ABSTRACT
A surface enhanced Raman scattering (SERS) method is described for the determination of vanillin, methyl vanillin and ethyl vanillin at trace levels. Flower-like silver nanoparticles on a silicon wafer are used as the SERS substrate, and the analytes can be specifically and non-destructively recognized by their specific Raman bands. The molecules can be recognized rapidly by identifying the characteristic bands. The SERS spectra of vanillin (C8H8O3) were used as mid-contrast, and specific bands of methyl vanillin and ethyl vanillin (C9H10O3) were acquired at 775 cm-1, 1350 cm-1 and 1282 cm-1, 1382 cm-1, respectively. In addition, by using an improved principal component analysis (PCA) algorithm, the organic molecule can be quantitatively determined. Dissolved in water, vanillin, methyl vanillin and ethyl vanillin still can be detected at a concentration of 10-8 M, at which their characteristic Raman peaks are still visible. The method was successfully applied to the determination of vanillin in milk powder products. Graphical abstract Vanillin can be identified at trace levels by laser irradiation of milk and by using flower-like silver nanoparticles as the surface enhanced Raman scattering (SERS) substrate. Vanillin and its methyl and ethyl derivatives can be quantitatively analyzed by the principal component analysis (PCA) algorithm.
