Rapid Analysis Of Adulterated Chinese Wine By Extractive Electrospray Ionization And Single Photon Ionization Mass Spectrometry

At present, a large amount of adulterated wine products have been intermingled into the market, the manufacture and sale of adulterated wines not only undermine the normal market order, but also gives serious damage to the consumers’ interests and health. It is urgent to develop a rapid, sensitive, and effective method for analysis of fake wines. Ambient ionization mass spectrometry techniques, with the characterization of effective, fast, in-situ, real-time, on-line, non-destructive testing, etc., have become increasedly important in food safety. Herein, a novel approach, based on the extraction electrospray ionization(EESI) and single photon ionization(SPI) mass spectrometry, combined with principal component analysis(PCA) and cluster analysis(CA) methods, has been presented in this study. The method proposed here can be employed for fast and accurate identification of true and false wine without any sample pretreatment. The main research content of this thesis involves as following:(1) A novel method based on single photon ionization time-of-flight mass spectrometry(SPI-TOF-MS) was established for the fast and accurate differentiation of different types of true and fake wines combined with principal component analysis(PCA) without any sample pretreatment. Moreover, the accuracy and reliability of analysis by SPI-TOF-MS were validated by photoelectron ionization time-of-flight mass spectrometry(PEI-TOF-MS). The preliminary results showed that not only five types of true and fake wines(e. g. Maotai, etc.) could be rapidly distinguished respectively in this study, but also the characteristic compounds which influence the quality of the wine were investigated, the signal intensity of characteristic compounds most attributed to the distinctions were obtained. In comparison with other ionization techniques(such as EI, PEI, ICP, etc.), the softer single photon ionization is easier for the generation of molecule ions and the simpler mass spectrum. Research shows that the proposed method is stable and short response time, it is a useful tool for the quality evaluation and identification of volatile organic compounds(VOCs) in wines, playing a significant role in the application of rapid screening the inferior liquor products.(2) A novel analytical platform based on a home-made extractive electrospray ionization(EESI) source coupled with LTQ-XL mass spectrometer has been developed for fast and accurate identification of eight different kinds of adulterated Chinese liquors such as Maotai. Normalized mass spectra of authentic and counterfeit liquors were differentiated by principal component analysis(PCA). Reproducibility of the method was characterized by cluster analysis(CA). Several constituents of liquor vapor were identified by tandem mass spectrometry(MS/MS). The analysis time for a single sample was less than 1 min. The accuracy of identification predicted by PCA was 96.5%. The feasibility of this method was verified by testing several unknown samples. In addition to EESI-LTQ-MS, volatile compounds in Maotai vapor were also studied by single photon ionization time-of-flight mass spectrometry(SPI-TOF-MS), and molecular fingerprints obtained by these two methods were compared. These two detection means showed their respectively outstanding advantages and synergy for the analysis of volatile organic compounds(VOCs). The introduced method provides an important tool for the quality control of alcoholic beverages with high speed and simplicity of analysis on the market.