Morphological Changes of α-Lactose Monohydrate (α-LM) Single Crystals Under Different Crystallization Conditions Using Polar Protic and Aprotic Solvents

In this study, polar protic (water) and aprotic (DMSO) solvents were used to analyse the morphological changes of alpha-lactose monohydrate (α-LM) single crystals. The solubility of α-LM determined in DMSO by gravimetric method is nearly 2.5 times higher than that found in water at 33 °C. Surprisingly, the weight of the solution increases with time in DMSO as it is highly hygroscopic, whereas the weight of the solution decreases with time in water as it evaporates. Also it is found that the supersaturation of aqueous solution gradually increases by evaporation of solvent, whereas the supersaturation of DMSO solution gradually increases by moisture absorption which reduced the solubility of α-LM. The increasing level of supersaturation in multiple ways in DMSO and water at 33°C induces the mean crystal size, which can be explained by taking into account the role of solvent in the growth environment. The form of grown crystals was confirmed by powder x-ray diffraction (PXRD) and differential scanning calorimetry (DSC) study.