title: Determination of the plasma levels of metyrapone and its enantiomeric metyrapol metabolites by direct plasma injection and multidimensional achiral-chiral chromatography.
abstract: The development and validation of a direct injection high-performance liquid chromatographic (HPLC) method, with column switching, for the determination of metyrapol enantiomers and metyrapone in human plasma is described. The system used in this work was composed of a restricted access media (RAM) bovine serum albumin (BSA) octyl column coupled to an amylose tris(3,5-dimethoxyphenylcarbamate) chiral column. Water was used as eluent for the first 5 min at a flow rate of 1.0 ml/min for the elution of the plasma proteins and then acetonitrile-water (30:70 v/v) for the transfer and analysis of metyrapol enantiomers and metyrapone, which were detected by UV at lambda = 260 nm. The total analysis time was about 32 min. The calibration curves for each enantiomer and for the metyrapone were linear in the ranges 0.075-0.75 microg/ml and 0.150-1.50 microg/ml, respectively. Recoveries, intra- and interday precision and accuracy were determined using three quality controls, one low (0.18 microg/ml), one medium (0.75 microg/ml), and one high (1.35 microg/ml) plasma concentration. Quantitative recoveries and good precision and accuracy were obtained. The limit of quantitation were 0.045 microg/ml for both enantiomers and for the metyrapone.
authors.affiliation: Departamento de Química, Universidade Federal de São Carlos, SP, Brazil.
authors.forename: Neila M
authors.initials: NM
authors.lastname: Cassiano
authors.forename: Quezia B
authors.initials: QB
authors.lastname: Cass
authors.forename: Ana Luiza G
authors.initials: AL
authors.lastname: Degani
authors.forename: Irving W
authors.initials: IW
authors.lastname: Wainer
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000097:blood*; D006801:Humans; D008797:Metyrapone / Q000031:analogs & derivatives* / Q000097:blood*; D013237:Stereoisomerism
chemical_list: D004791:Enzyme Inhibitors; C002196:metyrapol; D008797:Metyrapone