title: On-line radiometric determination of [14C]-urapidil and its main metabolises in rat plasma, using post-column ion-pair extraction and solvent segmentation techniques.
abstract: Post-column ion-pair extraction has been applied to the on-line radiometric determination of [(14)C]-urapidil and its main metabolises in reversed-phase liquid chromatography (LC). [(14)C]-remoxipride was used as internal standard. Chromatography was performed isocratically, using acetonitrile-water (pH = 2.2) as eluent on a cyanobonded column. Various ion-pair reagents were tested for their extraction efficiency of the analytes mentioned from the eluent into chloroform. Quantitative extraction was possible using sodium dodecylbenzenesulphonate as ion-pair reagent. The influence of the extraction solvent composition, the percentage organic modifier in the eluent and the flow-rates of eluent and scintillator on the extraction percentage and the (14)C-counting efficiency has been studied. In addition, the enhancement of sensitivity is possible using an on-line radiometric procedure. Finally, the method has been applied to the analysis of rat plasma for [(14)C] -labelled urapidil and its metabolises.
authors.affiliation: Netherlands Energy Research Foundation, Westerduinweg 3, 1755 LE Pettell, The Netherlands.
authors.forename: A C
authors.initials: AC
authors.lastname: Veltkamp
authors.forename: H A
authors.initials: HA
authors.lastname: Das
authors.forename: R W
authors.initials: RW
authors.lastname: Frei
authors.forename: U A
authors.initials: UA
authors.lastname: Brinkman