Determination of 4(5)-methylimidazole in carbonated beverages by isotope-dilution liquid chromatography-tandem mass spectrometry

作者：Ratnayake Geemitha; Halldorson Thor; Bestvater Lianna; Tomy Gregg T^*

来源：Food Additives and Contaminants Part A-Chemistry Analysis Control Exposure& Risk Assessment, 2015, 32(7): 1075-1082.

DOI：10.1080/19440049.2015.1045557

• reversed phase
• mass spectrometry
• electrospray
• isotope dilution
• liquid chromatography
• carbonated beverages
• 4-methylimidazole

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 (d(6)-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 d(6)-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 5.8ngml(-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 mu gday(-1). Conversely, 4-MEI in the samples was orders of magnitude smaller than the European Food Safety Authority acceptable daily intake threshold value of 100mgkg(-1) bwday(-1).

• 出版日期2015-7-3