Nitrosation of sarcosine, proline and 4-hydroxyproline by exposure to nitrogen oxides

The nitrosation of amino acids (sarcosine, proline and 4-hydroxyproline) was investigated in model experiments. The compounds were exposed in crystalline form and as aqueous solutions to defined concentrations of nitrogen oxides (in the range of 1-100 ppm) in the atmosphere of a reaction chamber. Nitrosated amino acids were analysed by GC/TEA after silylation. Generally the extent of nitrosation increased with NOx concentration, reaction time and air humidity. Nitrosation of aqueous amino acid solutions decreased markedly with increasing pH.