Use of potentiometric detection in (ultra) high performance liquid chromatography and modelling with adsorption/desorption binding kinetics
Faculty of Sciences. Biology
Faculty of Sciences. Chemistry
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences . Biomedical Sciences
Analytica chimica acta. - Amsterdam
, p. 25-31
University of Antwerp
Observation of a potentiometric sensor's response behaviour after injection in flow injection analysis at different concentrations allowed studying "on" and "off" kinetics of the analyte's adsorption/diffusion behaviour. The alkaloid metergoline was mostly used as an example. k(on) and k(off) rate constant values were measured, and the association constant K-ass, and Delta G values of the analyte-surface interaction were calculated with an adsorption-based model which proved to be fully applicable. k(on) increased by decreasing the sensor dimensions, while k(off) was unaffected by miniaturization. Increasing acetonitrile concentrations in the running buffer increased k(off), while k(on) was unaffected. The experimentally determined Delta G values of the analyte-surface interaction showed a linear relation to the response of the sensor, in my. This knowledge was applied to optimize the potentiometric detection of plant alkaloids in (U)HPLC. Sub-micromolar detection limits were obtained with the potentiometric detector/(U)HPLC combination. This is the first time that the response rates and the response itself can be modelled accurately for coated wire potentiometric sensors, and it is the first application of a potentiometric detector in UPLC. (C) 2013 Elsevier B.V. All rights reserved.