Akao Ken-ichi, Okubo Yusei, Inoue Yoshio, Sakurai Minoru
Spectroscopic Instruments Division, JASCO Corporation, Hachioji, Tokyo 192-8537, Japan.
Carbohydr Res. 2002 Oct 11;337(19):1729-35. doi: 10.1016/s0008-6215(02)00284-7.
Form II is a kind of metastable crystalline form of trehalose anhydrate, and it is easily converted to the dihydrate crystal by absorbing water in moist atmosphere at room temperature (Akao et al., Carbohydr. Res. 2001, 334, 233-241). It can be utilized as an edible and nontoxic desiccant, and thus its efficient production from the dihydrate is significant from a viewpoint of industrial applications. In this study, we attempt to extract crystal water from the dihydrate using supercritical CO(2). We examine the dependence of extraction efficiency on the extraction time, the temperature and pressure of the fluid. Then, FTIR measurements are carried out to detect the extracted water and to identify the polymorphic phase of the sugar sample after the extraction treatment. In particular, the so-called first derivative euclidean distance analysis for IR spectra is shown to be quite useful for the structural identification. Consequently, we demonstrate that form II is produced from the dihydrate through supercritical CO(2) fluid extraction if appropriate temperature and pressure conditions (around 80 degrees C and 20 MPa) are maintained.
II型是无水海藻糖的一种亚稳态晶型，在室温下的潮湿气氛中，它通过吸收水分很容易转化为二水合物晶体（赤尾等人，《碳水化合物研究》，2001年，第334卷，第233 - 241页）。它可用作可食用且无毒的干燥剂，因此从二水合物高效生产II型从工业应用角度来看意义重大。在本研究中，我们尝试使用超临界CO₂从二水合物中提取结晶水。我们研究了提取效率对提取时间、流体温度和压力的依赖性。然后，进行傅里叶变换红外光谱（FTIR）测量以检测提取出的水，并确定提取处理后糖样品的多晶型相。特别是，红外光谱的所谓一阶导数欧几里得距离分析对于结构鉴定非常有用。因此，我们证明，如果维持适当的温度和压力条件（约80℃和20MPa），通过超临界CO₂流体萃取可从二水合物制得II型。
