苦丁茶中总黄酮含量测定的不确定度评定

目的]为苦丁茶的综合利用与深度开发提供了科学依据。方法]采用紫外分光光度法测定苦丁茶叶中的总黄酮含量,运用测量不确定度评定的基本方法和程序,分析影响不确定度的各种因素,建立数学模型,合成计算总黄酮含量的不确定度。结果]通过分析及计算样品称量质量、样品定容体积(25、100ml容量瓶)、标准溶液配制、仪器读数的标准4个B类不确定度和回归方程y=a+bx中y残差的标准、样品测量重复性2个A类不确定度,最后合成苦丁茶中总黄酮含量的不确定度。苦丁茶中总黄酮含量的不确定度为ω=2.26%±0.15%,包含因子K95=2.06。样品质量及定容体积对不确定度的影响可以忽略不计。结论]标准溶液的配制、标准曲线的拟合及样品的重复性测定是苦丁茶中总黄酮含量不确定度的主要来源。

Uncertainty Evaluation on the Determination of Total Flavone Content in Kuding Tea

Objective The research aimed to provide scientific basis for the comprehensive utilization and further development of Kuding tea.Method The total flavone content in the leaves of Kuding tea were determined by ultraviolet spectrophotometry.By using the basic method and process of evaluating the determination uncertainty,each factor that affected the uncertainty was analyzed,the mathematical model was established and the uncertainty of determining total flavone content was synthetically calculated.Result Based on analyzing and calculating 4 B-type uncertainties of the weighted quality of sample,the constant volumes of sample(25,100 ml volumetric flasks),the preparation of standard solution,the standard of instrument readings and 2 A-type uncertainties of the standard of y residual error in the regression equitation y=a+bx and the determination repeatability of sample,the uncertainty of total flavone content in Kuding tea was finally synthesized.The uncertainty of total flavone content in Kuding tea was 2.26 % ±0.15 % with coverage factor K95 of 2.06.The effects of sample quality and constant volumes on the uncertainty could be neglected.Conclusion The preparation of standard solution,the fitting of standard curve and repeatability determination of sample were main sources of the uncertainty of total flavone content in Kuding tea.