Determination of polychlorinated biphenyls in marine fish samples by gas chromatography tandem mass spectrometry (GC-MS/MS)

Polychlorinated biphenyls (PCBs) are a typical group of persistent organic pollutants (POPs), which have been listed under Annex A (Elimination) and Annex C (Unintentional production) of the Stockholm Convention. In this study, a gas chromatography tandem mass spectrometry method was developed and applied to analyze concentrations of 28 PCB congeners in some Vietnamese marine fish samples. PCBs in fish samples were ultrasonically extracted with an acetone/n-hexane (1/1, v/v) mixture. The extracts were cleaned up by using multilayer silica gel columns with dichloromethane/n-hexane (1/1, v/v) as elution solvent. PCBs were separated on a DB-5MS column and quantified by using a triple quadrupole mass spectrometer. The MS detector was operated in positive electron impact ionization (EI) mode and selected reaction monitoring (SRM) mode. Calibration curves of 28 PCBs exhibited good linearity (R2 ≥ 0.9998). Instrument detection limits (IDLs) and method detection limits (MDLs) ranged from 0.08 to 0.023 ng/mL and from 0.07 to 1.84 ng/g, respectively. Recoveries of 28 PCBs native and 7 labeled standards in matrix-spike samples ranged from 62.3 to 88.1% and from 75.5 to 91.9%, satisfying criteria proposed by AOAC (recovery 60-115% for 10-100 ppb levels). The validated method was applied to analyze 10 marine fish samples, showing levels of ∑28PCBs from 17 to 851 (mean 230) ng/g lipid. The sum of 6in-PCBs (PCB-28; -52; -101; -138; -153; -180) based on wet weight (w/w) ranged from 1.24 to 3.15 ng/g, which is lower than the maximum level recommended by The European Union (75 ng/g (w/w). Congeners PCB-126 and PCB-169 were not detected in marine fish samples.