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

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0¹5.2mg/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。 

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

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.