气相色谱–质谱法测定食用植物油中短链脂肪酸的测量不确定度评定

采用气相色谱–质谱法(GC–MS)测定食用植物油中短链脂肪酸含量,对测量结果的不确定度进行评定,探讨提高测量准确度的方法。依据方法建立数学模型,分析得出不确定度主要来源于样品制备过程、计量器具的使用、标准溶液配制、测量设备、人员读数误差、方法回收率,计算各不确定度分量,得到相对标准不确定度和扩展不确定度。结果表明,当食用植物油中短链脂肪酸测定结果为13.1 mg/kg时,其扩展不确定度为1.8 mg/kg(k=2)。测量设备、标准溶液配制过程引入的不确定度较大,应在实验过程中予以控制和关注。

Evaluation of uncertainty for determination of short-chain fatty acids in edible vegetable oils by gas chromatography–mass spectrometry

The measurement uncertainty of determination of short-chain fatty acids in edible vegetable oils by gas chromatography–mass spectrometry(GC–MS)was evaluated,and the method of improving measurement accuracy was discussed.Based on mathematical model,the uncertainty mainly come from the sample preparation process,the use of measuring instruments,standard solution preparation,measurement equipment,reading error,method of recovery.Through calculating the uncertainty component,the relative standard uncertainty and expanded uncertainty were obtained.The results showed that the uncertainty of expansion was 1.8 mg/kg(k=2)when the determination of short-chain fatty acids in edible vegetable oils was 13.1 mg/kg.The preparation of standard solution and measuring equipment should be controlled and focus since they have significant influence on the result of uncertainty evaluation.