title: Use of direct injection precolumn techniques for the high-performance liquid chromatographic determination of the retinoids acitretin and 13-cis-acitretin in plasma.
abstract: A previously developed highly sensitive high-performance liquid chromatographic method for the determination of retinoids, using direct injection of large plasma volumes, on-line solid-phase extraction and ultraviolet detection, was improved and fully validated for the determination of acitretin and 13-cis-acitretin in plasma samples. The addition of acetonitrile to improve the recovery was performed on-line by a T-piece, avoiding any cis-trans isomerization which could occur when acetonitrile was added prior to storage in the autosampler. About 30 injections could be made onto one precolumn despite the large injection volume (1 ml of plasma containing the internal standard). Full automation was attained by the use of automated precolumn replacement. In addition, forward- and back-flush purging of the precolumn enhanced the longevity of the analytical column. This consisted of three coupled C18 columns of 125 mm length each. The quantification limit was 0.3 ng/ml, using ultraviolet detection at 360 nm, and the mean inter-assay precision was 3.8% for the two compounds.
authors.affiliation: Pharma Division, Preclinical Research, F. Hoffmann-La Roche Ltd, Basle, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Wyss
authors.forename: F
authors.initials: F
authors.lastname: Bucheli
mesh_terms: D017255:Acitretin; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D014212:Tretinoin / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014212:Tretinoin; D017255:Acitretin