13
Please cite this article in press as: W. Xu, et al., Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.026 ARTICLE IN PRESS G Model ACA-232528; No. of Pages 13 Analytica Chimica Acta xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Analytica Chimica Acta j ourna l ho mepage: www.elsevier.com/locate/aca Review Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review Weiguang Xu a,1 , Xian Wang a,b,1 , Zongwei Cai a,a Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China b College of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan, Hubei 430074, People’s Republic of China h i g h l i g h t s Current analytical techniques for POPs in environment and biota are reviewed. The review covers most updated lit- eratures reports on POPs analysis. For the first time, analysis of new POPs under Stockholm Convention is reviewed. Future perspectives on POPs, espe- cially the potential POPs, are dis- cussed. g r a p h i c a l a b s t r a c t a r t i c l e i n f o Article history: Received 21 November 2012 Received in revised form 8 April 2013 Accepted 12 April 2013 Available online xxx Keywords: Persistent organic pollutants Sample preparation Instrumental analyses Gas chromatography–mass spectrometry Liquid chromatography–mass spectrometry a b s t r a c t Persistent organic pollutants (POPs) are major environmental concern due to their persistence, long- range transportability, bio-accumulation and potentially adverse effects on living organisms. Analytical chemistry plays an essential role in the measurement of POPs and provides important information on their distribution and environmental transformations. Much effort has been devoted during the last two decades to the development of faster, safer, more reliable and more sensitive analytical techniques for these pollutants. Since the Stockholm Convention (SC) on POPs was adopted 12 years ago, analytical methods have been extensively developed. This review article introduces recent analytical techniques and applications for the determination of POPs in environmental and biota samples, and summarizes the extraction, separation and instrumental analyses of the halogenated POPs. Also, this review covers important aspects for the analyses of SC POPs (e.g. lipid determination and quality assurance/quality control (QA/QC)), and finally discusses future trends for improving the POPs analyses and for potential new POPs. © 2013 Elsevier B.V. All rights reserved. Abbreviations: AMAP, Arctic monitoring and assessment programme; APCI, Atmospheric pressure chemical ionization; BDE, Brominated diphenyl ether; BFR, Brominated flame retardant; CPE, Cloud point extraction; CRM, Certified reference material; DCM, Dichloromethane; DDD, Dichlorodiphenyldichloroethane; DDE, Dichlorodiphenyldichloroethylene; DDT, Dichlorodiphenyltrichloroethane; DL-PCBs, Dioxin-like PCBs; ECD, Electron capture detector; ECNI-MS, Electron capture negative ion mass spectrometry; EI, Electron ionization; ESI, Electrospray ionization; EU/CEN, European Union/Comité Européen de Normalisation; GC, Gas chromatography; GC × GC, Comprehensive two-dimensional gas chromatography; GMP, Global monitoring plan; HBCD, Hexabromocyclododecane; HCB, Hexachlorobenzene; HCH, Hexachlorocyclo- hexane; HRMS, High resolution mass spectrometry; ITMS, Ion trap mass spectrometry; JIS, Japanese industrial standards; LC, Liquid chromatography; LRAT, Long-range atmospheric transport; LLE, Liquid–liquid extraction; LOD, Limit of detection; MAE, Microwave assisted extraction; MS, Mass spectrometry; NIST, National Institute of Stan- dards and Technology; OCP, Organic chlorinated pesticide; PBDE, Polybrominated diphenyl ether; PCB, Polychlorinated biphenyl; PCDD, Polychlorinated dibenzo-p-dioxin; PCDE, Polychlorinated diphenyl ether; PCDF, Polychlorinated dibenzofuran; PCN, Polychlorinated naphthalene; PFAS, Per- and polyfluoroalkylated substances; PFCA, Perflu- oroalkyl carboxylic acid; PFOA, Perfluorooctanic acid; PFOS, Perfluorooctane sulfonic acid; PFOSF, Perfluorooctane sulfonyl fluoride; PFSA, Perfluoroalkyl sulfonic acid; PLE, Pressurized liquid extraction; POPs, Persistent organic pollutants; POPRC, Persistent organic pollutants review committee; PUF, Polyurethane foam; QA/QC, Quality assurance and quality control; SC, Stockholm Convention; SCCP, Short-chain chlorinated paraffins; SFE, Supercritical fluid extraction; SIM, Selected ion monitoring; SPE, Solid-phase extraction; SPMD, Semi-permeable membrane device; SPME, Solid-phase microextraction; TBBPA, Tetrabromobisphenol A; UAE, Ultrasonic assisted extraction; UNEP, United Nation Environment Programme; UPLC, Ultra-performance liquid chromatography; USEPA, U.S. Environmental Protection Agency; WHO, World Health Organization. Corresponding author. Tel.: +852 34117070; fax: +852 34117348. E-mail address: [email protected] (Z. Cai). 1 The authors contributed equally to this work. 0003-2670/$ see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aca.2013.04.026

Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

  • Upload
    zongwei

  • View
    234

  • Download
    0

Embed Size (px)

Citation preview

Page 1: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

G

A

R

At

Wa

b

h

ARRAA

KPSIGL

BDiChadPoPaeN

0h

ARTICLE IN PRESS Model

CA-232528; No. of Pages 13

Analytica Chimica Acta xxx (2013) xxx– xxx

Contents lists available at SciVerse ScienceDirect

Analytica Chimica Acta

j ourna l ho mepage: www.elsev ier .com/ locate /aca

eview

nalytical chemistry of the persistent organic pollutants identified inhe Stockholm Convention: A review

eiguang Xua,1, Xian Wanga,b,1, Zongwei Caia,∗

Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, ChinaCollege of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan, Hubei 430074, People’s Republic of China

i g h l i g h t s

Current analytical techniques forPOPs in environment and biota arereviewed.The review covers most updated lit-eratures reports on POPs analysis.For the first time, analysis of newPOPs under Stockholm Convention isreviewed.Future perspectives on POPs, espe-cially the potential POPs, are dis-cussed.

g r a p h i c a l a b s t r a c t

a r t i c l e i n f o

rticle history:eceived 21 November 2012eceived in revised form 8 April 2013ccepted 12 April 2013vailable online xxx

eywords:

a b s t r a c t

Persistent organic pollutants (POPs) are major environmental concern due to their persistence, long-range transportability, bio-accumulation and potentially adverse effects on living organisms. Analyticalchemistry plays an essential role in the measurement of POPs and provides important information ontheir distribution and environmental transformations. Much effort has been devoted during the last twodecades to the development of faster, safer, more reliable and more sensitive analytical techniques forthese pollutants. Since the Stockholm Convention (SC) on POPs was adopted 12 years ago, analytical

methods have been extensively developed. This review article introduces recent analytical techniques

determination of POPs in environmental and biota samples, and summarizes and instrumental analyses of the halogenated POPs. Also, this review covers

e analyses of SC POPs (e.g. lipid determination and quality assurance/qualityally discusses future trends for improving the POPs analyses and for potential

© 2013 Elsevier B.V. All rights reserved.

I, Atmospheric pressure chemical ionization; BDE, Brominated diphenyl ether; BFR,ence material; DCM, Dichloromethane; DDD, Dichlorodiphenyldichloroethane; DDE,s, Dioxin-like PCBs; ECD, Electron capture detector; ECNI-MS, Electron capture negative, European Union/Comité Européen de Normalisation; GC, Gas chromatography; GC × GC,n; HBCD, Hexabromocyclododecane; HCB, Hexachlorobenzene; HCH, Hexachlorocyclo-etry; JIS, Japanese industrial standards; LC, Liquid chromatography; LRAT, Long-range

Microwave assisted extraction; MS, Mass spectrometry; NIST, National Institute of Stan-iphenyl ether; PCB, Polychlorinated biphenyl; PCDD, Polychlorinated dibenzo-p-dioxin;lychlorinated naphthalene; PFAS, Per- and polyfluoroalkylated substances; PFCA, Perflu-ic acid; PFOSF, Perfluorooctane sulfonyl fluoride; PFSA, Perfluoroalkyl sulfonic acid; PLE,

organic pollutants review committee; PUF, Polyurethane foam; QA/QC, Quality assuranceffins; SFE, Supercritical fluid extraction; SIM, Selected ion monitoring; SPE, Solid-phase

ersistent organic pollutantsample preparationnstrumental analysesas chromatography–mass spectrometryiquid chromatography–mass spectrometry

and applications for the

the extraction, separationimportant aspects for thcontrol (QA/QC)), and finnew POPs.

Abbreviations: AMAP, Arctic monitoring and assessment programme; APCrominated flame retardant; CPE, Cloud point extraction; CRM, Certified referichlorodiphenyldichloroethylene; DDT, Dichlorodiphenyltrichloroethane; DL-PCB

on mass spectrometry; EI, Electron ionization; ESI, Electrospray ionization; EU/CENomprehensive two-dimensional gas chromatography; GMP, Global monitoring plaexane; HRMS, High resolution mass spectrometry; ITMS, Ion trap mass spectromtmospheric transport; LLE, Liquid–liquid extraction; LOD, Limit of detection; MAE,ards and Technology; OCP, Organic chlorinated pesticide; PBDE, Polybrominated dCDE, Polychlorinated diphenyl ether; PCDF, Polychlorinated dibenzofuran; PCN, Poroalkyl carboxylic acid; PFOA, Perfluorooctanic acid; PFOS, Perfluorooctane sulfonressurized liquid extraction; POPs, Persistent organic pollutants; POPRC, Persistentnd quality control; SC, Stockholm Convention; SCCP, Short-chain chlorinated para

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

xtraction; SPMD, Semi-permeable membrane device; SPME, Solid-phase microextractionation Environment Programme; UPLC, Ultra-performance liquid chromatography; USEP∗ Corresponding author. Tel.: +852 34117070; fax: +852 34117348.

E-mail address: [email protected] (Z. Cai).1 The authors contributed equally to this work.

003-2670/$ – see front matter © 2013 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.aca.2013.04.026

ersistent organic pollutants identified in the Stockholm Convention:026

; TBBPA, Tetrabromobisphenol A; UAE, Ultrasonic assisted extraction; UNEP, UnitedA, U.S. Environmental Protection Agency; WHO, World Health Organization.

Page 2: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

G Model

A

2

C

1

cirwdtaafih

ARTICLE IN PRESSCA-232528; No. of Pages 13

W. Xu et al. / Analytica Chimica Acta xxx (2013) xxx– xxx

ontents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 002. Overview of the chemical analysis of POPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

2.1. Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 002.2. Lipid determination for POPs analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 002.3. International monitoring programme and QA/QC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

3. Chlorinated POPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 003.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 003.2. Sampling and sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

3.2.1. Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 003.2.2. Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 003.2.3. Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

3.3. Instrumental analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 004. Brominated POPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

4.1. Polybrominated diphenyl ethers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 004.1.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 004.1.2. Sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 004.1.3. Instrumental analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

4.2. Hexabromocyclododecane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 005. Per- and polyfluoroalkylated substances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

5.1. Perfluorooctane sulfonic acid and its salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 005.2. Perfluorooctane sulfonyl fluoride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 005.3. Interlaboratory studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

6. Future perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 006.1. Improvements of environmental analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 006.2. Potential POPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

7. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

Dr. Weiguang Xu graduated from College of Chem-istry and Molecule Engineering of Peking University in2001 and has been studied chemical analysis of chlori-nated chemicals such as PCDD/PCDFs and PCBs since2005. He received his Ph.D. degree from Hong KongBaptist University in 2012.

Dr. Xian Wang graduated from the University ofOttawa, Canada, with a Ph.D. degree in Mass Spec-trometry in 2006. She is currently an associateprofessor in South-Central University for Nation-alities, China. The major research interest of Dr.Wang is the development of mass spectrometry-based techniques for the structural identifications andcharacterizations of small molecule compounds andprotein–drug complexes.

Prof. Zongwei Cai graduated from Xiamen University,China with Bachelor degree in Chemistry in 1982 andUniversity of Marburg, Germany with Ph.D. degree inAnalytical Chemistry in 1990. Currently he is ChairProfessor of Chemistry and Director of Dioxin Lab-oratory, Hong Kong Baptist University. The majorresearch interest of Prof. Cai is method developmentand applications of chromatography coupled withmass spectrometry for trace environmental analysis.Prof. Cai has been invited to join Asian-Pacific RegionalOrganization Group for Stockholm Convention onPOPs. He is the principal author in Asian-Pacificregional report on POPs under the StockholmConvention.

