Towards a remote IR fiber-optic sensor system for the determination of chlorinated hydrocarbons in water

A laboratory prototype of a mid-infrared (MIR) fiber-optic sensor system capable of remote on-site and real-time determination of chlorinated hydrocarbons (CHCs) in water has been developed. The system is based upon fiber evanescent-wave spectroscopy (FEWS) and consists of silver halide fibers that are coupled to a portable Fourier transform infrared (FTIR) spectrometer. These fibers serve both as signal transfer lines and as sensing elements. In the latter case they are coated with thin films of ethylene/propylene copolymer for the purposes of enrichment of the analytes and exclusion of water. A detection limit for tetrachloroethylene of 300 ppb has been achieved with a total contact time between sample and sensor of 10 min.