Presentation Title

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

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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.