Characterizing titanium dioxide and zinc oxide nanoparticles in sunscreen spray

Abstract

Objective: Numerous commercial products contain titanium dioxide (TiO2 ) and zinc oxide (ZnO) nanoparticles (NPs); however, many of these are not labelled as containing NPs. This study sought to develop an effective means of characterizing TiO2 and ZnO NPs in sunscreen sprays, including the size, shape and composition of the particles as well as their aggregation/agglomeration characteristics.

Methods: Transmission electron microscopy (TEM) coupled with a window-type microchip K-kit/copper grid and X-ray diffraction (XRD) was used to characterize the oxide NPs.

Results: TME pre-treatment was performed using two approaches: using a conventional copper grid (requiring dilution) and using a K-kit (not requiring dilution). The use of K-kit in conjunction with XRD makes it possible to obtain direct measurements from samples that have not undergone pre-treatment, which could otherwise alter the nature of the samples, such as the degree of agglomeration. XRD was used to obtain information related to particle size and crystal structure. A strong correlation was observed between XRD and TEM measurements.

Conclusion: The proposed measurement methods were shown to be highly effective in the characterization of oxide NPs in sunscreen sprays, providing consistent information related to NPs and their interactions in the formulations.

Keywords: chemical analysis; claim substantiation; formulation; sunscreen spray; titanium dioxide; zinc oxide.