Evaluation of an automated clean-up system for the isotope-dilution high-resolution mass spectrometric analysis of PCB, PCDD, and PCDF in food

An automated clean-up system was evaluated for the simultaneous analysis of polychiorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF), and biphenyls (PCB) in different foods. In addition to the seventeen 2,3,7,8-substituted PCDDIPCDF and four non-ortho PCB, by use of the clean-up system studied, it was possible to collect the eight mono-ortho and two di-ortho PCB and the seven indicator PCB in two separate fractions during the same clean-up run. The study was first performed using standard mixtures containing PCDD, PCDF and PCB, and a certified reference material. The recoveries of the 13C-labeled compounds ranged from 51 to 90%, indicating that the PCDD, PCDF, and PCB clean-up worked satisfactorily. Next, the automated system for PCDD, PCDF, and PCB analysis was evaluated for foods such as milk, egg, meat (beef, chicken, and pork), mussel, and olive oil. The recoveries of the 13C-labeled compounds ranged from 40 to 120% for PCB and from 57 to 113% for PCDD/ PCDF, meeting the requirements of well accepted methods. Thus, the automated clean-up system studied is a suitable alternative to conventional clean-up methods.     

Computer-assisted peak recognition for polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in environmental samples

A software has been developed for the peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) after high resolution gas chromatography coupled with mass spectrometry (HRGC/HRMS). Based on the retention times of ¹³C labelled 2,3,7,8-substituted PCDD/F internal standards, the retention times of all PCDD and PCDF can be calibrated automatically and accurately. Therefore, it is very convenient to identify the peaks by comparing the retention of samples and the calibrated retention times of their chromatograms. Hence, this approach is very significant because it is impossible to obtain always a standard chromatogram and PCDD/F analysis are very expensive and time consuming. The calibration results can be transferred to Excel for calculation. The approach is a first step to store costly and environmentally relevant data for future application.     

Importance of clean-up for comparison of TEQ-values obtained by CALUX and chemo-analysis

This paper presents Chemically Activated LUciferine gene eXpression (CALUX) TEQ-values obtained for nine plasma samples following two different purification procedures, one of them involving fractionation. CALUX results obtained for the dioxin (DX) and dioxin + PCB (DX + PCB) fractions were then compared to the GC-HRMS TEQ-values calculated for the 17 polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (17 PCDD/F) and 17 PCDD/F + 4 cPCB congeners, respectively. The overestimation of the CALUX (DX fraction) TEQ-values in comparison with the chemo-analyses of the 17 PCDD/F is mainly explained by the presence of other AhR agonists, like brominated compounds. Otherwise, the constancy of the CALUX (DX + PCB fraction) TEQ-value which compares to increasing the GC-HRMS (17 PCDD/F + 4 cPCB) TEQ results raises questions concerning (1) the significance of CALUX results obtained without fractionation as well as (2) the toxicological effect of a cocktail of contaminants on the human health.     

Fractionation of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and planar polychlorinated biphenyls by high performance liquid chromatography on a pyrenyl-silica column

Analytical procedures for the determination of polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and non-ortho polychlorinated biphenyls (PCB) require a fractionation step to separate PCDD/F from planar PCB and the bulk of PCB. An HPLC method which achieves the separation of the bulk of PCB (0–6 mL of hexane), mono-ortho PCB (6–8 mL of hexane), non-ortho PCB (8–15 mL of hexane) and PCDD/F (15–50 mL of toluene) on a PYE column (2-(1-pyrenyl) ethyldimethylsilylated silica gel) in a single step without the use of backflush as other authors proposed was developed. The method shows a good accuracy and precision and it is linear in the range studied, e.g from 5.8 to 2420 pg injected in HPLC for TCDD/F, from 28.8 to 12100 pg for PeCDD/F, HxCDD/F, HpCDD/F and from 57.6 to 24200 pg for OCDD/F. It has been successfully applied to the analysis of technical mixtures of PCB (Aroclors), a pine wood sample and several water samples of different origins. Received: 29 November 1998 / Revised: 25 February 1999 / Accepted: 3 March 1999     