. Introduction

Persistent organic pollutants (POPs) are a group of chemi-als that have been intentionally or inadvertently produced andntroduced into the environment. Due to their stability and long-ange transport properties, they are now ubiquitous around theorld and are even found in places such as the arctic regions, faristant from where they had been intensively used. Because of

and reproductive systems and even diminished intelligence aresuspected to be related to an exposure to these chemicals. TheStockholm Convention (SC) on POPs was adopted on May, 2001 andcame into force in 2004 [1]. It is a global treaty under the UnitedNation Environment Programme (UNEP), with the participation of171 countries and one regional economic integration organization.The SC aim is to protect humans and the environment from haz-ardous and persistent chemicals by reducing or eliminating theirproduction and introduction to the environment. The initial SC listin 2004 included 12 chemicals called the “dirty dozen”. In August2009, nine new chemicals were added in an amendment and cameinto force 1 year later. During the fifth meeting held in 2011, endo-sulfan became the 22nd POP.

The development of analytical methods for POPs provides reli-able data for their environmental and biological occurrence andtherefore plays an important role in the investigation of their

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

heir high fat solubility, such chemicals tend to bio-accumulate innimals, especially in species at the top of the food chain. POPsppear at higher concentrations in fat-containing foods, includingsh, meat, eggs and milks, and so traces of POPs are found in theuman body. Some cancers, birth defects, dysfunctional immune

distribution, temporal and spatial trends, environment fates and

ersistent organic pollutants identified in the Stockholm Convention:026

potential sources. Such quantitative analysis-based monitoring notonly helps shareholders to share responsibility, but also providesthe vital information required by regulators. However, exemptionsand the loose regulation of POPs may still result in their release,

Page 3: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ARTICLE IN PRESSG Model

ACA-232528; No. of Pages 13

W. Xu et al. / Analytica Chimica Acta xxx (2013) xxx– xxx 3

Table 1POPs listed in the Stockholm Convention amendment.

Item Chemicals CAS no. Type Isomers and homologues

2001 amendment1 Aldrin 309-00-2 Pesticide Aldrin and isodrin2 Dieldrin 60-57-1 Pesticide –3 Endrin 72-20-8 Pesticide –4 Chlordane 57-74-9 Pesticide �- and �-isomers5 Heptachlor 76-44-8 Pesticide –6 HCB 118-74-1 Pesticide and industrial –7 Mirex 2385-85-5 Pesticide –8 Toxaphene 8001-35-2 Pesticide Hundreds of isomers9 DDT 50-29-3 Pesticide p,p′-DDT; o,p′-DDT; p,p′-DDE; p,p′-DDD10 PCBs – Industrial and by-product 209 congeners11 and 12 PCDDs and

PCDFs– By-product 75 PCDD congeners and 135 PCDF congeners

2009 amendment13 Chlordecone

(Kepone)143-50-0 Pesticide –

14 Lindane(�-HCH)

58-89-9 Pesticide –

15 �-HCH 319-84-6 Pesticide and by-product –16 �-HCH 319-85-7 Pesticide and by-product –17 Hexabromobiphenyl 36355-01-8 Industrial 42 congeners18 Tetra-BDE and

penta-BDE– Industrial Co-exist in commercial Penta-BDE

19 Hexa-BDE andhepta-BDE

– Industrial Co-exist in commercial Octa-BDE

20 PFOS and itssaltsPFOSF

1763-23-1

307-35-7

Industrial Side-chain isomers

21 Pentachlorobenzene 608-93-5 Pesticide, industrial and by-product –

ide

esn

rlvMhd

2

2

bsswTdttmtdmsNsTt

2011 amendment22 Endosulfan 115-29-7 Pestic

ven after the chemicals have officially been phased out. Moreover,econdary sources are often particularly poorly regulated, makingecessary a continuous monitoring programme.

The literature on POPs analyses has grown exponentially inecent years. This review focuses mainly on the POPs that have beenisted by the SC (see Table 1), describing and comparing the con-entional and novel analytical techniques applied to these POPs.ethods for measuring the levels of POPs in food, animal and

uman samples, and the analytical chemistry in QA/QC and lipidetermination are also described here.

. Overview of the chemical analysis of POPs

.1. Methods

Methods for the analysis of POPs in a variety of environmental,iota and food matrices have been well developed during the pasteveral decades, and appear in both academic articles and in thetandard operational procedures from various authorities that areidely used as references in scientific research and testing services.

he United States Environmental Protection Agency (USEPA) haseveloped comprehensive analysis protocols for POPs, in additiono the European standard (EU/CEN methods) and Japanese indus-rial standards (JIS). The standard methods cover either several

atrices or individual matrix. While employing common extrac-ion and cleanup procedures as well as GC-HRMS for dioxins andioxin-like PCBs (DL-PCBs) analysis, some of the method perfor-ance criteria are different, as discussed in later sections. Although

everal standard methods for specific matrix are available from the

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

ational Environmental Methods Index [2], there is no detailed ortep-by-step analytical method recommended for specific POPs.hus, performance-based approaches are used by analytical labora-ories instead. Such flexibility allows analytical chemists to choose

�- and �-isomers

the most suitable methods depending upon their applications andlimitations.

Because some categories of pollutant contain hundreds ofcongeners, it is impractical to determine the concentrationof each congener. Therefore the chemical analysis of thesegroups of pollutants commonly refers to the most importantor indicator congeners. For example, the analysis of poly-chlorinated dibenzo-p-dioxin/furan (PCDD/PCDF) includes 172,3,7,8-substituted analogues that were shown to be the most toxicamong the 209 congeners, while polychlorinated biphenyl (PCB)concentrations mainly refer to the sum of seven indicators (PCB-28, 52, 101, 118, 138, 153 and 180). The total concentration ofpolybrominated diphenyl ether (PBDE) also normally refers to thesum of several individual congeners, namely BDE-28, 47, 99, 100,153, 154, 183 and 209. Several reviews on POPs analysis havebeen published [3–8], covering various matrices including OCPsin air [4], dioxins and PBDEs in various environmental samples[5], and new hydrophilic POPs in water, human blood and milk[6–8].

2.2. Lipid determination for POPs analysis

Because it is ecologically relevant to report the residue lev-els of lipophilic persistent pollutants on a fat weight basis, thedetermination of lipid contents is essential to quantify target com-pound levels in biota samples. Nevertheless, there is no standardlipid determination method for environmental tissue samples.An aliquot of tissue extract or a separate tissue sample is nor-mally used for the lipid determination [9]. It should be notedthat the two strategies are quite different in character and their

ersistent organic pollutants identified in the Stockholm Convention:026

lipid extraction efficiencies can be significantly different, espe-cially in low lipid content matrices [10]. Thus attention must bepaid when the data for POPs in lipids from different sources arecompiled.

Page 4: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ING Model

A

4 imica

2

pPthiaa2itmcfiEarAmpt

om15PgPuna1ttS

irePnbarapStpmstlocehrvaN

l

ARTICLECA-232528; No. of Pages 13

W. Xu et al. / Analytica Ch

.3. International monitoring programme and QA/QC

International authorities have employed several monitoringrogrammes to elucidate the historic and current occurrence ofOPs for academic and regulation purposes. With the coopera-ion of national and international monitoring programmes, UNEPas issued a global monitoring plan (GMP) for POPs, and which

s the most comprehensive survey of the presence of POPs fromll regions, to evaluate the effectiveness of SC. The GMP guid-nce for POPs was initially published in 2007 and was revised in011 [11,12]. It provides the overall technical guidance for the

mplementation of the GMP worldwide. According to environmen-al importance and sampling applicability, GMP takes ambient air,

aternal blood and maternal milk as the key monitoring matri-es. The first global monitoring reports and regional reports fromve regions (Africa, Latin America, Asia and the Pacific, Central andastern Europe, Western Europe and other states) were availables a baseline for future evaluation in 2009 [13,14]. According to theegional report of Western Europe and other states, some POPs (e.g.ldrin and endrin) exist at levels too low to be detected. Levels ofost POPs in air and in humans have generally decreased in the

ast 10–15 years. Representative data are too limited to indicaterends in the other regions, due to the significant data gap.

The World Health Organization (WHO), along with UNEP, hasrganized four rounds of exposure studies on POPs in humanilk to investigate their levels and trends in certain locations in

987–1988, 1992–1993, 2000–2001 and 2006–2007 [15,16]. Theth round of study is currently in progress [17]. All the “dirty dozen”OPs in the 2001 amendment were included in the fourth investi-ation and its scope was expanded to include new POPs such asBDEs. The Arctic monitoring and assessment programme (AMAP),nder the Arctic Council, with eight country members, has orga-ized comprehensive investigations of the environment, wildlifend human risks for exposures to pollutants (including POPs) since991 [18]. Some polychlorinated organic compounds were foundo be ubiquitous in the Arctic environment and wildlife, a resulthat helped stimulate global activity on POPs and finally initiatedC.

The large scale monitoring programs as well as other academicnvestigations provide information to scientists, shareholders andegulators, and have resulted in the QA/QC that is essential tonsure the reliability and comparability of quantification data forOPs from laboratories around the world. Otherwise the effective-ess of any research or international data-based evaluation woulde undermined. Field blank and laboratory method blank samples’nalyses have shown that POPs are ubiquitous and their occur-ence in the blank samples may result in their overestimation. Forir and water sampling, the sampling media (e.g. XADTM resin,olyurethane foam (PUF), semi-permeable membrane device orPMD) that have been exposed at the sampling site are used ashe field blank samples. For solid environmental and food sam-le collections, sand and corn oil are recommended as field blankaterials, respectively [19]. Matrix-spiked samples are made by

piking individual analytes prior to their extraction, to evaluateheir recovery from the sample preparation and to determine theimit of detection (LOD) when 3–5 times of estimated LOD levelf analytes is spiked. However, since the analyte does not associatelosely with the matrices, the recovery is higher than the true recov-ry of the analytical method used. To obtain the true recovery andence the accuracy of the analytical method, the analysis of certifiedeference material (CRM) is necessary. Although there is no indi-idual CRM that contains all POPs with certified values, many CRMs

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

re provided by national authorities and commercial institutes, e.g.ational Institute of Standards and Technology (NIST).

As well as the appropriate activities for routine QA/QC, the inter-aboratory analytical quality assurance studies of various matrices

PRESS Acta xxx (2013) xxx– xxx

are indispensable in the implementation of successful QA/QC. Ana-lytical laboratories are urged to use these proficiency tests ofanalysis to improve the reliability of their analytical methods,especially for those laboratories that provide data to internationalmonitoring programs. Van Bavel and Abad [20] have reviewed theinterlaboratory comparison results for dioxin-like compounds inenvironmental samples from 1992 to 2007, and showed that asignificant improvement had been achieved. Although the rela-tive standard deviation (RSD) values found did not relate to theconcentrations of the POPs in the samples, the RSD was higher inmore complicated samples. Quality assurance of information formarine environmental monitoring (QUASIMEME) is an EU-basedproficiency test scheme that organizes the interlaboratory compar-isons of pollutants, covering most POPs on the SC list in a variety ofmarine matrices [21]. Similar proficiency tests are also organizedfor food analysis by the Norwegian Institute of Public Health, andinclude PCDD/PCDFs, PCBs, PBDEs and HBCDs.

International monitoring programs provide interlaboratorycomparisons, assure the reliability of their quantification data andprovide workshops for the laboratories to attend. The ChemicalBranch of the UNEP coordinated the 1st biennial global interlab-oratory assessment of POPs in 2010. A total of 103 laboratoriesparticipated in the evaluation of the initial 12 POPs in various matri-ces, including neat solutions, fly ash, sediments, fish and humanmilk [22–24]. The report indicated that the UNEP criterion of 25%RSD was met only for PCDD/PCDFs in standard solutions, sediments,and human milk, and also for PCBs in human milk. Improvementfor the analyses of OCP and PCBs in all these matrices was thusrequired. The 2nd round of interlaboratory assessment will beheld in 2013 and its scope will be expanded to include PBDEs aswell as per- and polyfluorinated alkyl substances (PFAS). Besides,suggestions have been made for the analytical capacity buildingin developing countries after reviewing the inter-calibration data[25–29]. The international proficiency test for human plasma sam-ples collected under the AMAP monitoring programme from theArctic region has been organized by the Centre de Toxicologie duQuebec.

3. Chlorinated POPs

3.1. Introduction

Organic chlorinated pesticides (OCPs) on the “dirty dozen”list include aldrin, chlordane, DDT, dieldrin, endrin, heptachlor,mirex, toxaphene and hexachlorobenzene. In the Conference ofthe Parties in 2009, four new OCPs (chlordecone, � and �-hexachlorocyclohexane, Lindane) were added to the Annex of SC.Endosulfan that was recently added to Annex A in April 2011becoming the 22nd chemical in the POPs list. Chlorinated POPs areusually analyzed together due to the similarities of their physico-chemical properties. Analysis of the OCPs involves extraction,cleanup and GC or GC–MS based instrumental analysis. Toxapheneis unique among the OCPs because it is a complex mixture, ratherthan a single compound or mixture of several isomers. Theoret-ically, toxaphene has more than 30,000 potential congeners andmost of them are enantiomers. The actual number is estimated to beapproximately 1000 [30]. For several decades this has been a signif-icant challenge to analytical chemists. The common method for theidentification of the toxaphene complex is the Parlar number sys-tem that is based on the GC elution order [31]. Major congeners ofParlar 26, 50 and 62 that have been determined in monitoring pro-

ersistent organic pollutants identified in the Stockholm Convention:026

grams and interlaboratory comparisons showed good agreementbetween laboratories [32].

