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Optical chemical sensor for chlorocarbon measurement

A sensor for the measurement of volatile aliphatic chlorocarbons is reported based on quenching of a fluorescent indicator. Chlorocarbon vapors when in contact with the fluorescent indicator immobilized in a polymer film cause a quantitative decrease in the fluorescence intensity. The quenching is rapid and reversible for a range of chlorocarbons investigated, including carbon tetrachloride, trichloroethylene, perchloroethylene, chloroform and 1,1,1- trichloroethane. Quenching constants for the sensor ranged from 700 M-1 (trichloroethylene) to 8500 M-1 (perchloroethylene) allowing detection limits of 28 (mu) M (660 ppm v/v) and 2.4 (mu) M (56 ppm v/v) respectively. The sensor offers response time of ca. 100 s and recovery times, governed by diffusion of the analyte in the polymer film, are less than 100 s.