title: Development and validation of a sensitive assay of valproic acid in human plasma by high-performance liquid chromatography without prior derivatization.
abstract: Sensitive and selective determination of valproic acid in plasma by high-performance liquid chromatography (HPLC) is usually achieved with pre-column derivatization. In the present work, the derivatization is omitted due to using a simple but highly selective plasma extraction procedure and an optimized chromatographic condition. Valproic acid and the internal standard octanoic acid were extracted from plasma samples with n-hexane under acidic condition followed by back-extraction into diluted triethylamine. Chromatography was performed on a CN column (250 x 4.6 mm, 5 microm) under isocratic elution with acetonitrile-40 mM aqueous sodium dihydrogen phosphate (30:70, v/v), pH 3.5. Detection was made at 210 nm and analyses were run at a flow-rate of 1 ml/min. The method was specific and sensitive with a quantification limit of 1.25 microg/ml and a detection limit of 0.1 microg/ml in plasma. The mean absolute recovery for valproic acid using the present plasma extraction procedure was 75.8%. The intra- and inter-day coefficient of variation and percent error values of the assay method were all in acceptable range. Calibration curves were linear (r>0.999) from 1.25 to 320 microg/ml in plasma.
authors.affiliation: Department of Pharmacology, Neuroscience Research Center, Shaheed Beheshti University of Medical Sciences, P.O. Box 19835-355, Tehran, Iran. hamini@sbmu.ac.ir
authors.forename: Hossein
authors.initials: H
authors.lastname: Amini
authors.forename: Mohammad
authors.initials: M
authors.lastname: Javan
authors.forename: Abolhassan
authors.initials: A
authors.lastname: Ahmadiani
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results; D014635:Valproic Acid / Q000097:blood* / Q000592:standards
chemical_list: D014635:Valproic Acid