Chromatographic determination of dissociation constants of pramipexole and its impurities
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The main goal in this investigation was monocratic HPLC determination of dissociation constant values (pK(a)) of pramipexole and its impurities, BI-II 546 CL, BI-II 751 xx and 2-aminobenzothiazole. The chromatographic method is advantageous as a small amount of substance is needed and the degree of substance purity is less important. Analysis was carried out using stationary phases stable in a wide pH range. Triethylamonium phosphoric buffer was selected as appropriate pH controlling solution because it can cover a wide pH range. Detection was done on two different wavelengths, 262 nm for pramipexole, BI-II 751 xx and 2-aminobenzothiazole and at 326 nm for BI-II 546 CL. The constants were calculated from the typical sigmoidal curves of analyte obtained as retention factor versus the pH of the mobile phase.
Keywords:column liquid chromatography / dissociation constants / impurities / pramipexole
Source:Chromatographia, 2007, 65, 9-10, 633-635
- Vieweg, Wiesbaden