液态乳中氯丙二醇脂肪酸酯的检测与污染水平初步调查

采用固相支持液-液萃取净化，结合同位素稀释的气相色谱-质谱联用（gas chromatography-massspectrometry，GC-MS）技术建立液态乳中氯丙二醇脂肪酸酯（单氯丙醇酯）的检测方法。液态乳样品经正己烷超声提取，以甲醇钠-甲醇溶液进行酯键断裂反应后，用硅藻土小柱进行净化，经七氟丁酰基咪唑衍生，以GC-MS测定。3-氯-1,2-丙二醇脂肪酸（3-monochloropropane-1,2-diol，3-MCPD）酯和2-氯-1,3-丙二醇脂肪酸（2-monochloropropane-1,3-diol，2-MCPD）酯含量在5～500 μg/L之间均呈良好线性关系，相关系数（r）大于0.999 5，检出限均为2.0 μg/kg。空白样品中3-MCPD酯和2-MCPD酯在10、50、100 μg/kg和200 μg/kg水平的加标回收率在73.5%～106.6%之间，相对标准偏差均小于10%。本方法灵敏度高，定量准确，适合液态乳中氯丙二醇脂肪酸酯的检测。采用建立的方法测定了30 份牛乳样品，3-MCPD酯和2-MCPD酯的含量在未检出～13.8 μg/kg之间，污染水平较低。初步暴露评估结果显示，牛乳中的氯丙醇酯对人体产生的健康风险较低。

Determination and Occurrence of Fatty Acid Esters of Chloropropanediols in Milk

A method for the determination of fatty acid esters of chloropropanediols in milk samples by gas chromatographymass
spectrometry (GC-MS) was established. The milk samples were ultrasonically extracted with hexane, followed by
transesterification with sodium methylate/methanol, and purified by matrix solid-supported liquid-liquid extraction (SLE).
After being derivatized with heptafluoro butyrylimidazole (HFBI), fatty acid esters of 3-monochloropropane-1,2-diol
(3-MCPD esters) and 2-monochloropropane-1,3-diol (2-MCPD esters) were determined using GC-MS. The target
compounds were separated on a HP-5 capillary chromatographic column, and the tandem mass spectrograph was operated
in the selected ion-monitoring mode (SIM). An excellent linear correlation in the range of 5–500 μg/L was acquired for both
3-MCPD esters and 2-MCPD esters with coefficient correlations higher than 0.999 5. The limits of detection (LODs) for
both 3-MCPD esters and 2-MCPD esters were 2.0 μg/kg. The recoveries of the 3-MCPD esters and 2-MCPD esters spiked in the blank
milk at levels of 10, 50, 100 and 200 μg/kg were all in the range of 73.5%–106.6%, with relative standard deviations (RSDs) less than
10%. The method was found to be suitable for the determination of 3-MCPD esters and 2-MCPD esters in milk samples. A total of
30 milk samples were analyzed using this method, and the concentrations of 3-MCPD esters and 2-MCPD esters were determined to
be relatively low, ranging from undetectable levels to 13.8 μg/kg. According to the estimated exposure assessment results, there was
relatively low health risk associated with the intake of 3-MCPD esters and 2-MCPD esters from the milk for the general Chines epopulation.