title: Liquid-chromatographic quantification compared with gas-chromatographic-mass-spectrometric determination of verapamil and norverapamil in plasma.
abstract: A high-performance liquid chromatographic (HPLC) method for determining verapamil and norverapamil in plasma is presented and compared with gas chromatography/mass spectrometry (GC-MS). The plasma samples were extracted at alkaline pH with hexane containing 2-butanol (20 mL/L) and then back-extracted into phosphate buffer (0.1 mol/L, pH 3.0). For chromatography we used a reversed-phase column (Supelcosil LC-18 DB) with a mobile phase of the phosphate buffer and acetonitrile (70/30 by vol). Fluorescence detection was used (excitation at 203 nm, emission at 320 nm). Overall analytical recovery was 85%. Standard curves were linear from 1 to 1000 micrograms/L. The detection limit was 1 microgram/L. The assays are accurate and precise. We found no interferences by those substances tested. Results by HPLC and GC-MS agreed well (r = 0.99) for both verapamil and norverapamil determinations.
authors.affiliation: Department of Clinical Pharmacology, Karolinska Hospital, Stockholm, Sweden.
authors.forename: P A
authors.initials: PA
authors.lastname: Hynning
authors.forename: P
authors.initials: P
authors.lastname: Anderson
authors.forename: U
authors.initials: U
authors.lastname: Bondesson
authors.forename: L O
authors.initials: LO
authors.lastname: Boréus
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D006863:Hydrogen-Ion Concentration; D014700:Verapamil / Q000031:analogs & derivatives* / Q000097:blood*
chemical_list: C016904:norverapamil; D014700:Verapamil