Abstract
A gas chromatography-high resolution mass spectrometry (GC-HRMS) method with solid-phase extraction has been developed for the quantitation of organophosphorous pesticides in surface water. Target compounds in this study were bromacil, cyanazine, dichlorovos (DDVP), metribuzin, phorate, propazine, trifluralin, edifenphos, molinate, iprobenfos (kitazine), diazinon, parathion ethyl, fenitrothion, parathion methyl, simazine and chlorpyrifos. Prior to sample analysis, solid-phase extraction was optimized using RP-1, FL-PR, C18, PESTICIDE, ENVI18 and LRC-SI. The result of the recovery test showed there was no ideal SPE cartridge to produce over 80% recovery. The order of recoveries was RP-1 > PESTICIDE > C18 > ENVI18 > FL-PR > LRC-SI. The use of a 5% acetone in dichloromethane helped to increase the recovery rates for some pesticides. Method detection limits of HRMS using RP-1 ranged from 2.2 to 11 ng/L for all of target compounds. The method was applied to the measurement of organophosphorus pesticide residues in surface water (n=56) from Han River. Major pesticides detected in the samples were iprobenfos (nd~160 ng/L), chlorpyrifos (nd~10 ng/L) and others with the low ranges of ng/L. Higher concentrations for these compounds were observed in sites close to highly populated or agricultural area. The use of HRMS with optimized SPE provides increasing sensitivity of detection for target compounds.