费休氏水分测定法的不确定度评定

Estimation of uncertainty on moisture determination by Karl Fischer's method

目的:对药品检验中的费休氏水分测定法的不确定度进行评定。方法:根据对药品水分测定的标准操作规范(Chinesestandard operating procedure for drug analysis,SOP),建立评价水分测定不确定度的计算模型,对水分测定中的各影响因素进行了考察。结果:分别计算各分量的不确定度,再计算出合成不确定度,并取 k=2(置信概率95%)得出扩展不确定度。结论:滴定的水分量越小,结果的偏差越大;实验中被测样品中的含水量至少在10mg 以上,才能得到可靠的结果。

Objective：To estimation of uncertainty on moisture determination by Karl Fischer＇s method. Method： The model for evaluation of the uncertainty was established based on the Chinese standard operating procedure for drug analysis（SOP） procedure of moisture determination. The factors influenced upon the mensuration were analysed and the uncertainty, of each the effects was calculated Result： The combined uncertainty was obtained by combining all standard uncertainty, then the expanded uncertainty was calculated by using a coverage factor K = 2 （gives a level of confidence of approximately 95% ）. Conclusion ：The less moisture content of the sample contains, the more deviation the determination method produce. A reliable result could be obtained only when the moisture content is not less than 10 mg in once determination.