The in-situ analysis of lipsticks by surface enhanced resonance Raman scattering
The use of surface enhanced resonance Raman scattering (SERRS) spectroscopy is reported for the in-situ characterization of chromophores in lipstick smears on glass and cotton surfaces. A surfactant is required to obtain SERRS spectra of the dyes and pigments in these waxy samples. Of the surfactants tested, poly(L-lysine) is preferred for this purpose and serves a dual function, since it also produces the required aggregation of the silver colloid. The method is quick, effective and sensitive, and with the silver colloid distributed on the surfaces tested, no appreciable background fluorescence from the substrates is detected. For six commercial lipstick samples examined by this in-situ SERRS method, discrimination between the samples could be achieved and it was possible to identify some of the individual pigments present, thus indicating the potential of the technique for forensic and quality control applications.