Determination of Butachlor and Fipronil in Liquid Milk Using Ionic Liquid Dispersive Liquid-Liquid Microextraction Coupled with Ultra-High Performance Liquid Chromatography

Abstract A novel method for the determination of butachlor and fipronil in liquid milk has been developed using ionic liquid dispersive liquid-liquid microextraction coupled with ultra-high performance liquid chromatography ( UHPLC ). The optimum extraction conditions were determined to be 60 μL of 1-octyl-3-methyl imidazole six fluorine phosphate extraction solvent, 1000 μL of acetonitrile as the dispersing solvent, vortex extraction time of 3 min, centrifugation for 5 min at room temperature at 10 000 rpm. After extraction, 30 μL of extraction solvent was obtained from the sample for UHPLC analysis. It was shown that good linearity was obtained with butachlor and fipronil concentrations from 5 to 1000 μg/kg with correlation coefficient of 0.999. The average recoveries were in the range of 90 to 104% at spiked levels from 10 to 50 μg/kg with intra-day relative standard deviations lower than 3.7% ( n = 6) and inter-day relative standard deviations lower than 6.1% ( n = 3). The limits of detection were 0.5 and 0.3 μg/kg for butachlor and fipronil, respectively.