title: Determination of 4(5)-methylimidazole in carbonated beverages by isotope-dilution liquid chromatography-tandem mass spectrometry.
abstract: The purpose of this study was to develop a method to quantify 4(5)-methylimidazole (4-MEI), a suspected carcinogen, in carbonated beverages by simple sample dilution and isotope-dilution reverse-phase LC-MS/MS. Isotope dilution using hexa-deuterated methylimidazole (d6-4-MEI) was used to quantify native 4-MEI and to assess matrix effects quantitatively. The accuracy of the method was assessed by intentionally fortifying a negative control sample at three doses: low, medium and high (replicates of n = 5 each) with a known amount of 4-MEI. The respective absolute error in each case was 18.7 ± 0.7%, 14.6 ± 2.8% and 21.1 ± 9.7%. Within-day (intra-) and day-to-day (inter-) repeatability, determined as the relative standard deviation by fortifying a negative control sample (n = 5), were 9.5% and 15.4%, respectively. Average ion suppression of d6-4-MEI in beer was 63.9 ± 3.2%, while no suppression or enhancement was seen in non-alcoholic samples. The instrument and method limit of detection were calculated as 0.6 and 5.8 ng ml(-1), respectively. 4(5)-Methylimidazole was quantified in a variety of store-bought consumer beverages and it was found that in many of the samples tested consuming a single can of beer would result in intake levels of 4-MEI that exceed the no significant risk guideline of 29 µg day(-1). Conversely, 4-MEI in the samples was orders of magnitude smaller than the European Food Safety Authority acceptable daily intake threshold value of 100 mg kg(-1) bw day(-1).
authors.affiliation: a Acadia Junior High School , Winnipeg , MB , Canada.
authors.forename: Geemitha
authors.initials: G
authors.lastname: Ratnayake
authors.forename: Thor
authors.initials: T
authors.lastname: Halldorson
authors.forename: Lianna
authors.initials: L
authors.lastname: Bestvater
authors.forename: Gregg T
authors.initials: GT
authors.lastname: Tomy
mesh_terms: D002253:Carbonated Beverages / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D005504:Food Analysis / Q000379:methods*; D007093:Imidazoles / Q000737:chemistry*; D015394:Molecular Structure; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D007093:Imidazoles; C023439:4-methylimidazole
keywords: 4-methylimidazole; carbonated beverages; electrospray; isotope dilution; liquid chromatography; mass spectrometry; reversed phase