• Keisuke Maruyoshi
  • Dinu Iuga
  • Abigail E. Watts
  • Colan E. Hughes
  • Kenneth D.M. Harris
  • Steven P. Brown

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 languageEnglish
Pages (from-to)3372-3377
Number of pages6
JournalJournal of Pharmaceutical Sciences
Issue number11
Early online date25 Jul 2017
Publication statusPublished - Nov 2017
Externally publishedYes

    Research areas

  • analytical chemistry, double-quantum, hydrogen bonding, magic-angle spinning, NMR, physical characterization, solid-state

ID: 5019835