Solid-State Nuclear Magnetic Resonance Determination of the Physical Form of BHA on Common Pharmaceutical Excipients

Numerical modeling of polymorphic transformation of oleic acid via near-infrared spectroscopy and factor analysis

Near-infrared (NIR) spectroscopy as a tool for direct and quantitatively screening the minute polymorphic transitions of bioactive fatty acids was assessed basing on a thermal heating process of oleic acid. Temperature-dependent NIR spectral profiles indicate that dynamical variances of COOH group dominate its γ → α phase transition, while the transition from active α to β phase mainly relates to the conformational transfer of acyl chain. Through operating multivariate curve resolution-alternating least squares with factor analysis, instantaneous contribution of each active polymorph during the transition process was illustrated for displaying the progressive evolutions of functional groups. Calculated contributions reveal that the α phase of oleic acid initially is present at around -18 °C, but sharply grows up around -2.2 °C from the transformation of γ phase and finally disappears at the melting point. On the other hand, the β phase of oleic acid is sole self-generation after melt even it embryonically appears at -2.2 °C. Such mathematical approach based on NIR spectroscopy and factor analysis calculation provides a volatile strategy in quantitatively exploring the transition processes of bioactive fatty acids; meanwhile, it maintains promising possibility for instantaneous quantifying each active polymorph of lipid materials.

Application of Solid-State NMR to Reveal Structural Differences in Cefazolin Sodium Pentahydrate From Different Manufacturing Processes

Solid-state Nuclear magnetic resonance, thermogravimetric analysis, X-ray diffraction, and Fourier-transform infrared spectroscopy were combined with theoretical calculation to investigate different crystal packings of α-cefazolin sodium obtained from three different vendors and conformational polymorphism was identified to exist in α-cefazolin sodium. Marginal differences observed among cefazolin sodium pentahydrate 1, 2, and 3 were speculated as being caused by the proportion of conformation 2.

NMR studies of organic polymorphs and solvates

This review article describes the applications of NMR to the study of polymorphs and related forms (solvates) of organic (especially pharmaceutical) compounds, for which it is of increasing academic and practical importance. The nature of the systems covered is briefly introduced, as are the techniques constituting solid-state NMR. The methodologies involved are then reviewed under a number of different headings, ranging from spectral editing through relaxation times to shielding tensors and NMR crystallography. In each case the relevant applications are described. Whilst most studies concentrate on structural matters, motional effects are not neglected. A special section discusses studies of solvates (especially hydrates), and another reviews quantitative analysis.