2-Methyltetrol Sulfate Oxidation by Hydroxyl Radical in Atmospheric Water Mimics and Implications for the Fate of Isoprene-Derived Secondary Organic Aerosol

2-Methyltetrol sulfate diastereomers (2-MTS) form from acid-driven multiphase chemical conversion of inorganic sulfate (Sulf_inorg) aerosol by isoprene-derived epoxydiols (IEPOX). Studies have explored 2-MTS sinks within aerosols, but observations of 2-MTS in atmospheric waters indicate a need to understand the fate of 2-MTS in clouds and fogs. In batch reactor experiments, we oxidized 2-MTS in 30, 300, and 3000 μM solutions to understand 2-MTS fate in cloud, fog, and aerosol water. Ion chromatography (IC) revealed production of acetate, oxalate, and Sulf_inorg with 2-MTS oxidation. Our 30, 300, and 3000 μM experiments revealed a 5%, 20%, and 32% gap in the sulfur mass balance, respectively, suggesting organosulfates (OSs) formed from 2-MTS oxidation. OSs produced by 2-MTS oxidation were detected by hydrophilic liquid interaction chromatography interfaced to electrospray ionization high-resolution tandem mass spectrometry at mass-to-charge ratios 139 (C₂H₃O₅S^-), 169 (C₃H₅O₆S^-), 185 (C₃H₅O₇S^-), 199 (C₄H₇O₇S^-), 211 (C₅H₇O₇S^-), 213 (C₅H₉O₇S^-), 227 (C₅H₇O₈S^-), and 229 (C₅H₉O₈S^-). 2-MTS oxidation was then accurately predicted with a rate constant of 1.5×10⁹ M^-1s^-1. Results emphasize the utility of 2-MTS for sulfur cycling in the atmosphere, and the potential for IC to measure 2-MTS in atmospheric waters.