Abstract

This report describes the development of a new method for the analysis of polar, phenolic pesticides in water, like polychlorophenols, bromofenoxym, ioxynil and ethirimol. By this method, phenolic pesticedes are simultaneously extracted and derivatized with pentafluorobenzoylchloride (PFBOCl) and analysed by gaschromatography with negative ion chemical ionization mass spectrometry. Optimal condition for the derivatization have been established for the major parameters of the process, being the amount of reagent, the nature of the organic solvent and the Ph of the aqueous phase. Under these conditions, the overall recovery for the extraction of the phenolic compounds and formation of derivatives was better than 90%. The compounds appeared to be very sensitive for detection with negative ion mass spectrometry, yielding intense and diagnostic [M-195] ions for all compounds investigated except for bromefenoxym, which PFBOCI-derivative thermally decomposed in the infection port to give a compound similar to the PFBOCI-bromoxynil derivative. This high sensitivity allows full scan analysis for the screening of water on the presence of pesticides at the level of approximately 0.1 mug/ml using small, easy-to-handle sample sizes (10ml). Some nitrophenols are also investigated by this method to give the corresponding PFBOCI-derivatives. Under the negative ion mass spectrometry conditions, however, these compounds yielded non-diagnositic ions.