JEOL USA has developed new methodology using its ROYAL HFX Probe to offer a powerful and practical alternative for the elucidation of structural information. It has particular merit in the analysis of complex pharmaceutical mixtures that contain a drug substance plus its various metabolites.
In the SRI-FESTA method, 19F to 1H polarization transfer is followed by a selective labelling of a single 1H. The experiment finishes with a TOCSY transfer to reveal all the protons that are coupled to the selected 1H. Though powerful and highly selective, SRI-FESTA requires expert knowledge in order to choose the specific excitation points for both 19F and 1H, potentially limiting its practical application in routine pharmaceutical labs.
Now, building on this experimental approach and taking advantage of the features of the ROYAL HFX Probe, JEOL scientists have replaced the need for selective pulses with the use of broadband pulses. This may give a complex initial spectrum; however, a clean result can be simply obtained by modification of the phase cycle to select the desired pathway.