Application Of LC-MS/MS In Food Safety Analysis

Confirmatory multiresidue analysis for organic compounds at trace levels in complex matrixes is required in food analysis. Conventional techniques in food analysis, such as Gas chromatography (GC), Liquid chromatography (LC), Gas chromatography mass spectrometry (GC-MS), etc., can't meet the demands. Liquid chromatography tandem mass spectrometry (LC-MS/MS) technique frequently provides specific, selective and sensitive quantitative results, and allows unequivocal identification of traces of contaminants in complex food matrices, which has become one of the major tools in food analysis.The main contents in this thesis are described as follows:(1)The paper reviews the importance of food safety and the status of food analysis, and introduces the basic principle, characteristics of LC-MS/MS and its application in food analysis.(2)A liquid chromatography tandem mass spectrometry (LC-MS/MS) method was described for Simultaneous determination of residues of malachite green (MG),leucomalachite green(LMG),rystal violet(CV)and leucocrystal violet(LCV) in aquatic products. The 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 (0.05mM) and acetonitrile(10/90,V/V)without the need for in-line post-column oxidation with PbO₂. Identification and quantification were performed using multiple reaction monitoring (MRM) with one precursor ion and two product ions for each analyte and electrospray ionization in positive mode. Limits of detection were 0.5ng/g. Recoveries were in the range of 77.6%～98.1%, and the RSDs were less than 8.2%.(3)A method was presented for simultaneous determination residues of Chloramphenicol (CAP),Thiamphenicol (TAP) and Florfenicol (FF) in royal jelly by using high performance liquid chromatography tandem mass spectrometry (LC–MS/MS).After a preliminary homogenization in negative honey and water, samples were extracted with ethyl acetate, and evaporated to dryness; the following clean up was carried out on a C18 SPE cartridge. After reversed-phase HPLC separation, identification and quantification were performed using multiple reaction monitoring (MRM) and electrospray ionization in negative mode. In order to dispel the matrix interference, the conditions of solid phase extraction were optimized. The detection limits of the method were 0.1ng/g,0.2ng/g and 0.5ng/g for CAP, FF and TAP, respectively. The average recoveries were 79.9%⁸8.4%, and the RSD were lower than 8.2.%.