凯氏定氮法测定大米中蛋白质含量的不确定度评定

Evaluation of Uncertainty for Determination of Protein Content in Rice by Kieldahl Method

本文分析了凯氏定氮法测定大米中蛋白质含量的测量不确定度,其测量不确定度来源于样品称量、消化、定容、移取消化液、稀释标准溶液、蒸馏及滴定等过程。结果表明,大米中蛋白质含量(以氮计)为(1.606±0.020)%,k=2,测量结果的不确定度主要来源于滴定时硫酸溶液的浓度和滴定用硫酸溶液的体积。

In this article,the uncertainty for determination of protein content in rice by kieldahl method was analyzed.The measurement uncertainty was tracked from such experimental processes as sample weighing,digestion ,volume ,pipet digestion ,dilution of standard solution, distillation and titration ete.The results showed that the protein content in rice （in nitrogen ） was （1.606±0.020）%, k =2, and the uncertainty was mainly tracked from the concentration and volume of sulfuric acid solution for titration.