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Published on: November 12, 2016
Determination of pKa values of organic bases in aqueous acetonitrile solutions using capillary electrophoresis
Stephan M C Buckenmaier1, David V McCalley, Melvin R Euerby
1Centre for Research in Analytical Methods and Sensors, University of the West of England, Frenchay, Bristol BS16 1QY, UK.
Abstract:
Capillary electrophoresis (CE) was used for the determination of ionisation constants (pKa) of a variety of organic bases in aqueous acetonitrile solutions over the range 0-60% (v/v) acetonitrile. These bases are used as test compounds in HPLC column evaluation, thus knowledge of their pKa in hydro-organic solutions is useful. The base pKa decreased with acetonitrile concentration and significant shifts from the aqueous pKa (up to -0.8) were found using 60% acetonitrile. The CE application was confirmed to be very suitable for fast and accurate pKa measurement in aqueous organic solutions.
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