Determination of polychlorinated biphenyls in serum using gas chromatography–mass spectrometry with negative chemical ionization for exposure estimation

A sensitive and selective method for the determination of 24 polychlorinated biphenyls (PCBs) by gas chromatography–mass spectrometry with negative chemical ionization (GC–MS-NCI) was applied for the recent needs of occupational exposure in waste incineration. The three most abundant ions were used in determining compounds with at least five chlorine atoms in the PCB molecule. Selecting ions Cl35 and Cl37 for di-, tri-, and tetrachlorinated PCBs resulted in reliable quantification of these compounds. The detection limits for the 24 individual compounds varied from 0.01 to 0.08 μg/l. The recovery of the method was 113±16%. Stability tests showed no degradation of the compounds studied during 6 weeks. The sum of 24 PCB compounds measured from the sera of workers in a disposal plant was 1.9–10.9 μg/l, and 0.3–3.0 μg/l for controls, respectively. The mean proportion of the low chlorinated PCB compounds (with four or less chlorine atoms) was 20% for workers in the disposal plant and 14% for the controls.