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Determination of Acidity Constants by the Capillary Electrophoresis Internal Standard Method. IV. Polyprotic Compounds

Determination of Acidity Constants by the Capillary Electrophoresis Internal Standard Method. IV. Polyprotic Compounds

Joan Marc Cabot, Elisabet Fuguet, Clara Ràfols, Martí Rosés

J Chromatogr A. 2013 Mar 1;1279:108-16.

PMID: 23357751

Abstract:

The IS-CE method is developed for pK(a) determination of polyprotic compounds. In this method, the internal standard (IS) and the polyprotic test compound are injected into the capillary electrophoresis (CE) system in buffers with appropriate pH. The pH of the buffers is not externally measured, but determined inside the capillary from the mobilities of the internal standards. Then the pK(a) values of the polyprotic compounds are obtained by fitting its mobilities to the in situ pH values. The method is faster than the classical CE method (a diprotic compound can be done in less than 15 min), and also than other methods like potentiometric and spectrophotometric titrations. The method has been successfully applied to 20 polyprotic test compounds of different chemical nature, including compounds with extreme or very close pK(a) values.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AS212791	Acidity Standard			Price

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