EVALUATION OF A SOLID-PHASE EXTRACTION MEMBRANE AS A SURFACE-ENHANCEDRAMAN SUBSTRATE

A commercially available solid-phase extraction membrane was evaluated as a substrate suitable for routine analysis by surface-enhanced Rama n spectrometry (SERS). The material was silver coated in-house via che mical reduction. Because the material has chromatographic capabilities , the use of SERS as a detection method for thin-layer chromatography (TLC) was considered by separating, then detecting, a mixture of commo nly used sulfonamides from the bare and coated material. While the mob ilities of the sulfa drugs were not strongly affected by the silver, t he SER response was weak anal analyte degradation was apparent. Some s ignal improvement was gained by dampening the surface with water in a simple surface modification. General substrate performance in both dry and in the modified dampened states was evaluated by using the model, crystal violet. The resulting analytical curves were linear across 1- 2.5 orders of magnitude with limits of detection in the subnanogram ra nge (total analyte applied). Under routine preparation and analysis pr ocedures, reproducibility was <30%, but improvement to similar to 10% was possible when great care was used. Typical spectra for two compoun d series having a variety of functional groups were obtained and showe d general trends for response dependence on functional group.