气相色谱-质谱法测定食用植物油中氯丙醇酯的含量方法验证研究

目的建立一种同时测定食用植物油中3-氯-1,2-丙二醇脂肪酸酯(3-MCPD酯)、2-氯-1,3-丙二醇脂肪酸酯(2-MCPD酯)、1,3-二氯-2-丙醇脂肪酸酯(1,3-DCP酯)和2,3-二氯-1-丙醇脂肪酸酯(2,3-DCP酯)含量的气相色谱-质谱(GC-MS)方法。方法植物油样品经叔丁基甲基醚-乙酸乙酯溶液(8∶2,V/V)溶解,在甲醇钠-甲醇溶液中发生酯键断裂反应,用冰乙酸中和正己烷去脂,经硅藻土小柱净化,七氟丁酰基咪唑(HFBI)衍生,以GC-MS法测定,采用同位素内标进行定量。结果经5家检验机构验证,4种氯丙醇酯(以对应的氯丙醇计)在0.02~0.4 mg/L范围内线性良好,相关系数r~2均大于0.999,在0.2~2.0 mg/kg水平的加标回收率在78.5%~109.8%之间,RSD为2.2%~18.8%,检出限均为0.1 mg/kg。结论 2014年英国FAPAS分析实验室能力验证和5家机构协同验证的结果证实,该方法线性良好,准确度、精密度高,检测成本较低,适用于食用植物油中氯丙醇酯的检测。

Development and validation of a method for the determination of total fatty acid esters of chloropropanols in edible vegetable oils by gas chromatography-mass spectrometry

To establish a method for the simultaneous determination of total fatty acid esters of 4 chloropropanols including 3-monochloropropane-1,2-diol (3-MCPD esters), 2-monochloropropane-1,3-diol (2-MCPD esters), 1,3-dichloropropan-2-ol (1,3-DCP esters) and 2,3-dichloropropan-1-ol (2,3-DCP esters) in edible vegetable oils by gas chromatography-mass spectrometry (GC-MS).Methods The edible vegetable oil samples were dissolved in tert-butyl methyl ether/acetic ether, followed by ester cleavage reaction using sodium methylate/methanol as the reagent. The solution was neutralized with acetic acid and cleaned up with hexane, then purified by matrix solid-supported liquid-liquid extraction using diatomaceous earth as the sorbent. After being derivatized with heptafluoro butyrylimidazole (HFBI), the analytes were detected by GC-MS and quantified by the multi-isotopic internal standards. Results Validated by five inspection and research institutes, a good linear relationship between peak area and concentrations was obtained within the range of 0.02-0.4 mg/L with correlation coefficients(r²) above 0.999 for 4 kinds of chloropropanols esters(calculated as dissociated chloropropanols). Recoveries ranged from 78.5% to 109.8% at spiked levels ranging from 0.2 to 2 mg/kg, and the relative standard deviations (RSDs) were in the range of 2.2%-18.8%. The limits of detection were 0.1 mg/kg for all the chloropropanols esters.Conclusion The collaborative validate test results validated by five inspection and research institutes and proficiency test results of the official Food Analysis Performance Assessment Scheme (FAPAS) indicated that the method presented a good linear relationship, and is low-cost, accurate and sensitive, suitable for the determination of total fatty acid esters of chloropropanols in edible vegetable oils.