Rapid Determination of Residues of Malachite Green and Its Leucometabolite in Aquatic Poducts by a New Liquid Chromatography Tandem Mass Spectrometry

Objective To develop a method for determination of residues of malachite green(MG) and its leucometabolite leucomalachite green(LMG) in aquatic products by liquid chromatography tandem mass spectrometry(LCMS/MS).MethodsThe targeted analytes were extracted from homogenized samples with a mixture of acetonitrile and ammonium acetate buffer,partitioned against methylene chloride,and purified on tandem neutral alumina and PRS SPE cartridges.Chromatographic separation was achieved by using ZORBAX SB-C18 column with an isocratic mobile phase consisting of ammonium acetate(0.05 mmol/L) and acetonitrile(10/90,V/V) without the need for in-line post-column oxidation with PbO_(2).Identification and quantification were performed using multiple reaction monitoring(MRM) with one precursor ion and two product ions for each analyte and electrospray ionization(ESI) in positive mode.Results The limit of detection for MG and LMG was 0.5 ng/g,correlation coefficient of linear regression equations was above 0.99 and the recoveries were in the range of 78.4%~92.1%,82.4%~98.1% respectively,at spiked levels of 0.5-2.0 ng/g.The RSD of the method was less than 5.7%.Conclusion After a large amount of incurred samples were detected,the results showed that the method is suitable for determination of residues of MG and LMG in aquatic products.