[Simultaneous determination of ephedrine and N-methylephedrine in urine by solid phase extraction-ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry].

A rapid and sensitive method has been developed for the simultaneous determination of ephedrine and N-methylephedrine in urine samples by solid phase extraction-ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (SPE-UPLC-ESI MS/MS). The samples were extracted with Oasis MCX solid phase extraction cartridges and measured in the modes of electrospray positive ionization (ESI +) and multiple reaction monitoring (MRM). Good linearities were observed in the range of 0.025 0 - 2.50 microg/L with correlation coefficient over 0.999 0 for both analytes. The recoveries were above 80% with RSDs less than 5.0%. The limits of detection were 0.01 microg/L. The method proves to be rapid and sensitive for the trace determination of ephedrine and N-methylephedrine in urine samples.