Some reactions of DMSO and MSIA in the aqueous phase of sea-spray

The reactions of DMS with ozone and MSIA and MSA with H202 and OH were studied by stopped flow, UV spectrophotometry and ion chromatography. The rapid reaction of DMS with ozone was confirmed and found to be at the limit of capabilities of the stopped-flow technique. MSA was found to be relatively inert compared with MSIA, the reaction of both compounds with H2O2 is slow enough (i.e. can be neglected in the atmosphere) to allow the use of H2O2 as OH precursor in photochemical studies of OH-induced photooxidation, leading to sulphate, finally. The pH-dependence of the UV spectra of MSIA and MSA was determined in a wide range of pH and the dissociation constants were determined.