Nucleation control and crystallization of l-glutamic acid polymorphs by swift cooling process and their characterization

✍ Scribed by K. Srinivasan; P. Dhanasekaran

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 771 KB
• Volume: 318
• Category: Article
• ISSN: 0022-0248
• DOI: 10.1016/j.jcrysgro.2010.11.050

✦ Synopsis

The region of preferred crystal nucleation of the two known polymorphs of L-glutamic acid (C 5 H 9 NO 4 ), the metastable a and stable b, from pure aqueous solution has been recognized by following a swift cooling crystallization process in the temperature range 1-40 1C. Aqueous solution prepared for a selected saturation was taken to 80 1C and cooled down to various temperatures in the range 1-40 1C in steps of every 1 1C abruptly with constant stirring. The observed nucleation and grown micro-crystallites in the solution were examined under optical microscope and their morphologies and polymorphic forms were evaluated. Results obtained from this investigation at all the 40 experimental temperatures elucidated a clear distinction of the preferred nucleation regions of a, b and combinations of a and b in the solution in the above mentioned temperature range and the results are repeatable. Form of crystallization was confirmed by Powder X-ray Diffraction (PXRD). Further the grown polymorphs were characterized by Differential Scanning Calorimetry (DSC), optical transmittance and Second Harmonic Generation (SHG) studies.