Determination of 4-Methylimidazole in Ammonia Caramel Using Gas Chromatography–Tandem Mass Spectrometry (GC-MS/MS)

Martyna N Wieczorek,Henryk H Jeleń,Krzysztof Przygoński

doi:10.1155/2018/4696074

Abstract

One of Maillard reaction products formed in the production of ammonia caramel is 4(5)-methylimidazole (4-MeI) classified as carcinogen. A method of 4-MeI determination based on ion-pair extraction and derivatisation with isobutyl chloroformate with subsequent gas chromatography-tandem mass spectrometry analysis was proposed. Tandem mass spectrometry was applied to reduce the influence of matrix and increase the selectivity and sensitivity of the method. Triple quadrupole GC-MS system was used for this study. The collision energies were optimized for MRM mode. The detection (LOD) and quantification limits (LOQ) of the elaborated method were 17 and 37.8 μg kg−1, respectively, repeatability was <15% RSD for analyzed caramel samples, and the recovery for 4-MeI was 101%. Comparison of MS/MS with SIM detection on the same instrument proved almost 30 times lower LODs achieved by tandem mass spectrometry compared to SIM. Described method can be routinely used for monitoring 4-MeI as a quality and safety marker in the production of ammonia caramel.

Highlights

Caramel is one of the worldwide most popular food colorants, labeled with the symbols E150a: caustic caramel, E150b: caustic sulfite caramel, E150c: ammonia caramel, and E150d: sulfite ammonia caramel
In the present work the GC-MS/MS method was chosen to compensate for the complex matrix of Maillard reaction products that are formed in caramel production process
The intensity of m/z formed from fragmentation of m/z 182 was monitored in product ions mode using different collision induced dissociation (CID) energies in a range of 5–50 V. 10 V was chosen for subsequent analyses as minimal abundance was obtained of ion m/z 182 with highly abundant product—m/z 82

Summary

Introduction

Caramel is one of the worldwide most popular food colorants, labeled with the symbols E150a: caustic caramel, E150b: caustic sulfite caramel, E150c: ammonia caramel, and E150d: sulfite ammonia caramel. It is added for variety of foods and beverages, such as sauces, wines, beers, desserts, confectionary products, cola beverages, and baked goods [1]. At neutral to basic pH solutions there are two tautomers: 4methylimidazole and 5-methylimidazole exist in equilibrium [2]. Methylglyoxal was proposed as the starting precursor in 4-MeI formation (Figure 1). The level of 4-MeI, which is deemed to pose no significant risk, is 29 μg/day [2]

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