An assay for 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline and 2-amino-3,4,8-trimethylimidazo-[4,5-f]quinoxaline in fried beef using capillary column gas chromatography electron capture negative ion chemical ionization mass spectrometry.

A gas chromatographic/mass spectrometric assay has been developed for the simultaneous measurement of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx) in fried beef. The method employs capillary column gas chromatography, electron capture negative ion chemical ionization mass spectrometry and a stable isotope labelled analogue of MeIQx as common internal standard. Two patties of lean minced beef which had been cooked separately were analysed and found to contain both compounds (patty 1:2.4 ng MeIQx g-1 meat, 1.2 ng DiMeIQx g-1 meat; patty 2:1.3 ng MeIQx g-1 meat, 0.5 ng DiMeIQx g-1 meat). Neither compound was present in the meat prior to cooking.