Fingerprinting polychlorinated biphenyls in environmental samples using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

Abstract

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.

Can polychlorinated biphenyl (PCB) signatures and enantiomer fractions be used for source identification and to age date occupational exposure?

“…Analysis was conducted based on the method described by Megson et al (2013b) which is summarised below. Samples were analysed using a time-of-flight mass spectrometer (LECO, St. Joseph, MI Pegasus 4D) coupled to a two dimensional gas chromatograph (Agilent Technologies 7890A) equipped with a thermal modulator (LECO, St. Joseph, MI).…”

“…Due to all of the subtle changes that can occur to the PCB profile, it is imperative that signatures are created using detailed congener specific datasets when attempting to identify the source of exposure. Analysis using comprehensive two dimensional chromatography has proven to be an excellent technique for this purpose as it is able to separate over 190 individual PCB congeners (Focant et al, 2004;Korytar et al, 2006;Harju et al, 2003;Zapadlo et al, 2011;Megson et al, 2013b).…”

Simultaneous analysis of polychlorinated biphenyls and polychlorinated naphthalenes by isotope dilution comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry

“…The sample extraction and cleanup procedures followed US EPA Method 1668 and have been described in detail previously [11,28,29]. Briefly, a 10 g (dry weight) fish sample was spiked with 1 ng of 13 C 12 -labeled PCB internal standards (1668C-LCS) and 13 C 10 -labeled PCN internal standards (ECN-5102). The sample was then extracted with a 1:1 mixture of dichloromethane and n-hexane using an ASE 350 extraction unit (Dionex, CA, USA) at an extraction temperature of 120 C and a pressure of 10.35 MPa.…”

“…Consequently, it is of important to be able to separate these specific PCBs and PCNs from other congeners and contaminants. Although there are some high-resolution capillary columns that can separate some of PCB and PCNs congeners, no chromatographic method can unambiguously and simultaneously separate the 12 dioxin-like PCBs, six indicator PCBs, and 16 PCNs from the other PCBs and PCNs [13,14]. Consequently, PCBs and PCNs are usually analyzed separately by gas chromatography coupled with highresolution mass spectrometry (GC-HRMS) in selected ion monitoring mode using 13 C isotope dilution for quantification in two injections [11,15].…”

“…The ratios of the two most intense exact mass ions were calculated and compared with theoretical values (tolerance of 20%) for identification. The isotope dilution method with 13 C-labeled internal standard (100 pg mL À1 for each) was used for quantification of the PCBs and PCNs. For compounds with no available 13 C-labeled internal standard, a 13 Clabeled standard for a compound with a similar structure was used for quantification (Table S1).…”