Stir bar sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry applied to the analysis of polychlorinated biphenyls in human sperm

Stir bar sorptive extraction (SBSE) on polydimethylsiloxane (PDMS) was appl ied to the enrichment of polychlorinated biphenyls (PCBs) from human sperm. The seven Ballschmiter PCBs were used as model compounds. The extracted PC Bs were then thermally desorbed from the stir bar and analysed on-line by c apillary gas chromatography (CGC) with mass spectrometric detection (MS). M ethod development started with the analysis of PCBs spiked in water. Methan ol had to be added to the samples in order to reduce the influence of glass adsorption on recovery and reproducibility. Recoveries in water for all PC Ss varied around 50-60% and were limited for low molecular mass (MM) PCBs b y polarity changes in the sample due to methanol addition and for high MM P CBs by non-equilibrium conditions. Matrix suppression by the lipophilic med ium lowered the recoveries in the sperm samples proportional with PCB polar ity. The method was validated and although limits of detection (LOD) for th e individual congeners were in the sub-ppt level (<pg/ml), the limit of qua ntification (LOQ) was set at 10 ppt (10 pg/ml). (C) 2001 Elsevier Science B .V. All rights reserved.