2-AMINO-3,4-DIMETHYLIMIDAZO[4,5-F]QUINOLINE IS NOT DETECTABLE IN COMMERCIAL INSTANT AND ROASTED COFFEES

A sensitive method has been developed for the isolation of 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) from instant coffee and lyophilized home-brewed coffee. Sample cleanup was performed in four steps using Amberlite XAD-2, Extrelut/copper phthalocyanine-Sephasorb, Sephasorb HP, and propanesulfonic acid silica/octadecyl silica. The purified extracts were then separated by high-performance liquid chromatography. To validate the procedure, picogram levels of [2-C-14]MeIQ were added prior to extraction to the coffee samples; 61 % and 49 % of the added reference standard could be recovered in chromatographic fractions from purified instant and home-brewed coffee, as measured by liquid scintillation and Ames test mutagenicity (TA98, +S-9). At 600 and 60 ppt spiking levels, clear signals were observed allowing the estimation of the detection limit for MeIQ to be about 5-10 pg/g of coffee beans. On this basis, MeIQ was not detectable in either sample of instant or roasted coffee.