Determination of plasma cocaine and ethylcocaine (cocaethylene) in mice using gas chromatography—mass spectrometry and deuterated internal standards

A gas chromatographic—mass spectrometric method is described for the determination of cocaine and ethylcocaine (cocaethylene) from mouse plasma microsamples (50 μl). ²H₃]Cocaine and ²H₅]ethylcocaine served as internal standards, analytical separations were performed on a (5% phenyl)methylpolysiloxane capillary column, and detection was by selected-ion monitoring of electron-impact generated fragment ions M --- CO₂Ph]. Pilot study plasma concentrations of ethylcocaine following coadministration of cocaine and ethanol were less than 5% of the parent drug.