同位素稀释-气相色谱-质谱法测定面包中3-氯-1,2-丙二醇脂肪酸酯

采用同位素稀释的气相色谱-质谱(GC-MS)联用技术,建立了面包中3-氯-1,2-丙二醇脂肪酸酯(3-MCPD酯)的检测方法.样品经正己烷超声提取后用甲醇钠/甲醇水解,硅藻土小柱净化,提取液经七氟丁酰咪唑(HFBI)衍生后注入GC-MS测定.目标化合物经弱极性的气相毛细管色谱柱分离,采用选择离子监测模式(SIM)监测,以同位素内标进行定量.3-MCPD酯在0.025~1.600 mg/L范围内均呈良好的线性关系,相关系数(r)为0.9999,其在面包中的检出限(LOD)低至10μg/kg.以空白面包样品进行加标水平为40、100、160和240μg/kg的加标回收实验,回收率在78.9%~117.0%之间,相对标准偏差(RSD)为2.1%~4.9%,说明该方法的精密度和准确度均良好.本方法灵敏度高、定性准确,适合于面包中3-MCPD酯的检测.

Determination of 3-chloropropane-l,2-diol esters in bread products by isotope dilution-GC-MS

A method was established to detect 3-chloropropane-l,2-diol esters in bread products by gas chromatography-mass spectrometry （GC-MS）. The bakery products were ultrasonically extracted with hexane, followed by transesterification with sodium methylate/methanol, and then passed through matrix solid-supported liquid-liquid extraction （SLE） for purification. After derivatization with heptafluoro butyrylimidazole （HFBI）, 3-MCPD was 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）. There was an excellent linear correlation （r = 0.9999） between the ratio of the 3-MCPD to the internal standard and the mass in the range of 0.025-1.600 mg/L of 3-MCPD esters （calculated as 3-MCPD）. The limit of detection of 3-MCPD esters in bread products was 10 ~tg/kg. The recoveries of the 3-MCPD esters were in the range of 82.9%-113.7% at the spike levels of 40, 100, 160 and 240 ~tg/kg into blank bread products matrix, and the relative standard deviations （RSDs） were 2.1%-4.9%. The method is sensitive and accurate, which could be suitable for the determination of 3-MCPD esters in bread products.