Research and Development Division, Kikkoman Corporation, 399 Noda, Noda, Chiba 278-0037, Japan.
J Agric Food Chem. 2011 Sep 28;59(18):9770-5. doi: 10.1021/jf201736c. Epub 2011 Aug 31.
A method for the determination of 4(5)-methylimidazole (4MeI) in naturally brewed soy sauce was developed for the first time using solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). SPE on silica-based reversed-phase cartridges with heptafluorobutyric acid as an ion-pairing reagent was used for the efficient cleanup of 4MeI. A multimode ODS column was employed for the chromatographic separation. To subtract the matrix effect during LC-MS/MS analysis, a standard addition method was used. The levels of 4MeI found in naturally brewed soy sauce were extremely low (ranging from <0.002 to 0.023 μg/g), whereas those in soy sauces containing caramel color were generally high (ranging from 0.43 to 4.8 μg/g). The method proved to be useful for the analysis of 4MeI in other foods such as caramel colors, drinks, and Worcestershire sauce.
首次建立了固相萃取（SPE）-液相色谱-串联质谱（LC-MS/MS）法测定天然酿造酱油中 4（5）-甲基咪唑（4MeI）的方法。以硅胶基反相柱为 SPE 填料，庚氟丁酸为离子对试剂，可有效净化 4MeI。采用多模式 ODS 柱进行色谱分离。为了在 LC-MS/MS 分析中扣除基质效应，采用标准加入法。天然酿造酱油中 4MeI 的含量极低（<0.002 至 0.023 μg/g），而含有焦糖色素的酱油中 4MeI 的含量一般较高（0.43 至 4.8 μg/g）。该方法可用于其他食品如焦糖色素、饮料和伍斯特沙司中 4MeI 的分析。
