{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T22:57:11Z","timestamp":1790549831473,"version":"4.1.0"},"reference-count":23,"publisher":"Wiley","license":[{"start":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T00:00:00Z","timestamp":1790467200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T00:00:00Z","timestamp":1790467200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["analyticalsciencejournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Drug Testing and Analysis"],"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>A method compliant with World Anti\u2010Doping Agency (WADA) requirements was validated for carbon isotope ratio (CIR) analysis enabling the simultaneous confirmation of 6\u2010oxo\u2010androstenedione (6\u2010oxo) metabolites and testosterone steroid profile markers from a single urine sample aliquot. The approach allows differentiation between endogenous and exogenous steroid origins when 6\u03b1\u2010hydroxy\u2010androst\u20104\u2010ene\u20103,17\u2010dione (6\u03b1\u2010OH), a marker of misuse of 6\u2010oxo or testosterone prohormones, is detected in athlete samples. CIR analysis is laborious and usually requires large sample volumes. Therefore, this study aimed to validate a method capable of simultaneously performing both confirmations from a single sample aliquot. Based on a previously validated method for testosterone confirmation, 6\u03b1\u2010OH, its 6\u03b2\u2010epimer, and 6\u2010oxo were included and validated as markers of 6\u2010oxo intake. The proposed method, anchored in two liquid\u2010chromatography clean\u2010up steps, yielded peaks of adequate purity, negligible isotopic fractionation, and amplitudes suitable for CIR steroid analysis within typical linear ranges. Limits of quantification were 5.0\u2009ng\/mL for 6\u03b1\u2010 and 6\u03b2\u2010OH and 15\u2009ng\/mL for 6\u2010oxo, with combined uncertainties of 0.6\u2030, 0.5\u2030 and 0.4\u2030, respectively. Application to authentic samples demonstrated the method's fitness for purpose in differentiating negative from positive samples. Overall, the outcomes show that all WADA method validation requirements were met and that the proposed strategy for simultaneous CIR analysis of 6\u2010oxo and testosterone markers in a single analytical workflow was successful.<\/jats:p>","DOI":"10.1002\/dta.70157","type":"journal-article","created":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T22:45:36Z","timestamp":1790549136000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Single\u2010Aliquot Strategy for Simultaneous Carbon Isotope Confirmation of 6\u2010Oxo\u2010Androstenedione and Testosterone Misuse in Doping Control"],"prefix":"10.1002","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7407-1229","authenticated-orcid":false,"given":"F\u00e1bio","family":"Azamor de Oliveira","sequence":"first","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cristiane","family":"Abrantes da Silva","sequence":"additional","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-4420-7842","authenticated-orcid":false,"given":"Carolina","family":"dos Reis Farias","sequence":"additional","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariana","family":"Trad Rosner da Motta","sequence":"additional","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thais","family":"Reis da Silva","sequence":"additional","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Natasha","family":"Veiga Louzada","sequence":"additional","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3760-8231","authenticated-orcid":false,"given":"Monica","family":"Costa Padilha","sequence":"additional","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8597-416X","authenticated-orcid":false,"given":"Henrique Marcelo","family":"Gualberto Pereira","sequence":"additional","affiliation":[{"name":"Federal University of Rio de Janeiro\u2014UFRJ, Brazilian Doping Control Laboratory\u2014LBCD, LADETEC  Rio de Janeiro Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,9,27]]},"reference":[{"key":"e_1_2_9_2_1","first-page":"3468s","article-title":"Closing Remarks to the Conference, Aromatase: New Perspectives for Breast Cancer","volume":"42","author":"Lipton A.","year":"1982","journal-title":"Cancer Research"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1210\/endo\u2010108\u20104\u20101597"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/0022\u20104731(87)91028\u20104"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/0006\u20102952(96)00479\u20100"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jchromb.2005.08.024"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/bmc.496"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1186\/1550\u20102783\u20104\u201013"},{"key":"e_1_2_9_9_1","volume-title":"The 2026 Prohibited List","author":"WADA","year":"2026"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0039\u2010128X(02)00005\u20103"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1093\/jat\/23.5.357"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jchromb.2008.10.047"},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.steroids.2010.06.013"},{"key":"e_1_2_9_14_1","doi-asserted-by":"publisher","DOI":"10.1002\/dta.1618"},{"key":"e_1_2_9_15_1","doi-asserted-by":"publisher","DOI":"10.1039\/c7ra04608a"},{"key":"e_1_2_9_16_1","unstructured":"WADA.WADA Technical Letter \u2013 TL21: In\u00a0Situ Formation of 4\u2010Androstene\u20103 6 17\u2010Trione (6\u2010Oxo) and Metabolites. Accessed August 03 s https:\/\/www.wada\u2010ama.org\/sites\/default\/files\/resources\/files\/tl21_6oxo_eng_2021_1.pdf."},{"key":"e_1_2_9_17_1","unstructured":"WADA.WADA Technical Document \u2013 TD2022IRMS: Detection of Synthetic Forms of Prohibited Substances by GC\/C\/IRMS. 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