I am looking for somebody who has experience in the use of 33S solid-state NMR for the determination of the protonation state of a sulphate counterion of a "salt" of a drug molecule in a formulated solid state. Is this at all possible?
Related question: are there vendors for 33S labelled sulphate? Any ideas on price?
Thanks for any comment/idea/answer.
There is a report on natural abundance 33S NMR solid-state NMR to differentiate potassium sulfate salts:
http://pubs.acs.org/doi/full/10.1021/jp908206c
You would probably expect a change in the quadrupolar coupling of the 33S nucleus due to additional asymmetry upon protonation. The degree probably depends on the counterion- if the immediate environment of the sulfate is already asymmetrical due to the counterion the change upon protonation will probably be less. However, I've never done it and I don't know know anyone who has. You may try reposting with the solid-state NMR tag or just email Prof. Ripmeester directy ( http://johnripmeester.ca/ )
Sigma sells 33S sulfate
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