DEVELOPMENT OF CATALYTIC ELECTROCHEMICAL GAS SENSOR FOR ARSINE

A catalytic electrochemical gas sensor for arsine has been developed a nd its performance investigated. The sensor consists of a working and a counter electrode and an inner solution is filled between the two el ectrodes. The working electrode is a gas-permeable catalytic membrane prepared by sintering a PTFE membrane coated with a Nafion solution co ntaining noble metal particles. The species of the metal and its parti cle size affect the sensitivity and selectivity of the sensor. The sen sor shows high selectivity to arsine against carbon monoxide, hydrogen and nitrogen monoxide. The selectivity coefficients for gases relativ e to arsine gas are 10(-6) for hydrogen, acetone, toluene, 10(-5) for carbon monoxide, 10(-4) for ethanol, 0.27 for sulfur dioxide, and 0.25 for nitrogen dioxide. The lower limit of detection is 0.01 ppm. The 9 0% response time is about 30 s for 0.05 ppm arsine. The reproducibilit y and repeatability for detection of 0.05 ppm arsine are less than 6.0 %. The sensor has been applied to monitoring in a field where arsine g as will leak out, and it has maintained stable response for more than one year. The sensor proves to be practical in use for arsine detectio n.