Gas Chromatography-high Resolution Mass Spectrometry Research Articles

METHOD DEVELOPMENT FOR RAPID ANALYSIS OF DIOXIN IN SOME FOOD AND FEED USING FREEZE DRYING AND ACCELERATED SOLVENT EXTRACTION TECHNIQUES

The global methods approved and reliable for the analysis of dioxins in food and feed, which take a lot of time, money and effort in addition to that, take many harmful solvents. A simple and rapid method for sample preparation and extraction of dioxins from food developed using freeze-drying (FD) and accelerated solvent extraction (ASE) techniques, respectively. Average recoveries of dioxins extracted from the food obtained by a conventional soxhlet extraction and the ASE almost equal, when the data compared by both methods. Moreover, decrease the time of tissue extraction from 24 hours using soxhlet to only 35 minutes using ASE technique. Development of dioxin analysis in food and feed samples by entire method of fat extraction based on ASE for determination of dioxin compounds with high-resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) from food and feed samples was developed. Optimization conditions for ASE method are effective and reliable by using Dionex ASE 350 as follows oven temperature: 150 °C, static cycle time: 5 minute, cycle’sno.: 4, flush volume: 100%, purge time: 90 sec, cell pressure: 1590 psi (nitrogen gas) and total extraction time: 35 min per sample.Extraction solvents used for fatty-food samples such as fish, meat and liver were Hexane: DCM (1:1 v,v). While toluene used for extraction of Non-fatty food samples. Quality assurance for ASE extraction method such as precision and recovery as well as robustness and natural contaminated samples evaluated through certified reference materials (CRM) analysis. Accuracy of PCDD/Fs estimated with CRM for Trout sample was below 4% for both ASE and soxhlet, (complying with EU requirement ≤ 20%). This study was to compare efficiency of various extraction tools to determine the content of dioxins in food and feed samples by using accelerated solvent extraction technique (ASE) with those prepared by extraction in soxhlet technique.

High-resolution mass spectrometry

High-resolution mass spectrometry (HRMS) using doublefocusing mass analyzers was established in chemistry laboratories in the 1960s. Coupled to a direct insertion probe or to gas chromatography, it revolutionized the elemental analysis of organic compounds. It also became a powerful tool in bioanalytical research providing high selectivity and specificity. However, modern benchtop GC–MS instruments cost significantly less and have been coupled to the faster scanning quadrupole or ion-trap mass analyzers, largely displacing GC–HRMS in most fields. Modern LC–MS instruments using electrospray ionization have many applications in bioanalytical laboratories and in “omics” research. Manufacturers, for arguably the first time, recognized a sizeable market for HRMS. In the past few years, robust GC–MS and, particularly, LC–MS equipment, mainly using time-of-flight or Fourier-transform mass-analyzer technology, are becoming increasingly affordable by many laboratories. This is also apparent from the remarkable increase in the number of publications. Therefore, the objective of this special volume is to give an overview of the current use of HRMS in the life sciences. Four review articles critically assess the use of HRMS in clinical and forensic toxicology, doping control, drug metabolism studies, food analysis, and the environmental sciences. This overview is followed by four original papers with new results from application of HRMS to drug screening, doping control, glycomics, and proteomics. We hope you find this special issue an invaluable source of information; it is intended for all readers with an interest in application of HRMS in clinical and forensic toxicology, doping control, drug metabolism, food analysis, environmental sciences, and proteomics and related fields. We thank all authors for submitting their interesting contributions for this special issue, the referees for their critical but constructive comments, and the editorial office and the editors for their friendly cooperation.

Analysis of polybrominated diphenyl ethers in textiles treated by brominated flame retardants

