Dear NMR experts,
I am looking for a reference with information on the dependence of the chemical shift of typical NMR solvents if varying amounts of acid (e.g. HCl, TFA, MSA...) are present in solutions? Thanks in advance for any hint.
Alfred
P.S. normally one can't see this pH effect due to locking, but if NMR data are measured without lock it is easily seen.
Don't know much but here are some potentially helpful references:
1) https://www.researchgate.net/post/Does_presence_of_acids_impact_the_position_of_H2O_peak_in_1H_NMR_spectrum
2) https://www.researchgate.net/post/Does_pH_influences_the_NMR_chemical_shift_of_31P_And_if_it_is_the_case_how_strong_is_this_influence
3) Article A pH-enhanced resolution in benchtop NMR spectroscopy
Dear Mikhail,
thanks for looking into my question. The references you provide are related to the topic, but do not answer my question.
I am looking for the consequence of presence of Acid contaminants on the solvent (also used for locking) itself and not for analytes. If the spectrometer is locked to a solvent (which may/does have a pH dependency) all chemical shifts of any analyte will shift as well. Therefore for pH titrations one needs to know the dependence of shift of the solvent to separate shifts of analytes from the shift of the solvent. This problem is traditionally resolved by adding a chemcial shift reference (TSP, DSS,...), but unfortunately these may have a pH dependence as well....you see - quite a tricky question...
Thanks again
Alfred
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