Quadrupole ion storage tandem mass spectrometry and high-resolution mass spectrometry: complementary application in the measurement of 2,3,7,8-chlorine substituted dibenzo-p-dioxins and dibenzofurans in US foods

Global warming and environmental contaminants in aquatic organisms: the need of the etho-toxicology approach

Environmental contaminants are associated with a wide spectrum of pathological effects. Temperature increase affects ambient distribution and toxicity of these chemicals in the water environment, representing a potentially emerging problem for aquatic species with short-, medium- and long-term repercussions on human health through the food chain. We assessed peer-reviewed literature, including primary studies, review articles and organizational reports available. We focused on studies concerning toxicity of environmental pollutants within a global warming scenario. Existing knowledge on the effects that the increase of water temperature in a contaminated situation has on physiological mechanisms of aquatic organisms is presented. Altogether we consider the potential consequences for the human beings due to fish and shellfish consumption. Finally, we propose an etho-toxicological approach to study the effects of toxicants in conditions of thermal increase, using aquatic organisms as experimental models under laboratory controlled conditions.

Ion-trap tandem mass spectrometry for the analysis of polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in food

This paper reports on the applicability of gas chromatography coupled to ion-trap tandem mass spectrometry (GC/ITMS/MS) for the analysis of polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in food. MS/MS parameters were selected to achieve the high sensitivity and selectivity required for food analysis. Good precision (RSD=5-18% for PCDD/Fs and 6-14% for dl-PCBs) and low limits of detection for PCDD/Fs (0.1-0.93 pg/g of fat) and dl-PCBs (0.1-0.89 pg/g of fat) were obtained. A comparative study of the congener-specific determination using both GC/ITMS/MS and GC-high resolution mass spectrometry (GC/HRMS) was performed by analyzing several matrices such as milk, fish oil, chicken, pork, fish, eggs, and a chicken compound feed, at low pg/g levels. The results using GC/ITMS/MS were in good agreement with those obtained by GC/HRMS. Consequently, GC/ITMS/MS is proposed for the analysis of PCDD/Fs and dl-PCBs in food and feed samples.

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.

Levels of PCDD/PCDFs and PCBs in edible marine species and human intake: a literature review

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) are lipophilic organic compounds whose origin comes from many different sources. PCDD/Fs and PCBs are ubiquitous and persistent environmental pollutants with a well known potential toxicity, which were included at the 1998 UN-EC POP protocol. Although human exposure to PCDD/Fs and PCBs can occur by various routes, food is the primary source. A number of studies have shown that the major food sources of these organic pollutants are fat-containing animal products, including fish and other seafood. Because of the frequent health recommendations concerning fish consumption, to determine the contribution to the dietary intake of chemical contaminants such as PCDD/Fs and PCBs through fish and other seafood consumption is an issue of special interest. This paper reviews the state of the science regarding recent literature on PCDD/F and PCB levels in marine species and human intake through fish and seafood consumption. The concentrations of these pollutants depend basically on the environment in which the respective species are caught. It is concluded that some groups of population frequently consuming high quantities of certain species could be significantly increasing health risks due to PCDD/F and PCB exposure.

Evaluation of GC-ion trap-MS/MS methodology for monitoring PCDD/Fs in infant formulas

The application of high resolution gas chromatography in combination with low resolution mass spectrometry with electron ionization and MS/MS detection (HRGC-MS/MS) is tested for its use in the analysis of PCDD/Fs in infant formulas. Development of the analytical method was based upon EPA directrices and international recommendations. Calibration linearity was tested and average relative response for any native and labelled compound over the five-point calibration range below 14% was found. The precision and accuracy of the proposed analytical procedure are also presented. Results obtained are in agreement with EPA criteria. The method is applied to the analysis of a number of initial and follow-on milk based infant formulas. In general, HRGC-MS/MS constitutes an interesting method for the analysis of dioxins in such matrices.

Ion-trap tandem mass spectrometry-based analytical methodology for the determination of polychlorinated biphenyls in fish and shellfish

Optimization of the Varian Saturn 2200 ion-trap tandem mass spectrometry (IT-MS/MS) system and comparison of its data quality with two other detection methods [electron-capture detection (ECD) and high-resolution mass spectrometry (HRMS)] was pursued by measuring polychlorinated biphenyls (PCBs) levels in fish and shellfish samples. IT-MS/MS methodology provided limits of detection (LOD) comparable to those obtained by ECD but superior specificity for the detection of a selected number of 39 PCB native congeners and 9 (13)C-labelled PCB standards. The method detection limits (MDLs) established for IT-MS/MS ranged between 1.0 and 5.0 pg/g on a wet weight basis while those obtained by ECD and HRMS were 1.0-4.0 pg/g and 0.1-2.0 pg/g, respectively. Overall, the results obtained in the study demonstrate that gas chromatography (GC) combined with IT-MS/MS provide higher data quality than those achievable by GC-ECD. For this particular set of target analytes the specificity achievable with IT-MS/MS was comparable to that obtained by HRMS and both techniques provided comparable data in terms of accuracy and precision.

