Study of L-glutamic Acid's in situ Polymorphic Phase Transition through Solution Mediated

In the current work, we report the solution-mediated polymorphic conversion of L-glutamic acid from its metastable -α to stable state - β at various crystallization temperatures, including 5°C, 10°C, 20°C, and 30°C. L-glutamic acid (LGA) solution-mediated polymorphic transformation was observed using an optical microscope, and the gravimetric approach was used to analyze concentration changes that occurred during crystallization. Supersaturation change with respect to time during solution mediated polymorphic transformation was investigated. Solubility of L-Glutamic acid polymorphs in aqueous solution was determined by gravimetric method. It is found that the onset of the polymorphic transformation is manifested as the point in time when crystals of the stable β phase of L-Glutamic acid were first detected and elucidated. Only α-polymorphs nucleated and grew at the crystallization temperature of 5°C with the concentration of 4.5g/300ml rather β-polymorphs nucleated and grew in the temperature of 30°C. Solution mediated polymorphic transformation observed in the crystallization temperatures of 10°C and 20°C. The polymorphs obtained during the crystallization were analyzed by powder X-ray diffraction (PXRD) technique. The effect of time and temperature on the crystallization and solution mediated polymorphic transformation of L-Glutamic acid was intensely observed. The growth and dissolution behaviors of both polymorphs were investigated with time.