Brominated flame retardants (BFRs) have been widely used as additives or as chemical reactants in polymers and textiles. The aim of this study was to develop methods for the analysis of synthesized polybrominated diphenyl ethers (PBDEs) in textiles. Analytical methods for the determination of PBDEs in textile samples were performed, including gas chromatography/mass spectrometry (GC/MS), thermal desorption (TD)-GC/MS, and high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The experiments consisted of three different sub-experiments that centered on detecting the presence of deca-BDE in textiles by (1) GC/MS, (2) TD-GC/MS, and by (3) target molecule analysis of 27 PBDE congeners by HRGC/HRMS. Results indicated that deca-BDE detection by TD-GCMS was the most precise methodology and did not require extraction or cleanup procedures. The analyses of the 27 PBDE congeners were used for the HRGC-isotope dilution HRMS by EPA method 1614. TD-GC/MS with pyrolysis was the most effective method for monitoring of deca-BDE in textiles because of its simplicity. HRGC/HRMS analysis was the most appropriate method for determination of low concentrations of deca-BDE in textiles compared with the other analytical methods. GC/MS analysis may also be used but high-concentration samples are needed for detection. BDE-28, -66, -100, -119, -153, -197, -206, and -209 were detected in all textile samples by the HRGC/HRMS method, of which the concentration of BDE-209 was the highest. BDE-3, -7, -47, -49, -71, -99, -126, and -156 were not detected in any textile samples.

Identification of 2-alkylcyclobutanones in nutmeg (Myristica fragrans)

The natural existence of the irradiation markers, namely, 2-decylcyclobutanone (2-DCB) and 2-dodecylcyclobutanone (2-dDCB), in nutmeg (Myristica fragrans) has recently been reported. In this study, 2-DCB and 2-dDCB were extracted from nutmeg of five different origins using supercritical fluid extraction (SFE). A 50-kGy irradiated sample was used to optimise the parameters of SFE and solid-phase extraction. The irradiated samples were analysed by gas chromatography–mass spectrometry, whereas the non-irradiated samples were analysed with high-resolution gas chromatography–mass spectrometry. Both 2-DCB and 2-dDCB were detected and identified in the irradiated samples at 5 kGy or greater. However, neither was present in the non-irradiated samples. Moreover, although the concentrations of 2-DCB and 2-dDCB were significantly reduced, a positive identification was obtained in irradiated nutmeg even after 30 weeks of storage.

Analysis of major congeners of polybromobiphenyls and polybromodiphenyl ethers in office dust using high resolution gas chromatography–mass spectrometry

The study focused on analysis of polybromobiphenyls (PBBs) and polybromodiphenyl ethers (PBDEs) congeners in office dust obtained in Pretoria, South Africa. Of the 32 congeners considered for identification, (BB-1, 2, 4, 10, 15, 26, 29, 30, 31, 38, 49, 80, 103, 153, 155, 209 and BDE-3, 15, 17, 28, 47, 66, 77, 85, 99, 100, 126, 138, 153, 154, 183, 209) only BB-2, 4, 30, 153, 209 and BDE-47, 66, 85, 99, 153 and 209 congeners were detected. The sum of PBBs concentration detected in office dust ranged from <dl−196ngg−1 dry weight (dw) with a median and mean of 11.4 and 38.2ngg−1, respectively. On the other hand, the sum of PBDEs concentration detected ranged from 21.6 to 578.6ngg−1dw with a median and mean of 162 and 169ngg−1dw, respectively. A Spearman rank correlation between ∑5PBBs and ∑6PBDEs (rs=0.55, p=0.003), indicated a statistical significant positive correlation for the similarity of pollution sources for both compound classes. However, no correlation was observed between the number of electronic materials and summation of concentrations of PBBs and PBDEs congeners detected. Concentrations of PBDEs detected in this study are substantially lower than reported in office dust in developed countries.

Determination of ten monohydroxylated polycyclic aromatic hydrocarbons by liquid–liquid extraction and liquid chromatography/tandem mass spectrometry

The aim of this study is to develop and validate an analytical method for the quantitation of ten urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) through high pressure liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). After enzymatic deconjugation, urine samples were extracted by liquid–liquid extraction (LLE) and OH-PAHs were analyzed by HPLC/MS/MS operated in negative electrospray ionization (ESI) and multiple reaction monitoring (MRM) mode. LLE was conducted with the solvent mixture of pentane and toluene, which reduced the matrix interferences and enhanced the method sensitivity significantly. Deuterated and 13C-labeled analogs are used as internal standards. Calibration curves of all target analytes shows favorable linearity within the concentration range of 5.9–15,000.0ng/L for different OH-PAHs with the regression coefficients above 0.993. The limits of detection (LODs) in pooled urine ranged from 1.72 to 17.47ng/L, which were much lower than those obtained by a gas chromatography/high resolution mass spectrometry (GC/HRMS) method. The method shows satisfactory accuracy and precision when analyzing three different levels of OH-PAHs spiked in pooled urine. Except for 1-hydroxynaphthalene, recoveries of other OH-PAHs were in the range of 100±20% with a variation coefficient of less than 13%. The measurement of OH-PAHs from a QC sample of the Centers for Disease Control and Prevention (CDC) generated results close to the values measured by CDC. This method has been successfully employed in the California Biomonitoring Program.

