title: Ion-pair solid-phase extraction of cimetidine from plasma and subsequent analysis by high-performance liquid chromatography.
abstract: An improved method is described for the solid-phase extraction of cimetidine from plasma or serum with subsequent analysis by HPLC. New aspects of the method include protein precipitation with metaphosphoric acid (5%, w/v), followed by selective adsorption of cimetidine and the internal standard ranitidine on the surface of a solid-phase phenyl (PH Bond Elut) column, using octanesulfonate as an ion-pairing agent. Separation was achieved on a LiChrosorb RP-18 column with a mobile phase consisting of acetonitrile-0.01 M phosphate buffer pH 3.0 containing 0.005 M octanesulfonate (22:78, v/v). The intra-assay coefficient of variation varied between 0.7 and 4.0%. The procedure provides cleaner and more stable samples and a better recovery (90 +/- 2.3%) and sensitivity (limit of detection 5 ng/ml and limit of quantitation 25 ng/ml) as compared with previous methods.
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, University of Nijmegen, Netherlands.
authors.forename: F G
authors.initials: FG
authors.lastname: Russel
authors.forename: M C
authors.initials: MC
authors.lastname: Creemers
authors.forename: Y
authors.initials: Y
authors.lastname: Tan
authors.forename: P L
authors.initials: PL
authors.lastname: van Riel
authors.forename: F W
authors.initials: FW
authors.lastname: Gribnau
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002927:Cimetidine / Q000097:blood* / Q000302:isolation & purification; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012680:Sensitivity and Specificity
chemical_list: D002927:Cimetidine