Assessing the Detection Limit of a Minority Solid-State Form of a Pharmaceutical by 1H Double-Quantum Magic-Angle Spinning Nuclear Magnetic Resonance Spectroscopy

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

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 languageEnglish
Pages (from-to)3372-3377
Number of pages6
JournalJournal of Pharmaceutical Sciences
Volume106
Issue number11
Early online date25 Jul 2017
DOIs
Publication statusPublished - Nov 2017
Externally publishedYes

Keywords

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

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