OPTIMIZATION OF THE SEPARATION, ISOLATION AND RECOVERY OF SELECTED PESTICIDES IN WATER SAMPLES BY SOLID-PHASE EXTRACTION AND HPLC PHOTODIODE-ARRAY DETECTION

An optimized HPLC method for the analysis of selected pesticides (Atra zine, Diuron, Dichloran, Methiocarb, Folpet, Triazophos, Vinclozolin, Tetradifon and Carbophenothion) is developed by applying a solvent elu tion programme with two steps, isocratic and gradient mode, both in re verse phase (RP). In the isocratic step, the mobile phase is optimized by a grid search procedure over an water-acetonitrile-methanol solven t triangle. Off-line solid-phase extraction (SPE) has been combined wi th HPLC using a photodiode array detector (DAD) to isolate, recover an d quantify the selected pesticides from water samples at ppb levels. T he recoveries are higher than 75% in all cases except for atrazine in sea water (50%) and ground water (64%).