Time Resolved Study of Hydroxyl Radical Oxidation of Oleic Acid at the Air-Water Interface
The ubiquity of oleic acid (OA) renders it a poster child for laboratory investigations of environmental oxidation chemistry. In the current study, mechanistic details of the oxidation of OA by hydroxyl radicals at the air-water interface are investigated using field-induced droplet ionization mass spectrometry (FIDI-MS). Products from OH oxidation of both unsaturated and saturated carbon atoms are identified, and mechanisms for both types of oxidation processes are proposed. Uptake of oxygen in the interfacial layer increases linearly with time, consistent with Langmuir-Hinshelwood reaction kinetics. These results provide fundamental knowledge relating to OH initiated degradation of fatty acids in atmospheric aerosols.
© 2017 Elsevier B.V. Received 24 March 2017, Accepted 19 May 2017, Available online 20 May 2017. This work was supported by the Beckman Institute at Caltech and by the NSF grant CHE-1508825.