RENEWABLE LIQUID FILM-BASED ELECTROCHEMICAL SENSOR FOR GASEOUS HYDROPEROXIDES

Electrochemical sensors for hydroperoxides based on thin flowing films were investigated. The sensor is composed of two segments of Nafion t ubing put on a silver wire. A small portion of the silver wire is expo sed and is chloridized to function as the reference electrode. One Naf ion segment has a Pt-wire coil wrapped on it to function as the counte r electrode and the other has a similar Pt-Rh wire coil that functions as the working electrode. A collection solution flows as a thin film on the sensor surface and also functions as the collection medium. Hyd rogen peroxide and cumene hydroperoxide were examined as test compound s. The former can be oxidatively determined with a Pt-Rh electrode ove r a large range (ppb-ppm) without any significant influence of relativ e humidity. By using a technique to stop the liquid flow, the sensitiv ity can be further improved. Cumene hydroperoxide, an industrially imp ortant hydroperoxide, can be determined easily with a relative precisi on of better than 5% in the vapor phase over simulated process reactio n mixtures containing percentage levels of the analyte by reduction on a Pd electrode. The sensor is simple and inexpensive to fabricate and requires only a suitably equipped personal computer for operation. (C ) 1997 Elsevier Science B.V.