Detection of beta-blockers in human urine by GC-MS-MS-EI: perspectives forthe antidoping control

We have developed a general method for the detection of beta-blockers and/o r of their metabolites in human urine. The method comprises a pretreatment procedure (enzymatic hydrolysis, liquid/liquid extraction and derivatizatio n by pentafluoropropionic anhydride, PFPA), carried out on an initial aliqu ot of 2.5-5.0 mi of urine, and the instrumental analysis of the derivatives , performed by CC-MS-MS (ion trap) with electronic impact ionization (EI). The GC-MS-MS analysis allows to isolate and to characterize specific fragme nts of the original molecular structure, and particularly the fragments ori ginating from parent ion clusters specific for all beta blocking drugs, giv ing rise to m/z = 366 and 202 ions respectively. MS-MS analysis of the pare nt ion allows checking for the presence of the above-mentioned peaks in the CC-MS chromatogram. Thp proposed method is capable of detecting a great va riety of known (and possibly also of newly synthesized) beta-blockers, with an average sensitivity limit of 20 ng/ml of drug/metabolite in urine. The method is presently being evaluated as a general screening protocol to be f ollowed by an antidoping laboratory to detect illicit beta-blockers adminis tration to the athletes. (C) 2000 Elsevier Science B.V. All rights reserved .