PCB was produced as a mixture (theoretically 209 congeners)with the trademark “Arochlor”. It is recommended to analyze

Page 5: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ING Model

A

imica

iA1tfBofppdlishfin

3

3

P(seTvaasssol

cepcswevmaepchea[bGthsPrtaroc

ARTICLECA-232528; No. of Pages 13

W. Xu et al. / Analytica Ch

ndividual congeners rather than the mixture, for better accuracy.t least seven ortho-substituted PCBs (PCB-28, 52, 101, 118, 138,53 and 180) were used as the indicator PCBs and used for rou-ine monitoring. Twelve non-ortho and mono-ortho PCBs that mayorm co-planar conformations like PCDD/PCDFs are called DL-PCBs.ecause their occurrence in Arochlor is much lower than thosef the indicator PCBs, the analysis of DL-PCBs is similar to thator dioxins rather than other PCBs. PCDD/PCDF is a group of com-ounds with 75 PCDDs and 135 PCDFs congeners that are mainlyroduced unintentionally by thermal processes or by pesticide pro-uction. The levels of PCDD/PCDF are 2–3 orders of magnitude

ower than those of other halogenated man-made chemicals bothn the environment and in the food chain. Only the 17 2,3,7,8-ubstituted congener are required to be monitored, because of theirigh toxicity. Because an extremely low detection limit is required

or PCDD/PCDF analysis, complicated sample preparation, includ-ng cleanup, and highly sensitive instrumental detection are ofteneeded.

.2. Sampling and sample preparation

.2.1. SamplingTwo air sampling methods are normally applied to gaseous

OPs: cumulative sampling by active high volume sampling0.5–1 m3 min−1) and continuous, cumulative passive (diffusive)ampling. Active sampling is a conventional air sampling methodmployed in monitoring programs. For example, USEPA-methodO-9A for the analysis of PCDD/PCDFs in ambient air and uses a higholume air sampler equipped with a quartz-fiber filter and a PUFdsorbent contained in a glass cartridge for sampling 325–400 Nm3

ir. The European and Japanese standard methods for the stationaryource and environmental monitoring of dioxins and DL-PCBs applyimilar active sampling procedures [33,34]. A novel mobile activeampling method using an automobile air intake filter was devel-ped by Zhang et al. [35] for analyzing the PCDD/PCDFs pollutionevels in a large urban area.

Passive air sampling has undergone considerable technologi-al development in the past 15 years because it is both simple andconomic. This sampling method relies on a sorbent with an appro-riate capacity for POPs, such as PUF and styrene/divinylbenzeneo-polymer resin (e.g. XAD-2). For PUF-disk samplers, a 3-monthampling period uses approximately 270–360 m3 of air volume,hich may be sufficient for the detection of POPs [36]. The wind

ffect on the design of the domed chamber may increase the sampleolume and has been evaluated by field study and flow simulationodels [37,38]. More precise measurements of air volume may be

chieved by spiking compounds that do not typically exist in thenvironment such as �-HCH-d6, PCB-107 and 198 on the sorbentrior to exposure to the real sample [36,37]. For the relatively lowapacity of PUF disks, the equilibration of more volatile POPs (likeexachlorobenzenes or HCBs) may occur during the sampling time,specially in warm places [37,39]. In contrast, XAD-based samplersre commonly deployed for longer time samplings (typically a year)40]. Although SPMD was firstly used for water sampling, it haseen used to survey POPs in air over large spatial scales [41,42].lobal atmospheric passive sampling (GAPS), is a long-term moni-

oring program for the investigation of POPs’ spatial trends, whichas demonstrated the feasibilities of the samplers for the globalpatial mapping at more than 60 sites around the world [36,43].assive sampling of PCDD/PCDFs by PUF has also been evaluatedecently [44,45]. The information of POPs in the Arctic and Antarc-ic obtained from passive sampling are significant for long-range

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

tmospheric transportation modeling because of the difficulty ofegular provision and maintenance of electricity [46,47]. The databtained by passive sampling has been applied to evaluate the POPsoncentration in five continents [48].

PRESS Acta xxx (2013) xxx– xxx 5

The application of passive sampling to solid and aquatic sam-ples has so far been mainly restricted to research use. The levels ofPCDD/PCDFs in wastewater have been described [49]. The resultsof Zhang et al. [50] showed a good correlation of the OCPs uptakeby earthworms and adsorbed by SPMD from soil, suggesting thatone advantage of passive sampling is that the bioavailability ofchemicals to organisms can be estimated in this way. However,such comparisons have not been observed in many studies betweenaquatic living organisms and SPMD in marine monitoring [51,52].A review of the application of the passive sampling technique toenvironmental studies has been published in this journal [53].

Sample storage may be important for POPs analysis. Althoughmost POPs do not change significantly during storage, dehydrochlo-rinations of DDT and �- and �-HCH may occur. For biota samples,oxidation and deterioration of lipids took place even at −25 ◦C overa 2-year period and the transformation of triglycerides to fattyacids could decrease the lipid extraction efficiency. Freeze-dryingwas commonly applied for water removal [54,55]. However, morevolatile pollutants such as HCB and low chlorinated PCBs may belost during freeze-drying. Moreover, potential contamination, e.g.PCB-28, may be introduced by this procedure [56]. Alternatively,the homogenized wet sample can be mixed with a desiccant, suchas sodium sulfate and Celite that can absorb the water from samplematrices.

3.2.2. ExtractionSolid samples include soil, sediment, sewage sludge, adsorbent

materials from gas sampling and biotic samples. The solid samplesare ground to a fine powder with a moisture adsorbent prior to theextraction step. A brief summary of solid sample extraction tech-niques is shown in Table 2. The conventional Soxhlet extractionmethod is still one of the most widely used for various matricesand analytes, and has been well summarized [57,58]. Soxhlet haslong been one of the standard methods for trace POPs analyses,e.g. EU/CEN EN-1948 [33], JIS K 0311 [34], and USEPA 1613 [59].The performance of other extraction techniques has often beenvalidated by comparison with Soxhlet extraction [60].

In order to increase the diffusion and desorption rate of ana-lytes from the sample matrix to the solvent and consequentlyrequire less solvent, pressurized liquid extraction (PLE), microwaveassisted extraction (MAE), ultrasonic assisted extraction (UAE) andsupercritical fluid extraction (SFE) have been applied to envi-ronmental analyses [61–64]. Compared with ca 300 mL solventrequired for Soxhlet extraction, 10–50 mL of selected solvent isgenerally enough. The optimization of temperature and pressure,time, solvent type and volume are the key parameters of thesesolvent-based extraction methods. Among these extraction tech-niques, PLE and MAE have been shown to be more reliable than UAEand SFE and therefore widely used for various matrices [65–68].Besides, combining PLE/MAE and head-space solid-phase microex-traction (SPME) has been reported for the extraction of OCPs andPCBs from sediment [69,70]. As well as the advantages of timeand cost effectiveness, the adsorption efficiency may be affected bymatrix complexity owing to the limited capacity of SPME fibers. Thesolvents for solid extraction commonly contain a water-misciblesolvent (typically acetone) and a water-immiscible one (e.g., hex-ane or dichloromethane). Acetone/hexane binary mixtures wereused most commonly in the extraction of POPs. If validated, a pureorganic solvent such as toluene can be used, in order to reduce theuse of water containing adsorbents.

The applications of liquid–liquid extraction (LLE) in water, bloodand milk have been widely accepted in standard methods for

ersistent organic pollutants identified in the Stockholm Convention:026

POPs analysis, including PCDD/Fs and PCBs [71–73]. Liquid samplesare often adjusted to neutral or slightly acidic conditions prior totheir extraction, because alkaline conditions may cause decompo-sition of some OCPs, including endosulfan and endrin. A mixture

Page 6: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ARTICLE IN PRESSG Model

ACA-232528; No. of Pages 13

6 W. Xu et al. / Analytica Chimica Acta xxx (2013) xxx– xxx

Table 2Extraction methods for POPs analysis.

Extraction Solvent Conditions Ref.

For solid matricesSoxhlet extraction Toluene for environmental samples and hexane/DCM

for biota tissue.16–24 h of extraction for OCPs, PCBs, PCDD/Fs [21,22,49,50,62]

MAE Same solvents as those for Soxhlet extraction 100–115 ◦C; 50–150 psi; 10–20 min; for OCPs, PCBs,PCDD/Fs

[53]

PLE Same solvents as those for Soxhlet extraction; solventwere filled with 60% volume of PLE cell

100–180 ◦C; 1500–2000 psi; 5–10 min; threeextractions; for OCPs, PCBs, PCDD/Fs

[52]

UAE Acetone/hexane (1:1) or acetone/DCM (1:1) for bothOCPs and PCBs

3 min; 300 W; a total of three extractions [54]

SFE CO2 supercritical fluid 40–150 ◦C; 4000 psi; 40 min; for OCPs and PCBs [55]

For aqueous matricesLLE DCM Three times; shaking 2 min each time [59,60]SPE C18 disk; washed with 5 mL acetone; eluted with 15 mL

DCM for OCPs; eluted with 20 mL ACN for PCBsConditioned with 20 mL DCM, 10 mL acetone, 20 mLMeOH and 20 mL water

[67]

oii(pmmspasSbou

3

itbpu(moofoawbcoiscvwsTu

3

p

SPME –

f water-miscible and immiscible solvents and sodium oxalates commonly used to avoid the production of an emulsion dur-ng blood and milk extraction. Ammonium sulfate/ethanol/hexane1:1:3) was used in the extraction of POPs from Inuit blood sam-les and hexane/acetone was employed in OCPs extraction fromilk [74,75]. A modified LLE method, called dispersive liquid–liquidicroextraction for OCPs and PCBs consumed considerably less

olvent and therefore is more environment-friendly [76–78]. Solid-hase extraction (SPE) is one widely used sorbent-based techniquend can be applied to the extraction, cleanup and concentrationteps [79,80]. The recoveries of PCBs and OCPs on six differentPE devices, including XAD-2 resin, C18 disk and various divinylenzene-based adsorbents, were satisfactory [81]. The applicationf a C18 SPE cartridge in blood and milk was also proven, but these of denaturant to eliminate clogging was required [82].

.2.3. SeparationAfter sample extraction, cleanup is needed thereafter to remove

nterfering substances in order to obtain unambiguous results. Fur-hermore, different types of halogenated POPs are often required toe separated into different analytical groups to reduce co-elutionroblems in chromatography. The primary step is lipid removal bysing concentrated sulfuric acid or gel permeation chromatographyGPC). Elemental sulfur is another interfering substance that com-

only occurred in sediment and sewage sludge. Activated copperr tetrabutylammonium sulfite mixed with the extract or mountedn the top of the silica column has been used to remove sul-ur. Multi-layer adsorption columns, with different combinationsf neutral/acidic/basic silica, alumina, Florisil® and active carbonre often used to remove co-extracted pigments, low moleculareight lipids and other interferences [65–68]. Active carbon has

een applied for co-planar PCDD/PCDFs and DL-PCBs due to thehallenges of achieving lower LOD [59]. Some detailed evaluationsf such pretreatment techniques for POPs were published earliern this journal [83]. Automation of extraction and cleanup con-umed significantly less solvent and labor. Spinnel et al. applied PLEoupled with integrated carbon trap for PCDD/PCDFs analysis andalidated by environmental CRMs [65]. Similar automation of PLEith silica, Florisil®, alumina, Celite® for dioxin and DL-PCBs analy-

is also achieved satisfied recoveries (80% and 65, respectively) [68].ang et al. developed a novel cleanup method for PCDD/PCDFs bysing GC and LC columns [84].

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

.3. Instrumental analysis

The occurrence of hundreds of halogenated compounds in com-lex matrices makes chromatographic separation a challenge. Since

Extract 3–5 mL aqueous sample, direct inject tube toGC

[58]

the 1960s, chlorinated POPs have been determined by using GC-ECD and GC–MS according to standard methods of the US, the EUand Japan [33,34,59,72,85–88]. While sharing similar extraction,cleanup and detection techniques, the EU and Japanese standardprocedures improved the acceptable QC criteria (60–120% recoveryfor PCDD/Fs and 70% for PCBs) compared to the USEPA methods, inorder to fit more stringent regulations. The standard procedureswere also revised for the improvement of analytical technique andperformance. For example, the LOD of EN-1948 and JIS K 0311 fordioxin analysis of stack gas were estimated to be 3–4 pg I-TEQ m−3,compared to 6–10 pg I-TEQ m−3 of USEPA-method 23. In addition,analysis of DL-PCBs is included in the Japanese method for theircontribution to the total toxic equivalent.

