Conference paper

https://doi.org/10.5599/admet.5.4.452

Solubility-pH profiles of a free base and its salt: sibutramine as a case study

Diego Lucero-Borja ; Institute of Biomedicine (IBUB) and Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona - Martí i Franquès, 1-11, 08028 Barcelona, Spain
Òscar Castilla ; Institute of Biomedicine (IBUB) and Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona - Martí i Franquès, 1-11, 08028 Barcelona, Spain
Rafael Barbas ; Polymorphism and Calorimetry Unit, Scientific and Technological Centers, Universitat de Barcelona – Travessera de Les Corts, 131-159, 08028 Barcelona, Spain
Xavier Subirats ; Institute of Biomedicine (IBUB) and Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona - Martí i Franquès, 1-11, 08028 Barcelona, Spain
Clara Ràfols ; Institute of Biomedicine (IBUB) and Department of Chemical Engineering and Analytical Chemistry, Universitat de Barcelona - Martí i Franquès, 1-11, 08028 Barcelona, Spain

Abstract

In the present study the solubility-pH profiles of sibutramine free base and its hydrochloride salt were determined in the pH range between 2.0 and 9.5 by means of the recommended shake-flask method, and the solids collected were dried and studied by X-ray diffraction in order to elucidate their free base or salt structure. Above pHmax (or Gibbs pKa) the solid collected was always identified as free base, whatever the sibutramine species (free base or hydrochloride salt) initially solved. However, in the pH range below pHmax different solids were isolated depending on the buffers employed.

Keywords

Buffer; free base; pH profile; potentiometry; salt; shake-flask, solubility

Hrčak ID:

191426

URI

https://hrcak.srce.hr/191426

Publication date:

24.12.2017.

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