Development of a gas chromatography/ion trap mass spectrometry based method for the quantification of polybrominated diphenyl ethers and polychlorinated biphenyls in adipose tissue

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in adipose tissue of women from Grand Tunis and their association with demographic factors and dietary habits

Dichlorodiphenyl trichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and polychloronated biphenyls (PCBs) were measured in 25 woman adipose tissues collected in 2016 from Grand Tunis, Tunisia. p,p'-DDE, p,p'-DDT, HCB and β-HCH were the dominant organochlorine pesticides (OCPs) in decreasing order in all samples. The total OCP levels varied from 79 to 343 ng g-1 lipid with a median value of 189 ng g-1 lipid and DDTs contributed approximately 88% to sum OCP. The ratio of p,p'-DDT/p,p'-DDE across all samples is below one, which suggests mainly historic exposure but may indicate some recent exposure to the banned pesticide. The median concentration of PCBs was 109 ng g-1 lipid and ranged between 27 and 204 ng g-1 lipid. PCB-153, PCB-180, PCB-138 and PCB-170 were the most abundant congeners, which contributed about 78% of the total PCBs. Spearman analysis showed that dominant organochlorine compounds (OCs) are highly positive correlated except for PCB-28/31, indicating that women from Tunis are exposed via similar routes. Inhalation exposure could be a possible pathway for the uptake of the less chlorinated congeners. We found positive and statistically significant association with subjects age for HCB (r = 0.517; p = 0.009) and PCBs (r = 0.65; p = 0.001) levels and a weak age-dependent accumulation was found for HCHs (r = 0.375; p = 0.065) and DDTs (r = 0.388; p = 0.056). The concentrations of OC subgroups were not associated with BMI, parity and residence. No association was observed between fish, red/white meat, milk and dairy products consumption and levels of HCB, HCHs and PCBs. DDTs levels were significantly correlated only with milk (p = 0.048) and milk products (p = 0.047) intake.

Organochlorine pesticides and polychlorinated biphenyls in human adipose tissue from northern Tunisia: Current extent of contamination and contributions of socio-demographic characteristics and dietary habits

The aims of the present study were to investigate the current exposure levels of persistent organochlorine compounds (OCs) in adipose tissues intraoperatively collected from 40 patients over 20 years undergoing non-cancer-related surgery residing in Northern region of Tunisia (Bizerte), which constitutes an exemplary case, and examined association between levels of contamination and both socio-demographic characteristics and dietary habits. Concentration of hexachlorobenzene (HCB), hexachlorocyclohexane isomers (α-HCH, β-HCH, γ-HCH and δ-HCH), dichlorodiphenyltrichloroethane isomers (p,p'-DDT and o,p'-DDT) and metabolites (p,p'-DDE, o,p'-DDE, p,p'-DDD and o,p'-DDD) and 12 polychlorinated biphenyls (PCBs) congeners were measured using capillary gas chromatography with electron capture detector. Overall, residue levels of OCs followed the decreasing order of DDTs > PCBs > HCB > HCHs. DDTs levels ranged from 74.49 to 1834.76ngg^-1 lipid and contributing to more than 90% to the sum of organochlorine pesticides (OCPs). p,p'-DDE was the most abundant in all samples and the p,p'-DDT/p,p'-DDE ratio (range between 1.85% and 58.45%) suggesting recent and ongoing exposure to banned commercial DDT products. PCB concentrations varied from 29.27 to 322.58ngg^-1 lipid and PCB-180, PCB-153 and PCB-138 were the dominant congeners accounting for 70% of total PCBs. We did not find significant correlations between OC exposure levels and sex, parity, habitat areas and smoking habits. In females, the adipose tissue concentrations of DDTs, HCB and PCB-118 were positively correlated with age. There was statistically significant relationship between body mass index (BMI) changes and the adipose tissue levels of HCB and HCHs. No association was found between OCPs levels and dietary factors. However, our study suggests that fish consumption may be an important contributor of PCBs adipose tissue content of PCBs in Tunisian people. The presented work is highly significant, being the first study pointing out the chronic exposure to OCs in Bizerte.

