Determination of indoxacarb enantiomers in tomato,grape and water by liquid chromatography-tandem mass spectrometry

A reversed-phase chiral method for the determination of indoxacarb enantiomers was established using liquid chromatography-tandem mass spectrometry (LC-MS/MS).The target analytes were quantified by external standard method,and the difference in matrix effect between matrix dispersed extraction and solid phase extraction was compared.The tomato and grape samples were extracted by acetonitrile and then purified by NH2/Carb solid phase extraction (SPE),while water was pre-concentrated and cleaned up by C18-H SPE cartridges.The chromatographic conditions were as follows:Chiralpak AD-RH column,V(acetonitrile)∶V(water)=65∶35,column temperature was 25 ℃,and flow rate was 0.4 mL/min.The results showed satisfied recoveries of the enantiomers in the range of 65.5%-117.0% at levels from 0.005 mg/kg (or mg/L) to 0.5 mg/kg (or mg/L) with relative standard deviations of 4.1%-18.1% (n=5).Limits of detection (LOD) of the enantiomers were in the range of 1.4-4.3 μg/kg (or μg/L),and limits of quantification (LOQ) were 4.7-14.2 μg/kg (or μg/L).The method is simple and suitable for the routine analysis of indoxacarb enantiomers in tomato,grape and water.