Simultaneous Analysis of 2- and 4-Methylimidazole in Caramel Color and Soft Drinks Using IC-PAD with Post-Column Addition of Hydroxide

High-performance cation exchange chromatography with pulsed integrated amperometric electrochemical detector (HPCEC-PAD) with post-column addition of hydroxide was first developed for simultaneous analysis of 4-methylimidazole (4-MeI) and 2-methylimidazole (2-MeI) in caramel color and soft drinks after solid-phase extraction (SPE). A CS12A cation exchange column was used to separate the targeted analytes with a perfect resolution (2.70). This method demonstrated low limit of quantification (0.05–10 mg/L) and excellent linearity with correlation of determination (R2 > 0.999 for 2-MeI and 0.997 for 4-MeI). Low concentrations of 4-MeI were found in five soft drinks, whereas those in caramel color were generally high. Additionally, the suggested method showed higher resolution and sensitivity comparing with previous reported methods for 4-MeI and 2-MeI analyses.