Determination of Fipronil Residue in Soil and Water in the Rice Fields in North of Iran by RP-HPLC Method

Mohammad Reza Hadjmohammadi*, Seyed Mohammad Nikou, Kamyar Kamel

Department of Chemistry, University of Mazandaran, P.O.Box 453,Babolsar,

A method for the determination of amount of residue of insecticide fipronil in paddy water and soil was developed based on RP-HPLC. Trials were carried out on rice fields in Iran using a fipronil granular formulation at a rate of 40 g ai/ha just after transplanting, which corresponded to 20 kg/ha of formulated product. Liquid-Liquid Extraction (LLE) and Soxhlet extraction were applied for extraction of fipronil from paddy water and soil respectively. In paddy water, Fipronil levels declined from 0.018 to 0.0028 mg/ml from one day to 40 days after application. No analyte was observed after 40 days at levels exceeding limit of detection. Soil analysis also showed that the amount of fipronil declined from 0.032 to <0.009 mg/kg from one day to14 days after application and after 28 days, no analyte was left. The hydrolysis of Fipronil was also studied in aqueous buffer solution of pH 7.8 at  temperature of 20 and 30 ºC. Results showed that the Fipronil degradation was increased at 30 ºC .

Keywords: insecticide, fipronil, RP-HPLC