Anal. Chem. 2008, 80, 7594–7608
TiO2 in Commercial Sunscreen Lotion: Flow Field-Flow Fractionation and ICP-AES Together for Size Analysis Catia Contado* and Antonella Pagnoni Department of Chemistry, University of Ferrara, Via Luigi Borsari 46, I-44100 Ferrara, Italy A new method for determining the size of titanium dioxide particles is proposed and assayed in a commercial sunscreen product. Today many sun protection cosmetics incorporate physical UV filters as active ingredients, and there are no official methods for determining these compounds in sunscreen cosmetics. Here flow field-flow fractionation (FlFFF) has been tested, first to sort two different types of TiO2 nano- and microstandard materials (AeroxideTiO2 Degussa P-25 and TiO2 rutile 0.1-0.2-µm size) and then to fractionate TiO2 particles, extracted from a commercial sunscreen lotion. All the TiO2 FlFFF separations were detected by UV but during elution fractions were collected and their Ti content measured by inductively coupled plasma-atomic emission spectrometer (ICPAES); the Ti concentration profiles obtained by ICP-AES were well correlated with the UV signals. The TiO2 particle mass-size distribution were calculated from the UV profiles. This methodology is relatively simple and rapid, and the sample treatment is as a whole easy and low cost. For several years now the rapidly developing field of nanotechnology has been capturing the attention of the scientific community. The dramatic increase in the use of engineered nanoparticles (ENPs) in various sectors of human life promises great benefits for society although there is also increasing concern that exposure to engineered nanomaterials may result in significant adverse effects for both man and the environment.1-4 Commercial ENPs join a class of particles that are
