乳粉中磷含量检测的不确定度比较

Comparison of uncertainty in detection of phosphorus content in milk powder

目的为提高乳粉中磷检测结果的准确性。方法对干法消化和湿法消化两种方法的不确定度进行评定和比较。结果采用干法消化后测得样品磷含量为488 mg/100 g,其不确定度结果为30.0 mg/100 g,采用湿法消化后测得磷含量为495 mg/100 g,其不确定度结果为33.4 mg/100 g。结论2种检测方法对结果的准确性影响上是一致的。样品称量、标准溶液配制和样液定容体积带入的相对标准不确定度可忽略不计,标准溶液的配制及分光光度法的稳定性及样品回收率是检测结果准确与否的关键所在。

Objective To improve the accuracy of phosphorus in milk powder.Methods The uncertainty of dry digestion and wet digestion were evaluated and compared.Results The uncertainty was 30.0 mg/100 g when the phosphorus content of the sample was 488 mg/100 g after dry digestion.The uncertainty was 33.4 mg/100 g when the phosphorus content was 495 mg/100 g after wet digestion.Conclusion Two test methods have the same effect on the accuracy of the results.The relative standard uncertainty of sample weighing,preparation of standard solution and constant volume of sample solution can be ignored.The preparation of standard solution,the stability of spectrophotometry and the recovery of samples are the key to the accuracy of test results.