Abstract
The lower detection limit for 2 distinct crystalline phases by 1H magic-angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) is investigated for a minority amount of cimetidine (anhydrous polymorph A) in a physical mixture with the anhydrous HCl salt of cimetidine. Specifically, 2-dimensional 1H double-quantum (DQ) MAS NMR spectra of polymorph A and the anhydrous HCl salt constitute fingerprints for the presence of each of these solid forms. For solid-state NMR data recorded at a 1H Larmor frequency of 850 MHz and a MAS frequency of 30 kHz on ∼10 mg of sample, it is shown that, by following the pair of cross-peaks at a 1H DQ frequency of 7.4 + 11.6 = 19.0 ppm that are unique to polymorph A, the level of detection for polymorph A in a physical mixture with the anhydrous HCl salt is a concentration of 1% w/w.
Original language | English |
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Pages (from-to) | 3372-3377 |
Number of pages | 6 |
Journal | Journal of Pharmaceutical Sciences |
Volume | 106 |
Issue number | 11 |
Early online date | 25 Jul 2017 |
DOIs | |
Publication status | Published - Nov 2017 |
Externally published | Yes |
Keywords
- analytical chemistry
- double-quantum
- hydrogen bonding
- magic-angle spinning
- NMR
- physical characterization
- solid-state