DETERMINATION OF PESTICIDES IN ENVIRONMENTAL WATERS BY SOLID-PHASE EXTRACTION AND GAS-CHROMATOGRAPHY WITH ELECTRON-CAPTURE AND MASS-SPECTROMETRY DETECTION

A group of pesticides with different chemical structures was determine d by solid-phase extraction on LiChrolut EN cartridges and gas chromat ography with electron-capture detection or mass spectrometry. The para meters affecting the solid-phase extraction process were optimized and the responses obtained by both GC detection systems were compared. Th e use of an electron-capture detector enabled the organochlorine pesti cides studied to be determined at ngl(-1) levels whereas mass spectrom etry under selective ion monitoring acquisition enabled levels of low mu gl(-1) to be reached. The R.S.D. (n=6) of the method in tap water w as lower than 8.1% for electron-capture and mass spectrometric detecti on. The methods developed were used to determine the pesticides studie d in tap and river water and some pesticides could be found in Ebro ri ver and Ebro delta water.