Polybrominated diphenyl ethers and polychlorinated biphenyls in commercially wild caught and farm-raised fish fillets in the United States

Wild caught and farm-raised fish fillets collected in fish markets and large-chain super markets located in the Maryland, Washington, DC, and North Carolina were measured for their polybrominated diphenyl ether (PBDE), polychlorinated biphenyl (PCB), and polychlorodibenzo-p-dioxins/dibenzofurans (PCDD/Fs) levels. PCB and PBDE concentrations were the highest in a wild bluefish fillet (800 and 38 ng/g wet weight, respectively) and the lowest in wild Coho salmon fillet (0.35 and 0.04 ng/g, respectively). Levels for both PCBs and PBDEs in ng/g wet weight decreased from bluefish with medians of 200 and 6.2, to rockfish 66 and 4.7, followed by farmed-raised salmon with 9.0 and 1.1, with the lowest in wild salmon, 4.0 and 0.3 ng/g for PCBs and PBDEs, respectively (PCBs are the sum of 25 congeners). The chlorinated biphenyl (CB)-153 and brominated diphenyl ether (BDE)-47 levels correlated in the 22 fish fillets with a Pearson correlation coefficient of 0.94. Bluefish, rockfish (striped bass), wild caught and farm-raised salmons all showed different linear regression slopes between CB-153 and BDE-47 of 7.5, 2.7, 0.97, and 1.5, respectively. A Wilcoxon rank sum test showed no significant difference in the CB-153/BDE-47 ratios between farmed raised and all species of wild salmon combined, but was significant between bluefish and rockfish, farmed raised salmon or wild salmon.

Tetrachlorodibenzo-p-dioxin in baby food made from chicken produced before and after the termination of ball clay use in chicken feed in the United States

Polychlorodibenzo-p-dioxin/furans were determined in chicken-containing baby foods collected from an annually conducted total diet survey by the US FDA during the last half of fiscal year (FY) 1997 through the first half of FY 1998. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was found in 8 of 11 baby food samples. The levels were between 0.025 and 0.28 ng kg(-1) wet wt (0.25-5 ng kg(-1) lipid). The mean TCDD value for chicken-containing baby food with "nondetects" equal to 0 was 1.2 ng kg(-1) lipid, eight times higher than the average level found during a previous survey of chicken lipid TCDD levels in 1996. All other 2,3,7,8-chlorine-substituted dibenzo-p-dioxin congeners were also found with a profile consistent with the use of ball clay in chicken feed. TCDD was not detected in any FY 2000 baby foods made with chicken, with an average limit of detection (LOD) of 0.025 ng kg(-1) wet wt. Whole eggs collected in 1997 from producers that never used ball clay in feed revealed TCDD measurements that were nearly all nondetects and none above the median LOD of 0.015 ng kg(-1) wet wt. The percentage of chickens fed ball clay in their feed was estimated to be between 2.6% and 3.5% of all chickens produced in the United States in 1997.

Optimization of quadrupole ion storage mass spectrometric conditions for the analysis of selected polybrominated diphenyl ethers. Comparative approach with negative chemical ionization and electron impact mass spectrometry

Gas chromatography coupled to quadrupole ion storage mass spectrometry (QISTMS) operating in the non-resonant mode is presented as an innovative approach for the analysis of selected polybrominated diphenyl ethers (PBDEs). Although reductions in complexity and time needed for optimization are achieved in comparison with the resonant option, precise adjustment of the mass spectrometric conditions is required. Differences in isolation and fragmentation patterns of target species with degree of bromination were observed. The reliability of the method was confirmed by using standard solutions through the evaluation of certain quality parameters such as accuracy (92-108%), injection repeatability and reproducibility (coefficient of variation below 10% and 15%, respectively). Detection limits ranged from 62 to 621 fg, providing sensitivity similar to that of negative chemical ionisation (NCIMS) and greater than that of electron ionization mass spectrometry. The applicability of QISTMS method to real samples and matrix effects were evaluated through the analysis of some PBDE congeners in a sewage sludge sample from a Spanish waste-water treatment plant. Comparable results were obtained using QISTMS and NCIMS. According to these observations, QISTMS performed in the non-resonant mode may constitute a low-cost, rapid and reliable alternative to high-resolution devices for the analysis of selected PBDEs in environmental samples.

Modern developments in gas chromatography-mass spectrometry-based environmental analysis

Gas chromatography coupled with mass spectrometry (GC-MS) continues to play an important role in the identification and quantification of organic contaminants in environmental samples. GC-MS is one of the most attractive and powerful techniques for routine analysis of some ubiquitous organic pollutants due to its good sensitivity and high selectivity and versatility. This paper presents an overview of recent developments and applications of the GC-MS technique in relation to the analysis in environmental samples of known persistent pollutants and some emerging contaminants. The use of different mass analysers such as linear quadrupole, quadrupole ion-trap, double-focusing sectors and time-of-flight analysers is examined. The advantages and limitations of GC-MS methods for selected applications in the field of environmental analysis are discussed. Recent developments in field-portable GC-MS are also examined.