The TiO2-mediated photooxidation of squalene, a 30-carbon isoprenoid in human skin oil and plant oils, was investigated using diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), solid-phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS) and UV-Vis spectrophotometry. The oxidation proceeds under UVA radiation (λmax = 365nm), as well as under longer wavelengths into the blue light spectrum. Oxidation photoproducts include aldehydes, ketones and surface-bound carboxylates, coordinated in a bidentate fashion to the particle surface. The kinetics of the loss of squalene –CH2 and –CH3 absorptions and the rise of carbonyl features were studied, and proposed mechanisms are consistent with kinetics and photoproducts identified using DRIFTS, SPME/GC-MS and UV-Vis spectrophotometry.

Photooxidation of squalene on titanium dioxide particles

251st National Meeting (2016)

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