Study On Several Kinds Of Synthetic Pigments With Three-dimensional Fluorescence Coupled With Second-order Calibration

Food safety is associated with people’s health and life. In recent years, somebusinessmen still excessively used edible synthetic pigments under the temptation of interests.At present, the conventional ways to determine the concentrations of pigments in food areusually complicated and time-consuming. Therefore, one rapid and convenient method isnecessary. In this paper, three-dimensional fluorescence spectra of several kinds of pigmentswere scanned with FLS920P spectrometer produced by Edinburgh Instrument in England.Meanwhile, the second order correction algorithms were also applied to determine thecontents of the pigments.In the introduction, we introduced the edible pigments, and then described thedevelopmental process, current research situation and application scope of chemometrics, andsummarized the research purpose and meaning of this paper finally.In chapter2, mainly introduced the theory of fluorescence spectroscopy, the relationshipbetween the fluorescent matters and their molecule structures, the main parameters and thecharacteristic of fluorescence spectra, and the experimental instruments and workingprinciple.In chapter3, different concentration ratios of carminum, allura red and amaranthmixtures were prepared for calibration and prediction set, respectively, and amaranth wasthought to be the interference. FLS920P fluorescence spectrometer was applied to measurethree dimensional fluorescence spectra of pigment solution samples, and we can observe thatthe spectral overlapping is serious. Meanwhile, parallel factor analysis (PARAFAC)algorithms based on second-order calibration was combined to predict the content ofcarminum and allura red in mixtures. The proper number of the components fixed for themixed solution was3with CORCONDIA determination, the average recoveries of carminumand allura red were99.3±5.0%and102.2±5.6%, and root mean square error of prediction(RMSEP) were0.054and0.205, respectively. The results show that the methodology ofcombining excitation-emission matrices with the PARAFAC can be applied directly todetermine carminum and allura red in the mixed solutions even in the presence of interferingAmaranth, which was simple and convenient, rapid, etc., and provide help for synthetic foodpigments detection.In chapter4, the three-dimensional fluorescence spectroscopy combined withsecond-order calibration methods like PARAFAC, ATLD, ANWE and AFR were applied toresolve carmine in carmine solutions mixed with brilliant blue and erythrosine in erythrosinesolutions blended with lemon yellow, respectively. The average recoveries of carmine anderythrosine were104.46±4.03%,95.06±5.52%,103.716±3.05%,102.28±5.0%and96.14±2.58%,95.72±3.13%,95.92±2.77%,95.82±2.86%, respectively. RMSEP of carminewere0.0810,0.1812,0.0560, and0.0872(ug/ml), respectively. Meanwhile, RMSEP oferythrosine were0.0227,0.0240,0.0235, and0.0243(ug/ml), respectively. The resultsindicated that the methods can be used to quantitative determination of food pigments, evenspectral overlapping of the test and interference substance was heavy. By comparing the analytical results, ANWE algorithm was more suitable for detection of carmine. For detectionof erythrosine, PARAFAC algorithm is better. The results of the study can provide referencefor synthetic pigments detection.In chapter5, Three-dimensional fluorescence spectroscopy combined with alternate aweighted residual (ANWE) based on second-order calibration algorithms was applied to thedirect concentration determination of carmine in carbonated beverages. Firstly,3-Dfluorescence spectra of carmine and sunset yellow mixed solutions were obtained byemploying spectrometer, and analyzed by using ANWE, the results show that the ANWEalgorithm was reliable. Then, the commercial carbonated soft drinks in8,9,12and13timesdiluted concentrations were detected by using ANWE algorithm, the correlation coefficientbetween relative concentration and the actual concentration were0.9930,0.9930,0.9932,0.9930, respectively, and the content of carmine in beverage were38.88ug/ml,37.71ug/ml,37.68ug/ml,39.65ug/ml, respectively, the average concentration was38.48±0.96ug/ml, andthe average recovery was102.99±2.15%, the method can provide a new idea for the rapidcontent determination of food pigments in commercial beverages.