Simultaneous Determination of Codeine and Morphine in Biological Samples by Gas Chromatography with Electron Capture Detection

Abstract
A sensitive gas chromatographic method for simultaneous determination of codeine and morphine in plasma and brain samples is described. It involves solvent extraction of compounds from plasma, derivatization with pentafluoropropionic anhydride and subsequent separation on a 3% OV-17 column. Quantification is performed with electron capture detection. Sensitivity of the method (0.75 ng of morphine and 7.5 ng of codeine in a sample) makes it especially useful for pharmacokinetic investigations. It was successfully applied to determine the time course of codeine and its metabolite morphine after i.v. codeine administration to the rat.