Fractionation of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and planar polychlorinated biphenyls by high performance liquid chromatography on a pyrenyl-silica column

Analytical procedures for the determination of polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and non-ortho polychlorinated biphenyls (PCB) require a fractionation step to separate PCDD/F from planar PCB and the bulk of PCB. An HPLC method which achieves the separation of the bulk of PCB (0–6 mL of hexane), mono-ortho PCB (6–8 mL of hexane), non-ortho PCB (8–15 mL of hexane) and PCDD/F (15–50 mL of toluene) on a PYE column (2-(1-pyrenyl) ethyldimethylsilylated silica gel) in a single step without the use of backflush as other authors proposed was developed. The method shows a good accuracy and precision and it is linear in the range studied, e.g from 5.8 to 2420 pg injected in HPLC for TCDD/F, from 28.8 to 12100 pg for PeCDD/F, HxCDD/F, HpCDD/F and from 57.6 to 24200 pg for OCDD/F. It has been successfully applied to the analysis of technical mixtures of PCB (Aroclors), a pine wood sample and several water samples of different origins. Received: 29 November 1998 / Revised: 25 February 1999 / Accepted: 3 March 1999     

Polychlorinated naphthalene concentrations and profiles in cheese and butter,and comparisons with polychlorinated dibenzo-p-dioxin,polychlorinated dibenzofuran and polychlorinated biphenyl concentrations

Polychlorinated naphthalenes (PCNs) are candidates for inclusion in the Stockholm Convention on persistent organic pollutants. PCNs are structurally and toxicologically similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and its analogues. Intake in food is considered to be an important human exposure pathway for PCNs. In this preliminary study, cheese and butter samples were analysed for PCNs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) using an isotope dilution gas chromatography high-resolution mass spectrometry method. The aim of this study was to evaluate the PCN concentrations in the cheese and butter samples and to compare them with the PCDD, PCDF and PCB concentrations. The PCN concentrations were 5.6–103 pg g^?1 of wet weight in the seven cheese samples tested and 5.0–199 pg g^?1 of wet weight in the seven butter samples tested. The mass concentrations of lower chlorinated congeners were greater than those of the higher chlorinated congeners. Congeners of CN45/36, CN27/30 and CN33/34/37 were much more abundant than other congeners found in tetrachlorinated PCNs. Congeners of CN51, CN66/67 and CN73 were determined to be the predominant congeners in penta-, hexa- and heptachlorinated homologs, respectively. The PCNs contributed around 5% of the total PCN, PCDD, PCDF and PCB toxic equivalence (TEQ) values. CN73 was found to be the dominant PCN congener and contributed more than 40% to the PCN TEQ value. Congeners CN66/67, CN69 and CN63 were also found at relatively high levels. The PCB congener CB118 was the predominant congener (by mass-based concentration) of the 12 dioxin-like PCBs (dl-PCBs). The PCBs contributed 53.8% of the total TEQ, and congener CB126 contributed more than any other compound that was analysed to the total TEQ. The PCDDs and PCDFs contributed 11.6% and 29.7% of the total TEQ values, respectively.     

Semivolatile organic compounds — polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF), biphenyls (PCB), hexachlorobenzene (HCB), 4,4'-DDE and chlorinated paraffins (CP) — as markers in sewer films

A municipal sewer system has been investigated for the sources of a set of semivolatile compounds, such as polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethene (4,4'-DDE), and chlorinated paraffins (CP), using sewer films as the sampling medium. A cleanup method for these semivolatile compounds in sewer films is described. The project has been undertaken for the differentiation and localization of specific inputs of xenobiotics from defined regions of the city. A unique pattern of PCDD/PCDF found in sewage sludge has led to the search for a specific source within the sewer system, which has finally been localized as a distinct plant. Other organochlorine compounds proved to be significant indicators for industrial and domestic sewers. PCB appeared as an industry correlated parameter, while 4,4'-DDE indicated domestic sewers. Chlorinated paraffins have been detected in the mg/kg range and are markers and indicators for metal-working industries. Finally, the release of CP by the sewage treatment plant, into the nearby river, has been investigated.     

