HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH DIODE-ARRAY DETECTION FORTHE DETERMINATION OF PESTICIDES IN WATER USING AUTOMATED SOLID-PHASE EXTRACTION

An accurate, economical and sensitive method was developed for the sim ultaneous determination of phenylureas, phenoxy acids, some nitriles a nd nitrophenols in aqueous samples. The method is based on automated s olid-phase extraction and high-performance liquid chromatography with diode-array detection. The analytes were separated on a 25 cm C-18 ana lytical column and determined at three wavelengths simultaneously, 220 , 240 and 270 nm. The solid-phase extraction time was less than 1 h fo r sis water samples and the lowest detectable concentrations were in t he range 25-100 ng l(-1) The recoveries of the pesticides ranged from 85 to 99% and the relative standard deviations were in the range 1-10% at 200 ng l(-1) (n = 6).