Direct and selective determination of atmospheric gaseous hydrogen peroxide by diffusion scrubber and 1,1'-oxalyldiimidazole chemiluminescence detection

An on-line method is described for the determination of atmospheric hydrogen peroxide, collected by a diffusion scrubber and detected in a now system by using 1,1'-oxalyldiimidazole peroxyoxalate chemiluminescence. Interferences from the organic peroxides most abundantly occurring in the atmosphere [methyl hydroperoxide and hydroxymethyl hydroperoxide (HMHP)] were investigated and showed that the method had a selective response for hydrogen peroxide. The pH-dependent dissociation rate of HMHP to hydrogen peroxide and formaldehyde was estimated and could be controlled by a buffered scrubber Liquid (pH 5.0) to eliminate the contribution of hydrogen peroxide from dissociated HMHP. The linearity of the response was excellent in the tested interval from the detection limit (23 pptv) to 3.37 ppbv. The time resolution was high, with an injection throughput of 120 h(-1). The applicability of the technique was assessed by measurement of the atmospheric hydrogen peroxide concentration outside the laboratory over a period of 22 h.