title: Novel precolumn deproteinization method using a hydroxyapatite cartridge for the determination of theophylline and diazepam in human plasma by high-performance liquid chromatography with ultraviolet detection.
abstract: The deproteinization of human plasma was carried out using a hydroxy apatite cartridge as a precolumn. After human plasma had been passed through the cartridge followed by suitable elution, protein-free eluate was obtained within only 1 min without the need for centrifugation. Deproteinization was evaluated by the determination of albumin, gamma-globulin and transferrin in the eluate by high-performance liquid chromatography (HPLC) with UV detection. Determination of theophylline and diazepam in human plasma was performed by HPLC with UV detection. The proposed method was suitable for the determination of these two drugs in human plasma, because it is simple and rapid (retention time of each drugs approximately 15 min) and microamounts of sample are required (50-100 microliters). The calibration graphs for theophylline and diazepam were linear in the range 0.1-10 micrograms and 0.1-65 ng, respectively. Recoveries of both drugs were over 90% by the standard addition method.
authors.affiliation: Ajinomoto Co., Inc., Central Research Laboratories, Kawasaki, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Iwase
authors.forename: K
authors.initials: K
authors.lastname: Gondo
authors.forename: T
authors.initials: T
authors.lastname: Koike
authors.forename: I
authors.initials: I
authors.lastname: Ono
mesh_terms: D000418:Albumins / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003975:Diazepam / Q000097:blood*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites; D007202:Indicators and Reagents; D013056:Spectrophotometry, Ultraviolet; D013806:Theophylline / Q000097:blood*; D014168:Transferrin / Q000032:analysis; D005719:gamma-Globulins / Q000032:analysis
chemical_list: D000418:Albumins; D006882:Hydroxyapatites; D007202:Indicators and Reagents; D014168:Transferrin; D005719:gamma-Globulins; D013806:Theophylline; D003975:Diazepam