MULTICOMPONENT GAS-ANALYSIS - AN ANALYTICAL-CHEMISTRY APPROACH APPLIED TO MODIFIED SNO2 SENSORS

Commonly used electronic conductivity sensors show significant cross-sensitivities for different gases and usually irreproducible results above or below certain temperatures and partial pressures of critical components in the gas phase. The present paper characterizes conditions for reversible sensor response with respect to partial pressures of CO, CH4 and H2O and temperature. Sensitivities and selectivities of the SnO2-based sensors are modified chemically in a systematic way. The results are discussed by using analytical expressions describing conductivity changes upon partial pressure changes. After introducing briefly the general concept of multicomponent analysis to identify the concentration of n components with m sensors in analytical chemistry, we present a simple application to identify CO and CH4 partial pressures in gas mixtures by using chemically modified sensors at different temperatures. © 1990.