Postnova Analytics has published a new application note that describes a new approach for analysis of titanium dioxide nanoparticles in commercial sunscreens.
The technique, which combines Inverse Supercritical Fluid Extraction (I-SFE) and Miniaturized Asymmetrical Flow Field-Flow Fractionation hyphenated with UV-Vis and MultiAngle Light Scattering (mAF4-UV-MALS) represents a promising tool for the verification of the nano-labelling of such products.
Due to the complexity of commercial sunscreen formulations, the determination of their nanoparticle content is usually very challenging and requires a tedious sample preparation step including the application of potentially hazardous organic chemicals.
The authors report on how 5 different commercial sunscreens were investigated for their nanoparticle content using I-SFE followed by mAF4-UV-MALS analysis. Nanoparticulate titanium dioxide identified via ICP-MS was found in three sunscreens which was in agreement with the nano-labelling in the respective ingredients lists.
The particle size distribution determined via MALS revealed particle sizes ranging from 50 nm to approximately 450 nm in diameter of gyration for all three samples. For the 2 sunscreens that were not nano-labeled, no nanoparticles were detectable
Combining i-SFE with mAF4-UV-MALS
This research demonstrates that the combination of i-SFE with mAF4-UV-MALS provides a powerful and efficient tool for the verification of the nanoparticle content of commercial sunscreens.
Due to its robustness and wide applicability, this setup is not limited to the analysis of sunscreens but may also be a helpful tool for the investigation of nanoparticle-containing cosmetics in general.