An Improved Nonenzymic Method for the Determination of Gas-phase Peroxides

We report an improved method for sampling and realtime determination of gaseous hydrogen peroxide, hydroxymethyl hydroperoxide (HMHP), and methyl hydroperoxide (MHP) in the atmosphere. The analytical method is based on the hydroxylation of benzoic acid by Fenton reagent [Fe(II) and H[sub 2]O[sub 2]] to form the fluorescent product, hydroxybenzoic acid. Fluorescence intensity is enhanced by complexation with aluminum ion. A novel sampling device with a surfaceless intake permitting collection of gas-phase peroxides without inlet line losses is described. SO[sub 2] interference in the measurements has been fully characterized, and experimental conditions have been specified for minimizing such interference. Significant concentrations of organic peroxides were observed when the improved method was fielded during the Southern Oxidant Study/Southern Oxidant Research Program on Ozone Nonattainment (SOS/SORP-ONA) in Atlanta, GA. in August 1992 and during the North Atlantic Regional Experiment (NARE) in Nova Scotia in August 1993. 44 refs., 5 figs., 3 tabs.