title: Methods to reduce background interferences in electron-capture gas chromatographic analysis of valproic acid and its unsaturated metabolites after derivatization with pentafluorobenzyl bromide.
abstract: Analysis of the branched, medium-chain fatty acid anticonvulsant, valproic acid, and its unsaturated metabolites by gas chromatography with electron-capture detection suffered from background interference caused by the derivatizing reagent pentafluorobenzyl bromide. Background was reduced by keeping the derivatization anhydrous, using an inert solvent, minimizing the amount of pentafluorobenzyl bromide, using hypernucleophilic bases and displacing the derivatization solvent with isooctane. However, these strategies proved difficult to reproduce. Post-derivatization clean-up with HPLC was much more reliable and provided sufficient sensitivity for the analysis of extracts of plasma and brain homogenate. The assay was validated for plasma and brain samples from humans, rats and mice.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle 98195, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Dills
authors.forename: D D
authors.initials: DD
authors.lastname: Shen
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000032:analysis* / Q000097:blood / Q000378:metabolism; D001923:Brain Chemistry; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005464:Fluorobenzenes; D006801:Humans; D051381:Rats; D015203:Reproducibility of Results; D014635:Valproic Acid / Q000032:analysis* / Q000097:blood / Q000378:metabolism; D005466:Fluorocarbons
chemical_list: D000927:Anticonvulsants; D005464:Fluorobenzenes; D014635:Valproic Acid; C025063:pentafluorobenzyl bromide; D005466:Fluorocarbons