Determination of endocrine-disrupting pesticides and polychlorinated biphenyls in human serum by GC–ECD and GC–MS–MS and evaluation of contributions to the uncertainty of the results
The chemicals endosulfan-α, endosulfan-β, endosulfan sulfate, endosulfan ether, endosulfan lactone, PCB-21, PCB-48, PCB-61, and PCB-136 have been determined in 100 serum samples from women living in agricultural areas of Almería (Spain). The study includes a surgically treated breast cancer patient and a matching group of women with no sign of estrogenic-dependent disease. The determination was performed by gas chromatography with electron capture detection (GC–ECD) and tandem mass spectrometry (GC–MS–MS). Recovery, precision, linear range, detection limit (LOD), and quantification limit (LOQ) were calculated for each pesticide as was the expanded uncertainty (U). The method was evaluated for our laboratory and could be applied to subsequent results with relevant quality-control data. Comparison of the results was performed. The advantage of MS–MS over ECD for determination of endocrine-disrupting compounds in complex matrices is presented. The most commonly encountered pesticide was endosulfan-α. Endosulfan-β and the PCB-48 congener were detected at concentrations lower than their LOQ. Endosulfan sulfate, endosulfan ether, endosulfan lactone, PCB-21, PCB-61 and PCB-136 were not found in any of the serum samples analysed.