FESTA (Fluorine-Edited Selective TOCSY Acquisition) is a new 1D NMR method for efficient structure elucidation in mixtures of fluorine-containing species. It allows simplified 1H spectra to be obtained that show only those protons that are in a spin system coupled to fluorine of interest.

Pulse sequence diagram:
The basic FESTA pulse sequence of generates 1H spectra showing only those protons that are in a spin system containing a chosen fluorine. At the beginning, the favorable high equilibrium polarization and excellent chemical shift dispersion of 19F are exploited in the initial excitation of a fluorine resonance of interest. The resultant coherence is transferred to its proton coupling partner or partners, giving anti-phase magnetization in a doubly selective reverse INEPT (SRI) sequence element. A 1H selective modulated echo (SME) then refocuses the 1H-19F coupling to provide in-phase magnetization at the starting point of the final TOCSY transfer. The complete pulse sequence is thus a 19F-decoupled doubly selective 19F → 1H refocused INEPT-TOCSY.

Bruker pulse program:
SRI-FESTA (right click and chose 'save ... as')
Selective fluorine reverse INEPT (SRI) (right click and chose 'save ... as')

Bruker pulse program for QNP probes:
SRI-FESTA_QNP (right click and chose 'save ... as')
SRI_QNP (right click and chose 'save ... as')

Experimental data:
Mixture of four pharmaceuticals: fluticasone propionate, rosuvastatin calcium and its precursor BEM, and fluconazole

FESTA: an efficient NMR approach for the structural analysis of mixtures containing fluorinated species, L. Castañar, P. Moutzouri, T. Barbosa, C. Tormena, R. Rittner, A. Phillips, S. Coombes, M. Nilsson, G. A. Morris. Analytical Chemistry, 2018. DOI: 10.1021/acs.analchem.8b00753

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