title: Analysis of low-dose benzodiazepines by HPLC with automated solid-phase extraction.
abstract: We describe a simple, specific, and sensitive reversed-phase HPLC method with automated solid-phase extraction (SPE) for analyzing alprazolam, clonazepam, and nitrazepam concentrations in human serum or plasma. We prepare samples and calibrators with an automated sample preparer, using 100-mg Bond-Elut C18 SPE columns. The HPLC method uses isocratic elution with acetonitrile:methanol:dipotassium hydrogen phosphate, 10 nmol/L, pH 3.7 (30:2:100 by vol), at a flow rate of 1.5 mL/min to separate the drugs. We detect the benzodiazepines with diode-array detector at 240 nm; analyses of peak purity are performed at 210-365 nm. The recoveries were between 94% and 100%. The intraassay and interassay CVs were between 1.0% and 4.1%. The detection limit is 5 nmol/L. The antiepileptic and antidepressant drugs tested did not interfere with the assay. We developed the method for use in a clinical laboratory for therapeutic drug monitoring.
authors.affiliation: Department of Clinical Chemistry, Kuopio University Hospital, Finland. Kari.okerman@messi.uku.fi
authors.forename: K K
authors.initials: KK
authors.lastname: Akerman
authors.forename: J
authors.initials: J
authors.lastname: Jolkkonen
authors.forename: M
authors.initials: M
authors.lastname: Parviainen
authors.forename: I
authors.initials: I
authors.lastname: Penttilä
mesh_terms: D000525:Alprazolam / Q000097:blood; D000928:Antidepressive Agents / Q000097:blood; D001331:Automation; D001569:Benzodiazepines / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000191:economics / Q000379:methods*; D002998:Clonazepam / Q000097:blood; D006801:Humans; D009567:Nitrazepam / Q000097:blood; D010640:Phenothiazines / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D000928:Antidepressive Agents; D010640:Phenothiazines; D001569:Benzodiazepines; D002998:Clonazepam; D009567:Nitrazepam; D000525:Alprazolam