Determination of organochlorine pesticides and polychlorinated biphenyls in human serum using headspace solid-phase microextraction and gas chromatography-electron capture detection

A simple procedure for the determination of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in human serum using headspace solid-phase microextraction (HS-SPME) was developed. The analysis was carried out by gas chromatography (GC) equipped with electron capture detector (ECD). A 2(7-4) Plackett-Burman reduced factorial design for screening and a central composite design for optimizing the significant variables were applied. A 100 microm PDMS fiber, 3/5 headspace ratio (3 ml in 5 ml vial), 85 degrees C extraction temperature, 50 min extraction time, and 1 ml of acidic solution (pH 3) added to 1 ml of diluted serum (1:1) were chosen for the best response in HS extraction mode. The detection limits found were from 1 pg/ml (PCB 167) to 52 pg/ml (beta-HCH), the relative standard deviation for the procedure varied from 3% (PCB 52) to 12% (PCB 189) and the accuracy was checked by using validated solid-phase extraction (SPE) procedure. The method that avoids the use of clean-up steps and the hazardous solvents enabled reliable determinations of the OCPs and the PCBs except beta-HCH. The method was applied to the analysis of 33 human serum samples. The most abundant target compound was p-p'-DDE (range, 0.3-8.0 ng/ml; median value, 2.1 ng/ml). Among the PCBs the prevalent congeners were 138, 153 and 180.