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

This document is currently not available here.

Share

COinS
 

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.