There is no single GC column (e.g. 5% phenyl methyl silicone andmodified by n-octyl or n-octyldecyl substitute) that can resolve allthe congeners of toxaphene, PCBs and PCDD/PCDFs. Co-elution ofsome PCB and OCP congeners has been well summarized, e.g., pairsof PCB-28 and 31, 118 and 149, etc. [89]. Thus, injection on two dif-ferent capillary columns, or confirmation of peak identity by usingthe second column was applied [90]. The optimization of certaincolumn combinations for selected analytes was studied by Bor-dajandi et al. [91], e.g. HT-8 × BPX-50 for PBDEs and PCDD/Fs andDB-17 × HT-8 for OCPs. Patterson et al. installed a liquid nitrogenjet-cooled thermal modulator to a GC × GC/HRMS with lower LOD[92]. By using the cryogenic zone compression technique, GC peaksof dioxins were trapped and remobilized in one event to achievesignificantly decreased LOD of 2,3,7,8-TCDD to attogram level [93].Krumwiede et al. claimed similar increase of sensitivity by using asimilar technique in a time controlled manner [94].

ECD is still a low cost routine detection technique for mostortho-substituted PCBs and OCPs, except for toxaphene. The instru-ment detection limits are 0.1–0.5 pg for OCPs [95]. Since the 1980s,MS has been used for POPs analysis and has now become the mostcommonly used detector, coupled with GC. The MS analysis mayresolve co-elution problems between different categories of ana-lytes because of the mass separation (e.g. PCB-180 and BDE-47).Another advantage of MS is that it enables application of the iso-tope dilution technique for the analysis of all categories of POPs[96]. A wide range of 13C- and 2H-labeled POPs standards is nowavailable commercially. Table 3 summarizes GC-based instrumentsand methods for the analysis of chlorinated POPs.

Currently, GC coupled with a quadrupole, low resolution MS(LRMS) has become the “standard” instrument in most analytical

ersistent organic pollutants identified in the Stockholm Convention:026

laboratories because of its ability to determine most PCB/OCPs atthe low pg level, by electron ionization (EI) in the selected ion mon-itoring (SIM) mode. Electron capture negative ion ionization (ECNI)is a softer ionization technique for GC–MS analysis. Toxaphene

Page 7: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ARTICLE IN PRESSG Model

ACA-232528; No. of Pages 13

W. Xu et al. / Analytica Chimica Acta xxx (2013) xxx– xxx 7

Table 3GC and GC–MS methods for the analysis of POPs.

Analytes GC parameters Detector LOD Pros and cons

Ortho-PCBs and OCPs,except toxaphene

DB-1, DB-5 or equivalent columns(30 m or 60 m)

ECD 0.1–1 pg for DDT/DDE;0.5 pg TEQ forPCDD/PCDFs

Low cost; good sensitivity; cannotidentify co-elution

PCBs and OCPs, not goodfor toxaphene

30 m low bleeding column; SIMmode

EI-LRMS 10–150 pg Less misidentification; goodsensitivity

All POPs except toxaphene 30 m low bleeding column; 60 mfor PCDD/PCDFs; SIM mode

EI-HRMS 10–160 fg of variousPOPs

Most sensitive and reliable;expensive

Toxaphene and highlychlorinated POPs

30 m low bleeding column; SIMmode

ECNI-MS 0.1–1 pg for OCPs;10 pg for toxaphene

Less misidentification; goodsensitivity and specificity

IT-MS

ismmlat

avrtoaviGffmf2bmorottLt

itvrmre[d

TE

All POPs 30 m low bleeding column; SIMmode

s most commonly detected by ECNI due to the method’s highensitivity and specificity [97]. Ion trap MS (ITMS) in the MS/MSode provides even better specificity by the monitoring of frag-ent ions. Enhancement of sensitivity was obtained by using a

arge volume, programmable temperature vaporizer injector, withn optimized injection volume of 10 uL for the detection of 2 pg ofetrachlorodibenzo-p-dioxin [98].

GC coupled to high resolution mass spectrometry (HRMS) with resolution of >10,000 provides much higher specificity for indi-idual congeners compared with GC-ECD and GC-LRMS. The highesolution technique has been widely applied for the determina-ion of ultra-trace levels of PCDD/PCDFs and DL-PCBs, with a LODf 2–3 orders of magnitude better than that of LRMS. Standardnalytical protocols using HRMS for dioxins and DL-PCBs are pro-ided by USEPA [59,73], EU/CEN [33] and JIS [34,72]. However,t is noteworthy that even HRMS coupled with high resolutionC can sometimes fail to ensure the separation of interferences

rom analytes or between analytes. The fragment ions of [M-2Cl]+

rom polychlorinated diphenyl ethers (PCDEs) have the same exactasses as the [M]+ ion of PCDFs that have two chlorine atoms

ewer, and thus cannot be resolved by HRMS. For example, the [M-Cl]+ ion of hexa-CDE interfered with the detection of tetra-CDFecause the two compounds were co-eluted under various chro-atographic conditions [99]. Another example is the interference

f penta-CBs by tri-BDEs that may be co-eluted in gas chromatog-aphy (e.g. PCB118 and BDE-28/33) [100]. A mass resolution ofver 23,000 is required to separate the [M]+ ion of penta-CB fromhe [M-Br]+ ion of tri-BDEs (Table 4). In addition to the conven-ion double-focusing HRMS, Matsui et al. claimed that a sub-fg ofOD of PCDD/PCDFs was achieved by multiphoton ionization on aime-of-flight MS coupled with GC [101].

Many OCPs on the SC list are optically active or have chiralsomers (e.g., o,p′-DDT, �- and �-chlordane and chiral isomers ofoxaphene). There are also 19 PCB congeners that are chiral byirtue of restricted rotation at the central biphenyl bond. A chi-al capillary GC column combined with a non-chiral GC column toake a tandem capillary system provides further separation of chi-

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

al compounds [102–104]. The enantiomeric degradation of PCBxpressed as the enantiomeric excess, was used by Wong et al.103] to identify the difference between urban and rural degra-ation rates. The transformation rates of POPs within a food web

able 4xamples of interference problem of POPs analysis by HRMS.

Target analytes

Formula Exact mass

PCDF vs. PCDE Tetra-CDF C12H435Cl4O 303.9016

C12H435Cl337ClO 305.8987

PCB vs. PBDE Penta-CB C12H535Cl437Cl 325.8804

C12H535Cl337Cl2 327.8775

/MS Similar as LRMS; 2 pgby PTV injector

Comparable sensitivity to EI-LRMS

were calculated by using enantiomer ratios in predators and preyspecies [104].

4. Brominated POPs

4.1. Polybrominated diphenyl ethers

4.1.1. IntroductionBrominated flame retardants (BFRs) have been used for many

years in commercial products including sleepwear, foam chaircushions, plastics, textile coatings and electronics. The SC addedtetrabromodiphenyl ethers (e.g. BDE-47) and pentabromodiphenylethers (e.g. BDE-99) in commercial “Penta-BDE”, as well ashexabromodiphenyl ethers (e.g. BDE-153 and BDE-154) and hep-tabromodiphenyl (e.g. BDE-175 and BDE-183) in commercial“Octa-BDE” in Annex A in 2009, together with hexabromobiphenyl.The only current in-production PBDE is the “Deca-BDE” that isexclusively BDE-209 (97%). The EU commissioned study indicatedthat “no further action” was required for the use of deca-BDE mix-ture due to its facile debromination and therefore was considerednot persistent. However, it has been argued that BDE-209 maybe converted into nona- and tetra-BDEs and even polybrominateddibenzofurans in the presence of UV light [105] and hydrolyzedwith sodium methoxide [106].

4.1.2. Sample preparationPBDEs are commonly sampled, extracted, purified and quanti-

fied by the same strategies established previously for conventionalchlorinated POPs [107–110]. The simultaneous determination ofboth chlorinated contaminants and PBDEs in various matrices arecommonly applied as well [111–115]. For example, miniaturizedPLE couple with in-cell purification can extract PCBs and tri- todeca-BDEs simultaneously from feed matrices with recoveries of86–114%, with only 0.25 g of sample and 8 mL solvent consumed[114]. It is noteworthy that the widely occurred highly chlorinatedPBDEs (e.g. BDE-209) are relatively unstable and their breakdownduring sampling, storage and analysis may cause potential over-

ersistent organic pollutants identified in the Stockholm Convention:026

estimation of the low chlorinated congeners [116]. Thus the useof brown bottles during sample storage, optimized the extractionparameters and minimized steps of cleanup are especially impor-tant Wang et al. [117] evaluated various extraction techniques and

Interference

Formula Exact mass

Hexa-CDE C12H435Cl4O ([M-2Cl]+) 303.9016

C12H435Cl337ClO ([M-2Cl]+) 305.8987

Tri-BDE C12H8O79Br2 ([M-Br]+) 325.8942C12H8O79Br81Br ([M-Br]+) 327.8922

Page 8: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ING Model

A

8 imica

farf[

4

bodtiOimtc[cm

detgupcaswMP0wPispptac

4

imm[alMohfcmdcesia

ARTICLECA-232528; No. of Pages 13

W. Xu et al. / Analytica Ch

ound that the high temperatures and pressures that were usu-lly preferred by MAE and PLE for chlorinated POPs may cause lowecovery of nona-BDE and deca-BDE. A standard analytical methodor PBDEs in environmental and tissue samples is also available118].

.1.3. Instrumental analysisFor GC analysis, a high inlet temperature (325 ◦C), was found to

e optimal to prevent discrimination effects but a significant lossf high brominated congeners were noticed [119]. Thermal degra-ation can be minimized by using short, narrow GC columns withhin films, moderate injector and column temperatures, and shortnjector residence times by using pressure-pulse splitless injection.perating parameters of programmable temperature vaporization

nlet was investigated [120]. The loss of injected PBDEs can beinimized by lowering initial and elevating final inlet tempera-

ure. The elution order of 126 PBDEs from seven different capillaryolumns with various film thicknesses was summarized by Korytár121]. DB-XLB (30 m, 0.25 mm, 0.25 um) was found to be the besthoice for separating many BFRs but a greater degradation of higholecular weight PBDEs was observed.GC coupled with EI-MS, especially HRMS, provides a reliable

etection method for PBDEs. Two ion masses are monitored atach level of bromination in the SIM mode. Both GC retentionime and MS ion ratio may be used to identify individual con-eners and reduce potential interference. ECNI-MS is also widelysed in PBDEs analysis, although co-extracted brominated com-ounds like MeO-BDE may cause interference. This soft ionizationannot discriminate 13C- and 2H-labeled PBDEs from the nativenalytes when negative Br ions are monitored. 81Br-labeled PBDEtandards were therefore utilized for PBDE determination in riverater matrices and validated by SRM 1947 fish tissue [122,123].ackintosh et al. compared triple quadrupole MS and HRMS on

BDEs determination [124]. The LOD of various congeners were.04–41 and 5–85 pg, respectively. Liquid chromatography coupledith MS (LC–MS) has been adapted as an alternative method for

BDEs analysis. Debrauwer et al. [125] found that electrospray ion-zation (ESI) and atmospheric pressure chemical ionization (APCI)howed a poor response to PBDEs, but that atmospheric pressurehoto ionization (APPI) MS/MS gave better results for mono toenta-BDEs in the positive ion mode, and hexa- to deca-BDEs inhe negative ion mode. Lagalante and Oswald [126] established annalytical method by using LC-APPI-MS/MS to analyze eight PBDEongeners in dust with a LOD of 2.4–27.8 pg.

.2. Hexabromocyclododecane

Concern has been extended to other BFRs, including HBCD thats currently a candidate for POPs. There are 16 potential stereoiso-

ers, six diastereomeric pairs and enantiomers, as well as foureso forms of HBCD, but only three predominant diastereomers

(±)�-, (±)�- and (±)�-HBCDs] are commonly analyzed [127]. Thenalysis of HBCD has only been carried out by a small number ofaboratories. Initially, total HBCD was analyzed by GC or GC-ECNI-

S, together with the PBDEs. However, isomer inter-conversionccurring in the inlet system and in the MS source due to theirigh temperatures may give rise to misleading results [128]. There-

ore, reversed-phase LC–MS/MS is the preferred choice for theseompounds, especially for the analysis of the specific stereoiso-ers (�-, �- and �-HBCDs). The enantiomers of the three prevalent

iastereomers can be isolated by using an enantio-selective LCombined with MS/MS [129]. To avoid matrix and/or instrument

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

ffects, isotopically labeled surrogate species were used [130]. Suchpecific analysis of selected enantiomers has been widely appliedn a variety of environmental matrices, such as sediments, fishnd predatory bird eggs [131–133]. The sensitivity of the LC–MS

PRESS Acta xxx (2013) xxx– xxx

method, is however about 10 times less than that of GC-ECNI-MS,making it less suitable for analyzing samples with extremely lowHBCD concentrations.

