Electron ionization mass spectral fragmentation study of sulfation derivatives of polychlorinated biphenyls

The most abundant and characteristic fragment ions of PCB TCE sulfate diesters were formed by releasing CHCCl3, SO3, HCl2 and/or CCl3 from the TCE sulfate moiety and Cl2, HCl, ethyne and chloroethyne from an intermediate phenylcyclopentadienyl cation. The fragmentation pattern depended on the degree of chlorination and the position of the TCE sulfate moiety (i.e., ortho vs. meta/para to the second phenyl ring), but were independent of the chlorine substitution pattern. These fragmentation pathways are similar to the fragmentation pathways of structurally related methoxylated PCBs.Knowledge of the fragmentation patterns of PCB TCE sulfate diesters will greatly aid in determining the position of sulfate moiety (ortho vs. meta/para) of unknown PCB sulfate metabolites isolated from environmental or laboratory samples.Polychlorinated biphenyls (PCBs) are a family of manmade chemicals that were sold commercially from the 1920s to the 1970s as stabilizing additives in flexible PVC coatings of electrical wiring and in electronic components, cutting oils, flame retardants, hydraulic fluids, sealants, and adhesives [1,2]. They are still used as dielectric fluids in transformers and capacitors in the United States. Their large scale use and their physicochemical properties, such as semi-volatility and stability toward biological, chemical and thermal degradation, have resulted in worldwide environmental contamination [1,2]. Since the first identification of PCBs in human and wildlife samples in 1966 [3] the study of PCBs' adverse effects on human health and the environment has received significant attention [1,2,4,5]. Laboratory and epidemiological studies have implicated PCBs in a broad range of adverse biological effects, including (neuro-) developmental toxicity [4] and carcinogenesis [5].PCBs are metabolized by cytochrome P450 (CYP) isoforms, such as CYP2B and CYP1A, to hydroxylated derivatives (HO-PCBs) [6]. HO-PCBs may be further metabolized by phase II enzymes to PCB su