食用油中多不饱和脂肪酸的含量及其不确定度的评定

Determination of the content of polyunsaturated fatty acid in edible oil and evaluation of its uncertainty

目的建立紫外分光光度法测定食用油中多不饱和脂肪酸含量和不确定度的数学模型。方法根据JJF1059.1-2012《测量不确定度评定与表示》,分析测量不确定度分量的主要来源,对各不确定度分量进行评定和计算。结果食用油中多不饱和脂肪酸含量在1~10μg/m L范围内与吸光度呈良好的线性关系,线性方程为Y=73.966X+0.006,相关系数为0.9998。当食用油中多不饱和脂肪酸为56.12%时,其测量结果的扩展不确定度U=1.84%,(k=2)。根据测量结果分析,不确定度的主要来源为重复性测量、标准溶液配制过程和标准曲线拟合等过程。结论该研究可为实验室评定食用油中多不饱和脂肪酸的测定结果质量提供参考。

Objective To established an ultraviolet-spectrophotometry method for determination of the content of polyunsaturated fatty acid in edible oil, and a mathematical model of the uncertainty.Method Based on JJF1059.1-2012 “Evaluation and expression of uncertainty in measurement”, the main source of uncertainty were analyzed, and the uncertainty components were evaluated and calculated.Result The results showed that the linear range of polyunsaturated fatty acid in edible oil was 1~10 mg/mL, the linear equation wasY=73.966X+0.006 (r=0.9998), and the expanded uncertainty was 1.84% (k=2) when the content of polyunsaturated fatty acid was 56.12% in edible oil. According to analysis of measurement, the main sources of uncertainty were repetitive measurement, dispensing process of standard solution and the fitting of the standard curve.ConclusionThis method can provide reference to evaluate quality of polyunsaturated fatty acid in edible oil.