Abstract
This article reviews polymorphism and impurity effect in the crystallization of amino acids, particularly L-glutamic acid. It is shown that the precipitation process of a and β polymorphs of L-glutamic acid is composed of four steps including a solution-mediated transformation. The predominant effect of the temperature on the nucleation process of the polymorphs is also indicated. As to the impurity effects, it is presented that amino acids such as L-leucine, L-phenylalanine, etc, give rise to the influence on nucleation, crystal growth and transformation processes of the polymorphs of L-grutamic acid. It is also referred that some chiral impurities of amino acids can be used for the optical resolution of the amino acids.