Methoxy-substituted octachlorodibenzo-p-dioxins in the Vietnamese soil

A lot of data have been accumulated to date on the sources of formation of polychlorinated dibenzodiox� ins (PCDD) and dibenzofurans (PCDF), their envi� ronmental levels, and effects on living organisms, but there relatively few data about the properties of these compounds (1). Indeed, the octachlorodibenzop� dioxin (OCDD) phenomenon, in particular, the fact that it is detected in very high concentrations in soils that have not been affected by any human interven� tion, while the concentrations of other PCDD in these soils exponentially decrease and the PCDF level is negligibly low, has not been explained as yet. Often, this abnormal profile is detected in hot climate areas such as Australia, Thailand (2, 8), and Vietnam (4). Moreover, this compound is not characteristic of any industrial process. The source of OCDD in these areas is unknown but probably detection of some precursors or metabolites would help to estimate the theory of natural formation of OCDD from pentachlorophenol (PeCP), which was indirectly supported by our earlier study (5). Here, we present the results of detailed analysis of a soil sample with abnormally high OCDD concentra� tion collected at the Sa Pa mountain range in the North of Vietnam. Due to the low absolute concentra� tions of PCDD/PCDF, these compounds are deter� mined most efficiently by gas chromatography/high� resolution mass spectrometry (GC/HRMS) with recording of selected characteristic ions. Since the compounds to be determined were unknown before� hand, we applied GC/HRMS in the full scan mode, i.e., recorded the full highresolution mass spectrum. EXPERIMENTAL The soil and bottom sediment samples were taken in 2010 by expeditions organized by the Russian- Vietnam Tropical Center. The samples were analyzed at the Laboratory for Analytical Ecotoxicology of the Institute of Ecology. In all samples, PCDD, PCDF, and PeCP were determined by gas chromatogra� phy/highresolution mass spectrometry (GC/HRMS) with isotope dilution (4). The possible OCDD metab� olites were determined by recording GC/MS patterns in the full scan mode and the selected ion detection (SID) mode. The samples were extracted with a toluene-ace� tone mixture and with an aqueous solution of sodium hydroxide; this was followed by acidification of the aqueous phase and reextraction into dichloromethane. The extracts were analyzed without purification and after passing through a silica gel layer impregnated with sulfuric acid.

Levels and congener profiles of polybrominated diphenyl ethers (PBDEs) in primipara breast milk from Shenzhen and exposure risk for breast-fed infants

This study aimed at revealing the levels of polybrominated diphenyl ethers (PBDEs) in breast milk from primipara in Shenzhen (China), and estimating daily intake of PBDEs for breast-fed infants. Concentrations of 7 PBDEs were measured in 60 breast milk samples by isotope dilution HRGC/HRMS (high-resolution gas chromatography/high-resolution mass spectrometry). The intake of PBDEs for breast-fed infants was estimated based on the infant's daily milk consumption. The range of total concentration of 7 PBDEs congeners in samples was 2.6-188.6 ng g(-1) lipid (mean: 14.8 ng g(-1) lipid; median: 7.2 ng g(-1) lipid). The mean estimated daily intake of PBDEs by breast-fed infants ranged from 9.9 to 335.9 ng kg(-1) body weight (bw) per day (mean: 52.5 ng kg(-1) bw per day; median: 28.6 ng kg(-1) bw per day). The levels of PBDEs body burden in the recruited mothers of Shenzhen were higher than those reported previously for the general population from other areas in China. No significant correlations were found between the body burden of PBDEs and the mothers' age, pre-pregnancy BMI, dietary habits, duration of residence in Shenzhen, weight and length of the newborns. BDE-47 and BDE-153 were major PBDE congeners in milk samples, while the congeners of BDE-183 and BDE-28 were also high in Shenzhen. The situation may be attributed to the special economic pattern including electronic production in Shenzhen in the past three decades. Continuous surveillance on PBDEs levels in human milk is needed in order to accurately evaluate the environmental impact of PBDEs to human health in Shenzhen.