Bioanalytical methods applied to endocrine disrupting polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. A review

The usual methods for determining polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) are generally expensive and time consuming. This fact has favored the development of faster and cheaper techniques, based on immunoassays and bioassays. This paper reviews these bioanalytical methods and their analytical importance at the present moment.     

Evaluation of a new automated cleanup system for the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans in environmental samples

An automated cleanup system (Power-Prep, Fluid Management Systems, Inc.) was evaluated for the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) in environmental samples. The study was firstly carried out against standard mixtures containing labeled and unlabeled PCDD/PCDF and a certified reference material (fly ash CRM 490). Next, a comparison between a conventional cleanup procedure and the new automated system for PCDD/PCDF analysis in environmental samples such as flue gas emissions, fly ashes, sludges, ambient air and soils was also made. The suitability of the system was finally assessed from the participation in an interlaboratory exercise. Owing to its capability to successfully perform the sample cleanup the Power-Prep apparatus is an alternative to the conventional methods.     

Micropore-free surface-activated carbon for the analysis of polychlorinated dibenzo-p-dioxins-dibenzofurans and non-ortho-substituted polychlorinated biphenyls in environmental samples

2,3,7,8-Substituted polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) and non-ortho-substituted polychlorinated biphenyls (PCBs) account for almost all of the total toxic equivalents (TEQ) in environmental samples. Activated carbon columns are used to fractionate the samples for GC-MS analysis or bioassay. Micropore-free surface-activated carbon is highly selective for PCDD/Fs and non-ortho-PCBs and can improve the conventional activated carbon column clean-up. Along with sulfuric acid-coated diatomaceous earth columns, micropore-free surface-activated carbon provides a rapid, robust, and high-throughput sample preparation method for PCDD/Fs and non-ortho-PCBs analysis.     

“永固紫”染料和四氯苯醌中多氯代二苯并二/呋喃的分析

 采用浓硫酸对5种不同来源的四氯苯醌和“永固紫”染料样品进行溶解分散,用甲苯提取和 多层色谱柱纯化,利用同位素稀释法及高分辨气相色谱/质谱 (HRGC/HRMS)联用技术,测定 了其中的多氯代二苯并二/呋喃(PCDD/F)的质量比。结果表明“永固紫”染料及其原料中P CDD/F的质量比异常高,八氯代二苯并二/呋喃(OCDD/F)已达到μg/g级甚至100 μg/g级,七氯代二苯并二/呋喃(HpCDD/F)和六氯代二苯并二/呋喃(HxCDD/F)质量比也达到 ng/g级。所有样 品的毒性当量浓度(TEQ)均已超过10 pg/g的危险水平,是纺织品中PCDD/F的一类重要污染源 。并进一步探讨了PCDD/F的来源。     

Analysis of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in vegetable oil samples by gas chromatography-ion trap tandem mass spectrometry

Gas chromatography coupled to ion trap tandem mass spectrometry (CG-MS-MS) has been evaluated for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in vegetable oil samples containing different concentration levels (0.2-6 pg WHO-TEQ g(-1) for both PCDD/Fs and dl-PCBs) of the 29 toxic congeners of PCDD/F and dioxin-like PCBs. The effect of potential interfering compounds such as polychlorinated naphthalenes (PCNs), polychlorinated biphenyls (PCBs) and polychlorinated diphenylethers (PCDEs) on the quantification of mono-ortho PCBs has been investigated. In addition, the influence of the clean-up procedure on the final determination by CG-MS-MS was studied, showing that the quality of the results depends to a great extent on this analytical step. Quality parameters have been established and good precisions (CV: 3-19%) and low limits of detection for PCDD/Fs (0.04-0.20 pg g(-1) oil) and dl-PCBs (0.08-0.64 pg g(-1) oil) were obtained. The method was validated by a comparison of the CG-MS-MS results with those obtained by GC-HRMS.     

