Analysis by surface enhanced Raman spectroscopy on silver hydrosols and silver coated filter papers

Surface enhanced Raman spectrometry (SERS) is an analytical technique with a sensitivity comparable to that of conventional molecular absorption or fluorescence spectroscopy, with the additional major advantage of selectivity inherent in vibrational spectroscopies. The analytical application of flowing silver hydrosols is described. Under the controlled experimental conditions of flow injection analysis, it was possible to detect as low as 30 ng of p-aminobenzoic acid. The linear range was two orders of magnitude (1-100 microg ml(-1)) with a signal reproducibility of 3.2%. Silver coated filter paper is another SERS active substrate that is simple to prepare and handle. The SERS spectra of several nitrogen-containing molecules were obtained on these substrates. The effects of laser power and paper hydration are described. The relative advantages of both substrates are compared.