A simple and reliable pretreatment approach in gas chromatography-mass spectrometry (GC-MS) was developed for concurrent clean-up of seawater and the concentration of lipophilic polychlorinated biphenyls (PCBs) with 1-8 chlorine atoms based on the combination of KMnO4 oxidation with headspace sampling and solid-phase microextraction (SPME). Factors affecting the extraction process were studied using a multivariable approach. Under optimum conditions such as PDMS 7 µm of fiber, 78 ºC of extraction temperature, 33 min of extraction time, 8 mL of volume, the limits of detection ranged from 0.3 to 7.5 ng L-1 and precisions were between 3.9 and 9.9% at spiked 0.05 µg L-1 PCBs. Humic acids in seawater exhibited remarkably negative effects; recoveries of PCBs were significantly improved, especially for more lipophilic CB171 and CB201 from 35% and 49% to 78% and 89%, respectively, after KMnO4 pretreating seawater samples at pH 6. The developed method was demonstrated to be simple, rapid, reliable and applicable for determining different PCBs in seawater containing large amounts of humic substances.
polychlorinated biphenyls; headspace solid-phase microextraction; humic substances; experimental design; gas chromatography-mass spectrometry; seawater
