Trace level determinations of carbamate pesticides in surface water by gas chromatography-mass spectrometry after derivatization with 9-xanthydrol

A sensitive and selective gas chromatographic mass spectrometric method, based on derivatization with 9-xanthydrol, has been established for the simultaneous determination of five carbamate pesticides (carbaryl, carbofuran, metolcarb, isoprocarb and ethiofencarb) in surface water. 4-Bromo-3,5-dimethylphenyl-N-methylcarbamate was chosen as the internal standard for analyzing water samples. The derivatization of carbamates was performed directly in water and the reaction conditions (9-xanthydrol of 50.0mM, HCl concentration of 0.05 M, reaction for 60 min at 60 degrees C) were established through the optimization of various parameters. Under the established conditions, the limits of quantification were in the range of 0.007-0.028 mu g/L, and the intra- and inter-day relative standard deviation were each less than 15% at concentrations of 0.1, 1.0 and 10 mu g/L. None of the carbamate pesticides were detected in any of the sixteen surface waters analyzed. (C) 2013 Elsevier B.V. All rights reserved.