Quantitation of carcinogenic heterocyclic aromatic amines and detection of novel heterocyclic aromatic amines in cooked meats and grill scrapings by HPLC/ESI-MS

A tandem solid-phase extraction method was used to isolate carcinogenic heterocyclic aromatic amines (HAAs) from cooked meats. The following 10 HAAs were identified by HPLC/ESI-MS/MS: 2-amino-9H-pyrido[2,3-b]indole (2-A alpha C), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MelQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMelQx), 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMelQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-1,7,9-trimethylimidazo[4,5-g]quinoxaline (7,9-DiMelgQx), and 2-amino-1-methylimidazo[4,5-b]quinoline (10[4,5-b]); the latter HAA has not previously been reported in cooked meats. The concentrations of these HAAs ranged from < 0.03 to 15 ppb in cooked meats and poultry, to 75 ppb in cooked beef extract, and to 85 ppb in grill scrapings. The product ion scan mode was used to confirm the identities of these HAAs. Six other compounds were detected that appear to contain the N-methylimidazoquinoxaline skeleton on the basis of their product ion spectra, and these compounds are probable isomers of IQx, 8-MelQx, and DiMelQx. A number of known HAAs and novel HAAs of unknown genotoxic potential are formed at appreciable levels in cooked meats.