TCD)Thermal conductivity detector (TCD) Heated filament from which heat is removed at Heated filament from which heat is removed at a constant rate by He gas stream. Change in a constant rate by He gas stream. Change in heat transfer is caused by presence of analyte heat transfer is caused by presence of analyte molecules with different thermal conductivities molecules with different thermal conductivities than He. Relatively low sensitivity, excellent than He. Relatively low sensitivity, excellent range and linearity. Non-destructive.range and linearity. Non-destructive.Electron capture detector (ECD)Electron capture detector (ECD)Electrons are captured by organic species in Electrons are captured by organic species in ionized carrier; used for trace sulfur ionized carrier; used for trace sulfur determination.determination.Isotope Ratio Mass Spectrometer (IRMS)Isotope Ratio Mass Spectrometer (IRMS)

DetectorsDetectors

TCD schematicTCD schematic

Typical output of EA, text Typical output of EA, text bookbook

N2

CO2

H2OSO2

Balance: Get the best Balance: Get the best

A 0.01mg readability translates in an A 0.01mg readability translates in an error of 0.25% on a 2 mg sample (say on error of 0.25% on a 2 mg sample (say on 100% carbon)100% carbon)

BalanceBalance

IAEA (and NIST) IAEA (and NIST) standardsstandards

Links available on Isogeochem

Best : %N, Best : %N, 1515N, %C, N, %C, 1313CC Test different materials and pray Test different materials and pray Make your own:Make your own:

CaffeineCaffeine L-glutamic acidL-glutamic acid Mixtures such as sucrose + potassium nitrateMixtures such as sucrose + potassium nitrate Mix in solution of natural + enriched/depleted material then Mix in solution of natural + enriched/depleted material then

dried, powdered, sieveddried, powdered, sieved

STD: Making it on your STD: Making it on your own…own…

STD: Not making it on your STD: Not making it on your own…own…

Can also contact other Can also contact other university labs to buy or university labs to buy or obtain their internal obtain their internal standards.standards.

STD: Not making it on your STD: Not making it on your own…own…

Calculation MethodsCalculation Methods

1. K-Factor (Single point calibration with blank substraction)

Calculated % = K * (Area unk – Area blk)Weight unk

Where K = Weight std * Theor std %Area std - Area blk


2. Linear Fit (Least square linear regression)

Calculated % = m * Area unk + b Weight unk

Peak Area

Wt *

Th

std

%


3. Quadratic Fit (Least square quadratic regression)

Calculated % =

a * Area unk2 + b * Area unk + c Weight unk

Peak Area

Wt *

Th

std

%

An update…An update…

Most elemental analysers manufacturershave considerably refined their calculation methods, with more complex algorithms, low-high ranges and statistical tools.

Common Problems (I)Common Problems (I)

CO2 Blank

Unreproducible blank

•Contaminated capsules Wash or change batch•Memory effect due to ashes Remove ashes

N2 Blank

Increasing blank values

•Copper exhausted Repack reduction tube•High mass 30Repack reduction tube

Common Problems (II)Common Problems (II)

Very high blank values

•Autosampler purge off•Very high mass 28 Switch on!!

High & constant blank

•Impure oxygen• High mass 28Replace O2

Common Problems (III)Common Problems (III)

No signal

•Detector off Switch on!•Broken filament Call engineer•Low carrier flow Check flow rate & blockage•MS valve closed, open split problem

Ghost/double peaks

•Leak Find and fix•CO2 or H2O trap exhausted Replace packing of trap

N2

? CO2?

Common Problems (IV)Common Problems (IV)

Peak broadening

•Presence of dead volume Check trap(s) or packing•Incomplete combustion Remove ashes, check drop time (flash), exhausted chemicals

Baseline drift

•Leak Find and fix•Carrier flow fluctuating Check GC oven temperature•Outgassing of chemicals

Leak check or check Leak check or check leaks (1)leaks (1)

EA

Pressure check

•Cap exit port•Increase P of He to 1.3 bar, wait 3 minutes•Close regulator•Pressure gauge should not move for 5 minutes

EA

Flow check (requires electronic mass flow controller)

•Cap exit port•Monitor flow for 3 minutes•Flow should drop to 0 ml/min

Leak check or check Leak check or check leaks (2)leaks (2)

EA Inter-face

Leak check with IRMS

•EA has been leak checked•EA chemicals have outgassed (12 hours) •Tune to Ar (mass 40)•Should meet manufacturer’s requirements•Use Ar cylinder to hunt

MS

Ar

Elemental Analyser Schematic for Elemental Analyser Schematic for IRMSIRMS

TCD

Combustion tube Reduction tube

Water trap

Gas chromatographyColumn


Autosampler

To MS

N2 CO2InterfaceDiluter & ref gas

Did you find the small error in the last slide?Did you find the small error in the last slide?

WAKE UP!WAKE UP!

Elemental Analyser Schematic for Elemental Analyser Schematic for IRMSIRMS

TCD

Combustion tube Reduction tube

Water trap

Gas chromatographyColumn


Autosampler

To MS

N2 CO2InterfaceDiluter & ref gas

Water is removed via Mg Perchlorate/sicapent Water is removed via Mg Perchlorate/sicapent traptrap---water and mass spectrometer ---water and mass spectrometer do not mixdo not mix--------

Configuration should be optimized for gas of Configuration should be optimized for gas of interestinterest

Leak free (mass 28 & 40, use Argon as leak probe)Leak free (mass 28 & 40, use Argon as leak probe) Low and stable background (mass Low and stable background (mass 2828, 18, 40, , 18, 40, 4444)) Dynamic range must be respected, do use target Dynamic range must be respected, do use target

beambeam Best sequence is carefully planned ie known Best sequence is carefully planned ie known

concentration of samplesconcentration of samples Garbage in……Garbage outGarbage in……Garbage out

Considerations for EA-Considerations for EA-IRMSIRMS

Some useful infoSome useful infoLab No. Sample type Nitrogen Carbon Hydrogen Sulphur C/N Comments

97-256-010 Adult mysids 10,20 50,97 na na 5,00 Whall JD, Trent U.

