Application Of LC-MS/MS In Food Safety Analysis

Food is fundamental substance for human being. With the appearance of food safety event in the past few years, the problem of food safety has been taken close attention by people in the world.The difficulty in food analysis is confirmatory multiresidue analysis for organic compounds at trace levels in complex matrixes. The conventional techniques, such as gas chromatography (GC), liquid chromatography (LC), gas chromatography-tandem mass spectrometry (GC-MS/MS) can not meet the demands. In rencently, liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has become one of the major tools in food analysis. The advantage of LC-MS/MS is that it has spectic, seltctive and sensitive quantitative results, and has marked prowess in the analysis of traces of contaminants in complex food matrices. Aiming at the difficulties of the analysis of pesticides in food, three sepects of food safety analysis based on LC-MS/MS technology are developed as following:(1) A method was developed for the simultaneous determination of pirimicarb and paclobutrazol in foods by HPLC-MS/MS. The samples were extrcted with acetonitrile (MeCN). cleaned up with C18sorbent and primary secondary amine sorbent (PSA). The identification and quantification were achieved by using electrospray ionization in positive ion mode. The internal standard calibration curves were used for quantitative determination. Limits of quantification were lower than10μg kg-1and recoveries of the spiked samples were in the range between74%and110%(with intra-day precision, expressed as relative standard deviations, lower than9.5%) for all the pesticides. The result of this strategy was satisfied and the developed method was successfully applied to detect the pesticides of pirimicarb and paclobutrazol in various food matrices.(2) Dispersive solid-phase extraction clean-up combined with dispersive liquid-liquid microextraction was development as a new approach for the extraction of triazole fungicides in fruits samples prior to liquid chromatography-tandem mass spectrometry detection. In the DSPE-DLLME method, triazole fungicides were first extrcted with0.1%formic acid in MeCN from fruits sample, followed by clean-up by a dispersive solid-phase extraction with C18sorbent and primary secondary amine sorbent (PSA). A1mL aliquot of the resulting extract was then added into a centrifuge tube containing10mL water and250μL chloroform (as the extraction solvent) for DLLME procedure. Under the optimum conditions, the linear ranges of the three insecticides were5ng/g-600ng/g, with correlation coefficients over0.9996. The method provided an acceptable accuracy (73.6%-106.3%recovery) and precision (≤3.8%relative standard deviation) for two samples with the limits of detection ranging from0.955to1.22ng/g. The proposed method has been successfully applied to the analysis of the three insecticides in fruits with satisfactory results.(3) Dispersive solid-phase extraction clean-up combined with dispersive liquid-liquid microextraction was development as a new approach for the extraction of triazole fungicides and the pesticides of carbamate in grains samples prior to liquid chromatography-tandem mass spectrometry detection. In the DSPE-DLLME method, triazole fungicides were first extrcted with0.1%acetic acid in MeCN from grains sample, followed by clean-up by a dispersive solid-phase extraction with C18sorbent and primary secondary amine sorbent (PSA). A1mL aliquot of the resulting extract was then added into a centrifuge tube containing10mL water and150(μL chloroform (as the extraction solvent) for DLLME procedure. Under the optimum conditions, the linear ranges of the three insecticides were5ng/g-300ng/g, with correlation coefficients over0.9991. At the two fortification levels of10-50ng/g, recoveries fell within79.6%-104.6%. The relative standard deviation was between1.5%-4.2%and the limits of detection ranging from0.954-2.87ng/g. The proposed method has been successfully applied to the analysis of the four pesticedes in grain samples, and a satisfactory result was obtained.