UHPLC-MS/MS Determination of Residual Amounts of Benzimidazoles and Its Metabolites in Dairy Products

The dairy product sample was extracted with water, acetonitrile and NaCl. n-Hexane saturated with acetonitrile was used for de-fat and purification. UHPLC-MS/MS was applied to the determination of residual amounts of benzimidazoles and its metabolites in the sample solution. Atlantis T3 chromatographic column was used as stationary phase, and the mixture of 0.1% (φ, the same below) formic acid acetonitrile solution and 0.1% formic acid solution mixed in different ratios was used as mobile phase in gradient elution. ESI⁺ and scheduled multi-reactions monitor mode were adopted in MS/MS.Isotope was used as internal standard. Linearity ranges of benzimidazoles and its metabolites were found in the same range of 0.02-5.0 μg·L^-1, with detection limits (3S/N) in the range of 0.010-1.0 μg·kg^-1 and lower limits of determination (10S/N) in the range of 0.025-4.0 μg·kg^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 81.4%-108%, with RSDs (n=6) of determined values in the range of 0.40%-9.3%.