title: Development and validation of an LC-MS/MS method for the quantification of ephedrines in urine.
abstract: The objective of this study was to develop a simple and robust LC-MS/MS method for the quantification of ephedrine type substances in urine. Sample preparation consisted of a 10-fold dilution step of the samples into the internal standard solution (ephedrine-d(3), 4 microg/mL in water). Baseline separation of the diastereoisomers norpseudoephedrine-norephedrine and ephedrine-pseudoephedrine was performed on a C8-column using isocratic conditions followed by positive electrospray ionisation and tandem mass spectrometric detection. The mobile phase consisted of 98/2 (H(2)O/ACN) containing 0.1% HAc and 0.01% TFA. Calibration curves were constructed between 2.5 and 10 microg/mL for norephedrine and norpseudoephedrine and 5 and 20 microg/mL for ephedrine, pseudoephedrine and methylephedrine. The bias ranged from -5.5 to 12% for norephedrine, -4.1 to 8.0 % for norpseudoephedrine, 0.3 to 2.1 % for ephedrine, 1.6 to 2.6 % for pseudoephedrine and 2.9 to 5.0 % for methylephedrine. Precision of the method varied between 2.8 and 10.4% for all compounds and the matrix effect was less than 15%. The applicability of the method has been checked by the analysis of 40 urine samples. The results were compared with those obtained with the common GC-NPD method. Results show a good correlation between both methods with correlation coefficients higher than 0.95 for all analytes.
authors.affiliation: DoCoLab, UGent, Department of Clinical Chemistry, Microbiology and Immunology, Technologiepark 30, B-9052 Zwijnaarde, Belgium. Koen.Deventer@UGent.be
authors.forename: K
authors.initials: K
authors.lastname: Deventer
authors.forename: O J
authors.initials: OJ
authors.lastname: Pozo
authors.forename: P
authors.initials: P
authors.lastname: Van Eenoo
authors.forename: F T
authors.initials: FT
authors.lastname: Delbeke
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D004809:Ephedrine / Q000652:urine*; D006801:Humans; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D004809:Ephedrine