CRYSTALLIZATION CONTROL BY ADDITIVES - MOLECULAR RECOGNITION - APPLICATION TO THE DETERMINATION OF L-GLUTAMIC ACID USING L-LYSINE AS SUBSTRATE

The effects of 19 amino acids on the crystallization of L-Asparagine and L-Lysine have been comparatively studied with analytical purposes. A very simple nephelometric procedure is used for determination of L-Glutamic acid, based on its inhibitory action on the crystallization of L-Lysine. The obtention of supersaturated solutions of L-Lysine was accomplished by means of the change in the solvent composition. Thus, the addition of isopropanol to stable aqueous solutions of this amino acid, allows to obtain unstable supersaturated solutions. The method suffers from very few interferences. The method was also applied to the determination of L-Glutamic acid in pharmaceutical products.