Direct Determination Of Banned Dyes In Textiles By Visible Reflectance Spectroscopy

At present,the detection methods of banned dyes in China's textiles all adopt the national standard test method,which is difficult to operate,high in cost,high in damage and long in time,and can only be carried out in a professional laboratory and the equipment is expensive and cumbersome.Compared with traditional wet chemical methods,spectroscopy has the advantages of no pollution,no pre-treatment,convenient and fast,and suitable for line monitoring.This topic proposes the use of visible reflection light intensity spectroscopy combined with chemometric analysis methods to quickly determine the banned dyes in textiles,and achieved satisfactory results.(1)Qualitative identification of banned dyes in textiles based on oblique projectionThe experiment simulates the actual production process,and samples of the acid dye series and direct dye series containing the banned dyes Acid Red 26 and Congo Red,respectively,are prepared,including single-component,two-component and threecomponent samples,which are visible by oblique projection.Reflectance spectroscopy was used to establish an analytical model of Congo red and Acid Red 26.The results show that the model can accurately complete the qualitative identification of the banned dyes Acid Red 26 and Congo Red on textiles with high instrument noise and high peak overlap.The recognition rate is 100%.(2)Quantitative analysis of Congo red in pure cotton cloth based on partial least squares regression analysisBased on the combination of visible reflection intensity spectrum and partial least squares,a quantitative analysis model for the banned dye Congo red in textiles was established.In this paper,the "leave one" method is used to calculate the optimal principal factor number by calculating the squared sum of the prediction residuals of each calibration set sample spectrum under different principal factors.Finally,the PLS quantitative analysis models under different pretreatment methods are established respectively.According to the evaluation indicators of each model,the robustness of the model after standardization is the best.According to the pretreatment method under the optimal model,the samples of the multi-component system were modeled by PLS.The SEC,SEP,RC and RP of the regression model were 0.466,0.532,0.973 and 0.9919,respectively.(3)Quantitative analysis of acid red 26 in wool thread based on oblique projectionBased on the combination of visible reflection intensity spectrum analysis and chemometrics,a quantitative analysis method for acid red 26 on wool thread was established based on the oblique projection algorithm.The results show that: 1 The analysis of the one-component system containing only acid red 26 has a good linear relationship with the established standard curve.Quantitative analysis of 'unknown' samples,the relative error between predicted and true values are within 10%;2 for mixed system samples,acid red 26 is in the range of 0.17~5.11 mg/g,and its standard curve is R2=0.9958 The RSD is 1.79%.The content of acid red 26 in the 'unknown' sample was predicted,and the relative error was less than 10%,and the prediction result was accurate.