Development and validation of a multiresidue method for determination of 82 pesticides in water using GC

Several methods used for the multiresidue analysis of pesticides from the environment and drinking water have been reported. However, most of these reports dealt with a small number of targeted pesticides or some special groups. A method that is simple, faster, and more cost-effective than the environmental protection agency (EPA) method has been developed for the analysis of 82 frequently used pesticides in water samples obtained from Yeongsan and Sumjin rivers, as well as rice fields located in various locations around the two rivers. The samples were extracted by dichloromethane, and the pesticides were analyzed using a GC-electron capture detector (ECD), followed by confirmation with GC-MS. Recoveries were found to be between 82 and 120.1% for most of the tested pesticides, which were in agreement with the standard values dictated by the EPA. The method was potentially applied to 66 water samples for human consumption and 90 water samples from the rice fields and irrigation ditches that were collected from June to September 2007. Oxadiazon, butachlor, and alachlor were detected in some of the river water samples collected in June, iprobenfos (IBP) was detected in samples collected in August, and no pesticide was detected in September. On the other hand, chlorpyrifos-methyl, IBP, hexaconazole, diazinon, oxadiazon, butachlor, and isoprothiolane were detected at relatively high concentrations in 48 rice paddy field water samples collected between June and September 2007. Alachlor in one sample and procymidone in some of the rice paddy field water samples were also detected in trace amounts. The results were consistent with the temporal pattern of pesticide application in Korean rice fields.