Surface-enhanced Raman scattering (SERS) system for continuous measurements of chemicals in sea-water

Abstract

A laboratory-based system for measurement of chemicals in sea-water with sol–gel-derived surface-enhanced Raman scattering (SERS) substrates is presented. The motivation behind this work was the development of a marinized prototype sensor. A long-term spectral stability of better than 1 cm−1 over a period of several months was observed. Photodegradation of the SERS layer was avoided by the choice of optical components and layout. Dielectric edge filters and holographic notch filters were compared. Coated fibres were tested and results are discussed in terms of fibre choice, reduction of background signal, sensitivity and time response. Continuous analysis was performed with two flow-through cells, the first a modification to a standard glass cuvette and the second an improved in-house-constructed aluminium cell. SERS investigations on samples whose turbidity ranged from 0 to 400 NTU were performed with both cells. These tests show the suitability of the developed system for continuous monitoring of real samples and possible application in on-line process control. Copyright © 2000 John Wiley & Sons, Ltd.