COLORATION REACTIONS BETWEEN NO2 AND ORGANIC-COMPOUNDS IN POROUS-GLASS FOR CUMULATIVE GAS SENSOR

Coloration reactions between nitrogen dioxide (NO2) and organic compou nds, such as diazocoupling reactions, were demonstrated to occur in po res by exposing organically impregnated porous glass chips to NO2. An NO2 concentration of under 1 ppm can be estimated from the absorbance changes after the coloration reactions. Good linear relationships were obtained between the absorbance changes and exposure time at 200 ppb, indicating the possibility of environmental-level analysis by accumul ation. Application to an actual analysis showed that this method can g ive the variations in NO, concentrations at the environmental level. ( C) 1998 Elsevier Science S.A. All rights reserved.