凝胶分散法用于TiO_2紫外屏蔽能力的测定

Gel dispersion method for determination of UV shielding capability of TiO_2

利用胶凝作用使颗粒均匀分散于凝胶介质,建立一种测定TiO_2紫外吸收的新方法。研究表明,质量分数为0.15%的卡波姆980凝胶可使锐钛型TiO_2在3 h内稳定分散。TiO_2在UVA和UVB波段无最大吸收,吸光度值随波长增大略有增大。吸光度的均值与其质量浓度在25～70 mg/L范围内线性关系良好,回归方程为A=0.009 7ρ+0.042 5,R^2=0.999,精密度高(RSD=0.20%～1.16%),准确度好(回收率为88.10%～110.3%,RSD=0.58%～1.24%)。该方法用于自制TiO_2防晒乳中TiO_2的质量浓度定量,相对误差<5%。研究结果可为颗粒型物质分光光度法定量测定提供方法借鉴。

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 TiO2disperse 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 TiO2sunscreen lotions, and the relative error is less than 5%. The research results can provide a reference for quantitative determination of granular materials by spectrophotometry.