Development of a cascade flow cell for dynamic aqueous phase detection using modified SERS substrates

We are reporting the development of an efficient flow-through cell for liquid chromatography (LC) and flow injection analysis(FIA). This is a continuation of previous efforts toward the development of molecular-specific chromatographic detectors using modified surface-enhanced Raman scattering (SERS) substrates, The flow-through cell incorporates a cascade geometry that is capable of accepting modified SERS substrates, It has an effective dead volume of 2.5 mu L, can withstand pressures in excess of 750 psi, and has a plano-convex GRIN lens design that produces an overall spectral throughput near 70%. We also report on limitations to the sensitivity of SERS under dynamic conditions and reduced sensitivity due to the presence of organic solvents, However, reasonable limits of detection were achieved with FIA-SERS for the detection of BTEX (benzene, toluene, ethylbenzene, and o-, m-, and p-xylene). The utility of multicomponent analysis software for interpreting both Raman and SERS spectral data under static conditions is also evaluated.