UHPLC-MS/MS Determination of Residual Amounts of Malachite Green, Crystal Violet and Their Metabolites in Aquatic Products

UHPLC-MS/MS was applied to the determination of residual amounts of malachite green (MG), crystal violet (CV) and their metabolites, i.e., leuco-malachite green (LMG) and leuco-crystal violet (LCV), in aquatic products. The homogenized sample was extracted with acetonitrile and defatted by acidic aluminum oxide. The eluants were evaporated to dryness by rotary evaporator, and the residue was dissolved with HCOOH+CH3CN+H2O (0.1+10+89.9) mixture which was separated by UHPLC and analyzed by MS/MS. The malachite green D5 and leuco-malachite green D6 were used as internal standard. Linear relationships between values of peak area and mass concentration of the 4 compounds were found in the same range within 5.0 μg·L-1, with their detection limits (3S/N) in the range of 0.10-0.12 μg·kg-1. Using blank aquatic products as matrix, test for recovery was made by standard addition method, giving recovery in the range of 90.2%-108.0% with RSD′s (n=6) in the range of 2.3%-7.6%.