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Proceedings Paper

UV photostability of insect repellents evaluated through Raman spectroscopy
Author(s): Viviane Gadret Bório; Adjaci Uchôa Fernandes; Landulfo Silveira Jr.
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Paper Abstract

The use of insect repellents either indoors or at places with incidence of solar radiation has been common due to dengue epidemics in Brazil. The lack of studies on the photostability of these substances has motivated this study, where the main goal was to verify the photostability and photodegradation of some of the commercially insect repellents available under the simulated ultraviolet (UV) radiation, by evaluating the molecular changes using dispersive Raman spectroscopy (830 nm excitation). A laboratory-made chamber was used for irradiating the repellents, where UV-A + UV-B radiations (UV-A: 5.5 mW/cm2 and UV-B 1.5 mW/cm2) can be obtained. The chamber internal temperature did not exceed 31 °C during experiments. The compounds n,n-diethyl-m-toluamide (DEET), IR-3535, andiroba and citronella oils, used as active ingredients in insect repellents, and commercial formula containing DEET (14.5% in ethanol and isopropyl myristate) and IR-3535 (16% in carbopol) were continuously irradiated for 8 h. The Raman spectrum of each sample was obtained before and after UV exposure. The compounds and the commercial formula containing IR-3535 showed photo-stability when irradiated, since no changes in the peaks were found. The commercial formula containing DEET showed spectral decrease at 524, 690, 1003 and 1606 cm-1, assigned to the DEET, and increase at 884 cm-1, assigned to the ethanol. These results indicate that the excipient could influence the photostability of the active ingredient. The Raman spectroscopy can be suitable to monitor the photodegradation under UV irradiation rapidly and reliably.

Paper Details

Date Published: 29 February 2016
PDF: 6 pages
Proc. SPIE 9689, Photonic Therapeutics and Diagnostics XII, 968919 (29 February 2016); doi: 10.1117/12.2214329
Show Author Affiliations
Viviane Gadret Bório, Univ. Camilo Castelo Branco (Brazil)
Adjaci Uchôa Fernandes, Univ. Camilo Castelo Branco (Brazil)
Landulfo Silveira Jr., Univ. Camilo Castelo Branco (Brazil)

Published in SPIE Proceedings Vol. 9689:
Photonic Therapeutics and Diagnostics XII
Hyun Wook Kang; Guillermo J. Tearney M.D.; Melissa C. Skala; Bernard Choi; Andreas Mandelis; Brian J. F. Wong M.D.; Justus F. Ilgner M.D.; Nikiforos Kollias; Paul J. Campagnola; Kenton W. Gregory M.D.; Laura Marcu; Haishan Zeng, Editor(s)

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