A bilateral study for the establishment of comparability in the measurement of ethanol in bioethanol fuel using isotope dilution mass spectrometry

A bilateral comparative study between two metrology institutes was conducted for the determination of ethanol in bioethanol fuel by isotope dilution mass spectrometry. Measurement procedures were independently developed by the Health Sciences Authority (Singapore) and the National Institute of Metrology (People’s Republic of China). The methods used included headspace gas chromatography–high-resolution mass spectrometry, headspace gas chromatography–mass spectrometry (GC-MS) and direct injection to GC-MS. An investigation of all potential sources of uncertainty, including a component of uncertainty due to the effect of using different instruments such as gas chromatography–flame ionization detector method, commonly adopted for the analysis of organic volatiles, was carried out. The results of the analyses are consistent within the associated measurement uncertainty of each laboratory, reported at approximately 95% confidence level.

Application of GC–HRMS and GC×GC–TOFMS To Aid in the Understanding of a Dioxin Assay’s Performance for Soil and Sediment Samples

There have been numerous attempts to correlate results obtained by gas chromatography-mass spectrometry (GC-MS) to alternative techniques such as immunoassays and bioassays for the analysis of dioxins in environmental samples. In spite of these efforts, uncertainties about the performance of these methods remain. Following a series of performance studies of various dioxin assays, an in-depth evaluation of sample extracts from the Procept Rapid Dioxin Assay was conducted to provide users with a clearer understanding of the differences in the assay's results compared to traditional mass spectrometry. Two powerful analytical techniques [high-resolution mass spectrometry (HRMS) and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS)] were used to provide a unique perspective about the assay's underlying analytical performance. HRMS analyses demonstrated that the target dioxin and furans were consistently captured in the assay's extracts. TOFMS analyses revealed that interferents in the sample extracts resulting from inconsistencies in the sample preparation process appear to be the primary factor contributing to the assay's imprecision. The conclusion of this research was the assay results cannot be expected to correlate directly with HRMS and should only be utilized as a screening technique (e.g., to identify the relative ranking of contamination, to determine if samples are above/below threshold levels, or to monitor a cleanup) for environmental matrices such as soil and sediment.

The predictive power of the elimination of dioxin-like pollutants from pigs: An in vivo study

Pigs accidentally given feed contaminated by dioxin-like pollutants are a serious public health issue. We have examined whether pigs with limited exposure during early periods of fattening would be categorized as non-compliant with the EU limit at slaughtering when growth-dilution, excretion and metabolism effects are considered. Sixteen female and sixteen castrated male weaned pigs were divided into four groups (e.g. DG0, DG1, DG2 and DG3) in week 2 after birth. From weeks 3 to 13, groups DG1, DG2, and DG3 pigs were fed with a polychlorinated dibenzo- p-dioxin/dibenzofuran (PCDD/F) and polychlorinated biphenyl (PCB) mixture at dosages of 1, 10 and 100 ng-toxic equivalent (TEQ) per kg dry mass feed in capsules, respectively. From weeks 13 to 23, the animals were nourished with clear feed. Control group DG0 was always fed with clear feed. Subcutaneous fat samples were collected at weeks 13, 18 and 23 by biopsies. The pollutant residues were analyzed by high resolution gas chromatography–high resolution mass spectrometry and quantified by a 13C-isotope dilution method. The results showed the following: (1) when slaughtered at week 23, the TEQ for DG1 pigs (0.66 ± 0.21 pg/g fat) was under the EU limit of 1 pg PCDD/F-TEQ/g fat; (2) PCDD/F congener-specific first-order elimination rates were linearly correlated with their toxicity equivalency factors (TEFs), and the rates were significantly dose-dependent for the more toxic congeners (TEF ≥ 0.1). Therefore, the pigs' exposure above the EU limit during the early fattening stage did not necessarily lead to their categorization as non-compliant pork; and the residual TEQ for pork can be predicted from early exposure concentrations based on the models established here.

