Phosphorescence Lifetime-Based Sensing of SO2in the Gas Phase

Abstract
Two different types of solid-state coatings based on the phosphorescent metalloporphyrins - polymer film compositions or Langmuir-Blodgett films - were studied comparatively with respect to their application to sensing of SO2. While the polymer films were only slightly sensitive to SO2, LB-coatings appeared to be highly suitable for analyzing SO2 in air in the range 0.01 - 2 % (v/v). Performance characteristics of the new phosphorescence lifetime-based sensor for SO2 were studied. Interferences by a number important species on sensing of SO2 in gas phase were studied. The new SO2 sensor was shown to be rather inert to quenching with molecular oxygen and interference by such species, as CO2, CO, NH3, CH4 gases. On the other hand, NOx interfere with SO2 sensing and vapors of water (i.e. high relative air humidity); alcohols, acids at concentrations close to saturated also cause interference by enhancing quenching with environmental oxygen.