Unité de Technologie et Valorisation Alimentaire, Centre d'Analyses et de Recherche, Université Saint-Joseph, Campus des Sciences et Technologies, Mar Roukos, Mkallès, P.O Box 11- 514, Riad El Solh, 1107 2050 Beirut, Lebanon, Université Paris-Saclay, Lipides, Systèmes Analytiques et Biologiques, 92296, Châtenay-Malabry, France, Obegi Chemicals, Esseily building, P.O. Box 11-2652, Riad el Solh, Beirut, Lebanon.
Physics department, UR TVA, Faculty of science, Saint Joseph University, B.P. 11-514 - Riad El Solh, 1107 2050 Beirut, Lebanon.
Eur J Dermatol. 2021 Jun 1;31(3):335-341. doi: 10.1684/ejd.2021.4049.
There exist different methods for the determination of sun protection factor (SPF) values for sunscreens. We aimed to develop a new in vitro method using EBT3 Gafchromic film as a substrate. The colour of EBT3 Gafchromic film changes when exposed to UV light. Films were covered by sunscreen preparations of different SPF values ranging from 0 to 50. Uncovered and covered films were exposed to different solar light energies and their colour change was compared. Absorbance spectra of films was measured at 633 nm using a UV-VIS spectrophotometer apparatus. The colour of the film darkens when ultraviolet energy increases, which means that absorbance increases with exposure time. However, when films are covered by sunscreens, the colour change is less visible and the absorbance significantly decreases with increasing SPF value. There is a linear correlation between the absorbance of EBT3 Gafchromic film and SPF value of sunscreens covering the film. Statistical analysis demonstrated that the SPF value of a sunscreen can be predicted using EBT3 Gafchromic film as a substrate. This is the first report of an in vitro method based on colour change of a substrate which takes into consideration exposure time, and relates more closely to conditions of real-life. Based on these parameters, this is a reliable in vitro method for SPF testing.
有不同的方法用于测定防晒霜的防晒因子（SPF）值。我们旨在开发一种新的体外方法，使用 EBT3 Gafchromic 胶片作为基质。EBT3 Gafchromic 胶片在暴露于紫外线下时颜色会发生变化。将 EBT3 Gafchromic 胶片覆盖不同 SPF 值（0 至 50）的防晒霜制剂。将未覆盖和覆盖的胶片暴露于不同的太阳光能量下，并比较它们的颜色变化。使用 UV-VIS 分光光度计在 633nm 处测量胶片的吸收光谱。当紫外能量增加时，胶片的颜色会变暗，这意味着吸收随暴露时间的增加而增加。然而，当胶片被防晒霜覆盖时，颜色变化不太明显，吸收显著随 SPF 值的增加而降低。EBT3 Gafchromic 胶片的吸收与覆盖胶片的防晒霜的 SPF 值之间存在线性相关性。统计分析表明，使用 EBT3 Gafchromic 胶片作为基质可以预测防晒霜的 SPF 值。这是第一个基于考虑暴露时间的基质颜色变化的体外方法的报告，并且与实际生活条件更密切相关。基于这些参数，这是一种可靠的 SPF 测试的体外方法。
