选择离子气质联用法同时测定食醋中2-甲基咪唑和4-甲基咪唑

Determination of 2-methylimidazole and 4-methylimidazole in vinegar by gas chromatography/selected ion mass spectrometry

建立了选择离子气／质联用法同时测定食醋中2-甲基咪唑和4-甲基咪唑的新方法。对色谱条件进行了筛选优化。样品经碱处理，硅藻土吸附，二氯甲烷洗脱，合并洗脱液并浓缩，以N-甲基甲酰苯胺为内标物，用二氯甲烷定容至10mL容量瓶后进行气／质联用测定。结果表明，2-甲基咪唑和4-甲基咪唑均在0-15．2mg／L范围内呈良好线性关系，其相关系数分别为0．9997和0．9996；相对标准偏差分别为3．0％和3．1％；2-甲基咪唑和4-甲基咪唑的平均回收率分别为101．3％和99．3％。使用该法对市售食醋中2-甲基咪唑和4-甲基咪唑的含量进行了同时测定，结果较优。

The method of the determination of 2-methylimidazole and 4-methylimidazole in vinegar by selected ion GC-MS was established. The chromatographic conditions were selected and optimized. The sample were first alkalized,purified by kieselguhr,eluted with dichloromethane. The eluate was combined and concentrated, then with N-methyl-formanilide as internal standard,volumed to the 10mL volumetric flask with dichloromethane, then determinated by GC. The results showed that the concentration of 2-methylimidazole and 4- methylimidazole both in the range of 0~15.2mg/L had good linear relationship. The correlation coefficients respectively were 0.9997 and 0.9996~the relative standard deviation were respectively 3.0% and 3.1%. The average recoveries of 2-methylimidazole and 4-methylimidazole were 101.3% and 99.3%. This method was used to determine 2-methylimidazole and 4-methylimidazole in commercial vinegar,and the satisfactory results was achieved.