1. Center for Preventive Doping Research—Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany
2. Department of Chemistry, University of Cologne, Greinstraße 4, 50939 Cologne, Germany
3. Moscow Anti-Doping Center, Elizavetinsky per. 10, 105005 Moscow, Russia
4. Department of Chemistry and Biochemistry, University of California Los Angeles, Paul D. Boyer Hall (MBI), 611 Charles E. Young Drive East, Los Angeles, 90095-1570, CA, USA