全自动电位滴定法测定菜籽油过氧化值的不确定度评定

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

建立全自动电位滴定法测定菜籽油过氧化值的不确定度分析评价方法。以GB 5009.227—2016的第二法自动电位滴定法为研究对象,建立数学模型,分析该方法测量不确定度的主要来源并对其进行评定。结果表明,标准溶液的标定和稀释、样品称量、样品的重复测定、电位滴定的定量重复性4个因素影响全自动电位滴定法测定菜籽油中过氧化值的检测结果,其中样品的重复测定是最主要的因素。当样品的过氧化值为3.59 mmol/kg时,扩展不确定度为0.0832 mmol/kg(k=2)。

The uncertainty in the determination of peroxide value in edible vegetable oil by automatic otentiometric titration was studied.The whole process of determination of peroxide value residues was analyzed based on the standard method of the second method of GB 5009.227—2016.The uncertainty of the detection method was evaluated from four aspects:sample weighting,the configuration of standard solution,repeatability of measurement and the quantitative repeatability of potentiometric titration.The results showed,the peroxide value of edible vegetable oil was 3.59 mmol/kg.The related expand uncertainty of peroxide value in edible vegetable oil was 0.0832 mmol/kg,the confidence factor k=2.The main factors influencing the uncertainty of the test results of peroxide value was repeatability of measurement.This paper provides a reference for objective analysis of the reliability of multi-component pesticide residue detection results in vegetables.