Study On Spectral Characteristics Of Synthetic Food Colors Erythrosine, New Red And Indigotine

The absorption and fluorescence spectral characteristics of three synthetic food colors Erythrosine, New Red, and Indigotine were studied in this paper, and the variations of their spectral characteristics under different external environmental conditions were analyzed. Based on the spectral characteristic data, we successfully realize simultaneous determination of multicomponent dyes by combining wavelet transformation, derivative fluorescence spectrometry, and artificial neural networks.From the absorption and fluorescence spectra measured experimentally, we obtained some spectral characteristics such as absorption peak wavelength, absorbance, optimal excitation wavelength, emission peak wavelength, emission spectral width, and we get spectral characteristics of fluorescence quantum yield and fluorescence lifetime according to quantum yield and fluorescence decay experiments. Moreover, we measured the fluorescence spectra of respective fifteen concentrations of Erythrosine, New Red, and Indigotine solutions excited by respective optimal excitation wavelengths. The relationships between spectral characteristics of fluorescence peak intensity, emission peak wavelength and concentrations of synthetic food colors solutions can also be obtained.In order to analyze the influence of external environmental conditions on spectral characteristics of synthetic food colors, we carried out a series of work as below: First, we measured the fluorescence emission spectra and fluorescence quantum yields of Erythrosine in water, methanol and ethanol respectively, and obtained the results that the fluorescence emission peaks of Erythrosine exhibited red shift with the increase of solution polarity and blue shift with the increase of hydrogen bond strength, and the fluorescence quantum yields reduced with the increase of hydrogen bond strength; Second, we measured the fluorescence intensities of Erythrosine solutions under different pH value and analyzed the variation law; Then, we measured the fluorescence intensities and fluorescence lifetime of New Red solutions under temperature, and obtained that the relationship between the fluorescence intensities and temperature accorded with the function ( F0 F) F=ke?E RT+C, and the fluorescence lifetime decreased linearly with the increase of temperature; Moreover, we irradiated Indigotine solution by sunshine, ultraviolet lamp, and fluorescent lamp and measured the absorption and fluorescence spectra after different irradiation time, in addition, we heated Indigotine solution under 85℃and measured the absorption and fluorescence spectra after different heating time, in conclusion, we got the mechanism of degradation. The results indicate that the external environmental conditions have significant effects on the spectral characteristics of the three synthetic food colors. Under certain external environmental conditions, synthetic food colors may appear to degrade and degenerate.In this paper, we introduced a method by combining wavelet transformation, derivative fluorescence spectrometry, and radial basis function (RBF) neural network together to establish a predicting model for simultaneous determination of multicomponent dyes. First, we prepared twenty-four different concentrations of mixed Brilliant Blue and Indigotine solutions, taking nineteen of them as training samples, and the other five solutions as predicting samples. And then we measured the fluorescence emission spectra of the samples respectively. Wavelet transformation was used to compress spectral data obtained by experiment, and derivative fluorescence spectrometry was used to narrow spectral width and decrease spectral overlap. We took the derivative wavelet coefficients as inputs to train and establish an RBF neural network model to predict the concentrations of the five predicting samples, the mean relative predicting errors of Brilliant Blue and Indigotine are 1.84% and 1.26% respectively. This method can also be applied to determinate other multicomponent colors and other fluorescent substances simultaneously.The studies on spectral characteristics of the three synthetic food colors can offer a help for improving the accuracy of spectral detection, safe use of synthetic food colors and toxicology research. The method of establishing a model for predicting the concentrations of multicomponent colors solutions can provide a new way for food safety detection.