Mass spectrometry parameters optimization for the 46 multiclass pesticides determination in strawberries with gas chromatography ion-trap tandem mass spectrometry

Multiclass analysis method was optimized in order to analyze pesticides traces by gas chromatography with ion-trap and tandem mass spectrometry (GC-MS/MS). The influence of some analytical parameters on pesticide signal response was explored. Five ion trap mass spectrometry (IT-MS) operating parameters, including isolation time (IT), excitation voltage (EV), excitation time (ET), maximum excitation energy or "q" value (q), and isolation mass window (IMW) were numerically tested in order to maximize the instrument analytical signal response. For this, multiple linear regression was used in data analysis to evaluate the influence of the five parameters on the analytical response in the ion trap mass spectrometer and to predict its response. The assessment of the five parameters based on the regression equations substantially increased the sensitivity of IT-MS/MS in the MS/MS mode. The results obtained show that for most of the pesticides, these parameters have a strong influence on both signal response and detection limit. Using the optimized method, a multiclass pesticide analysis was performed for 46 pesticides in a strawberry matrix. Levels higher than the limit established for strawberries by the European Union were found in some samples.

Extraction, isolation, and purification of analytes from samples of marine origin--a multivariate task

The development of a multivariate study for a quantitative analysis of six different polybrominated diphenyl ethers (PBDEs) in tissue of Atlantic Salmo salar L. is reported. An extraction, isolation, and purification process based on an accelerated solvent extraction system was designed, investigated, and optimized by means of statistical experimental design and multivariate data analysis and regression. An accompanying gas chromatography-mass spectrometry analytical method was developed for the identification and quantification of the analytes, BDE 28, BDE 47, BDE 99, BDE 100, BDE 153, and BDE 154. These PBDEs have been used in commercial blends that were used as flame-retardants for a variety of materials, including electronic devices, synthetic polymers and textiles. The present study revealed that an extracting solvent mixture composed of hexane and CH₂Cl₂ (10:90) provided excellent recoveries of all of the six PBDEs studied herein. A somewhat lower polarity in the extracting solvent, hexane and CH₂Cl₂ (40:60) decreased the analyte %-recoveries, which still remain acceptable and satisfactory. The study demonstrates the necessity to perform an intimately investigation of the extraction and purification process in order to achieve quantitative isolation of the analytes from the specific matrix.

Application of mass spectrometry in the analysis of polybrominated diphenyl ethers

This review summarized the applications of mass spectrometric techniques for the analysis of the important flame retardants polybrominated diphenyl ethers (PBDEs) to understand the environmental sources, fate and toxicity of PBDEs that were briefly discussed to give a general idea for the need of analytical methodologies. Specific performance of various mass spectrometers hyphenated with, for example, gas chromatograph, liquid chromatograph, and inductively coupled plasma (GC/MS, LC/MS, and ICP/MS, respectively) for the analysis of PBDEs was compared with an objective to present the information on the evolution of MS techniques for determining PBDEs in environmental and human samples. GC/electron capture negative ionization quadrupole MS (GC/NCI qMS), GC/high resolution MS (GC/HRMS) and GC ion trap MS (GC/ITMS) are most commonly used MS techniques for the determination of PBDEs. New analytical technologies such as fast tandem GC/MS and LC/MS become available to improve analyses of higher PBDEs. The development and application of the tandem MS techniques have helped to understand environmental fate and transformations of PBDEs of which abiotic and biotic degradation of decaBDE is thought to be one major source of Br(1-9)BDEs present in the environment in addition to direct loading from commercial mixtures. MS-based proteomics will offer an insight into the molecular mechanisms of toxicity and potential developmental and neurotoxicity of PBDEs.

Simultaneous use of gas chromatography/ion trap mass spectrometry - electron capture detection to improve the analysis of bromodiphenyl ethers in biological and environmental samples

Bromodiphenyl ethers (BDEs) are a class of synthetic flame retardants and are widely present in the environment. Analysis of higher BDE congeners has proven to be a challenge. We report the development of a method that enhances their analysis by splitting the eluent of a gas chromatograph (GC) between an electron capture detector (ECD) and an ion trap mass spectrometer (ITMS): 1:10, ECD:ITMS. This allowed the quantitation of the lower molecular weight (MW) BDE congeners (Br1-Br7) with the ITMS and of the higher MW BDEs (Br8-Br10) with the highly sensitive ECD. The IT temperature, ionization mode, and MS/MS parameters (excitation amplitude and stability parameter) were optimized. This method took the advantages of the best detector for the different BDE homologues and was suitable for the analysis of BDEs in environmental and biological samples. Average recoveries were 52-112% for BDEs from spiked sand samples and 57-126% from spiked lard samples after accelerated solvent extraction followed by silica gel and alumina column clean-up. Average recoveries ranged from 51% to 130% for 13C-labeled BDEs spiked in the real and in matrix samples. The method detection limits for specific congeners were 0.18-120 pg/g of the BDEs in animal tissue samples, and 0.05-40 pg/g in soil and indoor dust samples. The utility of the method was demonstrated by analyzing actual harbor seal blubber, indoor dust and soil samples. The concentration of each BDE ranged from non-detectable (nd) to 41 ng/g in the dry soil sample, nd to 1042 ng/g in the indoor dust, nd to 15 ng/g wet weight in the Alaskan harbor seal blubber sample, and 0.02 to 11 ng/microL of the identified 23 of the 42 breakdown products from BDE-209 after zerovalent iron treatment. Finally, an interlaboratory comparison showed high correspondence between the GC/ITMS-ECD method and a GC high-resolution MS system for the analysis of BDEs in soil samples.

