Non-isothermal Kinetics of Benzo[a]Pyrene Photooxidation in Glyceryl Trioctanoate

Abstract

Benzo[a]pyrene (BaP) was dissolved in glyceryl trioctanoate, heated in a glass reaction vessel within temperature range 297.95–361.85 K with heating rate of 1 K/min and simultaneously exposed to UV light at wavelength λ = 365 nm at radiation power 20 mW cm⁻² in order to study the decrease of BaP concentration due to its photooxidation. The concentration of BaP was determined by HPLC-FD periodically in 5 min intervals. As observed, the BaP concentration decreased from 62.2 μg L^-1 to 19.8 μg L^-1. From the experimental results, the parameters characterizing the non-isothermal kinetics of BaP photooxidation have been obtained. The parameters were tested at two various isothermal conditions (290.16 and 323.26 K) to verify a suitability of derived parameters. Comparing calculated and measured data of half-lives of BaP decrease at mentioned temperatures it was found that calculated half-lives are in a good accordance with those experimentally obtained values, when relative standard deviations at 290.16 K were 17.0% and 5.4% at 323.26 K, respectively. The kinetic parameters enable the calculation of the rate constant for any temperature in isothermal regime and make possible to model, in general, the kinetics of such processes without a deeper insight into their mechanisms.

Acknowledgments

This contribution is the result of the project implementation “Establishment of a “HiTech” centre for research on formation, elimination and risk analysis of contaminants in food” and “Centre of Excellence for Contaminants and Microorganisms in Food”, supported by the Research & Development Operational Programme funded by the ERDF and supported by Science and Technology Assistance Agency of Slovak Republic under the contract No. APVV-0602-07. Also, the financial support from the Slovak Scientific Grant Agency No. VEGA 1/0660/09 is gratefully acknowledged.