Trace determination of alpha- and beta-endosulfan and three metabolites inhuman serum by gas chromatography electron capture detection and gas chromatography tandem mass spectrometry

Endosufan, alpha and beta, and three conversion products, sulphate, ether a nd lactone, were simultaneously determined in human serum by means of an an alytical procedure which combines extraction with organic solvents, clean-u p with H2SO4 and by liquid column chromatography, and detection by gas chro matography (GC) using electron capture detection (ECD) and tandem mass spec trometry (MS/MS). The procedure was validated and the values of some merit figures, such as linear range, detection and quantitation limits, accuracy, precision and recovery, obtained with the GC/ECD and the GC/MS/MS methods, were compared, The lower limits of detection in GC/ECD and GC/MS/MS were 0 .03 and 0.05 mu g I-1, respectively. The recovery of the pesticides at the 20 mu g I-1 concentration level was 60-65%, with the exception of endosufan alpha. Recovery studies at higher levels (100 and 200 mu g I-1) were indep endent of pesticide concentration in serum samples. The application of the proposed analytical methodology to the determination of endosulfans and the ir metabolites in real samples was tested by analyzing serum samples from a population living in agricultural areas of Almeria (Spain). The results sh ow the advantage of MS/MS over the ECD detector in the analysis of serum sa mples where matrix interferences can be confused with target pesticides. Co pyright (C) 2000 John Wiley & Sons, Ltd.