Development and application of a simplified clean-up procedure for the determination of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in horse fat by gas chromatography-tandem mass spectrometry (GC-MS/MS)

A simplified clean-up procedure was developed in combination with gas chromatography-tandem mass spectrometry (GC-MS/MS) for the determination of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in adipose tissue. Clean-up was performed by the successive application of a Mega Bond Elut silica column and a Bond Elut PCB column. Validation of the method was conducted according to European Union Commission Decision 2002/657/EC. In order to evaluate the applicability of the method, 44 horse fat samples were analysed. The total PCB concentration (sum of PCBs 28, 52, 101, 118, 138, 153 and 180) ranged from 5.35 to 140 ng g(-1) lipid weight. The total PBDE concentration (sum of BDEs 28, 47, 99, 100, 153, 154 and 183) ranged from below the decision limit to 6.34 ng g(-1) lipid weight.

Distribution of polychlorinated biphenyls and polybrominated diphenyl ethers in birds of prey from Switzerland

Polychlorinated biphenyls (PCBs) and the structurally related polybrominated diphenyl ethers (PBDEs) have been associated with chronic neurotoxicity involving reduced motor activity and impaired attentiveness. Such neurobehavioral effects indicate that the central nervous system may represent an important target organ for the action of these persistent contaminants in wildlife. As a consequence, the brain of different terrestrial and aquatic birds collected in Switzerland was analysed for PCBs and PBDEs. In parallel, the same contaminants were examined in the accompanying adipose tissue. After clean-up by means of glass columns containing acidified silica, deactivated alumina and anhydrous sodium sulphate, the samples were analysed by high resolution gas chromatography/tandem mass spectrometry (HRGC-MS/MS). Median PCB concentrations in the brain (sum of PCB 28, PCB 52, PCB 101, PCB 118, PCB 138, PCB 153 and PCB 180) ranged between 13 ng g(-1) wet weight (ww) in blackbirds (Turdus merula) and 428 ng g(-1) ww in sparrow hawks (Accipiter nisus). Median PBDE concentrations in the brain (sum of BDE 28, BDE 47, BDE 99, BDE 100, BDE 153, BDE 154 and BDE 183) ranged from below the decision limit in buzzards (Buteo buteo) and blackbirds, to 14 ng g(-1) ww in sparrow hawks. After correction for the respective lipid content, higher PCB or PBDE concentrations in brain compared to adipose tissue, were found in three sparrow hawks, four buzzards and in all investigated blackbirds. These results suggest that a deficit in the neuroprotective function of the blood-brain barrier may cause unexpected levels of PCBs and PBDEs in the central nervous system.

Suitability of tandem-in-time mass spectrometry for polybrominated diphenylether measurement in fish and shellfish samples: Comparison with high resolution mass spectrometry

The first part of the present study focused on the development of an alternative automated sample preparation method for the measurement of selected polybrominated diphenyl ethers (PBDEs) in fish and shellfish. A previously developed automated method has been further optimized and simplified to decrease blank levels and cost. Sorbent and solvent quantities have been significantly reduced without altering extract quality. The second part of the study consisted of comparing tandem-in-time quadrupole ion storage mass spectrometry (QISTMS/MS) to high resolution mass spectrometry (HRMS) for the isotope dilution (ID) measurement step after gas chromatography (GC) separation. Both mass spectrometric methods performed similarly in terms of accuracy but better precision was observed for HRMS. Although better sensitivity can be attained with the high resolution sector instrument, method limits of quantification (mLOQs) were very similar for both approaches as they were dependent on the procedural blanks levels. The mLOQ values ranged between 0.04 and 3.56 ng/g fat, depending on the congener. They allowed the unambiguous identification and quantification of all target analytes, except for BDE-183, in most considered fish extracts. An analytical procedure based on rapid automated sample preparation and QISTMS/MS appeared to be suitable for the measurement of PBDEs in fish and shellfish speciment under quality assurance/quality control (QA/QC) criteria.

