title: Use of potentiometric detection in (ultra) high performance liquid chromatography and modelling with adsorption/desorption binding kinetics.
abstract: 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 ΔG 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 koff was unaffected by miniaturization. Increasing acetonitrile concentrations in the running buffer increased k(off), while k(on) was unaffected. The experimentally determined ΔG values of the analyte-surface interaction showed a linear relation to the response of the sensor, in mV. 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.
authors.affiliation: University of Antwerp, Department of Chemistry, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Daems
authors.forename: G
authors.initials: G
authors.lastname: Van Camp
authors.forename: M
authors.initials: M
authors.lastname: Fernandez
authors.forename: Y
authors.initials: Y
authors.lastname: Guisez
authors.forename: E
authors.initials: E
authors.lastname: Prinsen
authors.forename: L J
authors.initials: LJ
authors.lastname: Nagels
mesh_terms: D000097:Acetonitriles / Q000032:analysis; D000327:Adsorption; D000470:Alkaloids / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003042:Cocaine / Q000032:analysis; D004144:Diosgenin / Q000032:analysis; D007700:Kinetics; D008711:Metergoline / Q000032:analysis; D008956:Models, Chemical; D010208:Papaverine / Q000032:analysis; D010944:Plants / Q000737:chemistry; D011199:Potentiometry / Q000295:instrumentation
chemical_list: D000097:Acetonitriles; D000470:Alkaloids; D008711:Metergoline; D010208:Papaverine; D003042:Cocaine; D004144:Diosgenin; C013255:solanidine; C032159:acetonitrile