Distinguishment Of Shanxi Mature Vinegar By Synchronous Fluorescence Spectroscopy

Synchronous fluorescence spectroscopy, which is simplified the spectrum and operation and reduced the spectral overlap and so on, plays an important role in the detection of multi-component samples. The real mature vinegar produce some aromatic compounds or its derivatives (having a fluorescence characteristics) in unique fumigation and aging process. Different fumigation and aging time will lead to different accounts and kinds of these substances. Different Shanxi mature vinegar were distinguished by synchronous fluorescence spectroscopy which combined with different chemometrics methods. The main contents and results are as follows:1. Synchronous fluorescence spectroscopy was used to scan for 11 different mature vinegar samples. For getting synchronous fluorescence spectra and synchronous fluorescence fingerprints of different mature vinegar, the data was substituted into the origin7.0 mapping software. It was showed that the same brand and different years of mature vinegar appeared the same numbers and location of fluorescence characteristic peak, but the relative fluorescence intensity of characteristic peak is different to some degree; the same year and different brands of mature vinegar were significant differences of appearing location and numbers of fluorescence peaks.2. Synchronous fluorescence spectra of different years (same brand) mature vinegar was comparatively analyzed and as well different brands (same year) mature vinegar. The above obtained synchronous fluorescence data of different samples were systematic analysis by PCA. It was indicated that different brands of mature vinegar were located in different PCA scored regions; different years of mature vinegar perched in different locations of the same region. This method could better distinguish the different mature vinegar and it is feasible.3. The above data of the first part were analyzed by synchronous fluorescence parameters which extracted feature parameters (mean, standard deviation, Kurtosis and skewness). These parameters were used to principal component analysis with Unscrambler9.8 software. It was demonstrated that the differences of characteristic parameters were clear in different brands vinegar; there was not obvious in different years samples. The samples were correctly distinguished and the difference could be more clear and intuitive by PC A combining with synchronous fluorescence parameters.4. Different mature vinegar samples were scanned with constant energy synchronous fluorescence, the obtained data was used to principal component analysis. The research showed that PC1 and PC2 of cumulative variance contribution rate was up to 100% at △v-= 1500cm-1, which could cover whole information and achieve the best separative results.5. The data of △v-= 1500cm-1 was used to parametric analysis by constant energy synchronous fluorescence parametric methods, feature parameters was extracted and it was used to principal component analysis. The research shows that characteristic parameters of different brands of mature vinegar exist some differences; there are few differences in different years. Although constant energy synchronous fluorescence parameters of combining PCA can distinguish mature different vinegar, but it is inferior to the effect of synchronous fluorescence parameters combing with PCA.6. Different mature vinegar samples, mixed different proportions of acetic acid, reached an agreement with the minimum acidity. Then the samples were scanned by synchronized fluorescence and PLS calibration model was built. The unknown concentration of doping sample could be forecasted by the model. It was obvious that correlation coefficients of PLS calibration model of four kinds of samples were higher than 0.996 (except Shuita 5 years being 0.989) and root mean square errors were less than 0.04 after removing the deviates variables; the predicted values of unknown concentration samples which were substituted to the model were very close to the measured values and the relative deviation ranged within ±5%. It can quickly achieve quantitative analysis of doping acetic acid in mature vinegar by means of combining synchronous fluorescence spectroscopy method with PLS.