Influence of supersaturation and structurally related additives on the crystal growth of α-lactose monohydrate

It is shown that increasing the supersaturation during crystal growth of the title compound in water at room temperature induces an important increase in the mean crystal size, which can be explained by taking into account the role of the solvent and that of the fi-lactose anomer acting as large scale impurities in the crystallizing medium. Among the six structurally related additives tested, four of them lead to significant morphological changes, due to their anisotropic adsorption abilities. Depending on the nature of the additive, crystal habit varies from "elongated" along the b direction or "flattened" along the a axis. These data could be rationalized by a careful analysis of the 3D hydrogen bond network and by using molecular modelling for the simulation of the adsorption mechanisms, assuming that adsorption ability and desorption difficulty were directly dependent on the proportion of preserved intermolecular hydrogen bonds. (C) 2002 Elsevier Science B.V. All rights reserved.