S. Tadjiki, R. Reed, F. Meier, T. Klein
Postnova Analytics Inc.,
Keywords: sunscreen, titanium dioxide, field flow fractionation, characterization, size, nanoparticle, analysis, cosmetics
Summary:Engineered nanomaterials (ENM) find their applications in a multitude of consumer products including food and cosmetics. An example is the application of nanoparticulate titanium dioxide as a UV-protection agent in sunscreen formulations. Here, titanium dioxide nanoparticles are incorporated in a complex matrix consisting of a variety of thickeners, emulsifiers and solubilizers in order to obtain a homogeneous formulation. With existing (and upcoming) legislative regulations, e.g., the European Regulation EC No 12232009 of 30 November 2009 on cosmetic products, the declaration of nanoparticulate ingredients in cosmetics has become mandatory in Europe. Therefore, increased research is underway to find methods for the reliable detection and characterization of nanoparticles in such complex matrices. A promising approach is the application of supercritical CO2 (scCO2) extraction with subsequent analysis using asymmetrical flow-field flow fractionation (AF4). ScCO2 extraction can be considered a “green” extraction method capable of gently removing matrix components without using potentially hazardous chemicals. AF4 allows the reliable fractionation of the nanoparticulate components to gain detailed insight into the particle size distribution inside the sample. In this presentation, we describe the application of scCO2 extraction for the efficient pretreatment of sunscreen formulations containing nanoparticulate titanium dioxide (AeroDisp® w740x, Evonik Industries). Subsequent analysis of the dried samples using AF4-UV-MALS not only revealed the excellent applicability of scCO2 extraction as an FFF sample pretreatment tool, but also strongly suggests the presence of nanoparticles in the investigated sunscreen formulations.