Microcalorimetry, isothermal crystalline powders

Briggner L-E, Buckton G, Bystrom K, Darcy P. Use of isothermal microcalorimetry in the study of changes in crystallinity induced during the processing or powders. Int J Pharm 1994 105 125-135. 

Studies of the desolvation of solvatomorphs can be conducted using VT-XRPD. For instance, after the dehydration of a hydrate phase, one may obtain either a crystalline anhydrate phase or an amorphous phase and the XRPD pattern will clearly indicate the difference. In addition, should one encounter an equivalence in powder patterns between the hydrate phase and its dehydrated form, this would indicate the existence of channel-type water (as opposed to lattice boimd water). In one study, the solid-state properties of the isomorphic desolvates of cephalexin, cefaclor, erythromycin A, and spirapril hydrochloride were investigated, with the hygroscopicity of the compounds being evaluated using a vacuum moisture balance and the structural relaxation measured using a combination of VT-XRPD and isothermal microcalorimetry. " ... 

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