Use of Volatile Compound Metabolic Signatures in Poultry Liver to Back-Trace Dietary Exposure to Rapidly Metabolized Xenobiotics

The study investigated the feasibility of using volatile compound signatures of liver tissues in poultry to detect previous dietary exposure to different types of xenobiotic. Six groups of broiler chickens were fed a similar diet either noncontaminated or contaminated with polychlorinated dibenzo-p-dioxins/-furans (PCDD/Fs; 3.14 pg WHO-TEQ/g feed, 12% moisture), polychlorinated biphenyls (PCBs; 0.08 pg WHO-TEQ/g feed, 12% moisture), polybrominated diphenyl ethers (PBDEs; 1.63 ng/g feed, 12% moisture), polycyclic aromatic hydrocarbons (PAHs; 0.72 μg/g fresh matter), or coccidiostats (0.5 mg/g feed, fresh matter). Each chicken liver was analyzed by solid-phase microextraction - mass spectrometry (SPME-MS) for volatile compound metabolic signature and by gas chromatography - high resolution mass spectrometry (GC-HRMS), gas chromatography - tandem mass spectrometry (GC-MS/MS), and liquid chromatography - tandem mass spectrometry (LC-MS/MS) to quantify xenobiotic residues. Volatile compound signature evidenced a liver metabolic response to PAH although these rapidly metabolized xenobiotics are undetectable in this organ by the reference methods. Similarly, the volatile compound metabolic signature enabled to differentiate the noncontaminated chickens from those contaminated with PBDEs or coccidiostats. In contrast, no clear signature was pointed out for slowly metabolized compounds such as PCDD/Fs and PCBs although their residues were found in liver at 50.93 (±6.71) and 0.67 (±0.1) pg WHO-TEQ/g fat, respectively.

Determination of PCBs, PCDDs and PCDFs in insulating oil samples from stored Chinese electrical capacitors by HRGC/HRMS

Homologue and congener profiles of polychlorinated biphenyls (PCBs), polychlorinated dibenzo- p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in commercial PCBs formulations are key information for the source identification of PCBs contamination as well as for the risk assessment caused by potential exposure. The isotope dilution technology in combination with high resolution gas chromatography–high resolution mass spectrometry (HRGC/HRMS) has made the accurate determination of such profiles possible. So far, various commercial PCB formulations except Chinese products have been successfully determined. Two PCBs containing insulating oil samples from stored Chinese electrical capacitors have been determined with the same methodology for comparability. The total concentration PCBs in two oil samples were 790 000 μg g −1 and 720 000 μg g −1, respectively. TriCBs, TetraCBs, and DiCBs were found to be most abundant. Concentration of dioxins contamination in two samples is 650–670 ngTEQ g −1, of which 69–71 ngTEQ g −1 from PCDD/Fs with the predominant congeners of 1,2,7,8-TeCDF; 2,3,7,8-TeCDF; 2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDF. The contributions of DL-PCBs in total TEQ in both samples were more than 85%. The dioxin-like toxicity in insulating oils contained in electrical capacitors could be considered receive attention as an important dioxins source if such wastes are not managed in an environmentally sound manner.

Retention time profiling of all 136 tetra- through octa- chlorinated dibenzo-p-dioxins and dibenzofurans on a variety of Si-Arylene gas chromatographic stationary phases

The applicability of three different Silphenylene Silicone co-polymer (Si-Arylene) GC stationary phases (J&W Scientific DB-5ms, Varian VF-5ms, and VF-Xms) has been evaluated for the separation of all 136 tetra- through the octa- chlorinated dibenzo-p-dioxins (PCDD) and chlorinated dibenzofurans (PCDF) from closely eluting isomers using gas chromatography/high resolution mass spectrometry (GC/HRMS). Their relative performance data are compared to the “conventional” 5% diphenyl 95% dimethylpolysiloxane GC column (Supelco Equity-5) and to each other based on absolute retention times, visualized mass chromatograms, and the separation of 2,3,7,8-substituted isomers. VF-Xms GC column was able to demonstrate a better performance towards separation of 2,3,7,8-substituted PCDD/PCDF compared to other Si-Arylene GC columns tested, where only 2,3,4,7,8-PnCDF can not be resolved from 1,2,3,6,9-PnCDF and 2,3,4,6,7,8-/1,2,3,6,8,9-HxCDF and 1,2,3,7,8,9-/1,2,3,4,8,9-HxCDF can be at least partially resolved. These data suggest that the development of a single GC column for the separation of all 17 2,3,7,8-substituted dioxins and furans is feasible, which therefore could be used as a standard tool for the PCDD/PCDF methods globally including USEPA methods 1613b, 8290A, 8280B, European Standard Method EN 1948, Canadian methods DFPCB-E3418, EPS 1/RM/19, Japanese methods JIS K0311 and JIS K0312. Having one specific GC column to separate all 2,3,7,8-substituted PCDD/PCDF will significantly improve the data quality, comparability by the various methods and assessment techniques while simultaneously leading to a more cost and time efficient operation.