Recoveries of organochlorine compounds (polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) in water using steam distillation-solvent extraction at normal pressure

A simultaneous steam distillation-solvent extraction (SDE) procedure was used for determining polychrlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCBs, PCDDs and PCDFs) at sub-ppb levels in water samples. Recoveries of 39.8–138.7% and a standard deviation of lower than 10% were achieved for the individual coplanar PCB and the 2,3,7,8-substituted PCDD/F congeners. SDE is a fast, clean, inexpensive and reproducible procedure for the determination of individual PCBs, PCDDs and PCDFs in waters at very low concentrations.     

Separation of polychlorinated dibenzo-p-dioxins/furans,non-ortho/mono/di/tri/tetra-ortho-polychlorinated biphenyls,and polybrominated diphenyl ethers groups of compounds prior to their determination with large volume injection gas chromatography—Quadrupole ion storage tandem mass spectrometry

Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are important environmental contaminants. Their maximum legally allowable levels in food and environment are in the low pg g⁻¹ range. Therefore some highly selective and sensitive analytical methods must be used to determine them. Prior to final determination by GC/MS the cleaned-up samples have to be split into some fractions in view of large differences in concentrations of various analytes and existence of numerous chromatographic co-elutions (which in any case cannot be fully avoided). The aim of this study was to: (i) develop a robust, time-saving analytical method to isolate, clean-up and fractionate PCBs, PBDEs and PCDD/Fs prior to their determination with gas chromatography/ion trap mass spectrometry; (ii) assess method performance using laboratory validation data and some certified reference materials; (iii) use the developed method to assess PCB/PBDE/PCDD/F levels in samples of commercially available food. A combination of alumina, florisil, modified silica gel and two carbon columns were used for sample cleanup and fractionation. Separate fractions containing dioxins/furans, PBDE, non-ortho, mono-ortho and di-/tri-/tetra-ortho PCBs were obtained. The method statistical parameters were compatible with 1883/2006 EC Regulation (80–120%, RSD below 15%). The method performance was successfully used to evaluation of some real life food samples.     

New strategy for comprehensive analysis of polybrominated diphenyl ethers,polychlorinated dibenzo-p-dioxins,polychlorinated dibenzofurans and polychlorinated biphenyls by gas chromatography coupled with mass spectrometry

A strategy for determination of polybrominated diphenyl ethers, polychlorinated dibenzodioxins, polychlorinated dibenzofurans and polychlorinated biphenyls on fatty matrices has been established. After extraction, the proposed method allows the purification and the fractionation of all target groups of compounds in a simple multi-step automated clean-up. Furthermore, their subsequent analysis is carried out using a single benchtop mass spectrometer, in four separate injections. Required sensitivity considering levels found in the environment is attained using electron impact ionisation followed by tandem in time mass spectrometry. The whole method has been evaluated on standard solution and quality control samples consisting of fortified beef fat. Sensitivity, selectivity, accuracy and repeatability were tested with satisfactory results.     

Development and validation of a method for analyzing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sewage sludge samples

Summary A method has been developed for the analysis of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) in sewage sludge samples. It was found that PCDD/F are best Soxhlet extracted from the matrix with toluene for 24h, after having tested other solvents (dichloromethane and hexane/acetone 41/59) and other extraction times. Several clean up steps (sulfuric acid, multilayer silica and Florisl columns) and concentration are required prior to analysis of the extract by high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS). The complete procedure has been validated and the accuracy and precision data (repeatability and reproducibility) are given. The method is linear in the range studied and the limit of detection ranges between 0.2 and 2.2 pg g⁻¹ of dry matter for the 2,3,7,8-substituted congeners. Moreover, the suitability of the method has been checked in an international interlaboratory comparison. The successful application of this method to several samples from Catalan and Dutch urban wastewater treatment plants was demonstrated.     

