Proposed protocol for determination of photostability Part I: cosmetic UV filters

Abstract

Synopsis The protocol described here has been developed to measure the stability of UV-B filters; a modified version is recommended for UV-A filters. It should be considered as a tool to predict the effectiveness remaining after exposure to UV-A and UV-B light. It is a simple and reliable in vitro model simulating conditions of actual use. The results show that each filter requires an appropriate choice and fine tuning of reproducible analytical conditions. While absolute values are directly influenced by uncertainties in irradiance (dosimetry), comparative measurements with respect to a known standard are very reliable.

Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

“…Reduced leaching from B-DA is likely due to the greater number of siloxane linkages between the silica particle and the monomer, but may also benefit from less segregation of the on the particles' surfaces. 51) To test if incorporation increases UV stability, thin-film solutions of 2, E-DA particles, P-DA particles, and B-DA particles sandwiched between quartz slides were examined according to the protocol presented in Berset, et al 51) The samples were exposed with a Xenon arc lamp at irradiances of 0.039 W/cm 2 (290320 nm) and 0.052 W/cm 2 (320400 nm) for a total of 6.0 h during which UVVisible absorption spectra were taken every hour (Fig. 7).…”

Combination of retinyl palmitate and UV-filters: Phototoxic risk assessment based on photostability and in vitro and in vivo phototoxicity assays

“…It is able to absorb UV photons and it has been shown to improve the photostability of sunscreen formulations containing the combination octyl methoxycinnamate/avobenzone (Chaudhuri et al, 2006). Photostability evaluation studies are usually performed using quantitative separation techniques as High Performance Liquid Chromatography (HPLC) Deflandre and Lang, 1988;Berset et al, 1996).…”

Photostability evaluation of five UV-filters, trans-resveratrol and beta-carotene in sunscreens

“…The lamps emission spectrum shows that of the total light emitted between 320 and 460 nm, 86.1% is UVA and 13.9% corresponds to visible light. Irradiance, which was approximately 40w/m 2 , was calculated with a VLX-3W Vilber Lourmat (Marne-la-Vallee, France) Radiant Power Meter equipped with UVA (365 nm) and UVB (312 nm) sensors (Berset et al, 1996;Marginean Lazar et al, 1997). For each exposed glass plate there was a negative (non-irradiated) control, which was kept in a dark place Campos, 2010, 2007;Gaspar and Maia Campos, 2006).…”