PARTICLE AND POWDER PROPERTIES OF CYCLODEXTRINS

The particle and powder properties of alpha-, beta, gamma- and hydroxy propyl-beta- (HP beta) cyclodextrins (CDs) were examined. Special atte ntion was paid to water interaction and thermal properties of CDs. The CDs studied showed big differences in particle size distribution and particle shape. In all cases, with the exception of PCD, the log-norma l distribution described adequately the particle size distribution. Ho wever, the beta-distribution characterized well particle shape factor distribution. The typical alpha and beta parameters obtained from the beta-distribution fitting are related to sphericity and shape uniformi ty of the particles. Water content results for CDs, obtained by loss o n drying at 160 degrees C and Karl Fisher methods, yielded similar res ults, thus, it was possible to evaporate practically all the water at 160 degrees C. Water content of CDs 'as received' was dependent on the storage history of the samples after manufacturing. The DSC profiles of the CDs showed a broad, intense endothermic effect in the range 20- 130 degrees C, this asymmetric peak was ascribed to water removal. alp ha CD showed a characteristic peak with an onset temperature 138 degre es C. This peak seems to be independent of water content, and only sma ll modifications are observed after drying at high temperature. Thus, a feasible structural change is associated with this peak. (C) 1997 El sevier Science B.V.