Role of amino acids in the formation of polycyclic aromatic amines during pyrolysis of tobacco

Non-isothermal pyrolysis of 13 kinds of α-amino acids and of tobacco spiked with one of 6 α-amino acids was carried out at up to 800 °C under N2 flow to evaluate the yields of four polycyclic aromatic amines – 1- and 2-aminonaphthalene and 3- and 4-aminobiphenyl. The pyrolysis of amino acids yielded 2.4–36 ng of the aminonaphthalenes and up to 2.9 ng of the aminobiphenyls from 50 mg of each amino acid, except for phenylalanine which yielded much higher amounts of the four PAAs than did the other amino acids. However, on addition of 50 mg each of individual amino acids (alanine, proline, aspartic acid, asparagine and arginine) to 1 g of tobacco, the yields of the four PAAs increased by 140–300 ng and by 10–26 ng in the cases of the aminonaphthalenes and the aminobiphenyls, respectively. On addition of phenylalanine to tobacco, formation of the aminobiphenyls was promoted but that of the aminonaphthalenes was found to be not. The results indicated that in co-pyrolysis of amino acid and tobacco cut filler: (1) amino acids would work as donators of amino-moieties of the four PAAs and (2) the aromatic ring in the side chain of phenylalanine would supply some aryl carbons, which were facilitated formation of the aminobiphenyls but not of the aminonaphthalenes.