METHOD DEVELOPMENT FOR MONITORING PESTICIDES IN ENVIRONMENTAL WATERS - LIQUID SOLID EXTRACTION FOLLOWED BY LIQUID-CHROMATOGRAPHY

Our recent method based upon liquid-solid extraction of pesticides from drinking water followed by high-performance liquid chromatography (HPLC) was modified to make it suitable for monitoring 89 pesticides in groundwater and river water. The modified method involved passing 2, 1.5, and 0.5 L, respectively, of drinking water, groundwater, and river water through a 300-mg Carbopack cartridge at 120-130 mL/min. The complete separation of base-neutral pesticides from acidic ones was accomplished by a stepwise elution. After concentration of the two extracts, pesticides were separated and quantified by reversed-phase HPLC with UV detection. The goal of analyzing base-neutral pesticides with a low probability of false positives was reached by using a C-18 HPLC column as the primary column and a cyano column as the confirmational column. Except for few pesticides, the limits of quantification (5 times the limit of detection) of this method for the pesticides considered in municipal water and groundwater samples were lower than 0.1-mu-g/L.