SOLID-PHASE EXTRACTION OF HALOGENATED PESTICIDES FROM GROUND AND SURFACE WATERS AND THEIR DETERMINATION BY CAPILLARY GAS-CHROMATOGRAPHY

A critical study of a solid phase extraction method using Cls SPE colu mns for the determination of 23 halogenated pesticides is presented. T ype of sorbent, sorbent mass, now rate in the extraction process, samp le concentration of the different compounds, sample volume, pH, ionic strength and type of water were evaluated. Recoveries of pesticides un der study yield a linear relationship, except for conazole fungicides and captan. Losses can be expected for heptachlor, aldrin, and captan. Sample volume and flow rate of extraction affect recoveries. Matrix e ffects from surface and groundwaters were observed. Recoveries for vin clozolin and dieldrin from groundwater were lower than those obtained from nanopure water. In river water losses of these compounds are high er. Captan and penconazole were not present and high losses were obtai ned for trifluralin, alpha-BHC, gamma-BHC, tri-allate and chlorpyripho s. Impurities arising from the sorbent materials of cartridges have be en detected.