Impurity profile of amino acids?

Amino acids are produced by various manufacturing processes, i.e. chemical and enzymatic synthesis, extraction from protein hydrolysates, and fermentation. Each process produces a different impurity profile. Since the European Pharmacopoeia wants to replace the non-selective and non-sensitive "ninhydrin-positive substance" TLC test with chromatographic or electrophoretic methods limiting the impurities to 0.1 per cent, the information about the production processes and the related impurity profile is urgently needed from the manufacturers.