Novel Teflon-coated optical fibres for TCE determination using FTIR spectroscopy

The evaluation of a novel Teflon-coated fibre-optic chemical sensor for analysis of chlorinated hydrocarbons in water is described. The sensor which is based on evanescent wave absorption, consists of a Teflon-coated silver halide optical fibre. The Teflon coating is used to enrich the chlorinated hydrocarbon species within the penetration depth of the evanescent field of the fibre-optic sensor. The polymer-coated fibre was mounted in a glass cell containing inlet and outlet ports for the aqueous samples. Trichloroethylene (TCE) was used to calibrate the sensor and absorbance data were recorded at 938 cm(-1) The time constant for 90% saturation of the polymer with TCE was 3 min. The useful calibration range has a correlation coefficient of 0.9990 and relative standard deviation of 0.0002 in the range 5-50 ppm. A limit of detection of 1 ppm was achieved for TCE determination using the Teflon-coated optical fibre.