Gas chromatographic mass spectrometric determination of 4-(5) methylimidazole in ammonia caramel colour using ion-pair extraction and derivatization with isobutylchloroformate

A procedure for the gas chromatographic-mass spectrometric quantification of 4-(5-)methylimidazole in ammonia caramel colours by using isobutylchloroformate as derivatizing reagent has been developed. The use of this reagent coupled to a previous ion-pair extraction of the compound with Bis-2-ethylhexylphosphate enabled routine determination of 4-(5) methylimidazole with several advantages compared to others methods previously described. Examples of the analysis of some samples are presented as well as data on linearity, recovery and repeatability. Under the adopted conditions the limit of detection and the limit of quantification were 0.250 mg kg(-1) and 1 mg kg(-1), respectively. (C) 1997 Elsevier Science B.V.