Particle-bound PCDD/Fs in the Atmosphere of an Electronic Waste Dismantling Area in China

Objective Particulate samples from the atmosphere in an electronic waste dismantling area were collected to investigate the levels and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Methods Particulate samples including total suspended particulates (TSP) and particulate matter <2.5 μm diameter (PM 2.5) were collected on selected non-rainy days in summer (Jul 10-12, 2006) and winter (Jan 11-13, 2007) from Fengjiang (FJ), an electronic waste (e-waste) dismantling area in eastern China, and an adjacent area Luqiao (LQ). The samples were analyzed by isotope dilution – high resolution gas chromatography / high resolution mass spectrometry (HRGC/HRMS). Results In FJ, the mean PCDD/F concentrations (mean TEQ values) were 280.6 pg Nm −3 (3.432 pg WHO-TEQ Nm −3) for the TSP samples and 223.3 pg Nm −3 (3.180 pg WHO-TEQ Nm −3) for the PM 2.5 samples. The total PCDD/F concentrations and TEQs in the PM 2.5 samples were about 66.8%-108.0% of the TSP samples, indicating that the fine particles contained higher levels of PCDD/Fs than coarse particles. The PCDD/F levels in FJ were much higher than those detected in common urban areas around the world, suggesting that the study area was heavily polluted by PCDD/Fs. Furthermore, the total average daily PCDD/F intake in FJ was estimated at 62.11 pg WHO-TEQ kg −1·day −1 for adults and 110.11 pg WHO-TEQ kg −1·day −1 for children, which greatly exceeds the WHO (1998) tolerable daily intake of 1-4 pg of WHO-TEQ kg −1·day −1. Conclusion The PCDD/F homologues and congener profiles confirmed that the PCDD/Fs in FJ originated from crude e-waste recycling activities. The severe dioxin pollution present in FJ has also substantially influenced the adjacent area of LQ through atmospheric transport. Open burning of medical waste was another source of PCDD/Fs identified in LQ.

Establishing an alternative method for the quantitative analysis of polychlorinated dibenzo- p-dioxins and polychlorinated dibenzofurans by comprehensive two dimensional gas chromatography–time-of-flight mass spectrometry for developing countries

Comprehensive Gas Chromatography–Time-of-Flight Mass Spectrometry (GC × GC–TOFMS) methodology has been refined for the analysis of polychlorinated dibenzo- p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in samples with different matrices. This is specifically for application in developing countries where access to gas chromatography–high resolution mass spectrometry (GC–HRMS) and highly skilled personnel is limited. The method, using an Rxi-5 Sil MS column in the first dimension ( 1D) coupled with an Rtx-200 column in the second dimension ( 2D), was used to quantify PCDDs and PCDFs in different environmental sample matrices. The results were compared with those obtained using GC–HRMS and good agreement was observed. The limit of detection (LOD) for the method (300 fg on column for spiked soil samples) was determined using an Rxi-XLB ( 1D) column coupled with an Rtx-200 column ( 2D). Preliminary South African sample results are also discussed. Isomer specificity for different tetrachloro dibenzo- p-dioxins (TCDDs) and tetrachloro dibenzofurans (TCDFs) was investigated using a commercial standard. Adequate resolution was achieved. The method as described has great attraction for developing countries being both financially and operationally favourable.

Comprehensive two-dimensional gas chromatography time of flight mass spectrometry (GC × GC-TOFMS) for environmental forensic investigations in developing countries

The disposal and dumping of toxic waste is a matter of growing concern in developing countries, including South Africa. Frequently these countries do not possess access to gas chromatography-high resolution mass spectrometry (GC-HRMS) for the determination of persistent organic pollutants (POPs). This publication describes an alternative approach to the investigation of toxic waste using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC × GC-TOFMS). The technology permits both comprehensive screening of toxic samples for numerous classes of organic pollutants and also quantitative analysis for the individual compounds. This paper describes the use of this technique by analysing samples obtained from a hazardous waste treatment facility in South Africa. After sampling and extraction the samples were analysed for polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and four dioxin-like non- ortho substituted polychlorinated biphenyls (PCBs). The quantitative values, as well as detection limits, obtained using the GC × GC-TOFMS methodology compares well with those obtained using GC-HRMS; the accepted benchmark technology for this analysis. Although GC × GC-TOFMS is not a target compound analytical technique (as is GC-HRMS), it is possible to obtain information on numerous other classes of organic pollutants present in the samples in one analytical run. This is not possible with GC-HRMS. Several different column combinations have been investigated for handling very complex waste samples and suggestions are presented for the most suitable combination.

