Development of nitrogen monoxide sensing element using 2-Phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl impregnated porous glass

摘要

Nitrogen monoxide (NO) is an important bio-regulatory molecule, and high concentrations of NO are observed in the air exhaled by patients with asthma. Therefore, chemical sensors that can detect NO via a simple method are required. We focused on 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO) as a detection reagent. PTIO oxidizes NO to form nitrogen dioxide (NO2) and is used in passive samplers to measure atmospheric nitrogen oxide (NOx) concentrations. We used a porous glass as a substrate and impregnated PTIO into the pores, and evaluated the performance of the sensor element. The sensor showed absorption peaks at 567, 343, and 238 nm. Although the sensor element was stable in a nitrogen atmosphere and in air, it was not stable for light. Moreover, we performed a NO exposure experiment of the sensor element in dark conditions. We observed that the absorbance decreased when the sensor element was exposed to NO gas and that there was a linear relationship between the NO exposure time and the absorbance changes observed at both the 567 and 343 nm absorption peaks. Our results suggest that the sensor element may play both high selectivity and high sensitivity measurement of NO.