There is no currently available reference material, which hindersanalytical method validation for HBCD analysis. The interlaboratorycomparison studies has resulted in satisfactory quality (RSD < 35%),but the analysis of samples at low levels (<2 ng g−1 lipid weight)needs to be improved [134]. Haug et al. concluded that there wasno statistically significant difference of total HBCD concentrationsbetween GC-ECNI-MS and LC–MS/MS results, although the individ-ual isomeric concentrations had to be determined by LC–MS.

5. Per- and polyfluoroalkylated substances

PFAS consist of a hydrophobic C4–C18 alkyl chain and ahydrophilic functional group. Their high stabilities come from thestrong chemical bond (C–F), making some of them ubiquitousin the environment, wildlife and human blood [135–137]. PFASconsist of neutral PFAS and ionic PFAS, including perfluoroalkyl car-boxylic acids (PFCA) and perfluoroalkyl sulfonic acids (PFSA). Unlikethe non-polar POPs, ionic PFAS can only be distributed to distantregions via water flow, while neutral PFAS can undergo airbornedistribution. An important congener group of PFSA is perfluorooc-tane sulfonic acid (PFOS, C8F17SO3H) as well as its salts and itsprecursor (perfluorooctane sulfonyl fluoride or PFOSF) all of whichhave been banned by the SC in 2009.

Many articles on ionic PFAS determination in a variety of matri-ces have been published during the past 10 years, along with somereviews [8,138–141]. As well as the conventional sample prepa-ration techniques, SPE was preferred for extraction and cleanupfor the analysis of ionic PFAS, including PFOS and perfluorooctanicacid (PFOA). A weak anion-exchange SPE was considered best forthe analysis of short-chain PFAS and LLE was preferred for thelonger chains (>C10) [139,141]. In addition, a graphitized carbon-based cleanup (such as EnviCarbTM SPE column) has proved to beeffective for the removal of interferences. Isotopically labeled inter-nal standards are highly recommended for LC–MS analysis, thoughimpurity problems was reported and discussed [138].

5.1. Perfluorooctane sulfonic acid and its salts

PFOS and PFOA have been shown to be the dominant PFAS insea water, wastewater and even drinking water. Most methodsreported for PFOS analysis have been targeted on aqueous sam-ples. The use of glassware during sampling and sample preparationis avoided for PFOS analysis because background interferences aresuspected to be adsorbed onto glass. Fluoropolymeric material isavoided during the entire analytical process because of poten-tial background contamination and a pre-column can be installedbefore injection port to separate target analytes in backgroundand samples. Polypropylene or polyethylene materials are recom-mended instead, and all containers should be washed by polaror semi-polar solvents prior to their use [142]. SPE is widelyapplied for extraction and cleanup for water matrices [143–147].Besides the standardized pretreatment, automated techniqueshave been applied. Automated online SPE with LC–MS achievedLOD of 3–15 pg mL−1 for various aqueous matrices [147]. Sim-ilarly, automated, in-tube SPME coupled with LC–MS has alsobeen developed for PFOA and PFOS analyses with LOD of 1.5 and3.2 pg mL−1, respectively [148]. LC coupled with ESI- or APCI-MSanalysis has been proposed as the standard method for PFOS and its

ersistent organic pollutants identified in the Stockholm Convention:026

salts. The majority of reports employed negative mode LC–MS/MSor UPLC–MS/MS due to their higher sensitivity and selectivity[143–147]. UPLC–MS/MS and capillary LC–MS were favored bycompared with HPLC–MS/MS for shorter elution time, better LODs

Page 9: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ARTICLE ING Model

ACA-232528; No. of Pages 13

W. Xu et al. / Analytica Chimica

auitfeaPw

thsps(sweetpwctP

5

B∼mPdttoit

TibrbfwM

5

i

Fig. 1. Derivatization and detection of PFOSF by using LC/MS [143].

nd linearity [146]. A triple quadrupole MS is the most commonlysed instrument for the quantification of PFOS. Ion pairs of [M-H]−

ons with [FSO3]− ions at m/z 99 are often used for multiple reac-ion monitoring [149]. It should be noted that the most abundantragment ion at m/z 80 is not selected due to its significant interfer-nce from environmental and biota matrices. Application of matrixssisted laser desorption ionization (MALDI) time-of-flight MS onFCAs and PFSAs were investigated [150]. Better LOD (0.015 ng L−1)as demonstrated compared to HPLC–MS/MS (0.036 ng L−1).

Unlike aromatic POPs, PFSAs are aliphatic chemicals poten-ially having branched isomers. Riddell et al. [151] analyzed twouman serum standard reference materials and showed sub-tantial differences of PFOS isomer patterns, demonstrating aotential application of isomer-specific analysis on the exposureource assessment. The dominant percentage of linear isomerse.g. 59–68% linear PFOS by Karrman et al.) was confirmed ineveral recent papers [152–155]. Enantiomer fractions of PFOSere noticed as a potential source for contaminant tracking. Wang

t al. [137] applied a novel chiral LC–MS/MS method for thenantiomers of �-perfluoromethyl branched PFOS (1m-PFOS) inhe sera samples of pregnant women and highly exposed peo-le. Two Chiralpak QN-AX columns that contain a quinine-basedeak anion-exchange site situated in a chiral environment were

onnected in tandem for the separation. Observation of the enan-iomers fraction of the samples suggested that human exposure toFOS mainly comes from precursors [137].

.2. Perfluorooctane sulfonyl fluoride

PFOSF is a major precursor of PFOS and is included in Annex of the SC. Its commercial production was estimated to be100,000 tons, and up to 45,250 tons were released to the environ-ent during the period 1970–2002 [156]. It is hypothesized that

FOSF may potentially degrade to PFOS in the presence of wateruring its life cycle. However, the environmental level, transporta-ion and degradation of PFOSF are still not well understood due tohe lack of a reliable analytical method. Direct analysis by GC–MSr LC–MS did not show chromatographic signals for PFOSF eithern the positive or negative ion modes [157], and this was attributedo the absence of an ionizable functional group.

Sun et al. [158] have recently reported a new analytical method.hey used benzylamine as a derivatising agent to react with PFOSFn dichloromethane (Fig. 1). The products, including linear andranched benzylperfluorooctane-1-sulfonamides were then sepa-ated and measured by LC–MS. By using this method, PFOSF coulde detected with an absolute detection limit of 2.5 pg. It was alsoound that PFOSF responded to an ECD detector, but the chemicalas not well retained by a variety of GC columns (DB-5, DB-1 andEGA WAX).

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

.3. Interlaboratory studies

The 1st worldwide interlaboratory comparison of 13 ionic PFASn water, fish and human sera were organized by van Leeuwen

PRESS Acta xxx (2013) xxx– xxx 9

et al. [159] in 2005 and 2006, and it demonstrated relativelypoor results. However, a significant improvement of data accu-racy and precision were obtained in the second round, due tothe improved access to standard compounds, well-adapted samplepreparation and appropriate instrumental analysis. Linstrom et al.[160] and van Leeuwen et al. [161] stated that experienced labora-tories worldwide were capable of determining the most prevalentPFAS in human blood. The accuracy (coefficient of variation of25–30%) improved considerably and this was attributed to theutilization of well-defined native- and isotope-labeled standardsand the improved experience of the participants. Quantificationwith a solvent-based calibration curve using labeled internal stan-dards was recommended for better precision, compared with theprevious standard addition quantification method [161]. Similarachievements were obtained in another study of human serum[162]. Standard reference materials for the validation of ionic PFASlevel in human serum and milk have been produced by NIST [163].

6. Future perspectives

6.1. Improvements of environmental analysis

Although the technologies for the analysis of trace levels of POPshave been well developed for decades, they are currently beingimproved for quick, low cost and environmental-friendly perfor-mance [164,165]. Novel passive sampling techniques (e.g. SPME,SPMD) have been adopted for their low environmental impactand low cost, which are especially important for analytical labo-ratories in developing countries, and consequently making globalmonitoring possible. The automation and consequent integration ofextraction, cleanup and quantification simplified the pretreatmentprocedures to a 1-day process with low solvent consumption. Oneof the advantages of PLE and MAE is that they are easy to automate.Combined with automated purification columns, the high through-put integration may allow the simultaneously sample preparationfor various POPs groups to be completed with satisfactory results[166–168]. The high costs of equipment and its maintenance hin-ders its applications, unless large numbers of samples are to beprepared.

Another trend is to reduce organic solvent consumption dur-ing sample preparation, e.g. the use of surfactants rather than anorganic solvent during extraction, is known as cloud point extrac-tion (CPE) [169]. Because CPE does not require a high temperatureduring extraction, isomerizations can be avoided, which is signifi-cant for the numerous diastereomers of POPs. Kajiwara et al. [170]compared Soxhlet, UAE and CPE extraction of HBCD and discov-ered that the �- and �-HBCD ratio varied when high temperatureextraction was used, and therefore CPE was chosen as a better pro-cedure. Extraction of POPs by surfactants can be applied not onlyin analysis but also in environmental remediation, because it doesnot consume organic solvents [171].

For complex aqueous samples, liquid–liquid partitioning basedmicroextraction employed micro-drops added from a needle tipto a stirred aqueous sample. The extracting syringe, a novel,membrane-based sample preparation technique has been appliedto OCPs analysis in leachate water and slurry. The recovery resultsshow good agreement with traditional Soxhlet and PLE techniques.The total consumption of organic solvent by the extracting syringewas reduced to only 4.2 mL, compared with 420 and 18 mL ofSoxhlet and PLE, respectively [172].

Advanced GC that may be potentially applicable to the analysis

ersistent organic pollutants identified in the Stockholm Convention:026

of POPs includes the commercial availability of two-dimensionalGC (GC × GC) and “fast GC”. In the comprehensive two-dimensionalGC, all of the analyte mass is transferred to a second column, andthus the resolving power is increased by an order of magnitude,

Page 10: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ARTICLE IN PRESSG Model

ACA-232528; No. of Pages 13

10 W. Xu et al. / Analytica Chimica Acta xxx (2013) xxx– xxx

Table 5Potential POPs under review by POPRC of Stockholm Convention.

Item Chemicals CAS no. Type Isomers and homologues

1 Short-chain chlorinated paraffins – Industrial Chlorinated alkanes (C10–13), chloro- (50–70%)2 Hexabromocyclododecane 25637-99-4 BFR �, � and �-isomers

IBP

mpcocPt[a

6

sSswacabcn(roi[fto[

ipttchfmciwrbCfcilabtcg

3 Chlorinated naphthalenes –

4 Hexachlorobutadiene 87-68-3

5 Pentachlorophenol, salts and esters –

aking possible the analysis of complicated mixtures. For exam-le, 192 PCB congeners were separated within 142 min [173]. Byombining with TOFMS, both comprehensive screening of numer-us classes of pollutants and quantitative analysis of individualompounds were achieved, making it a powerful tool for potentialOPs discovery [174,175]. However, the rich but complex informa-ion provided by GC × GC makes data interpretation complicated176,177]. Both GC × GC and “fast GC” techniques can be run withn ECD detector and are thus relatively inexpensive.

.2. Potential POPs

Great achievements have been accomplished for the global mea-urement and regulation of POPs following the ratification of theC. However, the list of chemicals measured by the SC is only amall fraction of the approximately 30,000 chemicals in world-ide commercial use, some of which are potential POPs. The global

greement is aware of this gap and defines criteria for new POPsandidates in terms of their persistence, long-range transport, bio-ccumulation and toxicity [178]. The chemicals under evaluationy POPRC can be found on the SC website [179], they include short-hain chlorinated paraffins (C10–13, SCCPs), HBCD, polychlorinatedaphthalenes (PCN), hexachlorobutadiene and pentachlorophenolPCP) (Table 5). These chemicals have been the subjects of intenseesearch and monitoring over the past decade. Some halogenatedrganics, cyclic siloxanes and substituted aromatics have beendentified as potential risks in the environment and food chain180]. Therefore, an expansion of the scope of analytical methodsor the emerging and potential POPs is required soon. For example,he “Analog” approach has been applied to assess the occurrencesf PCN and chlorinated paraffins in the environment and in biota181,182].

