Quantitative capillary electrophoresis-ion-trap mass spectrometry determination of methylphenidate in human urine

A quantitative capillary electrophoresis-mass spectrometry method has been demonstrated for the determination of methylphenidate in human urine over a dynamic range of 640. The samples were prepared by liquid-liquid extraction using 4 ml of human urine. The extracts were analyzed using a Finnigan LCQ ion-trap mass spectrometer in a two-event, positive-ion full-scan MS and tandem MS selected reaction monitoring mode. The lower level of quantitation was determined to be 1.5 ng/ml methylphenidate in human urine. The intra-assay precision had a relative standard deviation less than 6.8%. The intra-assay accuracy was less than +/-14.7% bias from the nominal concentration for the full-scan MS analysis, and less than +/-26.5% bias for the tandem MS analysis. Six incurred human urine samples containing methylphenidate were analyzed and a simple pharmacokinetic curve is presented.