Investigation Of Ambient Ionization Mass Spectrometry For Safety Analysis And Quality Assessment Of Wine

Mass spectrometry,as an accurate instrument analysis method,is able to provide structure information of analytes,and has the advantages of high sensitivity and high selectivity.The combination of ambient ionization techniques and mass spectrometer makes the mass spectrometry analysis more rapid,simple and diversified.Due to the unintentional and/or intentional action in the grape growth and wine made,the wine may appear different quality and safety problems.In this thesis,various ambient ionization techniques coupled with multiple mass spectrometers were proposed to analyze the exogenous residual pesticides and illegal adulterants in wine,the endogenous geographic traceability of wine,and establish the high-resolution MS/MS libraries based on characteristic fragment ions and neutral losses to screen known analytes and identify unknown analytes in wine.The main research contents of this thesis are as follows:1.Several methods for high-throughput rapid quantification and screening of multi-class exogenous residual pesticides and illegal adulterants in wine were proposed by various ambient ionization techniques combined with triple quadruple mass spectrometer.First of all,the detection parameters of instrument for anlyte standards were optimized,and two pairs of precursor ion and product ion were obtained for quantification and qualification,respectively.Then,in the sample determination,several effective sample preparation methods were compared,including modified QuEChERS,desorption-adsorption,and dilution.Under the multiple reaction monitoring mode,fifty pesticides and eighteen adulterants in wine could be determined in twelve minutes by direct analysis in real time and paper spray ionization coupled with mass spectrometer.The results showed pesticides achieved ng/mL level of linear ranges,limits of detection and limits of quantitation,and adulterants achieved ng/mL and μg/mL levels of linear ranges,limits of detection and limits of quantitation.Finally,method validations used three to four levels of recovery experiments and quality control experiments,and obtained the results ranging between 75%and 120%2.A method for non-targeted analysis of the geographic regions of Cabernet Sauvignon wine was proposed by ambient ionization techniques combined with high-resolution tandem mass spectrometer.First of all,dilution method was simply used for wine,in order to avoid overload in detection.Then,a great amount of mass spectrum data in positive mode and negative mode was obtained by direct analysis in real time coupled with QqTOF mass spectrometer,and processed by correlation analysis and information gain to remove redundant information.As a result,eighteen mass spectrum peaks were obtained,compared and confirmed by MS/MS library.Three chemometrics methods,i.e.,linear discriminant analysis,support vector machine and artificial neural network,were used for classification of Cabernet Sauvignon wine according to the different terrains and the different provinces in China;the results showed classification by artificial neural network was best,and the accuracy results of training set and test set were above 90%both for terrains and provinces.Moreover,as a targeted research method,HS-SPME-GC-MS could be also used for classification of geographic region of Cabernet Sauvignon wine.With artificial neural network for classification of all the feature peaks,all the alcohols and all the esters,all the accuracy results of Cabernet Sauvignon wine in different provinces were above 89%.3.Several methods for rapid,accurate screening of known compounds in wine and identification of unknown compounds in wine were proposed by the product ions and the neutral losses in ambient ionization techniques combined with high-resolution tandem mass spectrometer.According to the structure and the corresponding fragment ions and neutral losses of azole(i.e.,triazole,imidazole and pyrazole)pesticides and organophosphorus pesticides,various fragmentation patterns of phosphate and phosphorothioate were summarized.As for the organic acids in wine,four fragmentation pathways were summarized:alpha-cleavage and losing CO2,rearrangement and beta-cleavage,alpha-cleavage and losing H20,and alpha-cleavage and opening ring.Therefore,monoacid,diacid,polyacid and phenolic acid could be discriminated,and other function group of acids could be identified.Finally,two major categories of pesticides and multi-class organic acids in wine could be identified by summarized characteristic-common product ion and neutral loss,qualification-assistant product ion and neutral loss,and individual product ion and neutral loss.