Electrodeless, accurate pH determination in highly basic media using a new set of 1H NMR pH indicators

Gábor Orgován, Béla Noszál

Research output: Contribution to journalArticle

44 Citations (Scopus)


A set of indicator molecules was selected and applied to elaborate an NMR-based pH determination method, free of glass electrode errors in highly basic media. Accurate measurement of pH values and protonation constants was achieved by a successive build-up of overlapping, increasingly high pH solutions, using a collection of 8 compounds of appropriately incremented basicities.In order to verify the method, acid-base properties were quantified for two compounds with very high basicities in conflicting reports: two pharmaceutically important biguanidine drugs, metformin and phenformin.

Original languageEnglish
Pages (from-to)958-964
Number of pages7
JournalJournal of Pharmaceutical and Biomedical Analysis
Issue number5
Publication statusPublished - Apr 5 2011



  • Electrodeless pH determination
  • Highly basic media
  • Metformin
  • NMR-pH indicator
  • Protonation constant

ASJC Scopus subject areas

  • Analytical Chemistry
  • Pharmaceutical Science
  • Drug Discovery
  • Spectroscopy
  • Clinical Biochemistry

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