A high performance liquid chromatography tandem quadrupole mass spectrum (LC-MS/MS) method was developed for confirmatively determining of benalaxyl residues in 13 foodstuffs. The benalaxyl was extracted with acetone-hexane in animal-origin foods and ethyl acetate in plant derived food. The purification was used with Carbon-NH2 solid-phase extraction (SPE) column. A mixture of acetonitrile and 0.1% formic acid was selected as the mobile phase and the separation was carried out on Shiseido MGⅡ C18 column. The compound was analyzed quantitatively by mass spectrometry under positive electrospray ionization (ESI+) multiple reaction monitoring (MRM) mode. The linear range of analyte was from 2 μg/L to 100 μg/L and the limit of quantification (LOQ S/N≥10) was 5 μg/kg. Spiked with three concentration levels in 13 matrices, the method recoveries were between 66.0% and 104.2% with relative standard deviations 4.4% to 12.3%. The validated method was accurate, rapid and suitable for qualitatively determining benalaxyl residues in many foodstuffs.
