Gas-chromatographic analysis for cocaine in human plasma, with use of a nitrogen detector.

We describe a procedure for measuring the concentration of cocaine in plasma by gas chromatography, with use of a nitrogen detector. The procedure was tested on patients receiving intranasal cocaine for topical anesthesia. The propyl ester of benzoylecgonine is used as an internal standard. The lower limit of sensitivity of the procedure is 5--10 mug of cocaine per liter of plasma. The coefficients of variation are 5.3% and 3.0% for concentrations of 50 and 100 mug/liter, respectively.