Determination of TiO2 nanoparticles in sunscreen using N-doped graphene quantum dots as a fluorescent probe

The article describes a method for the determination of titanium oxide nanoparticles (TiO(2)NPs) in sunscreens using N-doped graphene quantum dots (N-GQDs). The TiO2-NPs are first extracted from the highly lipophilic sunscreen via liquid-liquid extraction. Subsequent fluorimetric analysis of the extracts is based on the quenching effect exerted by TiO(2)NPs on the fluorescence of N-GQDs. The effect is assumed to be due to an electrostatic interaction and/or hydrogen bonding between the particles. The limit of detection for TiO(2)NPs is 1.4 mu ga <...gaEuro3/4(1). The precision at a 5 mu ga <...gaEuro3/4(1) concentration of TiO(2)NPs is 6.95 %. The optimized procedure was successively applied to the determination of TiO2 NPs in sunscreens with different sun protection factors.