Determination of four pesticides in soil by homogeneous ionic liquid-based microextraction coupled with high-performance liquid chromatography

Homogeneous ionic liquid microextraction was developed for the simultaneceus extraction of dimethomorph, mefenacet, isoprothiolane and oxadiazon from soil. 1-Butyl-3-methylimidazolium tetrafluoroborate was used as extraction solvent, and ammonium hexafluorophosphate was used as ion-pairing agent. High-performance liquid chromatography(HPLC) was employed for separation and determination of the analytes. The calibration curves show good linear relationship(r>0.9988). The recoveries are between 74.2% and 97.9% with relative standard deviations(RSDs) lower than 5.97%. The present method is free of volatile organic solvents, and expenditures of sample, extraction time and solvent are lower, compared with ultrasonic and Soxhlet extraction. There was no obvious difference in the extraction recoveries of pesticides obtained by the three extraction methods.