Quantitation of 13 heterocyclic aromatic amines in cooked beef, pork, and chicken by liquid chromatography-electrospray ionization/tandem mass spectrometry

The concentrations of heterocyclic aromatic amines (HAAs) were determined, by liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI-MS/MS), in 26 samples of beef, pork, and chicken cooked to various levels of doneness. The HAAs identified were 2-amino-3-methylimidazo[4,5-f] quinoline, 2-amino-1-methylimidazo[4,5-b]quinoline, 2-amino-1-methylimidazo[4,5- g]quinoxaline (IgQx), 2-amino-3-methylimidazo[4,5-f]quinoxaline, 2-amino-1,7-dimethylimidazo[4,5-g]quinoxaline (7-MeIgQx), 2-amino-3,8- dimethylimidazo[4,5-f]quinoxaline, 2-amino-1,6-dimethylfuro[3,2-e]imidazo[4,5-b] pyridine, 2-amino-1,6,7-trimethylimidazo[4,5-g]quinoxaline, 2-amino-3,4,8- trimethylimidazo[4,5-f]quinoxaline, 2-amino-1,7,9-trimethylimidazo[4,5-g] quinoxaline, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole, and 2-amino-3-methyl-9H-pyrido[2,3-b]indole. The concentrations of these compounds ranged from <0.03 to 305 parts per billion (micrograms per kilogram). PhIP was the most abundant HAA formed in very well done barbecued chicken (up to 305 μg/kg), broiled bacon (16 μg/kg), and pan-fried bacon (4.9 μg/kg). 7-MeIgQx was the most abundant HAA formed in very well done pan-fried beef and steak, and in beef gravy, at concentrations up to 30 μg/kg. Several other linear tricyclic ring HAAs containing the IgQx skeleton are formed at concentrations in cooked meats that are relatively high in comparison to the concentrations of their angular tricyclic ring isomers, the latter of which are known experimental animal carcinogens and potential human carcinogens. The toxicological properties of these recently discovered IgQx derivatives warrant further investigation and assessment.