97-220-003 Amphipods 6,81 33,20 5,66 0,00 4,88 Pastershank G., U of O/ Biology

97-256-004 Chironomids 8,98 37,23 na na 4,15 Whall JD, Trent U.

97-256-014 Clam 12,30 48,91 na na 3,98 Whall JD, Trent U.

97-220-004 Clam muscle 11,26 43,41 6,77 1,10 3,85 Pastershank G., U of O/ Biology

97-220-005Clam shell

0,05 11,91 0,19 0,00231,6

3Pastershank G., U of O/ Biology

97-220-018 Cragon (shrimp) 10,03 37,22 5,91 0,00 3,71 Pastershank G., U of O/ Biology

97-220-020 Diatom 0,00 0,74 0,09 0,00 N.A. Bad trace

97-220-002 Egg white 11,85 45,83 6,93 1,14 3,87 Pastershank G., U of O/ Biology

97-220-001 Egg yolk 5,41 62,69 9,73 0,00 11,59 Pastershank G., U of O/ Biology

97-220-009 Fish bone 6,43 19,53 3,51 0,00 3,04 Pastershank G., U of O/ Biology

97-220-008 Fish eye 12,90 48,70 7,05 2,13 3,77 Pastershank G., U of O/ Biology

97-220-013 Fish fin 10,01 34,36 5,35 0,00 3,43 Pastershank G., U of O/ Biology

97-220-014 Fish gill 13,28 47,10 7,06 0,00 3,55 Pastershank G., U of O/ Biology

97-220-015 Fish gut content 9,56 44,88 7,07 1,13 4,69 Pastershank G., U of O/ Biology

Best are quartz filters; they are stable. Best are quartz filters; they are stable. However they are more expensive and offer However they are more expensive and offer less choice.less choice.

Silver filters are great too.Silver filters are great too. Mostly glass filters, cheap, huge choice.Mostly glass filters, cheap, huge choice. How much to use? How much to use?

Filters, we can do that!Filters, we can do that!

Filters, we can do that!Filters, we can do that!

Area = *R2

In this case, a punch is about 16mm2 and our whole filter is about 1490mm2 .Our punch hole is roughly 1% of the filter.

Sediment contaminationSediment contamination

Inorganic Carbon

Average 13C: 0‰

= Total CarbonOrganic Carbon

Average 13C: -25‰

0% + 100% = -25 ‰1% + 99% = -

24.75 ‰5% + 95% = -23.75 ‰10% + 90% = -22.50 ‰50% + 50% = -12.5 ‰

Honey, you think I’m Honey, you think I’m fat?fat?

% Nitrogen Wt required

100 0.1mg

10 1.0mg

5 5mg

2 7mg

1 10mg

0.1 100mg

0.001 Yeah, right!

Optimal amount of Nitrogen: 0.1mg

Open split, magical stuffOpen split, magical stuff

He + CO2 + N2 + He

EA 100 ml/min

Fused silica capillary100 um, 2m, insertedabout 30cm in EA line,0.4 ml/min going intosource of IRMS

2mm or 1/16” SSline from EA

In real life…Open splitIn real life…Open split

EA

IRMSRef 1

Ref 2

He

Ref 3 Ref 4Ref 5Ref 6

Ref 7Ref 8Ref 9

Ref 10Ref 11Ref 12

In real life…Open splitIn real life…Open split

EA

IRMSRef 1

Ref 2

He

Ref 3 Ref 4Ref 5Ref 6

Ref 7Ref 8Ref 9

Ref 10Ref 11Ref 12

The joy of sniffing EA onlyThe joy of sniffing EA only

Mass spectrometer outputMass spectrometer output

TCD output from EATCD output from EA

MagnetMagnetPeakjumPeakjumpp

N2

CO2

Mass 28, 29Mass 44,45,46

The joy of sniffing, totalThe joy of sniffing, total

Mass spectrometer outputMass spectrometer output

TCD output from EATCD output from EA

MagnetMagnetPeakjumPeakjumpp

N2

CO2

Mass 28, 29Mass 44,45,46

Masses 28 & 29 Masses 44, 45 & 46

To dilute or Not to To dilute or Not to dilute?dilute?

Second last suggestionSecond last suggestion

I strongly recommend that you create a basic document for your users explaining

the limits and pitfalls of EA-IRMS analysis, this will save you (and your users) an

enormous amount of time.

Removing inorganic carbon is not trivialRemoving inorganic carbon is not trivial Alkalies (Sodium, Potassium, Calcium) are difficult to Alkalies (Sodium, Potassium, Calcium) are difficult to

combust, catalist is definitively required to bind and help combust, catalist is definitively required to bind and help with oxydation.with oxydation.

Oxygen contribution to Oxygen contribution to 3434S is still a problem. S is still a problem.

Some unresolved Some unresolved issues with EAissues with EA

Last suggestion and only Last suggestion and only Official EndorsementOfficial Endorsement

The only product fully and officially endorsed by the author is:

Rickard’s Red

Thank you for not Thank you for not snoringsnoring

My thanks to:

Wendy Abdi, Nik Binder, Fred Longstaffe, Scott Hughes, Gilles St-Jean, Peter Stow and Patricia Wickham for the use of material, brain power and time …

Documents

Elemental, My Dear Watson