Concentrations of polychlorinated biphenyls in water from US Lake Ontario tributaries between 2004 and 2008

Research on the environmental fate and transport of PCBs in Lake Ontario basin depends, among other aspects, on the availability of representative data sets for upstream sources, but data are lacking for most US Lake Ontario tributaries. In this study, water samples were collected between September 2004 and October 2008 from five tributaries and were analyzed for 209 polychlorinated biphenyls (PCB) with high-resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) following EPA Method 1668A. Total PCB concentrations ranged between 0.31 and 42.75 ng L −1. Congeners between Di and Hexa PCBs accounted between 70 and 99% of the total PCB. The tributary with highest PCB concentrations presented similar pattern and percentage levels to Aroclor 1242. Total average loads for the sampling events ranged between 1.85 g d −1 and 59.08 g d −1. PCB concentrations were evaluated against other variables and other studies (including different matrices) to better understand their transport. The methodology used is reliable to assess PCB contamination in surface water.

Characterization of dioxin-like contamination in soil and sediments from the “hot spot” area of petrochemical plant in Pancevo (Serbia)

Combinatorial bio/chemical approach was applied to investigate dioxin-like contamination of soil and sediment at the petrochemical and organochlorine plant in Pancevo, Serbia, after the destruction of manufacturing facilities that occurred in the spring of 1999 and subsequent remediation actions. Soil samples were analyzed for indicator polychlorinated biphenyls (PCBs) by gas chromatography/electron capture detection (GC/ECD). Prioritized soil sample and sediment samples from the waste water channel were analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). Microethoxyresorufin o-deethylase (Micro-EROD) and H4IIE-luciferase bioassays were used for monitoring of dioxin-like compounds (DLC) and for better characterization of dioxin-like activity of soil samples. Bioanalytical results indicated high dioxin-like activity in one localized soil sample, while the chemical analysis confirmed the presence of large quantities of DLC: 3.0 × 10(5)ng/g d.w. of seven-key PCBs, 8.2ng/g d.w. of PCDD/Fs, and 3.0 × 10(5)ng/g d.w. of planar and mono-ortho PCBs. In the sediment, contaminant concentrations were in the range 2-8ng/g d.w. of PCDD/Fs and 9-20ng/g d.w. of PCBs. This study demonstrates the utility of combined application of bioassays and instrumental analysis, especially for developing and transition country which do not have capacity of the expensive instrumental analysis. The results indicate the high contamination of soil in the area of petrochemical plant, and PCDD/Fs contamination of the sediment from the waste water channel originating from the ethylene dichloride production.

Confirmation of polychlorinated biphenyl (PCB) distribution in the blood and verification of simple quantitative method for PCBs based on specific congeners

We measured the concentration of each polychlorinated biphenyl (PCB) congener in whole blood, plasma and blood cells, and investigated the distribution of PCBs in human blood using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The PCB concentrations in plasma and whole blood in terms of lipid concentrations were almost equal, with a correlation coefficient of r = 0.972. In the blood, the ratio of PCBs in blood cells to those in plasma was generally about 1:9 and the congener distribution patterns in blood cells and plasma were similar. We performed verification of a simple mass screening method by obtaining information on the main PCB congeners for investigations on human accumulation and exposure. The total concentration of the seven PCB congeners (UNEP-7) proposed to the United Nations Environment Programme (UNEP) by Muir and Morita was about 50% of the total concentration of all PCB congeners, and UNEP-30 was about 80%. The seven main congeners in the blood (MCB-7) showed a value that was about 60%, and MCB-30 showed a value that was about 90%. Determinations with the main congeners in the blood showed a correlation of r = 0.990 or more between the main eight congeners (MCB-7 plus #74) and the total PCB concentration for all congeners. The results suggest that, although total PCB concentration can be effectively estimated from the main seven congeners, the main eight congeners would be preferable, and that the use of these congeners in the simple mass screening method would be effective for populations in areas uncontaminated by PCBs.