Critical evaluation of experimental conditions influencing the surface-enhanced Raman spectroscopic (SERS) detection of substances separated by layerliquid chromatographic techniques

Surface-enhanced Raman spectra (SERS) of p-dimethylaminobenzylidenerhodanin e have been recorded on silica gel 60 F-254 and Si60 F-254 Raman TLC plates . Spectra were enhanced by use of a silver sol prepared according to the mo dified Lee-Meisel procedure. The standard deviations of the intensities and the band ratios for the seven most intense peaks were calculated for 30 pa rallel measurements. Although the Raman plate gives more reproducible resul ts, several experimental difficulties are encountered in the development of chromatograms. SERS detection of ascorbigen and 1'-methylascorbigen was performed after ch romatography on silica gel 60 F254 TLC and HPTLC plates and on Si60 F254 Ra man TLC plates. Traditional development was used for the silica gel 60 F254 TLC plates and Si60 F254 Raman plates, and the personal OPLC technique for the silica gel 60 F254 HPTLC plates. It was found that the SERS spectrum g ave information about the indole ring only. Because bonding of the analyte to the stationary phase results in a change in molecular conformation-in co ntrast with the behaviour of rhodanine-the type of the plate used and the d evelopment procedure employed can significantly influence the quality of th e SERS spectrum.