Information on the environmental distribution and fate of SCCPs relatively limited, which is partially due to its very complex com-osition (>10,000 isomers, enantiomers and diastereomers) andhe present lack of suitable analytical methods [183]. Althoughhe sample treatment of SCCP is similar to that of conventionalhlorinated POPs, accurate and specific instrumental analysis isighly demanding. EI-MS/MS analysis cannot differentiate SCCPs

rom longer carbon chain homologues due to their similar frag-entation patterns and thus was only used to determine the sum of

hlorinated paraffins [184,185]. As a highly sensitive and selectiveonization method for halogenated chemicals, ECNI-HRMS coupled

ith GC could eliminate the potential interference of other chlo-inated pollutants [186]. ECNI-LRMS is more commonly appliedecause of the low cost of such instrumentation, in which the [M-l]− ion was monitored in the SIM mode. However, interference

rom medium-length chain chlorinated paraffins (MCCP) and otherhlorinated compounds is a major concern for LRMS analysis, asllustrated by Reth and Oehme [187]. The SCCP peaks may over-ap with congeners having the same nominal mass. For example,nalysis of C10H16

37Cl35Cl5 of SCCP at m/z 312.9 is interfered with

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

y C15H2835Cl4 of MCCP at m/z 313.1. With the improved quan-

ification procedure [188], this problem was removed and the CPoncentration can be reported, based on individual homologueroups for the evaluation of the origin, environmental fate and

ndustrial 75 congenersy-product –esticide and industrial Various salts and esters

biological modification [184,185,189]. An interlaboratory compar-ison for soil matrices was held and the large deviation of thereported results confirmed the difficulties of SCCP analysis [190].A successful interlaboratory comparison of SCCP in water was heldin 2011. By using GC-ECNI-MS for the quantification of the sum ofSCCPs having a chlorine content of 49–67%, a standard deviationof approximately 20% was achieved among the 17 participatinglaboratories [191]. Another major challenge of SCCP analysis byECNI-MS is that their response factor depends strongly on the levelof chlorination. The congener groups having a low number of chlo-rine atoms (1–4) often cannot be detected [188]. Moore et al. [192]utilized metastable atom bombardment ionization for the analy-sis of SCCP and the MS spectra of low chlorinated species wereobtained. To the best knowledge of the authors however, there iscurrently no validated analytical technique to determine the lowchlorinated SCCP, although they may be a non-negligible portionof the total concentration. Moreover, the separation of individualisomers from the complex mixture is an even greater challenge.

After the ban of PBDEs production, “novel” brominatedflame retardants have become their replacements in the electricand consumer product industries, compounds such as 1,2-bis(pentabromodiphenyl)ethane, 1,2-bis(2,4,6-tribromophenoxy)ethane etc. The environmental occurrence and long-range trans-portation of these new BFRs have recently been reported [193,194].However, because the current analytical methodologies are mainlyoptimized and validated for traditional BFRs (PBDEs, HBCDs andtetrabromobisphenol A/TBBPA), the reliability of the new BFRs dataneeds to be verified. The lacks of appropriate internal standards,standard reference materials and interlaboratory comparisons aremajor obstacles for future environmental research [195]. Yeunget al. [196] suggested the presence of other forms of organic fluorinein addition to known perfluorinated compounds by mass balanceanalysis. Extractable organic fluorine was determined by combus-tion ion chromatography and the mean concentration of knownPFAS was only 56%. Therefore, the screening of more POPs is anothermajor challenge to environmental analytical chemists.

7. Conclusions

This review has explored the merits and development of analyti-cal chemistry in the Stockholm Convention of POPs over the last fewyears. POPs are bio-accumulative through the food web and theiradverse effects on wildlife and humans are very serious concerns.As the result of academic research and public interest, SC bannedthe production and use of 12 categories of POPs in 2004, includingOCPs, PCBs and PCDD/Fs. The analytical studies of POPs (especiallyfor those listed by the SC) have improved significantly and interlab-oratory QA/QC analysis of POPs in various matrices has aided thereliabilities of analytical methods and provided new data for inter-national monitoring programs. Conventional analytical methods oforganic pollutants have been mainly based on Soxhlet extractionand GC-ECD. With the fast development of chromatography and

ersistent organic pollutants identified in the Stockholm Convention:026

mass spectrometry, congener-specific analysis has become a main-stream method. The analysis of PCDD/PCDFs at trace levels is nowroutine due to the advancement of HRGC-HRMS. The analysis ofPBDEs is similar to that of chlorinated POPs because they share

Page 11: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ING Model

A

imica

sdsrPi

taRPtPafba

A

OTGeK(

R

ARTICLECA-232528; No. of Pages 13

W. Xu et al. / Analytica Ch

imilar physico-chemical properties. However, highly brominatediethyl ether is easily degraded at elevated temperatures if theame analysis is applied. HBCD is listed as a potential POPs undereview by POPRC. The analysis of HBCDs is different from the OCPs,CBs and PCDD/PCDFs. LC is commonly used for the separation,nstead of GC.

Fluorinated POPs are quite different from other POPs becausehey are water-soluble or even exist as anions. Currently, only PFOSnd its salts and their precursor PFOSF were included in the SC list.esearch on the distribution and transportation of the fluorinatedOPs relies greatly on analytical chemistry. LC–MS/MS has becomehe standard technique for the analyses of PFSA and PFCA includingFOS and PFOA. However, the analytical challenge still remains for

direct analysis of PFOSF. Other great challenges are also posedor potential POPs, including SCCPs that are currently under reviewy POPSC. Although their toxicities are still in doubt, appropriatenalytical strategies should be developed in advance.

cknowledgments

The authors would like to thank Dr. John L. Holmes (University ofttawa, Canada) for his valuable comments and help in English edit.he authors also thank the financial supports by Faculty Researchrant from Hong Kong Baptist University (FRG2/11-12/118), Gen-ral Research Grant from the Research Grant Committee of Hongong SAR (HKBU200310), National Sciences Foundation of China

NSFC21175025 and NSFC21275267).

eferences

[1] Updated 2013 Feb., http://www.pops.int[2] Updated 2013 Feb., http://www.nemi.gov[3] H.P. Tang, Trends Anal. Chem. 45 (2013) 48–66.[4] M. Kosikowska, M. Biziuk, Trends Anal. Chem. 29 (2010) 1064–1072.[5] I. Fulara, M. Czaplicka, J. Sep. Sci. 35 (2012) 2075–2087.[6] D. Muir, R. Lohmann, Trends Anal. Chem. (2013), http://dx.doi.org/

10.1016/j.trac.2012.12.019.[7] S. Salihovic, H. Nilsson, J. Hagberg, G. Lindström, Trends Anal. Chem. (2013),

http://dx.doi.org/10.1016/j.trac.2012.06.009.[8] A. Kärrman, G. Lindström, Trends Anal. Chem. (2013), http://dx.doi.org/

10.1016/j.trac.2012.10.009.[9] M.E. Honeycutt, V.A. Mcfarland, D.D. Mccant, Bull. Environ. Contam. Toxicol.

55 (1995) 469–472.[10] G. Ewald, G. Bremle, A. Karlsson, Mar. Pollut. Bull. 36 (1998) 222–230.[11] Guidance on the global monitoring plan for persistent organic pollutants,

preliminary version, UNEP, Feb. 2007.[12] UNEP/POPS/COP.5/INF/27 Draft revised guidance on the global monitoring

plan for persistent organic pollutants, UNEP, March 2011.[13] UNEP/POPS/COP.4/33, Global monitoring report under the global monitoring

plan for effectiveness evaluation, UNEP, Jan. 2009.[14] UNEP/POPS/COP.4/INF/19, Regional monitoring reports under the global

monitoring plan for effectiveness evaluation, UNEP, Mar. 2009.[15] A. Colles, G. Koppen, V. Hanot, V. Nelen, M.C. Dewolf, E. Noel, R. Malisch,

A. Kotz, K. Kypke, P. Biot, C. Vinkx, G. Schoeters, Chemosphere 73 (2008)907–914.

[16] A.J. Hedley, L.L. Hui, K. Kypke, R. Malisch, F.X.R. van Leeuwen, G. Moy, T.W.Wong, E.A.S. Nelson, Chemosphere 79 (2010) 259–265.

[17] Chemical Branch, UNEP, UNEP-coordinated Survey of Mothers’ Milkfor Persistent Organic Pollutants – guidelines for organization, samp-ling and analysis, Updated 2012, http://www.chem.unep.ch/pops/GMP/Mothers milk guide POPs.pdf

[18] C.A. De Wit, D. Muir, Sci. Total Environ. 408 (2010) 2852–2853.[19] USEPA, Method 1668 Revision B: Chlorinated biphenyls in water, soil, sedi-

ment and tissues by HRGC-HRMS, 2008.[20] B. Van Bavel, E. Abad, Anal. Chem. 80 (2008) 3956–3964.[21] Updated, Feb. 2013, http://www.quasimeme.org/[22] H. Fiedler, E. Abad, B. van Bavel, J. de Boer, C. Bogdal, R. Malisch, Trends Anal.

Chem. (2013), http://dx.doi.org/10.1016/j.trac.2013.01.010.[23] S.P.J. Van Leeuwen, B. Van Bavel, J. De Boer, Trends Anal. Chem. (2013),

http://dx.doi.org/10.1016/j.trac.2012.12.020.

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

[24] M. Abalos, E. Abad, S.P.J. van Leeuwen, J. de Boer, S.P.J. van Leeuwen, M.Abalos, G. Lindström, B. van Bavel, H. Fiedler, Trends Anal. Chem. (2013),http://dx.doi.org/10.1016/j.trac.2012.11.003.

[25] H.A. Leslie, J. de Boer, B. van Bavel, E. Abad, Trends Anal. Chem. (2013),http://dx.doi.org/10.1016/j.trac.2013.01.009.

PRESS Acta xxx (2013) xxx– xxx 11

[26] J. de Vos, L. Quinn, C. Roos, R. Pieters, H. Bouwman, P.G. Allman, E.Rohwer, J.P. Giesy, Trends Anal. Chem. (2013), http://dx.doi.org/10.1016/j.trac.2013.02.003.

[27] S.P.J. Van Leeuwen, H.A. Leslie, J. De Boer, S.P.J. Van Leeuwen, B. Van Bavel,E. Abad, H. Fiedler, Trends Anal. Chem. (2013), http://dx.doi.org/10.1016/j.trac.2013.01.008.

[28] V. Lal, W. Aalbersberg, H. Fiedler, B. van Bavel, J. de Boer, Trends Anal. Chem.(2013), http://dx.doi.org/10.1016/j.trac.2012.12.018.

[29] G. Liu, M. Zheng, G. Jiang, Z. Cai, Y. Wu, Trends Anal. Chem. (2013),http://dx.doi.org/10.1016/j.trac.2012.05.012.

[30] P. Korytár, L.L.P. van Stee, P.E.G. Leonards, J. de Boer, U.A.T. Brinkman, J. Chro-matogr. A 994 (2003) 179–189.

[31] D. Hainzl, J. Burhenne, H. Barlas, H. Parlar, Fresenius J. Anal. Chem. 351 (1995)271–285.

[32] J. de Boer, M. Oehme, K. Smith, D.E. Wells, Chemosphere 41 (2000)493–497.

[33] EU/CEN, Stationary source emissions – determination of the mass concentra-tion of PCDDs/PCDFs and dioxin-like PCBs, EN-1948, 2006.

[34] Japanese Industrial Standard Committee, Method for determination oftetra-through octachlorodibenzo-p-dioxins, tetra-through octachlorodiben-zofurans and dioxin-like polychlorinatedbiphenyls in stationary sourceemissions, JIS K 0311, 2005.

[35] B. Zhang, L. Zhang, J. Wu, G. Liu, M. Zheng, Bull. Environ. Contam. Toxicol. 87(2011) 1–5.

[36] K. Pozo, T. Harner, F. Wania, D.C.G. Muir, K.C. Jones, L.A. Barrie, Environ. Sci.Technol. 40 (2006) 4867–4873.

[37] K. Pozo, T. Harner, M. Shoeib, R. Urrutia, R. Barra, O. Parra, S. Focardi, Environ.Sci. Technol. 38 (2004) 6529–6537.

[38] J. Thomas, T.M. Holsen, S. Dhaniyala, Environ. Pollut. 144 (2006) 384–392.[39] T. Harner, M. Shoeib, M. Diamond, G. Stern, B. Rosenberg, Environ. Sci. Technol.

38 (2004) 4474–4483.[40] M. Shoeib, T. Harner, Environ. Sci. Technol. 36 (2002) 4142–4151.[41] W.A. Ockenden, H.F. Prest, G.O. Thomas, A. Sweetman, K.C. Jones, Environ. Sci.

