SOLID-PHASE MICROEXTRACTION AND GAS CHROMATOGRAPHY WITH ELECTRON CAPTURE DETECTION FOR MULT1RESIDUE DETERMINATION OF PESTICIDES IN WATERS

摘要

A solid-phase microextraction (SPME) method for the simultaneous determination of a large number of pesticides (a-endosulfan, β-endosulfan, esfenvalerate, bromopropylate, tetradifon, bifethrin, dicofol, fluvalinate, trifluralin, ofurace, quinoxyfen, A-cyhalothrine, v-chlordane, chlozolinate, heptachlor, acrinathrine, δ-HCH) with a wide range of polarities and chemical structures (organochlorine, pyrethroids, acetamides, quinoline, trifluoromethyl and others) in water samples by GC-ECD has been developed. The main parameters affecting the SPME process such as extraction time, salt additives, memory effect, stirring rate and desorption conditions were studied. The selected conditions were: a 100 urn polydimethylsiloxane (PDMS) fibre, 60 min of extraction time, sample agitation (960 rpm), pH (4) and ionic strength (10% w/v). Good detection limits, linearity and repeatability were obtained with this method for all the pesticides studied. The detection limits were below 0.1 ug/L which is the maximum limit set by the European Directive 98/83/EC for each pesticide in waters for human consumption. Furthermore, repeatability (<14%) and intermediate precision (<17%) were shown to be satisfactory. To validate matrix effects for drinking and surface water (river water, sea water and lake water) analytical recoveries were calculated for these matrices. The results demonstrate the suitability of the SPME method for routine screening multiresidue analysis in natural waters.