Simultaneous quantitation of ephedrines in urine by gas chromatography–nitrogen–phosphorus detection for doping control purposes

A gas chromatographic method for the simultaneous quantitation of ephedrine, pseudoephedrine, norephedrine (phenylpropanolamine), norpseudoephedrine (cathine) and methylephedrine in urine is described. The method consists of a liquid–liquid extraction with tert.-butyl methyl ether at pH 14. The extracts are analysed on a GC system equipped with an Rtx-5 Amine column and a nitrogen–phosphorus detector. Method validation shows excellent separation, linearity, specificity, accuracy, precision, intra-laboratory repeatability and reproducibility, making the method especially suitable for quantitation of ephedrines in urine samples for doping control purposes. A statistical analysis on the abuse of the different ephedrines in urine from athletes controlled in the Flemish doping control laboratory during the period 1993–2000 is included.