DETECTION OF VOLATILE ORGANIC-SOLVENTS USING POTENTIODYNAMIC GAS SENSORS

Amperometric electrochemical gas sensors have the advantage of combini ng good sensitivity and selectivity at relatively low cost. However, t heir use is restricted to the detection of gases that are very reactiv e at potentials positive of that at which oxygen is reduced, We descri be here a new detection method for less reactive species such as benze ne and halogenated hydrocarbons, which cannot be directly oxidized, In stead, the species is continuously adsorbed at a potential below 0.5 V and then oxidized at potentials where oxygen coadsorbs, The oxidation current is corrected for the oxygen adsorption current by performing an additional potential cycle, in which no adsorption is allowed to oc cur. We have so far obtained sensitivities in the lower ppm range for benzene, toluene, tetrachloroethene, epichlorohydrin, and vinyl acetat e; for saturated halogenated hydrocarbons such as CFCl3, it is still b elow 1000 ppm.