Quantitative determination of morphine in biological samples by gas-liquid chromatography and electron-capture detection.

A highly sensitive method for the determination of morphine in plasma and brain samples down to 500 pg ml-1 in plasma and 100 pg in 30 mg of brain tissue is described. This sensitivity is in the range of that described for radioactive and radioimmunological tehcniques. The samples (50-500 mu-l) are extracted with toluene-butanol (9:1) at pH 8.9 and then re-extracted into 0.1 N sulphuric acid and back extracted to a toluene-butanol phase at pH 8.9. The pentafluoropropionic anhydride derivatives of morphine and the internal standard nalorphine were quantitatively determined by gas-liquid chromatography with a 3-H electron capture detector.