Rapid isolation of benzodiazepines with Sep-Pak C18 cartridges

A rapid method for isolation of various benzodiazepines from human samples with Sep-Pak C18 cartridges before wide-bore capillary gas chromatography is described. The drugs dissolved in alkaline samples were directly applied to the cartridges and eluted with hexane/isopropanol (9:1). The recoveries were excellent for all drugs in urine samples, but were somewhat lower for some drugs in plasma samples. The latter problem could be easily circumvented by using a deproteinization process before their application to the cartridge. We can recommend the Sep-Pak C18 cartridges for isolation of benzodiazepines because of their simplicity and rapidity.