Research On Detection Of Melamine And Sodium Thiocyanate Using Surface Enhanced Raman Spectroscopy

With the social and economic development, the public is more and moreconcerned with the safety of food. Especially in the matter of milk market, illegal foodadditives have created a great problem which needs to be settled down immediately.However, some kinds of food additives can only be analyzed by traditional chemicaltechnique. The traditional technique has the defection of high cost and long detectionperiod which limited its further development. In the contrast, Surface enhancedspectroscopy technology (SERS) has many advantages. It’s easy and quick to operateand make samples and it has a low requirement of laser light. For above reasons, SERShas the potential to become an advanced method in the area of food inspection.By the detection of melamine and sodium thiocyanate in Raman spectrum, Weanalyzed the Raman shift caused by different molecular structures of the two matters inthe article. With the characteristic peak of melamine is confirmed on676.8cm-1and984.6cm-1because of deformation vibration outside in plane of ring and the ringbreathing mode.In order to improve the SNR of Raman spectrum, We used the technique ofSurface enhanced spectroscopy. First is to experiment the different blending ratios ofSERS-active substrates and Melamine solution and sodium thiocyanate solution.Second, by making spectral characteristic of melamine solution, sodiumthiocyanate solution, melamine milk solution and sodium thiocyanate milk solution,We got the analysis results which prove that SERS-active substrates、deionized waterand milk don’t have interference influence on the qualitative analysis of melamine andsodium thiocyanate. The SNR decreases only in the two illegal additives mixed withmilk, but the extent of change is within the national standard of PRC.At last, the spectroscopy of melamine aqueous solution and milk was detected bytwo kinds of quantitative detection methods, then we analysed the two kinds of dataand fitted it. The results show that the two methods to get results of the high correlation,for the spectrum no internal standard peak by the normalization method for thequantitative analysis; When there’s internal standard peak using the standard methodwhen the quantitative analysis. And the detection limit theory was calculated by thestandard curves, the detection limit of melamine solution and melamine milk solutionwere0.41ppm and1.64ppm.