Technol. 32 (1998) 1538–1543.[42] W.A. Ockenden, B.P. Corrigan, M. Howsam, K.C. Jones, Environ. Sci. Technol.

35 (2001) 4536–4543.[43] S. Genualdi, S.C. Lee, M. Shoeib, A. Gawor, L. Ahrens, T. Harner, Environ. Sci.

Technol. 44 (2010) 5534–5539.[44] X. Li, Y. Li, Q. Zhang, P. Wang, H. Yang, G. Jiang, F. Wei, Chemosphere 84 (2011)

957–963.[45] Y. Moussaoui, L. Tuduri, Y. Kerchich, B.Y. Meklati, G. Eppe, Chemosphere 88

(2012) 270–277.[46] T. Harner, K. Pozo, T. Gouin, A. Macdonald, H. Hung, J. Cainey, A. Peters, Envi-

ron. Pollut. 144 (2006) 445–452.[47] S. Choi, S. Baek, Y. Chang, F. Wania, M.G. Ikonomou, Y. Yoon, B. Park, S. Hong,

Environ. Sci. Technol. 42 (2008) 7125–7131.[48] C. Bogdal, M. Scheringer, E. Abad, M. Abalos, B. van Bavel, J. Hagberg, H. Fiedler,

Trends Anal. Chem. (2013), http://dx.doi.org/10.1016/j.trac.2012.05.011.[49] L. Charlestra, D.L. Courtemanch, A. Amirbahman, H. Patterson, Chemosphere

72 (2008) 1171–1180.[50] B. Zhang, P.N. Smith, T.A. Anderson, J. Chromatogr. A 1101 (2006) 38–45.[51] G. Durell, T.R. Utvik, S. Johnsen, T. Frost, J. Neff, Mar. Environ. Res. 62 (2006)

194–223.[52] N. Degger, V. Wepener, B.J. Richardson, R.S.S. Wu, Mar. Pollut. Bull. 63 (2011)

91–97.[53] A.K. Wasik, B. Zabiegala, M. Urbanowicz, E. Dominiak, A. Wasik, J. Namiesnik,

Anal. Chim. Acta 602 (2007) 141–163.[54] D. Kozul, S.H. Romanic, Z.K. Gaspic, J. Veza, Environ. Monit. Assess. 179 (2011)

325–333.[55] C. Mugnai, S. Giuliani, L.G. Bellucci, C. Carraro, M. Favotto, M. Frignani, Environ.

Monit. Assess. 181 (2011) 243–254.[56] M. Söderström, K. Nylund, U. Järnberg, T. Alsberg, L. Asplund, Chemosphere

58 (2005) 355–366.[57] M.D. Luque de Castro, F. Priego-Capote, J. Chromatogr. A 1217 (2010)

2383–2389.[58] USEPA, Method 3540C: soxhlet extraction, 1996.[59] USEPA, Method 1613: tetra- through octa- chlorinated dioxins and furans by

isotope dilution HRGC/HRMS, 1994.[60] A. Hubert, K.D. Wenzel, M. Manz, L. Weissflog, W. Engewald, G. Schüürmann,

Anal. Chem. 72 (2000) 1294–1300.[61] USEPA, Method 3545A: pressurized fluid extraction (PFE), 2007.[62] USEPA, Method 3546: microwave extraction, 2007.[63] USEPA, Method 3550C: ultrasonic extraction, 2007.[64] USEPA, Method 3562: supercritical fluid extraction for polychlorinated

biphenyls and organochlorine pesticides, 2007.[65] E. Spinnel, C. Danielsson, P. Haglund, Anal. Bioanal. Chem. 390 (2008)

411–417.[66] J.L.M. Vidal, A.G. Frenich, M.N.B. Bonilla, R.R. Gonzalez, J.A.P. Sanchez, Anal.

Bioanal. Chem. 395 (2009) 1551–1562.[67] M.I.H. Helaleh, A. Al-Rashdan, A. Ibtisam, Talanta 94 (2012) 44–49.[68] B. Subedi, S. Usenko, J. Chromatogr. A 1238 (2012) 30–37.

ersistent organic pollutants identified in the Stockholm Convention:026

[69] P.N. Carvalho, P.N.R. Rodrigues, F. Alves, R. Evangelista, M.C.P. Basto, M.T.Vasconcelos, Talanta 76 (2008) 1124–1129.

[70] E.C. Grana, V.F. Gonzalez, G.G. Noche, S.M. Lorenzo, P.L. Mahia, E.F. Fernandez,D.P. Rodriguez, Chemosphere 79 (2010) 698–705.

[71] USEPA, Method 3510C, Separatory funnel liquid-liquid extraction, 1996.

Page 12: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ING Model

A

1 imica

ARTICLECA-232528; No. of Pages 13

2 W. Xu et al. / Analytica Ch

[72] Japanese Industrial Standard Committee, Method for determination oftetra-through octachlorodibenzo-p-dioxins, tetra-through octachlorodiben-zofurans and dioxin-like polychlorinatedbiphenyls in industrial water andwaste water, JIS K 0312, 2005.

[73] USEPA, Method 1668B, Chlorinated biphenyl congeners in water, soil, sedi-ment, biosolids and tissue by HRGC/HRMS, 2008.

[74] P. Ayotte, E. Dewailly, J.J. Ryan, S. Bruneau, G. Lebel, Chemosphere 34 (1997)1459–1468.

[75] E.R. Burke, A.J. Holden, I.C. Shaw, Chemosphere 50 (2003) 529–535.[76] J. Hu, L.Y. Fu, X.N. Zhao, X.J. Liu, H.L. Wang, X.D. Wang, L.Y. Dai, Anal. Chim.

Acta 640 (2009) 100–105.[77] X. Wang, Q.C. Xu, C.G. Cheng, R.S. Zhao, Chromatographia 75 (2012)

1081–1085.[78] S.Y. Wei, M.I. Leong, Y. Li, S.D. Huang, J. Chromatogr. A 1218 (2011) 9142–9148.[79] USEPA, Method 3535A, Solid-Phase Extraction (SPE), 2007.[80] F.X. Yang, S.W. Jin, D.Y. Meng, Y. Xu, Chemosphere 81 (2010) 1000–1005.[81] S. Usenko, K.J. Hageman, D.W. Schmedding, G.R. Wilson, S.L. Simonich, Envi-

ron. Sci. Technol. 39 (2005) 6006–6015.[82] C.D. Sandau, A. Sadin, M.D. Davis, J.R. Barr, V.L. Maggio, A.L. Waterman, K.E.

Preston, J.L. Preau, D.B. Barr, L.L. Needham, D.G. Patterson, Anal. Chem. 75(2003) 71–77.

[83] N.F. Used, E.B. Gonzalez, A.S. Medel, Anal. Chim. Acta 590 (2007) 1–16.[84] F.M. Tang, Y.W. Ni, H.J. Zhang, Y. Li, J. Jin, L.X. Wang, J.P. Chen, Anal. Chim. Acta

729 (2012) 73–79.[85] USEPA Method 8270D: semivolatile organic compounds by gas chromatog-

raphy/mass spectrometry (GC/MS), 2007.[86] EU/CEN 12766: petroleum products and used oils—determination of PCBs and

related products, 2004.[87] EU/CEN 61619: insulating liquids—contamination by polychlorinated

biphenyls (PCBs)—method of determination by capillary column gas chro-matography, 1997.

[88] Japanese Industrial Standard Committee, Testing method for polychloro-biphenyl in industrial water and wastewater, JIS K 0093, 2006.

[89] J.W. Cochran, G.M. Frame, J. Chromatogr. A 843 (1999) 323–368.[90] A.M. Muscalu, E.J. Reiner, S.N. Liss, T. Chen, Int. J. Environ. Anal. Chem. 90

(2010) 1–13.[91] L.R. Bordajandi, J.J. Ramos, J. Sanz, M.J. González, L. Ramos, J. Chromatogr. A

1186 (2008) 312–324.[92] D.G. Patterson Jr., S.M. Welch, W.E. Turner, J.-F. Focant, Organohal. Compd. 67

(2005) 107–109.[93] D.G. Patterson Jr., S.M. Welch, W.E. Turner, A. Sjödin, J-F. Focant, J. Chromatogr.

A 1218 (2011) 3274–3281.[94] D. Krumwiede, H. Mehlmann, K. D’Silva, Chrom. Today 5 (2012) 19–22.[95] P. Haglund, P. Korytá, C. Danielsson, J. Diaz, K. Wiberg, P. Leonards, U.A.T.

Brinkman, J. de Boer, Anal. Bioanal. Chem. 390 (2008) 1815–1827.[96] A. Mechlinska, L. Wolska, J. Namiesnik, L. Wolska, Trends Anal. Chem. 29

(2010) 820–831.[97] B. Lau, D. Weber, P. Andrews, Chemosphere 32 (1996) 1021–1041.[98] G. Eppe, J. Focant, C. Pirard, E.D. Pauw, Talanta 63 (2004) 1135–1146.[99] T. Nevalainen, J. Koistinen, P. Nurmela, Environ. Sci. Technol. 28 (1994)

1341–1347.[100] M. Alaee, S. Backus, C. Cannon, J. Sep. Sci. 24 (2001) 465–469.[101] T. Matsui, K. Fukazawa, M. Fujimoto, T. Imasaka, Anal. Sci. 28 (2012) 445–450.[102] Y. Naudé, E.R. Rohwer, Anal. Chim. Acta 730 (2012) 120–126.[103] F. Wong, M. Robson, M. Diamond, S. Harrad, J. Truong, Chemosphere 74 (2009)

404–411.[104] C.S. Wong, S.A. Mabury, D.M. Whittle, S.M. Backus, C. Teixeira, D.S. DeVault,

C.R. Bronte, D.C.G. Muir, Environ. Sci. Technol. 38 (2004) 84–92.[105] G. Soderstrom, U. Sellstrom, C.A. De Wit, M. Tysklind, Environ. Sci. Technol.

38 (2004) 127–132.[106] S. Rahm, N. Green, J. Norrgran, Å. Bergman, Environ. Sci. Technol. 39 (2005)

3128–3133.[107] Q. Luo, M. Wong, Z. Cai, Talanta 72 (2007) 1644–1649.[108] S. Lacorte, M.G. Ikonomou, M. Fischer, J. Chromatogr. A 1217 (2010) 337–347.[109] S. Losada, J. Parera, M. Abalos, E. Abad, F.J. Santos, M.T. Galceran, Anal. Chim.

Acta 678 (2010) 73–81.[110] J. Malavia, F.J. Santos, M.T. Galceran, Talanta 84 (2011) 1155–1162.[111] H. Liu, Q. Zhang, M. Song, G. Jiang, Z. Cai, Talanta 70 (2006) 20–25.[112] H. Liu, Q. Zhang, Z. Cai, A. Li, Y. Wang, G. Jiang, Anal. Chim. Acta 557 (2006)

314–320.[113] J. Chovancova, K. Conka, A. KoAean, Z.S. Sejakova, Chemosphere 83 (2011)

1383–1390.[114] M.P. Abaurrea, J.J. Ramos, M.J. Gonzalez, L. Ramos, J. Chromatogr. A 1273

(2013) 18–25.[115] C. Erger, P. Balsaa, F. Werres, T.C. Schmidt, J. Chromatogr. A 1249 (2012)

181–189.[116] A. Covaci, S. Voorspoels, J. de Boer, Environ. Int. 29 (2003) 735–756.[117] P. Wang, Q. Zhang, Y. Wang, T. Wang, X. Li, L. Ding, G. Jiang, Anal. Chim. Acta

663 (2010) 43–48.[118] USEPA, Method 1614: brominated diphenyl ethers in water soil, sediment

and tissue by HRGC/HRMS, 2007.

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

[119] J. Björklund, P. Tollbäck, C. Hiärne, E. Dyremark, C. Östman, J. Chromatogr. A1041 (2004) 201–210.

[120] H. Wei, P.S. Dassanayake, A. Li, Int. J. Environ. Anal. Chem. 90 (2010) 535–547.[121] P. Korytár, A. Covaci, J. de Boer, A. Gelbin, U.A.T. Brinkman, J. Chromatogr. A

1065 (2005) 239–249.

PRESS Acta xxx (2013) xxx– xxx

[122] A.G. Gago, S.H. Brandsma, P.E.G. Leonards, J. de Boer, J.M.M. Gayon, J.I.G.Alonso, Anal. Bioanal. Chem. 401 (2011) 2639–2649.

