ENHANCING THE SENSITIVITY OF CHEMICAL SENSORS FOR CHLORINATED HYDROCARBONS IN WATER BY THE USE OF TAPERED SILVER-HALIDE FIBERS AND TUNABLE DIODE-LASERS

Tapered silver halide fibers were used for the first time for high-sensitivity fiber evanescent wave spectroscopic (FEWS) measurements of chlorinated hydrocarbons (CHCs) in water at trace level. The sensor arrangement consisted of a tunable diode laser (TDL) source, a polymer-coated and tapered silver halide fiber, and a direct fiber/mercury cadmium telluride (MCT) detector coupling. A minimum detection limit of 50 mu g L(-1) was achieved by using a polyisobutylene-coated fiber with a 1:4 tapering ratio. The sensor response is in the minute range and shows reversible analyte enrichment.