title: Determination of 2-Methylimidazole, 4-Methylimidazole, and 2-Acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole in Licorice Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry Stable-Isotope Dilution Analysis.
abstract: A quick and selective analytical method was developed for the simultaneous quantitation of 2-methylimidazole, 4-methylimidazole, and 2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole, which are known to be formed by Maillard reactions. The methodology reported here employs stable-isotope dilution analysis (SIDA) using 4-methylimidazole-d6 and [(13)C6]-2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole as internal standards. It was successfully applied in a model assay to show that the addition of ammonium chloride during the manufacture of licorice promotes imidazole formation depending on the added amount of ammonium chloride without the well-known impact of present caramel food colorings. Furthermore, a monitoring assay of 29 caramel coloring-free licorice products showed that both 4-methylimidazole and 2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole are endogenously generated in detectable quantities. None of the samples showed 2-methylimidazole levels above the limit of detection, 50 μg/kg.
authors.affiliation: †Food Chemistry Institute of the Association of the German Confectionery Industry, Adamsstraße 52-54, D-51063 Köln, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Raters
authors.affiliation: §ELFI Analytik GbR, Massenhausener Strasse 18a, D-85375 Neufahrn, Germany.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Elsinghorst
authors.affiliation: †Food Chemistry Institute of the Association of the German Confectionery Industry, Adamsstraße 52-54, D-51063 Köln, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Goetze
authors.affiliation: †Food Chemistry Institute of the Association of the German Confectionery Industry, Adamsstraße 52-54, D-51063 Köln, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Dingel
authors.affiliation: †Food Chemistry Institute of the Association of the German Confectionery Industry, Adamsstraße 52-54, D-51063 Köln, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Matissek
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006035:Glycyrrhiza / Q000737:chemistry*; D007093:Imidazoles / Q000032:analysis*; D010936:Plant Extracts / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D007093:Imidazoles; D010936:Plant Extracts; C029899:imidazole; C023439:4-methylimidazole; C032655:2-methylimidazole
keywords: 2-acetyl-4-(1,2,3,4-tetrahydroxybutyl)imidazole; LC-MS/MS; SIDA; licorice; methylimidazole