Although most drugs are formulated in the crystalline state, amorphous or other crystalline forms are often generated during the formulation process. The presence of other forms can dramatically affect the physical and chemical stability of the drug. The identification and quantitation of different
Quantification of 13C in solids using CPMAS-DD-NMR spectroscopy
β Scribed by David G. Rethwisch; Mary A. Jacintha; Cecil R. Dybowski
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 985 KB
- Volume
- 283
- Category
- Article
- ISSN
- 0003-2670
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β¦ Synopsis
Quantitative analysis of several standard materials is used to evaluate various techniques for analysis of 13C cross polarization magic angle spinning dipolar decoupling (CPMAS-DD)_NMR spectra. These results suggest that uncertainty in the kinetics of the initial cross-polarization process may lead to systematic errors in the fitting of CPMAS-DD-NMR data. Methods are suggested to minimize the effects of this potential source. of error. These results indicate that "C CPMAS-DD-NMR can give quantitatively reliable results.
π SIMILAR VOLUMES
The solid-phase "C CPMAS NMR spectra of the crystallime h e r s from lo-, 12and 14-membered cyclic a-diketones were found to be in full accord with the symmeirical tricyclic 2,5-dihydroxycyclohexane-l,4dione structures previously proposed on the basis of molecular formulae and inβ¬rared spectroscopy.
Cross-polarized magic-angle-spinning NMR (CPMAS-NMR) techniques are assumed to be only semi-quantitative in the assessment of carbon distribution in humic substances or natural organic matter, due to a number of interferences such as spinning side bands (SSB) in spectra, paramagnetic species in samp
13 C labeling was used to enhance the sensitivity of 13 C solid-state NMR to study the effect of tabletting on the polymorphism of a steroidal drug. The steroidal drug Org OD 14 was 13 C labeled and formulated into tablets containing only 0.5-2.5% active ingredient. The tablets were subsequently