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Crystallization of Amorphous α-, β-, γ-Cyclodextrin by Water Sorption

1986; Pharmaceutical Society of Japan; Volume: 106; Issue: 5 Linguagem: Inglês

10.1248/yakushi1947.106.5_420

1347-5231

YOSHINOBU NAKAI, KEIJI YAMAMOTO, KATSUHIDE TERADA, Isao Sasaki,

Rheology and Fluid Dynamics Studies

Effects of the amount of sorbed water on the solid-state crystallization of amorphous α-, β-, and γ-cyclodextrin (CD) were investigated. Water vapor adsorption isotherms were measured at 40°C for each amorphous CD which was prepared by the grinding in tungsten carbide vibrational mill. At higher relative humidities, the amorphous CDs converted to the carresponding crystal CD hydrates. X-Ray powder diffraction measurements were made after the samples reaehed the water vapor adsorption equilibrium. The crystallization occurred when the amorphous CD took the same water content as that of the hydrate. It was found that α-CD recrystallized in two crystal forms of form I and form II at 61.5 and 79.0% relative humidities, respectively.