麻油中皂化值的测量不确定度评定

Evaluation of measurement uncertainty of the saponification value in sesame oil

中文关键词:  麻油  皂化值  不确定度

英文关键词:sesame oil  saponification value  uncertainty

中文摘要:

      目的 评定麻油中皂化值的测量不确定度, 如实反映检测的置信度和准确性。方法 采用2015年版四部通则(0713)《中国药典 脂肪与脂肪油测定法 皂化值》检测麻油中的皂化值, 并根据JJF 1059.1-2012《测量不确定度评定与表示》中的规定, 分析影响不确定度的主要影响因素, 找出不确定度分量, 进行测量不确定度评定。结果 由不确定度的评定可知, 对实验结果最主要的影响因素为麻油及空白样品消耗盐酸滴定液的体积; 其次为实验重复性。盐酸滴定液的浓度及麻油称样量对实验结果影响相对较小, 氢氧化钾摩尔质量对实验结果的影响可忽略不计。本实验测得麻油中皂化值为(192.2±2.4) mg/g (置信概率p=95%, 包含因子k=2)。结论 在实验时要提高滴定管读数的准确性并且要注意环境温度, 尽量减少由这些因素导致的不确定度。

英文摘要:

      Objective To evaluate the measurement uncertainty of the saponification value in sesame oil, which can faithfully reflect the metrical credibility and accuracy. Methods According to the Pharmacopoeia of people's republic of China 2015 Edition Vol Ⅳ General rule(0713) fats and fatty oils determination-saponification value, saponification value in sesame oil was tested. The main influence factors of uncertainty were analyzed according to JJF 1059.1-2012 evaluation and expression of uncertainty in measurement in order to find out the uncertainty components and evaluate the measurement uncertainty. Results According to the evaluation of uncertainty, the most important factors affecting the experimental results were the volume of hydrochloric acid solution consumed by sesame oil and blank samples. The second was the repeatability of the experiment. The concentration of hydrochloric acid solution and the amount of sesame oil samples had little influence on the experimental results. The influence of the molar mass of potassium hydroxide on the experimental results was negligible. In this experiment, the saponification value in sesame oil was(192.2±2.4)mg/g (probability level p=95%, coverage factor k=2). Conclusion The accuracy of the burette readings should be improved and environmental temperature should be paid attention in the experiment, as far as possible to reduce the uncertainty caused by these factors.