D-Mannitol is a common excipient used in pharmaceutical formulation of tablets. The glass property of D-Mannitol e.g. the glass transition temperature Tg, plays a key role in formulation development. Previously the Tg of D-Mannitol can not be measured directly in conventional DSC. The recent development of fast scan DSC technology gives new opportunity to characterize the glass transition of D-Mannitol. In this poster, HyperDSC is used to characterize the glass transition of D-Mannitol. Infra red and Raman spectroscopy are also used to identify different polymorphic forms of D-Mannitol. Experment results show that Only at quenching rate >= 300 C/min, is the sample partially quenched into the amorphous state, with the Tg detected during the subsequent heating. The higher the quenching rate the more amorphous material was generated.
The cold crystallization right after Tg prevented accurate Tg determination at conventional scanning rates. However, at much higher scanning rates, the cold crystallization was pushed to higher temperature so that Tg measurement become possible, as evidenced at 500 C/min. Both FTIR and Raman spectra showed the difference among these three polymorphs of D-Mannitol due to the different arrangement of molecules in the crystals. FTIR shows obvious difference between 1200 and 1400 cm-1 in the C-H deformation vibrations region. In Raman, the difference shows up in the region between 1000 and 1200 cm-1.
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