title: IRMS detection of testosterone manipulated with 13C labeled standards in human urine by removing the labeled 13C.
abstract: Isotope ratio mass spectrometry (IRMS) is applied to confirm testosterone (T) abuse by determining the carbon isotope ratios (δ(13)C value). However, (13)C labeled standards can be used to control the δ(13)C value and produce manipulated T which cannot be detected by the current method. A method was explored to remove the (13)C labeled atom at C-3 from the molecule of androsterone (Andro), the metabolite of T in urine, to produce the resultant (A-nor-5α-androstane-2,17-dione, ANAD). The difference in δ(13)C values between Andro and ANAD (Δδ(13)CAndro-ANAD, ‰) would change significantly in case manipulated T is abused. Twenty-one volunteers administered T manipulated with different (13)C labeled standards. The collected urine samples were analyzed with the established method, and the maximum value of Δδ(13)CAndro-ANAD post ingestion ranged from 3.0‰ to 8.8‰. Based on the population reference, the cut-off value of Δδ(13)CAndro-ANAD for positive result was suggested as 1.2‰. The developed method could be used to detect T manipulated with 3-(13)C labeled standards.
authors.affiliation: National Anti-Doping Laboratory, China Anti-Doping Agency, Beijing, China. Electronic address: wangjingzhu@chinada.cn.
authors.forename: Jingzhu
authors.initials: J
authors.lastname: Wang
authors.affiliation: Sport Science College, Beijing Sport University Beijing, Beijing, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Yang
authors.affiliation: School of Pharmacy, Beijing University of Chinese Medicine, Beijing, China.
authors.forename: Wenning
authors.initials: W
authors.lastname: Yang
authors.affiliation: National Anti-Doping Laboratory, China Anti-Doping Agency, Beijing, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: National Anti-Doping Laboratory, China Anti-Doping Agency, Beijing, China.
authors.forename: Yanyi
authors.initials: Y
authors.lastname: Xing
authors.affiliation: National Anti-Doping Laboratory, China Anti-Doping Agency, Beijing, China.
authors.forename: Youxuan
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000328:Adult; D002247:Carbon Isotopes / Q000652:urine; D006801:Humans; D057230:Limit of Detection; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D015813:Substance Abuse Detection / Q000379:methods; D013739:Testosterone / Q000652:urine*; D055815:Young Adult
chemical_list: D002247:Carbon Isotopes; D013739:Testosterone
keywords: (13)C labeled standard; Doping control; Isotope ratio mass spectrometry; Manipulated testosterone