Stability of heterocyclic amines during heating

The stability of 15 Heterocyclic Amine (HA) standards was kinetically studied during heating at 100, 150 and 200°C for varied lengths of time. Parameters used to evaluate the stability of each HA standard include the degradation rate constant (h−1), the activation energy (kJ/mol) and the A value. Results showed that the HA loss increased both with increasing temperature and heating time, and the degradation rate of each HA during heating fits a first-order model. 2-Amino-3-dimethylimidazo[4,5-f]quinoxaline (IQx) was found to possess the highest stability during heating, followed by 2-aminodipyrido[1,2-a:3′,2′-d]imidazole (Glu-p-2), 9H-pyrido[4,3-b]indole (Norharman), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-p-2), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx), 1-methyl-9H-pyrido-[4,3-b]indole (Harman), 2-amino-6-methyldipyrido-[1,2-a:3ʹ,2ʹ-d]imidazole (Glu-p-1), 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-p-1), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP).