PERFORMANCE STUDIES OF AN IR FIBER OPTIC SENSOR FOR CHLORINATED HYDROCARBONS IN WATER

Chlorinated hydrocarbons (CHCs) were monitored using a recently presen ted infrared fiber-optic physico-chemical sensor consisting of an MIR transparent, polymer coated, silver halide fiber coupled to a commerci al FTIR spectrometer. The aim of this study was to test the performanc e of this new fiber optic sensing device with respect to temperature d ependence, simultaneous detection of several CHCs, sensitivity and dyn amic response behavior. In addition the diffusion process of the CHCs into the polymer was analyzed in order to better understand and evalua te the obtained results. During the investigation of the temperature d ependence of the sensor response to real trend could be observed in th e temperature range of 0 to 22 degrees C. The dynamic response of the sensor is in the minute range when experiencing an increase in concent ration of the analyte while with a decrease in concentration, the resp onse is relatively slow. The sensor enabled the detection of 10 enviro nmentally relevant CHCs at concentrations of 1 to 50 ppm. The simulati on of the experimental diffusion data revealed Fick's 1st law diffusio n for CHCs into the polymer layers. Finally the sensing device was val idated with head space-gas chromatography (HSGC) analyses and showed g ood agreement with these already established methods. This work shows the great potential of IR fiber optic sensors as early warning systems for a variety of CHCs in water (''threshold alarm sensor'')