Evaluation of Uncertainty in the Determination of Moisturizing Efficacy of Cosmetics by Capacitance Method
This article evaluates the uncertainty of the difference in stratum corneum moisture content before and after applying cosmetics for 8 hours by analyzing and establishing a mathematical model.It mainly includes the random fluctuations in stratum corneum moisture content measurements before and after,unidentified systematic errors in testing and weighing instruments,the resolution of testing and weighing instruments,rounding errors in measurement results,and potential sources of uncertainty such as sample sampling volume,environmental temperature,and humidity.Finally,the combined standard uncertainty and expanded uncertainty are calculated.According to uncertainty propagation,considering the correlation of independent variables,and through validation of the assessment results,the determination of moisturizing efficacy in cosmetics should involve statistically measuring the difference in stratum corneum moisture content before and after sample application.Meanwhile,the formula for combined standard uncertainty should preferably utilize the difference between the standard uncertainties of moisture content measurements before and after testing.
万方数据
维普
