title: Light induced multiphase chemistry of gas-phase ozone on aqueous pyruvic and oxalic acids.
abstract: In this study for the first time it has been shown that pyruvic acid can affect the atmospheric multiphase reactions of ozone with oxalic acid due to its properties as a photosensitizer. To this end, the photochemical batch multiphase reactions of a mixture of pyruvic acid/oxalic acid (PA/OA) and gas-phase ozone under simulated sunlight were studied as a function of time using high pressure liquid chromatography equipped with a UV detector (HPLC-UV) and electrospray ionization mass spectrometry (ESI-MS) to investigate product formation. Following the simultaneous ozone and light irradiation the first peak for pyruvic and oxalic acids (retention time = 3.68 min) decreased to 67% of the initial intensity after a 12 h reaction while a broad and not well defined peak appeared at longer retention times. After prolonged exposure times this broad peak shifted to shorter retention times: from 14 min at 2 h reaction to 8 min at 12 h. The HPLC-UV analysis of the reaction mixture simultaneously exposed to ozone and irradiated by simulated sunlight for 6-12 h revealed the presence of high weight molecular mass products and formation at longer times of highly non-polar products. The results obtained from ESI-MS have clearly demonstrated that the distribution of high molecular weight products is consistent with an oligomer system. No evidence of oligomer formation was found after the sample (PA/OA) was exposed only to either ozone or irradiated with UV/Vis light using the same instrumental conditions.
authors.affiliation: Laboratory for Analytical Chemistry, National Institute of Chemistry, Hajdrihova 19, P.O. Box 660, SI-1001 Ljubljana, Slovenia.
authors.forename: I
authors.initials: I
authors.lastname: Grgić
authors.forename: L I
authors.initials: LI
authors.lastname: Nieto-Gligorovski
authors.forename: S
authors.initials: S
authors.lastname: Net
authors.forename: B
authors.initials: B
authors.lastname: Temime-Roussel
authors.forename: S
authors.initials: S
authors.lastname: Gligorovski
authors.forename: H
authors.initials: H
authors.lastname: Wortham