¹⁹F DOSY NMR analysis for spin systems with ⁿJ_FF couplings

Abstract

NMR is a powerful method for identification and quantification of drug components and contaminations. These problems present themselves as mixtures, and here, one of the most powerful tools is DOSY. DOSY works best when there is no spectral overlap between components, so drugs containing fluorine substituents are well-suited for DOSY analysis as (19)F spectra are typically very sparse. Here, we demonstrate the use of a modified (19)F DOSY experiment (on the basis of the Oneshot sequences) for various fluorinated benzenes. For compounds with significant (n) JFF coupling constants, as is common, the undesirable J-modulation can be efficiently suppressed using the Oneshot45 pulse sequence. This investigation highlights (19)F DOSY as a valuable and robust method for analysis of molecular systems containing fluorine atoms even where there are large fluorine-fluorine couplings.

Applications of NMR diffusion methods with emphasis on ion pairing in inorganic chemistry: a mini‐review

“…This may simply involve NH or OH containing molecules that H‐bond to one another or, for salts, the interaction of a suitable cation with polar solvents or anions . In the case of salts where the anion may contain a fluorine atom but no suitable proton, PGSE and DOSY studies reporting both 19 F and 1 H diffusion measurements have become increasingly popular.…”

19F NMR matrix‐assisted DOSY: a versatile tool for differentiating fluorinated species in mixtures

“…The 19 F{ 1 H} DOSY data were acquired using the Oneshot pulse sequence, modified to add broadband (waltz16) 1 H decoupling . The delay for gradient recovery (d16) and duration of the gradient purge pulse (p19) were fixed at 0.2 and 0.6 ms, respectively.…”

Quantitative NMR Studies of Multiple Compound Mixtures

“…Different types of spectral filtering or editing techniques can be applied to acquire 1 H 1D qNMR spectra, such as using relaxometric and diffusometric spectral editing techniques [12,13,39,40]. Most often used spectral editing method is the T 2 relaxation editing by means of CPMG pulse train [5,6], which suppresses the background signal interference from protein or other kind of macromolecules in the indirect 1 H 1D qNMR, thus enabling quantitative assessment of low-molecular weight metabolites.…”