Determination of inorganic elements in sunscreen by using energy dispersive x-ray fluorescence

Abstract

Nowadays there are no official in vitro methods to determine TiO2, ZnO or other inorganic elements in sunscreen cosmetics. The objective of this work is to determine the concentration of several inorganic elements in sunscreen composition, without sample preparation, by employing a portable Energy Dispersive X-Ray Fluorescence (EDXRF) device. Particularly in the case of TiO2 and ZnO, the aim is also to estimate their Sun Protection Factor (SPF) due to the physical protection barrier. A sensitivity curve for the determination of inorganic elements in sunscreen, with atomic numbers ranging from 19 to 35, is presented. Fifteen commercial samples with different SPF from different brands were analyzed. It was determined TiO2 and ZnO concentrations with their respective SPF values, as well as to detect the presence of K, Br, Sr and Ce in the sunscreen samples by identifying and quantifying chemical elements that had not been mentioned in the formulations.Colegio de Farmacéuticos de la Provincia de Buenos Aire