[123] A.G. Gago, J.M.M. Gayon, J.I.G. Alonso, Anal. Chem. 83 (2011) 3024–3032.[124] S.A. Mackintosh, A.P. Fuentetaja, L.R. Zimmerman, G. Pacepavicius, M. Clap-

sadl, M. Alaee, D.S. Aga, Anal. Chim. Acta 747 (2012) 67–75.[125] L. Debrauwer, A. Riu, M. Jouahri, E. Rathahao, I. Jouanin, J. Antignac, R. Cariou,

B. Le Bizec, D. Zalko, J. Chromatogr. A 1082 (2005) 98–109.[126] A.F. Lagalante, T.D. Oswald, Anal. Bioanal. Chem. 391 (2008) 2249–2256.[127] C.H. Marvin, G.T. Tomy, J.M. Armitage, J.A. Arnot, L. McCarty, A. Covaci, V.

Palace, Environ. Sci. Technol. 45 (2011) 8613–8623.[128] R. Köppen, R. Becker, C. Jung, I. Nehls, Chemosphere 71 (2008) 656–662.[129] N.V. Heeb, W.B. Schweizer, P. Mattrel, R. Haag, A.C. Gerecke, M. Kohler, P.

Schmid, M. Zennegg, M. Wolfensberger, Chemosphere 68 (2007) 940–950.[130] C.H. Marvin, G. MacInnis, M. Alaee, G. Arsenault, G.T. Tomy, Rapid Commun.

Mass Spectrom. 21 (2007) 1925–1930.[131] X. Hu, D. Hu, Q. Song, J. Li, P. Wang, Chemosphere 82 (2011) 698–707.[132] A.H. Feng, S.J. Chen, M.Y. Chen, M.-J. He, X.J. Luo, B.X. Mai, Mar. Pollut. Bull. 64

(2012) 919–925.[133] P. Guerra, M. Alaee, B. Jimenez, G. Pacepavicius, C. Marvin, G. Maclnnis, E.

Eljarrat, D. Barcelo, L. Champoux, K. Fernie, Environ. Int. 40 (2012) 179–186.[134] L.S. Haug, C. Thomsen, V.H. Liane, G. Becher, Chemosphere 71 (2008)

1087–1092.[135] K. Kannan, J. Koistinen, K. Beckmen, T. Evans, J.F. Gorzelany, K.J. Hansen,

P.D. Jones, E. Helle, M. Nyman, J.P. Giesy, Environ. Sci. Technol. 35 (2001)1593–1598.

[136] J.P. Giesy, K. Kannan, Environ. Sci. Technol. 35 (2001) 1339–1342.[137] Y. Wang, S. Beesoon, J.P. Benskin, A.O. De Silva, S.J. Genuis, J.W. Martin, Envi-

ron. Sci. Technol. 45 (2011) 8907–8914.[138] U. Berger, M. Haukås, J. Chromatogr. A 1081 (2005) 210–217.[139] C.G. Barreiro, E.M. Carballo, A. Sitka, S. Scharf, O. Gans, Anal. Bioanal. Chem.

386 (2006) 2123–2132.[140] A. Jahnke, U. Berger, J. Chromatogr. A 1216 (2009) 410–421.[141] U. Berger, M.A. Kaiser, A. Kärrman, J.L. Barber, S.P.J. van Leeuwen, Anal. Bioanal.

Chem. 400 (2011) 1625–1635.[142] USEPA, Method 537: determination of selected perfluorinated alkyl acids in

drinking water by solid-phase extraction and liquid chromatography/tandemmass spectrometry (LC-MS/MS), EPA/600/R-08/092, 2009.

[143] K. Wille, J.V. Bussche, H. Noppe, E. De Wulf, P. Van Caeter, C.R. Janssen, H.F.De Brabander, L. Vanhaecke, J. Chromatogr. A 1217 (2010) 6616–6622.

[144] S. Ullah, T. Alsberg, U. Berger, J. Chromatogr. A 1218 (2011) 6388–6395.[145] X. Esparza, E. Moyano, J. de Boer, M.T. Galceran, S.P.J. van Leeuwen, Talanta

86 (2011) 329–336.[146] M. Onghena, Y. Moliner-Martinez, Y. Pico, P. Campins-Falco, D. Barcelo, J.

Chromatogr. A 1244 (2012) 88–97.[147] F. Gosetti, U. Chiuminatto, D. Zampieri, E. Mazzucco, E. Robotti, G. Calabrese,

M.C. Gennaro, E. Marengo, J. Chromatogr. A 1217 (2010) 7864–7872.[148] K. Saito, E. Uemura, A. Ishizaki, H. Kataoka, Anal. Chim. Acta 658 (2010)

141–146.[149] K.J. Hansen, L.A. Clemen, M.E. Ellefson, H.O. Johnson, Environ. Sci. Technol. 35

(2001) 766–770.[150] D. Cao, Z.D. Wang, C.G. Han, L. Cui, M. Hu, J.J. Wu, Y.X. Liu, Y.Q. Cai, H.L. Wang,

Y.H. Kang, Talanta 85 (2011) 345–352.[151] N. Riddell, G. Arsenault, J.P. Benskin, B. Chittim, J.W. Martin, A. McAlees, R.

McCrindle, Environ. Sci. Technol. 43 (2009) 7902–7908.[152] A. Karrman, I. Langlois, B. van Bavel, G. Lindstrom, M. Oehme, Environ. Int. 33

(2007) 782–788.[153] A.O. De Silva, D.C.G. Muir, S.A. Mabury, Environ. Toxicol. Chem. 28 (2009)

1801–1814.[154] A. Kärrman, K. Elgh-Dalgren, C. Lafossas, T. Moskeland, Environ. Chem. 8

(2011) 372–380.[155] M.D. Malinsky, C.B. Jacoby, W.K. Reagen, Anal. Chim. Acta 683 (2011) 248–257.[156] A.G. Paul, K.C. Jones, A.J. Sweetman, Environ. Sci. Technol. 43 (2009) 386–392.[157] J.W. Martin, D.C.G. Muir, C.A. Moody, D.A. Ellis, W.C. Kwan, K.R. Solomon, S.A.

Mabury, Anal. Chem. 74 (2002) 584–590.[158] C. Sun, H. Sun, Y. Lai, J. Zhang, Z. Cai, Anal. Chem. 83 (2011) 5822–5826.[159] S.P.J. van Leeuwen, A. Karrman, B. Van Bavel, J. De Boer, G. Lindstrom, Environ.

Sci. Technol. 40 (2006) 7854–7860.[160] G. Lindstrom, A. Karrman, B. Van Bavel, J. Chromatogr. A 1216 (2009) 394–400.[161] S.P.J. van Leeuwen, C.P. Swart, I. van der Veen, J. de Boer, J. Chromatogr. A

1216 (2009) 401–409.[162] M.P. Longnecker, C.S. Smith, G. Kissling, J. Hoppin, J.L. Butenhoff, E. Decker,

D.J. Ehresman, M. Ellefson, J. Flaherty, M.S. Gardner, E. Langlois, A. LeBlanc,A. Lindstrom, W.K. Reagen, M. Strynar, W.B. Studabaker, Environ. Res. 107(2008) 152–159.

[163] J.M. Keller, A.M. Calafat, K. Kato, M.E. Ellefson, W.K. Reagan, M. Strynar,S. O’Connell, C.M. Butt, S.A. Mabury, J. Small, D.C.G. Muir, S.D. Leigh, M.M.Schantz, Anal. Bioanal. Chem. 397 (2010) 439–451.

[164] A.B. Gomez, S. Rubio, Anal. Chem. 83 (2011) 4579–4613.[165] S.D. Richardson, Anal. Chem. 82 (2010) 4742–4774.[166] Z. Zhang, E. Ohlozebau, S.M. Rhind, J. Chromatogr. A 1218 (2011) 1203–1209.[167] B. Subedi, S. Usenko, J. Chromatogr. A 1238 (2012) 30–37.

ersistent organic pollutants identified in the Stockholm Convention:026

[168] L. Foan, V. Simon, J. Chromatogr. A 1256 (2012) 22–31.[169] S. Xie, M.C. Paau, C.F. Li, D. Xiao, M.M.F. Choi, J. Chromatogr. A 1217 (2010)

2306–2317.[170] N. Kajiwara, M. Sueoka, T. Ohiwa, H. Takigami, Chemosphere 74 (2009)

1485–1489.

Page 13: Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

ING Model

A

imica

[[

[

[

[

[

[

[

[

[[[

ARTICLECA-232528; No. of Pages 13

W. Xu et al. / Analytica Ch

171] M.R. Huguet, W.D. Marshall, Chemosphere 83 (2011) 668–673.172] T. Barri, S. Bergström, A. Hussen, J. Norberg, J. Jönsson, J. Chromatogr. A 1111

(2006) 11–20.173] J.F. Focant, A. Sjodin, D.G. Patterson Jr., J. Chromatogr. A 1040 (2004)

227–238.174] J. De Vos, R. Dixon, G. Vermeulen, P.G. Allman, J. Cochran, E. Rohwer, J.F. Focant,

Chemosphere 82 (2011) 1230–1239.175] S. Hashimoto, Y. Takazawa, A. Fushimi, K. Tanabe, Y. Shibata, T. Ieda, N. Ochiai,

H. Kanda, T. Ohura, Q. Tao, S.E. Reichenbach, J. Chromatogr. A 1218 (2011)3799–3810.

176] S.E. Reichenbach, X. Tian, Q. Tao, E.B. Ledford Jr., Z. Wu, O. Fiehn, Talanta 83(2011) 1279–1288.

177] S. Hashimoto, Y. Zushi, A. Fushimi, Y. Takazawa, K. Tanabe, Y. Shibata, J. Chro-matogr. A 1282 (2013) 183–189.

178] United Nations Environment Program UNEP, Final Act of the Conference ofPlenipotentiaries on the Stockholm Convention on Persistent Organic Pollut-ants, UNEP/POPS/CONF/4, 2001.

Please cite this article in press as: W. Xu, et al., Analytical chemistry of the pA review, Anal. Chim. Acta (2013), http://dx.doi.org/10.1016/j.aca.2013.04.

179] Updated 2013, http://chm.pops.int/Convention/POPsReviewCommittee/Reviewedchemicals/tabid/781/Default.aspx

180] D.C.G. Muir, P.H. Howard, Environ. Sci. Technol. 40 (2006) 7157–7166.181] S.S. Bayen, J.P. Obbard, G.O. Thomas, Environ. Int. 32 (2006) 915–929.182] J. de Boer, J.R. Law, J. Chromatogr. A 1000 (2003) 223–251.

PRESS Acta xxx (2013) xxx– xxx 13

[183] E. Eljarrat, D. Barcelo, Trends Anal. Chem. 25 (2006) 421–434.[184] S. Iozza, P. Schmid, M. Oehme, Environ. Pollut. 157 (2009) 3218–3224.[185] U.E. Friden, M.S. Mclachlan, U. Berger, Environ. Int. 37 (2011) 1169–1174.[186] G.T. Tomy, G.A. Stern, D.C.G. Muir, A.T. Fisk, C.D. Cymbalisty, J.B. Westmore,

Anal. Chem. 69 (1997) 2762–2771.[187] M. Reth, M. Oehme, Anal. Bioanal. Chem. 378 (2004) 1741–1747.[188] M. Reth, Z. Zencak, M. Oehme, J. Chromatogr. A 1081 (2005) 225–231.[189] L. Zeng, T. Wang, T. Ruan, Q. Liu, Y. Wang, G. Jiang, Environ. Pollut. 160 (2012)

88–94.[190] F. Pellizzato, M. Ricci, A. Held, H. Emons, W. Böhmer, S. Geiss, S. Iozza, S. Mais,

M. Petersen, P. Lepom, Trends Anal. Chem. 28 (2009) 1029–1035.[191] S. Geiss, N. Lettmann, A. Rey, H. Lepper, B. Korner, S. Mais, T. Prey, B. Hilger, M.

Engelke, S. Lebertz, C. Chatellier, G. Sawal, D. Loffler, T. Schillings, Clean SoilAir Water 39 (2011) 537–542.

[192] S. Moore, L. Vromet, B. Rondeau, Chemosphere 55 (2004) 453–459.[193] T. Shi, S.J. Chen, X.J. Luo, X.L. Zhang, C.M. Tang, Y. Luo, Y.J. Ma, J.P. Wu, X.Z.

Peng, B.X. Mai, Chemosphere 74 (2009) 910–916.

ersistent organic pollutants identified in the Stockholm Convention:026

[194] C.A. de Wit, D. Herzke, K. Vorkamp, Sci. Total Environ. 408 (2010) 2885–2918.[195] A. Covaci, S. Harrad, M.A. Abdallah, N. Ali, R.J. Law, D. Herzke, C.A. de Wit,

Environ. Int. 37 (2011) 532–556.[196] L.W.Y. Yeung, Y. Miyake, P. Li, S. Taniyasu, K. Kannan, K.S. Guruge, P.K.S. Lam,

N. Yamashita, Anal. Chim. Acta 635 (2009) 108–114.