Measurement of PCDDs, PCDFs, and non-ortho-PCBs by comprehensive two-dimensional gas chromatography-isotope dilution time-of-flight mass spectrometry (GC x GC-IDTOFMS)

Comprehensive two-dimensional gas chromatography with isotope-dilution time-of-flight mass spectrometry (GC × GC-IDTOFMS) was used to measure polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), and coplanar polychlorinated biphenyl (cPCB) concentrations in ash, sediment, vegetation, and fish samples. The GC × GC capability was achieved by using a quad jet, dual stage, thermal modulator. Zone compression of the GC peaks from modulation resulted in a significant increase of the signal intensity over classical GC-IDTOFMS. The GC × GC column set used an Rtx-Dioxin 2 phase as the first dimension (¹D) and an Rtx-500 as the second dimension (²D). The chromatographic separation of the 17 PCDD/Fs and the 4 cPCBs was attained in ¹D except for 2,3,7,8-TCDD and CB126 for which deconvoluted ion currents (DIC) were required to be reported separately. The Rtx-500 phase separated the bulk matrix interfering compounds from the target analytes in ²D. The instrumental limit of detection (iLODs) was 0.5 pg for 2,3,7,8-TCDD. The calibration curves showed good correlation coefficients for all the compounds investigated in the concentration range of 0.5–200 pg. GC × GC-IDTOFMS results compared favorably to those from conventional isotope-dilution one-dimensional gas chromatography-high resolution mass spectrometry (GC-IDHRMS). The comprehensive mass analysis of the TOFMS further permitted the identification of other contaminants of concern in the samples.     

Advances in analytical techniques for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like PCBs

Analytical techniques for the determination of polychorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and dioxin-like PCBs (DLPCB) are reviewed. The focus of the review is on recent advances in methodology and analytical procedures. The paper also reviews toxicology, the development of toxic equivalent factors (TEF) and the determination of toxic equivalent quantity (TEQ) values. Sources, occurrence and temporal trends of PCDD/PCDF are summarized to provide examples of levels and concentration ranges for the methods and techniques reviewed.     

Method development for the analysis of polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzo-furans in single extract of sediment samples

A comprehensive method was developed for quantitative analysis of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) in one single extract of environmental samples. The sample preparation procedure included two fractionation steps using silver nitrate silica chromatography to separate PBDEs from PCBs and PCDD/Fs and florisil column to separate PCBs from PCDD/Fs. Acidic silica, acidic alumina and gel permeation chromatography (GPC, for PCBs) or activated carbon column (for PCDD/Fs) were used for further clean-up. The sample extracts were analyzed by using high-resolution gas chromatography/high-resolution mass spectrometry. The entire method was validated from the analysis of mixed standards of PBDEs, PCBs and PCDD/Fs (n = 3); the analysis of certified reference biota (WMF-01). The method was applied for the analysis of 10 sediment samples collected from Haihe River and Dagu Drainage River in Tianjin City. No significant PBDEs pollution was found in the areas.     

Comparison of gas chromatography-ion-trap tandem mass spectrometry systems for the determination of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls

Two gas chromatography-mass spectrometry systems equipped with an ion-trap mass analyzer working in tandem mode (GC-MS-MS) were evaluated for the determination of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in food samples. The performance of the two ion-trap instruments, which dispose of an external ion source (ThermoFinnigan GCQ/Polaris) and internal ionization (Varian Saturn 2,200), have been compared in terms of linearity, repeatability, limit of detection and long-term precision. Both instruments provided similar run-to-run and day-to-day precisions, ranging from 2% to 8% and between 2% and 13%, and instrumental limits of detection between 0.09 and 0.36 pg injected for PCDD/Fs and from 0.03 to 0.09 pg injected for dioxin-like PCBs. Although both instruments seem to be suitable for food analysis, only the use of external ionization allowed to achieve reliable results for PCDD/F determination at concentrations close to the maximum residue levels established by the EU for foods. Internal ionization provides high limits of detection (from 10- to 30-fold higher) and worse precision (RSD, 14-43%). In contrast, for dioxin-like PCBs both instruments allowed to obtain excellent results with precisions lower than 15%.