Selective spectrophotometric determination of proline and tryptophan as 4,6-dinitrobenzofuroxan derivatives in the presence of other amino acids

Working conditions of the spectrophotometric determination of proline and tryptophan as 4,6-dinitrobenzofuroxan derivatives in the presence of different amino acids were found. Optimal conditions of the detection of proline and tryptophan are 510-530 nm and 540-560 nm, respectively, after the reaction at pH 6.7-7.5. The detection limit is 1 mu g/mL for tryptophan and 0.7 mu g/mL for proline; the analytical range is 1-40 mu g/mL. It was demonstrated that proline and tryptophan can be determined by spectrophotometry in fermentation solutions in the biosynthesis of these amino acids.