SENSING OF CHLORINATED HYDROCARBONS AND PESTICIDES IN WATER USING POLYMER-COATED MIDINFRARED OPTICAL FIBERS

An IR fibre optic sensor which operates in the 4-16 mu m wavelength re gion has been developed for the in-situ monitoring of chlorinated hydr ocarbons and pesticides in mater, The sensing element consists of a si lver halide (AgClxBr1-x) optical fibre, coated with a polymer which bo th enriches the analyte in the evanescent wave region of the fibre and , when thick polymer coatings are used, minimizes water interference i n the IR absorption, Using trichloroethylene and alachlor as represent ative pollutants, evanescent wave spectrometry in the mid-IR region is shown to provide good performance down to single ppm levels, Furtherm ore, it is shown that the technique can be applied to multi-analyte sa mples.