Occurrence of polychlorinated biphenyls and polybrominated diphenyl ethers in belgian human adipose tissue samples

Levels of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were measured in 53 human adipose tissue samples. The samples consisted of adipose tissue from 31 men and 22 women having a mean age of 53 years. No information about diet or occupational exposure was collected. Cleanup was performed using a glass column containing acidified silica, deactivated alumina, and anhydrous sodium sulphate. Subsequently, samples were analyzed by high-resolution gas chromatography/tandem mass spectrometry. PBDE concentrations (sum of BDEs 28, 47, 99, 100, 154, 153, and 183) ranged between 1.23 and 57.2 ng g(-1) lipid weight and were comparable with levels in samples from other European countries. The sum of seven International Council for the Exploration of the Sea (ICES) indicator PCB congeners (PCBs 28, 52, 101, 118, 138, 153, and 180) ranged from 126 to 2090 ng g(-1) lipid weight. No age dependency was found for PBDEs (Pearson correlation -0.023, p = 0.873), whereas PCBs showed higher correlation coefficients with age (Pearson correlation 0.613, p < 0.0005). There was no relationship between PBDE and PCB levels (Pearson correlation -0.010, p = 0.943).

Quantitative analysis of polybrominated diphenyl ethers in adipose tissue, human serum and foodstuff samples by gas chromatography with ion trap tandem mass spectrometry and isotope dilution

A method based on gas chromatography (GC) separation followed by ion trap tandem mass spectrometry detection in EI mode (ITD-MS/MS), using isotope dilution, was developed for the determination of ten native polybrominated diphenyl ethers (PBDEs) and four (13)C(12)-labeled congeners in biological (fat tissue and human serum) and food samples. The highest-mass fragment ions were used as precursor ions for those congeners with molecular ions with m/z values higher than the maximum of the instrument. In these cases (hepta-BDEs and (13)C(12)-hexa-BDEs) no fragmentation was achieved under the experimental conditions employed. Repeatability (lower than 9%) and reproducibility (lower than 13%), expressed as relative standard deviation (RSD, n = 3 and 4, respectively), were satisfactory. Similarly, the coefficient of variation (n = 4) of the isotopic ratio between the two most abundant product ions was lower than 10 and 6% for native and labeled congeners, respectively. To evaluate the feasibility of the method, the optimized isotope dilution GC/ITD-MS/MS method was used for the quantitation of selected PBDE congeners in different samples including adipose tissue, human serum and foodstuff samples, from three inter-laboratory comparative exercises, covering a wide range of concentrations. A solid-phase extraction procedure, previously developed for PCB determination in small-size bird serum samples, was successfully applied to quantification of PBDEs in 1 mL samples of human serum.

Feasibility of gas chromatography - ion trap tandem mass spectrometry for the determination of polychlorinated biphenyls in food

The different parameters affecting the ionisation and fragmentation of selected polychlorinated biphenyls (PCBs) in an IT detector working in the MS/MS mode, ITD(MS/MS), have been optimised for maximum selectivity and sensibility. The low LODs (in the range 0.03-0.3 microg/L), the satisfactory repeatability (RSDs in general below 11%) and reproducibility (RSDs below 17%) obtained when analysing standard solutions ensured proper determination of the PCBs studied at the concentrations typically found in food samples. Foodstuffs naturally contaminated with varying levels of PCBs have been analysed using the optimised GC-ITD(MS/MS) method. The results obtained compared favourably with those found using more conventional detectors, such as (micro-)electron capture detection (for ortho-PCBs) and high-resolution MS (for non-ortho-PCBs), as well as with the consensus PCB levels established for these particular samples via an international interlaboratory exercise. The relative merits of these three detectors have been discussed.

