@article {Easterling:February 1986:0724-8741:45,
	author = "Easterling D.E.",
	author = "deTorres W.R.",
	author = "Desiraju R.K.",
	title = "Determination of Codeine in Plasma by High-Performance Liquid Chromatography",
	journal = "Pharmaceutical Research",
	volume = "03",
	year = "February 1986",
	abstract = "<P>An automated, sensitive, and selective reverse-phase high-performance liquid chromatographic assay has been developed to measure codeine in plasma. The analysis requires only 1 ml plasma and is accomplished by detection of the fluorescence of codeine following extraction and concentration. The method is simple and rapid, involving a one-step extraction of codeine from alkalinized (pH 10.0) plasma into an organic layer of hexane/dichloromethane, 2/1. The organic layer was evaporated under nitrogen and the residue reconstituted with the mobile phase. The samples were chromatographed on a reverse-phase C-18 column using a mobile phase of acetonitrile&#150;phosphate buffer, 80/20 (pH 5.80). The codeine and internal standard, <I>N</I>-allylnorcodeine, peaks were detected using a fluorescence detector. The retention times were 8.6 min for the internal standard and 11.3 min for codeine. Standard curves were linear from 10 to 250 ng/ml. The assay was validated by direct comparison with a gas chromatographic procedure that employed nitrogen&#150;phosphorus detection. The assay has been employed for the analysis of several codeine studies using human, dog, and rat plasma.</P>",
	pages = "45-47(3)",
	url = "http://www.ingentaconnect.com/content/klu/pham/1986/00000003/00000001/00306432"
}