自动电位滴定法测定食用植物油过氧化值、酸值的不确定度评定

利用自动电位滴定方法对食用植物油中过氧化值和酸值进行测定,通过建立不确定度数学模型,分析和计算试验过程中影响过氧化值和酸值测量结果的不确定度分量和扩展不确定度。测试结果表明:食用植物油的过氧化值平均值为1.22 mmol/L,酸值平均值为1.43 mg/g,其过氧化值项目扩展不确定度为0.016 mmol/L,酸值扩展不确定度为0.044 mg/g,置信因子k=2,测量重复性是影响过氧化值和酸值实验结果不确定度的主要因素。

Evaluation of Uncertainty in Determination of Peroxide Value and Acid Value of Edible Vegetable Oil by Automatic Potentiometric Titration

The peroxide value and acid value in edible vegetable oil were determined by automatic potentiometric titration. Through the establishment of uncertainty mathematical model, the uncertainty components and expanded uncertainty affecting the peroxide value and acid value measurement results were analyzed and calculated. The test results showed that the average peroxide value of the edible vegetable oil was 1.22 mmol/l, the average acid value was 1.43 mg/g, the expanded uncertainty of peroxide value was 0.016 mmol/l, the expanded uncertainty of acid value was 0.044 mg/g, the confidence factor k = 2, and the repeatability of measurement was the main factor affecting the uncertainty of the test results of peroxide value and acid value.