ISSN:
1573-904X
Keywords:
FT-Raman spectroscopy
;
trehalose dihydrate
;
dehydration
;
crystalline
;
amorphous
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Purpose. (1) To characterise the different phases of trehalose using FT-Raman spectroscopy. (2) To monitor the changes in the structure of trehalose dihydrate on isothermal heating at 80°C. Methods. Different phases of trehalose were prepared and FT-Raman spectra obtained. Trehalose dihydrate was sieved to 〈45 μm and 〉425 μm particle size fractions and FT-Raman spectra were obtained at various time intervals during heating at 80°C. Results. During heating at this temperature, the spectra of a 〈45 μm particle size fraction showed a loss of peak resolution with time and after 210 minutes resembled the spectrum of amorphous trehalose prepared by lyophilisation, indicating that the material was rendered amorphous by heating. In contrast, spectra obtained from a 〉425 μm particle size fraction altered with time and became characteristic of the crystalline anhydrate. The approximate kinetics of this transformation to the anhydrate were monitored by analysis of peak intensity ratios with time. A two stage rearrangement was indicated; some functional groups appeared to manoeuvre into the spatial arrangement found in the anhydrate initially before the rest of the ring structure relaxed into this conformation. This may be due to some parts of the molecule being immediately affected by the loss of the water molecules on dehydration prior to the subsequent reorientation of the entire molecule into the anhydrate crystal lattice. Conclusions. The 〈45 μm particle size fraction becomes disordered on dehydration induced by heating at 80°C whilst the 〉425 μm particle size fraction crystallises to the anhydrate under the same conditions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1011935723444
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