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Crystallization of polymorphs:the effect of solvent

KHOSHKHOO, S and ANWAR, J (1993) Crystallization of polymorphs:the effect of solvent. Journal of Physics D: Applied Physics, 26 (8B). B90-B93. ISSN 0022-3727

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Abstract

The effect of solvent in crystallization of polymorphs has been studied using the drug sulphathiazole as a model compound. The solubilities of the four polymorphic forms of sulphathiazole were determined as a function of temperature in various solvents. Within the temperature ranges studied, the rank order of solubility of the polymorphs was the same in all solvent systems. On the basis of this knowledge of the temperature dependence of the solubilities, recrystallization experiments, in which the supersaturation was systematically varied, were carried out in an endeavour to isolate each of the polymorphic forms from each solvent system. These recrystallization experiments reveal that not all of the known polymorphic forms can be crystallized from any given solvent by varying the supersaturation. Indeed some solvents selectively favour the crystallization of a particular form or forms. We conclude that thermodynamic effects are not responsible for the selective behaviour of a solvent. A kinetic mechanism is proposed. It is considered that the solvent acts by selective adsorption to certain faces of some of the polymorphs, and thereby either inhibits their nucleation or retards their growth to the advantage of others.

Item Type: Article
Journal or Publication Title: Journal of Physics D: Applied Physics
Subjects:
Departments:
ID Code: 62217
Deposited By: ep_importer_pure
Deposited On: 13 Feb 2013 15:41
Refereed?: Yes
Published?: Published
Last Modified: 22 Oct 2017 02:59
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/62217

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