Characterization and pseudopolymorphism of l-phenylalanine anhydrous and monohydrate forms

In this work, the preformulation study on the solid state characterization for the anhydrous form and the monohydrate form of l-phenylalanine has been initially conducted by the use of powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and microscopy. Meanwhile, the solubility of both forms and the transformation kinetics from anhydrous form to monohydrate form in different water/acetone mixtures were studied as well. The transformation rate can be prohibited by increasing temperature and reducing water content in the solvent mixtures. These results will contribute to a better understanding of drugs’ pseudopolymorphism for pharmaceutical industry.   Key words: Crystallization, l-phenylalanine, polymorphism, identification, transformation.