Potential of Gas Chromatography Coupled To Triple Quadrupole Mass Spectrometry for Quantification and Confirmation of Organohalogen Xenoestrogen Compounds in Human Breast Tissues

The potential of gas chromatography coupled to tandem mass spectrometry (GC/MS/MS) with a triple quadrupole analyzer (QqQ) has been investigated for the accurate and sensitive determination of xenoestrogens in human breast tissues. Special emphasis has been given to the confirmation of the identity of compounds detected in the samples analyzed in order to avoid the reporting of false positives. The work has been focused on the determination of approximately 30 organochlorine compounds (PCBs and pesticides) and organobromine compounds (polybrominated diphenyl ethers) in adipose breast tissue and in tumoral fragment. Analytes were extracted by dissolving the samples in hexane, and the extracts were purified by automated normal-phase HPLC prior to GC/MS/MS analysis. Three isotopically labeled standards were added before extraction as surrogates for the quality control of the analyses. Accuracy and precision were evaluated by means of recovery experiments using adipose breast tissue spiked at three concentration levels, with satisfactory results for most analytes. The excellent selectivity and sensitivity of QqQ in selected reaction monitoring mode allowed us satisfactory quantification and confirmation at levels as low as 5-25 ng/g, i.e., the lowest concentration level for which the method was fully validated. Two MS/MS transitions were selected for each analyte, using the concentration ratio obtained from them as a confirmatory parameter. The developed methodology was applied to the analysis of 51 breast samples (26 adipose tissues and 25 tumoral fragments), giving as a result the detection and confirmation of several organochlorine compounds in both types of samples. Due to its adequate analytical characteristics, the optimized method fits with the requirements of accurate quantification and reliable confirmation of the identity of compounds detected according to the most recent European Guidelines. As an ultimate unequivocal confirmation, several selected samples were reanalyzed by gas chromatography coupled to mass spectrometry with a time-of-flight (TOF) analyzer. Confirmation of analytes present at higher concentrations was successful with mass error less than 5 mDa. However, confirmation by TOF MS was not possible al low concentrations (i.e., at the few ng/g level) as a consequence of its lower sensitivity compared with that of triple quadrupole in selected reaction monitoring mode.

Analysis of organochlorines in harbor seal (Phoca vitulina) tissue samples from Alaska using gas chromatography/ion trap mass spectrometry by an isotopic dilution technique

A gas chromatography/ion trap mass spectrometry (GC/ITMS) method was developed for the determination of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in harbor seal (Phoca vitulina) tissues. Tissue samples were homogenized, lyophilized and fortified with (13)C-PCBs 28, 123, 169 and 170, and then extracted with an accelerated solvent extractor with a mixture of hexane and methylene chloride (1:1, v/v). After lipid removal using a 40% H(2)SO(4)-modified silica gel column, all organochlorines were collected in one fraction and further fractionated with an activated carbon/silica gel (1:20) column into a first fraction containing OCPs, non-coplanar PCBs and (13)C-PCBs 28, 123 and 170, and a second containing PCNs, coplanar PCBs and (13)C-PCB 169. Prior to GC/MS/MS analysis, (13)C-PCB 169 was added into the first fraction as an injection standard and (13)C-PCB 170 into the second fraction to calibrate the recoveries of the fortified internal standards. This method can effectively eliminate matrix interferences, and has high selectivity and sensitivity. Recoveries averaged 45-86% for OCPs with relative standard deviations (RSDs) of 2-14%, 52-137% for PCBs with RSDs of 3-29% and 36-152% for PCNs with RSDs of 7-29% from lard and chicken heart samples, which were used as alternative matrices to harbor seal samples in recovery studies. The limits of detection for OCPs, PCBs and PCNs were 0.7-1.9, 1.5-8.9 and 0.5-10 pg/g dry weight, respectively. This method can be used to analyze OCPs, PCBs and PCNs in harbor seal blubber, liver and kidney samples.

Congener-specific Analysis of PCBs in Food Samples by Using GC/MS

A GC/MS method for congener-specific analysis of polychlorinated biphenyls (PCBs) in food samples was evaluated. There was good agreement between total concentration of PCBs in fish samples (n = 16) measured by using the GC/MS method and the conventional GC-ECD method. The total diet study samples (fishery food, meat, egg, milk, and their products) collected from Osaka in 1982-2001 were analyzed by using the GC/MS method to estimate the temporal trend of daily intake of PCBs from food. The estimated daily intake of total PCBs (sum of tri- to heptaCBs) was in the range of 0.7-4.4 microg/person/day, far below the Japanese provisional acceptable daily intake (250 microg/50 kg-person/day). The dominant congener was 2,2',4,4',5,5'-hexachlorobiphenyl (#153), which accounted for 9-15% of total PCB. The ratio of lower chlorinated congeners decreased from the 1980's to post-2000. The results indicate that the PCB congener profile in foods has gradually changed.