title: Supercritical CO(2) fluid extraction of crystal water from trehalose dihydrate. Efficient production of form II (T(alpha)) phase.
abstract: 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.
authors.affiliation: Spectroscopic Instruments Division, JASCO Corporation, Hachioji, Tokyo 192-8537, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Akao
authors.forename: Yusei
authors.initials: Y
authors.lastname: Okubo
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Inoue
authors.forename: Minoru
authors.initials: M
authors.lastname: Sakurai
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D025924:Chromatography, Supercritical Fluid / Q000295:instrumentation / Q000379:methods*; D003460:Crystallization; D007700:Kinetics; D011312:Pressure; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014199:Trehalose / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D002245:Carbon Dioxide; D014199:Trehalose