气相色谱-串联质谱法测定食用植物油中邻苯二甲酸二正丁酯和邻苯二甲酸二(2-乙基)己酯的不确定度评定

Uncertainty evaluation of determination of dibutyl phthalate and bis(2-ethyl) hexyl phthalate in edible vegetable oil by gas chromatography-mass spectrometry

目的评定气相色谱-质谱法测定食用植物油中邻苯二甲酸二正丁酯和邻苯二甲酸二(2-乙基)己酯含量的不确定度。方法样品由正己烷、乙腈超声提取,提取液由固相萃取柱净进化,采用Rtx-5MS石英毛细管柱,程序升温,流速为1.0 mL/min;进样量1μL。依据JJF 1059-2012《测量不确定度评定与表示》,建立不确定度评定的数学模型,分析在检测过程中不确定度的主要影响因素。结果在95%的置信区间下,当邻苯二甲酸二正丁酯为1.2mg/kg,扩展不确定度为0.06mg/kg(k=2);当邻苯二甲酸二(2-乙基)己酯为1.1mg/kg,扩展不确定度为0.04 mg/kg (k=2)。实验过程中不确定度主要来源于测定重复性和标准曲线的拟合。结论该方法准确可靠,适用于气相色谱-串联质谱法测定食用植物油中邻苯二甲酸二正丁酯和邻苯二甲酸二(2-乙基)己酯的不确定度评定,对检测结果准确度的提高与有一定的指导意义。

Objective To evaluate the uncertainty of determination of dibutyl phthalate and diethyl phthalate （2-ethyl） hexyl ester in edible vegetable oils by gas chromatography-mass spectrometry. Methods The samples were extracted by n-hexane and acetonitrile ultrasound, and the extract fluid was purified by solid-phase extraction column. The samples were separated with Rtx-S5MS quartz capillary column by programmed temperature, with the flow rate of 1.0 mL/min, and the sample injection amount was 1 μL. According to JJF 1059.1-2012 Measurement uncertainty evaluation and presentation, the mathematical model of uncertainty evaluation was established, and the main factors influencing the uncertainty during the test were analyzed. Results When the content of dibutyl phthalate and dibutyl phthalate （2-ethyl） hexyl ester was 1.2 and 1.1 mg/kg, respectively, the extended uncertainties were 0.06 and 0.04 mg/kg （k=2） under the 95% confidence interval. The uncertainties of the experiment were mainly derived from measurement repeatability and the fitting of standard curve. Conclusion This evaluation method is accurate and reliable, which is suitable for the evaluation of uncertainty of determination of dibutyl phthalate and diethyl phthalate （2-ethyl） hexyl ester in edible vegetable oils by gas chromatography- mass spectrometry. It is instructive to improve the accuracy of test results.