Rapid Determination of Diuretics in Human Urine by Gas Chromatography – Mass Spectrometry Following Microwave Assisted Derivatization

This work presents a GC–MS–MS–MS method for the direct determination of clenbuterol in human urine. The method 3 comprises a pretreatment procedure and the instrumental analysis of the derivatives performed by GC–MS (ion trap) with 3 electron impact ionization. The GC–MS analysis allows isolation and characterization of specific fragments from the 1 original (MS ) molecular structure, and in particular, those fragments originating from the precursor ion cluster (m/z5335– 2 337) characteristic of clenbuterol. The MS product fragment m/z5300 is in turn used as a further precursor fragment 3 4 giving rise to a MS spectrum specific for clenbuterol. MS fragmentation spectra were also investigated. However, further 3 4 fragmentation of MS product ions does not lead to functional MS spectra nor to any significant increase in the 3 signal-to-noise ratio. The sensitivity limit of the MS technique is lower than 0.2 mg/ l, with a linear range between 0.5 and 5 mg/ l, thus matching the basic requirements for antidoping analysis according to the guidelines of the International Olympic Committee. Due to its overall analytical performance, the method is presently being evaluated as a confirmation protocol to be followed to detect illicit clenbuterol administration to the athletes, and compared with reference GC–MS and GC–MS–MS techniques.