Use of sol-gel techniques in the development of surface-enhanced Raman scattering (SERS) substrates suitable for in situ detection of chemicals in sea-water

Abstract.

The development of surface-enhanced Raman scattering substrates suitable for in situ environmental analysis in sea-water is presented. Substrates consist of metal colloids encapsulated in a sol-gel-derived xerogel layer. Control of the gel parameters, such as porosity, pore size, and polarity, enables tailoring of sensitivity to different analyte groups. Gold and silver colloids were used along with tetraethoxysilane (TEOS) and methyltriethoxysilane (MTEOS) precursors. Substrates are characterised by measurement of optical spectra and use of scanning electron microscopy (SEM). Activity is discussed in terms of the choice of precursor and choice of metal colloid. Spectra were obtained for a range of substituted benzene derivatives with limits of detection (LODs) of 100 ppb and 10 ppb for chlorobenzene and phenylacetylene, respectively. Substrate selectivity is shown by the contrasting response of a single substrate type to similar molecules, in particular phenylacetylene and benzonitrile. Details of mechanical and chemical stability tests on the substrates are also included.