title: pH indicator titration: a novel fast pKa determination method.
abstract: This study describes a fast spectrophotometic titration method for apparent ionization constant (pKa) determination. In this method, a Universal pH indicator is utilized instead of the conventional pH electrode. An autoburette is set to add HCl at a constant rate to a vigorously stirred 1 cm UV cuvette which contains sample and indicator solution. A spectrophotometer continuously records the spectra. Acquired spectral data are processed by calculating the pH from the indicator spectra in the visible region and extracting sample spectra from the UV region. Five compounds possessing pKa values in the range 2-10 were investigated. These results differed from measurements by conventional spectrophotometric titration by +/-0.05 to +/-0.10 log unit.
authors.affiliation: Division of Pharmaceutical Science King's College London, Franklin-Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: Xiaole
authors.initials: X
authors.lastname: Kong
authors.forename: Tao
authors.initials: T
authors.lastname: Zhou
authors.forename: Zudong
authors.initials: Z
authors.lastname: Liu
authors.forename: Robert C
authors.initials: RC
authors.lastname: Hider
mesh_terms: D000577:Amides / Q000737:chemistry; D001557:Benzenesulfonates / Q000737:chemistry; D002867:Chromones / Q000737:chemistry; D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D000077543:Deferiprone; D006851:Hydrochloric Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000737:chemistry*; D008027:Light; D008956:Models, Chemical; D011728:Pyridones / Q000737:chemistry; D013053:Spectrophotometry / Q000295:instrumentation; D013056:Spectrophotometry, Ultraviolet
chemical_list: C470209:3-hydroxy-2-(5-hydroxypentyl)chromen-4-one; D000577:Amides; D001557:Benzenesulfonates; D002867:Chromones; D007202:Indicators and Reagents; D011728:Pyridones; D000077543:Deferiprone; D006851:Hydrochloric Acid