化妆品中二氧化钛含量测定的不确定度评定

Uncertainty evaluation for the spectrophotometric determination of titanium dioxide in cosmetics

分析评定分光光度法测定化妆品中二氧化钛含量的不确定度。建立数学评价模型,对测定过程的主要不确定度进行了合理的评定,主要包括样品称样量、定容体积、样品溶液浓度、稀释倍数、回收率以及重复测量6个方面,最后计算合成标准不确定度及扩展不确定度。结果表明,样品的测量结果为(9.530±0.30)%(k=2),主要的不确定度来自样品溶液浓度、重复测量、稀释倍数以及回收率,称样量和定容体积的影响较小。

The uncertainty in the spectrophotometric determination of titanium dioxide in cosmetics was analyzed and evaluated. The mathematical model was created, the main uncertainty during the determina- tion process was reasonably evaluated, including sample weighting, sample constant volume, concentration of sample solution, dilution ratio, recovery and repeatability, the combined standard uncertainty and expanded uncertainty were calculated. The results showed that the sample result was （9.53 ± 0.30） % （ k = 2）. The uncertainty of components of concentration of sample solution, repeatability, dilution ratio and recovery are the main sources of uncertainty, while those of sample weighting, sample constant volume account for little proportion.