title: Identification of the long-acting erythropoiesis-stimulating agent darbepoetin alfa in human urine by liquid chromatography-tandem mass spectrometry.
abstract: The misuse of recombinant human erythropoietin (rhEPO) increases the proliferation/production of erythrocytes, which enhance oxygen transport capacities, and has grave consequences with respect to human health and fairness in sports. For sports drug testing, the current analytical methods for rhEPOs are mainly gel electrophoretic methods, such as isoelectric focusing-polyacrylamide gel electrophoresis. Mass spectrometry is fundamentally necessary for the reliable identification of rhEPOs in doping control. In this study, a high-sensitivity and high-throughput mass spectrometric qualitative detection method for darbepoetin alfa in human urine was established by a bottom-up approach. The novel method involves the immunopurification of human urine (10 mL), protease digestion with endoproteinase Glu-C (V8-protease) in an ammonium bicarbonate buffer (pH 7.8) and ultra-performance liquid chromatography using a charged surface hybrid C18 column coupled with electrospray-ionisation high-sensitivity tandem mass spectrometry for improved selectivity of the target molecules. The specific fragment digested from darbepoetin alfa was (90)TLQLHVDKAVSGLRSLTTLLRALGAQKE(117) (V11). The lower limit of detection of urinary darbepoetin alfa was 1.2 pg/mL. The limit of detection for the confirmation analysis was estimated to be 5 pg/mL. The developed method allows high-throughput confirmation analysis, namely 6 h for sample preparation and an analytical run time of only 10 min per sample; this high-throughput method dramatically decreases the workload in the laboratory. Darbepoetin alfa could be identified in human urine collected after the intravenous administration of 15 μg darbepoetin alfa (n = 3). This mass spectrometric method is an innovative and powerful tool for detecting darbepoetin alfa in human urine for doping control testing.
authors: Anti-doping Laboratory, Mitsubishi Chemical Medience Corporation, 3-30-1 Shimura, , Itabashi-ku, Tokyo, 174-8555, Japan, okano.masato@mk.medience.co.jp.
authors: Masato
authors: M
authors: Okano
authors: Mitsuhiko
authors: M
authors: Sato
authors: Shinji
authors: S
authors: Kageyama
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D000068256:Darbepoetin alfa; D004920:Erythropoiesis / Q000187:drug effects*; D004921:Erythropoietin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000652:urine; D057166:High-Throughput Screening Assays; D006801:Humans; D057230:Limit of Detection; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis; D058573:Performance-Enhancing Substances / Q000008:administration & dosage / Q000652:urine*; D012697:Serine Endopeptidases / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013177:Sports
chemical_list: D002021:Buffers; D010446:Peptide Fragments; D058573:Performance-Enhancing Substances; D004921:Erythropoietin; D000068256:Darbepoetin alfa; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase