IMPROVED NONENZYMATIC METHOD FOR THE DETERMINATION OF GAS-PHASE PEROXIDES

We report an improved method for sampling and real-time 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 H2O2] to form the fluorescent product, hydroxybenzoic acid. Fluore scence intensity is enhanced by complexation with aluminum ion. A nove l sampling device with a surfaceless intake permitting collection of g as-phase peroxides without inlet line losses is described. SO2 interfe rence in the measurements has been fully characterized, and experiment al conditions have been specified for minimizing such interference. Si gnificant concentrations of organic peroxides were observed when the i mproved method was fielded during the Southern Oxidant Study/Southern Oxidant Research Program on Ozone Nonattainment (SOS/SORP-ONA) in Atla nta, GA, in August 1992 and during the North Atlantic Regional Experim ent (NARE) in Nova Scotia in August 1993.