TiO2 mediated photooxidation of squalene: A kinetic and mechanistic study
Presentation Type
Poster
Department
Chemistry
Major
Chemistry
Abstract
The TiO2-mediated photooxidation of squalene, a thirty carbon isoprenoid found in the stratum corneum of human skin, was studied in situ using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and headspace solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). Irradiation experiments of squalene-coated TiO2 nanoparticles under UV-A radiation (λmax=365nm) in flowing air showed the temporal development of squalene oxidation products such as aldehydes, ketones, and surface-bound carboxylates. The kinetics of the loss of surface-bound water, the decline of –CH2 and –CH3 absorptions and the rise of carbonyl features were studied in detail. Carbonyl products formed via pseudo-zero order kinetics through squalene hydroperoxide intermediates. Headspace SPME/GC-MS of the irradiated samples showed volatile and semivolatile products consistent with proposed mechanisms.
Faculty Mentor
Dr. Jane Ganske
Funding Source or Research Program
Academic Year Undergraduate Research Initiative, Undergraduate Research Fellowship
TiO2 mediated photooxidation of squalene: A kinetic and mechanistic study
The TiO2-mediated photooxidation of squalene, a thirty carbon isoprenoid found in the stratum corneum of human skin, was studied in situ using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and headspace solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). Irradiation experiments of squalene-coated TiO2 nanoparticles under UV-A radiation (λmax=365nm) in flowing air showed the temporal development of squalene oxidation products such as aldehydes, ketones, and surface-bound carboxylates. The kinetics of the loss of surface-bound water, the decline of –CH2 and –CH3 absorptions and the rise of carbonyl features were studied in detail. Carbonyl products formed via pseudo-zero order kinetics through squalene hydroperoxide intermediates. Headspace SPME/GC-MS of the irradiated samples showed volatile and semivolatile products consistent with proposed mechanisms.