Abstract:

A new method for determining UV absorption of TiO₂ was established by using gelation to uniformly disperse particles in a gel medium. The results show that 0.15% Carbomer 980 gel can make anatase TiO₂ disperse stably within 3 hours. TiO₂ has no maximum absorption in the UVA and the UVB bands, and the absorbance value slightly increases with increasing wavelength. The mean absorbance has a good linear relationship with its mass concentration within 25-70 mg/L range, and the regression equation is A=0.009 7ρ+0.042 5, with R ²=0.999, and the precision is high（RSDs=0.20%-1.16%）and the accuracy is good（recoveries 88.10%-110.3%, RSD=0.58%-1.24%）. The method was applied to quantify the mass concentration of TiO₂ in self-made TiO₂ sunscreen lotions, and the relative error is less than 5%. The research results can provide a reference for quantitative determination of granular materials by spectrophotometry.

Key words: gel, anatase TiO₂, UV absorbance, sunscreen, cosmetic