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Retrospective Sample Analysis of Adverse Analytical Findings

The use of drugs in sport is regulated by the World Anti-Doping Agency (WADA). Enforcement of these regulations primarily occurs through the collection of urine samples from athletes at a training venue or home address (Out-of-Competition) or In-Competition. Subsequent analysis of these samples for the presence of substances on the WADA Prohibited List is carried out in an accredited laboratory such as the Drug Control Centre. To protect the rights of the athlete, the collected sample is distributed into an A- and B aliquot and rendered anonymous. While the A-aliquot is analysed upon arrival in the laboratory, the B-aliquot is stored and can be utilised by the athlete for repeat analysis if requested.

Since 2015, the WAD Code has allowed Anti-Doping Organisations to store doping control samples for up to 10 years following collection, to repeat analysis with updated and improved detection methods, e.g., with more sensitive methods or for the detection of compounds that were not possible during the first analysis. This reanalysis of samples carries the same consequences as the initial testing and thus detection of substances previously undetected can be used to file an alleged case of an Anti-Doping Rule Violation (ADRV).

As significant investment is required to store samples long-term and then request additional analysis at a future timepoint, one of the project’s aims is to provide some reassurance that this is money well spent. Anti-doping science has seen remarkable progress over the years, including decreases in detection limits and through the discovery of long-term metabolites such as those of Anabolic Androgenic Steroids (AAS) (e.g., dehydrochloromethyltestosterone and stanozolol). Retrospective sample analysis can simply involve reprocessing data that was first collected to confirm compounds previously identified, or each sample can be reanalysed to look for newer markers of drug metabolism after a period of storage. In addition, certain substances are not routinely screened for at the point of original analysis (particularly, peptide hormones), therefore it is important to understand how these substances behave following a period of storage.

This study will investigate whether prohibited substances such as exogenous AAS detected following the original analysis can still be identified after a period of storage. A comparison will also be made of the estimated concentrations of the compounds originally identified with the estimated concentrations following re-analysis, thereby assessing their level of degradation during storage. We will also explore whether new long-term metabolites can be identified after a period of storage.


Dr Chris Walker

Research Associate

Christiaan Bartlett

Lead Analyst Blood Doping

Elizabeth Yepez Gavilanes



Senior Analyst-Blood Doping

Abraham Ali

Lead Analyst GC-Technologies

Stephanie Farrant

Senior Analyst-GC-MS

Cheyanne Pierre

GC-MS Analyst

Scarlett Devey

Lead Analyst LC-MS


Adam Tilcock

Senior Analyst-LC-MS

Dean Nyarko-Mensah

Analyst LC-MS

Smita Ramma


Analyst Blood Doping

Pat Hartley

Head of Results, UK Anti-Doping (UKAD)

Dr Nikola Costa

Research & Innovation Lead, UK Anti-Doping (UKAD)

Ivana Gavrilovic


Nick Wojek




  • Confirm whether the compounds that were originally identified are still present following a period of storage.
  • Determine the presence of any new long-term metabolites that were not identifiable at the time of original analysis.
  • Compare the estimated concentrations of the compounds originally identified with the estimated concentrations following re-analysis.


Screening and confirmation of urine samples using Gas-Chromatography-Mass Spectrometry (GC-MS) and Liquid-Chromatography-Mass Spectrometry (LC-MS) and tests to detect Erythropoiesis-Stimulating Agents (ESAs) including erythropoietin (EPO)as employed by the Drug Control Centre

Trials Design

Before and after study

Summary of Findings



It has previously been shown that yearly world best performances increase with the emergence of new potent doping agents, such as anabolic steroids or EPO. Conversely, when new anti-doping tests are implemented, overall world best performances decrease as the effects of certain performance enhancing drugs become detectable and are therefore avoided by athletes. Shedding light on analytical advances through retrospective testing should act as a deterrent for doping efforts.

Our Partners

Project status: Ongoing

Principal Investigator


Funding Body: UK Anti-Doping

Amount: £20,000

Period: January 2019 - January 2022