Search

Two Guillemot carcases were dissected, each providing 12 discrete tissue samples and 3 samples of partially digested food. One hundred and five PCBs from the 209 PCBs determined by GCxGC-ToFMS were detected. The relative proportions of individual PCBs did not vary greatly within tissue types, although the PCB profile from undigested food could be distinguished. Enantiomer fractions (EFs) were determined for CB-95, CB-136 and CB-149 by GC-HRqToFMS. EFs in the partially digested food were near racemic, with high levels of enrichment for E1 CB-95 in the kidneys and liver (EF of 0.80 and 0.84 respectively). This provides some of the clearest evidence to date that fractionation takes place in the organs where metabolic biotransformation and elimination of PCBs occurs. Our findings also confirm the ability of non-lethal sampling techniques, such as collection of small (<1 g) blood samples, to provide PCB signatures that are representative of an individual organism., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Detailed polychlorinated biphenyl (PCB) signatures and chiral Enantiomer Fractions (EFs) of CB-95, CB-136 and CB-149 were measured for 30 workers at a transformer dismantling plant. This was undertaken to identify sources of exposure and investigate changes to the PCB signature and EFs over different exposure periods. Approximately 1.5 g of serum was extracted and PCB signatures were created through analysis by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) and EFs calculated following analysis by gas chromatography with high resolution mass spectrometry (GC-HRMS). A total of 84 PCBs were identified in the serum samples with concentrations of the 7 indicator PCBs ranging from 11-350 ng g(-1) of serum (1.2-39 μg g(-1) lipid). The PCB signatures were interpreted using principal component analysis (PCA) which was able to distinguish workers with background or recent minimal exposure from those with prolonged occupational exposure. Occupationally exposed individuals had a similar PCB profile to Aroclor A1260. However, individuals with prolonged exposure had depleted proportions of several PCB congeners that are susceptible to metabolism (CB-95, CB-101 and CB-151) and elevated proportions of PCBs that are resistant to metabolism (CB-74, CB-153, CB-138 and CB-180). The results also identified a third group of workers with elevated proportions of CB-28, CB-60, CB-66, CB-74, CB-105 and CB-118 who appeared to have been exposed to an additional source of PCBs. The results show near complete removal of the CB-95 E2 enantiomer in some samples, indicating that bioselective metabolism or preferential excretion of one enantiomer occurs in humans. By considering PCB concentrations along with detailed congener specific signatures it was possible to identify different exposure sources, and gain an insight into both the magnitude and duration of exposure., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

PCB signatures can be used for source identification, exposure studies, age dating and bio-monitoring. This study uses comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-ToFMS) to produce a PCB signature comprised of over 80 PCBs for individual Leach's storm petrels (Oceanodroma leucorhoa). The Leach's storm petrel is a relatively small, elusive, understudied pelagic bird, which only returns to remote islands under darkness during the breeding season. Samples were obtained from 25 Leach's storm petrels found dead in Canada and the UK following storm events in 2006 and 2009. Tissue samples were extracted and analysed by GCxGC-ToFMS and results showed that 83 PCB congeners were present in >60% of samples. An assessment of the PCB signature in four different tissue types showed that it did not vary greatly in samples obtained from the gut, heart, liver and stomach. Multivariate statistical analysis identified a distinctive PCB signature in birds from Canada and Europe which was used to identify the regional provenance and transatlantic movement of individual birds. The findings showcase the ability of GCxGC-ToFMS to provide the high quality congener specific analysis that is necessary for PCB fingerprinting, as well as highlighting the potential of PCB signatures for use in ecological studies of movement, foraging and behaviour., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A GC × GC-TOFMS installed with a Rtx-PCB (60 m × 0.18 mm × 0.18 μm) in the first dimension and Rxi- 17 (1.5 m × 0.1 mm × 0.1 μm) column in the second dimension was used to separate 188 out of 209 congeners. A further 12 congeners were identified through additional data processing resulting in the identification of a total of 200 congeners. However, caution is advised if these 12 congeners were to be used in quantitative assessments. The remaining 9 co-eluting congeners were three doublets (CB65 + CB62, CB160 + CB163 and CB201 + CB204) and one triplet (CB20 + CB21 + CB33). This method was tested on five Aroclors and resulted in the separation of all congeners present in the heavier Aroclor mixtures A1254 and A1260. The suitability of this method for applications in biological matrices was demonstrated on extracted whiting and guillemot liver samples which resulted in the identification of 137 individual PCBs in the whiting liver sample and 120 in the guillemot sample. Fingerprinting was able to show clear differences in the PCB signature of the two animals. This highlights the potential of this method for PCB fingerprinting in environmental forensics studies and other assessments that require congener specific analysis.

In human exposure studies involving Polychlorinated Biphenyls (PCBs), it is useful to establish when an individual was potentially exposed. Age dating PCB exposure is complex but assessments can be made because different PCB congeners have different residence times in the human body. The less chlorinated congeners generally tend to have shorter residence times because they are biotransformed and eliminated faster than more chlorinated congeners. Therefore, the presence of high proportions of less chlorinated congeners is often indicative of recent exposure. The 2003-04 National Health and Nutrition Examination Survey (NHANES) dataset contains results for the concentration of 37 PCBs in a sub-sample of the US population. Multivariate statistical analysis of the NHANES data showed that less chlorinated congeners are not always biotransformed faster than higher chlorinated compounds. For example, PCB 28 (a tri-chlorobiphenyl) appears to be more resistant to biotransformation than PCB 101 and 110 (penta-chlorobiphenyls). Using statistical analysis of the NHANES data in conjunction with previously published studies on PCB persistence in humans, it was possible to identify the structural relationships that determine if a PCB is likely to be from a recent exposure (termed 'episodic') or from steady state exposure. Congeners with chlorine atoms in the 2,5- and 2,3,6-positions appear to be more susceptible to biotransformation whereas congeners with chlorine bonds in the 2,3,4- 2,4,5- 3,4,5- and 2,3,4,5-positions appear to be more persistent. This work shows that future investigations to date PCB exposure would benefit from the analysis of a wide range of congeners, including the selection of key congeners based not only on the degree of chlorination but also on the positions of the chlorine atoms on the biphenyl., (Copyright © 2013 Elsevier B.V. All rights reserved.)