Thermogravimetric analysis polymorphism

The solid-state properties like crystallinity, polymorphism (crystal structure), shape (morphology), and particle size of drugs are important in the stability, dissolution, and processibility of drugs. Some commonly used methods in solid-state studies include microscopy, hot stage microscopy with polarized light, x-ray powder diffraction (XRPD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared FTIR/Raman, and solid-state NMR. 

Crystallinity and polymorphism X-ray powder diffraction Differential scanning calorimetry (DSC) Infiared spectroscopy Solid state NMR Raman spectroscopy Thermogravimetric analysis (TGA)... 

The thermal analysis methods reported for the characterization of ezeti-mibe were conducted using thermogravimetric analysis (TGA), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). As detailed in Table 3.2, the TGA and DSC characterization of polymorphs of ezefimibe was reported in a patent publication. 

Pharmaceutical examples of studies involving solvates are often linked with investigations into polymorphism hence, there is some overlap with the previous section. In addition, the chapter on thermogravimetric analysis in this book also deals with this subject. The examples given here have been chosen specifically on the basis of their illustrating the use of DSC, rather than outlining the properties of pharmaceutical hydrates in general. 

SSNMR spectroscopy. However, FTIR and Raman spectroscopy, thermal microscopy, variable-temperature x-ray diffractometry (VTXRD), and DSC may also be used to identify polymorphs. Solvates may be similarly characterized by the techniques mentioned above. In addition, the stoichiometric number of the solvent molecules in the crystal lattice of solvates may be determined by thermogravimetric analysis (TGA), gas chromatography, or, in the case of a hydrate, by Karl Fiseher titrimetry [37]. 

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