Assessment of 4-(5-)methylimidazole in soft drinks and dark beer

A faster and more robust version of a previously developed method based on ion-pair extraction, acylation with isobutylchloroformate and gas chromatography-mass spectrometry (GC-MS) analysis for determination of 4-(5-)methylimidazole (4-MeI) in soft drinks and dark beer is proposed. The performance of the method was evaluated in terms of linearity (r always > 0.998); recovery (90-101%, 3 levels); and precision (3-8%, 3 levels, n = 6). Limits of detection and quantification in the matrices studied were 0.60 μg/L and 2.2 μg/L, respectively. The optimized method was applied to a wide variety of soft drinks (brand name and generic colas, uncarbonated flavor and energy drinks) and dark beers (lager, ales trappist, ales-stout, weissbier). Overall, soft drinks presented higher amounts of 4-MeI (ranging from 37 to 613 μg/L) than those found in the dark beers (ranging from 3 to 424 μg/L), with colas presenting the highest levels. When the different colas analyzed were compared, the 4-MeI levels in generic colas were generally higher than those in brand-name colas. 4-MeI was found in only one of eight energy drinks studied. Based on available consumption patterns, consumer exposure to the maximum 4-MeI given by the soft drinks was 2.3 and 5.7 μg/kg body weight/day, in Europe and the United States, respectively.