Determination of Indicator Congeners of Polychlorinated Biphenyls in Water at Ultratrace Levels by Gas Chromatography-Tandem Mass Spectrometry

We validated a procedure for the determination of indicator congeners (ICs) of polychlorinated biphenyls (PCBs) (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) in water at an ultratrace concentration level in the range from 0.02 to 0.90 ng/L. The procedure includes collecting 1-L samples, extraction of PCBs with n-hexane, preconcentration of the extracts (k(conc) = 10(4)), and the direct analysis of the preconcentrates by gas chromatography-tandem mass spectrometry. The chromatographic separation of the preconcentrates in columns with a carborane stationary phase (HT-8, 30 m), the detection of analytical peaks in the selected reaction monitoring mode, and the use of ICs labeled with C-13 as surrogate internal standards ensured the high reliability of peak identification and the accuracy of quantitative determination with a total error (+/-delta, P = 0.95) of 35%. The procedure was tested in monitoring PCBs in the aquatic ecosystem of Lake Baikal, and the concentrations of ICs were determined in the upper water layer of the pelagic zone and the lake's tributaries.