On electrophoretic NMR. Exploring high conductivity samples

•A new pulse sequence for electrophoretic NMR.•Error introduced by flow caused by thermal gradient and electroosmosis is suppressed.•Accurate electrophoretic mobilities are obtained without uncharged reference molecules.•Demonstrated by 1H and 19F experiments on the cation and the anion, respectively, of a salt solution.

The performance of a new electrophoretic NMR (eNMR) method that uses a Carr-Purcell-Meiboom-Gill echo train with repeated electric field reversal is investigated. We show that this pulse sequence, with acronym CPMGER, yields strongly reduced artifacts from convective flow effects caused by the simultaneous presence of electroosmotic and thermal driving forces. We demonstrate the achieved improvements in various aqueous solutions. Ultimately, the method can be used for obtaining electrophoretic mobilities by eNMR without relying on uncharged reference molecules, otherwise a significant limitation for electrophoretic experiments performed with nuclei other than 1H.

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