Determination of ephedrines in urine by gas chromatography-mass spectrometry

A selective gas-liquid chromatographic method with mass spectrometry (GC-MS) for the simultaneous confirmation and quantification of ephedrine, pseudo-ephedrine, nor-ephedrine, nor-pseudoephedrine, which are pairs of diastereoisomeric sympathomimetic amines, and methyl-ephedrine was developed for doping control analysis in urine samples. O-Trimethylsilylated and N-mono-trifluoroacetylated derivatives of ephedrines--one derivative was formed for each ephedrine--were prepared and analyzed by GC-MS, after alkaline extraction of urine and evaporation of the organic phase, using d3-ephedrine as internal standard. Calibration curves, with r2>0.98, ranged from 3.0 to 50 microg/ml depending on the analyte. Validation data (specificity, % RSD, accuracy, and recovery) are also presented.