Analysis of tretoquinol and its metabolites in human urine by liquid chromatography–tandem mass spectrometry
Bibliographic record
Abstract
Tretoquinol (trimetoquinol), a β2-agonist, has been explicitly listed on the World Anti-Doping Agency Prohibited List 2019 since January 2019; however, it has been distributed as an antiasthmatic on the medical market. This study aimed to develop a liquid chromatography-tandem mass spectrometric method for the quantification of tretoquinol (free form plus glucuronide) in human urine for doping control purposes. An excretion study (n = 6) of tretoquinol hydrochloride hydrate (6 mg) was performed, and urine samples were collected prior to oral administration and during the first 48 h, along with spot urine samples at 7 and 14 days after administration. All the urine samples were analysed using the developed method. The limit of detection for the developed method was 0.03 ng/mL. The inter-day precision for the target analyte was excellent (2.7% to 9.2%), and the inter-day accuracy of target analyte was -0.6% to -3.6%. In all subjects, tretoquinol (free form plus glucuronide conjugate) was identified up to 48 h after administration. The maximum concentrations were in the range of 12.4-78.8 ng/mL and the mean concentration was 55.3 ng/mL. The metabolites O-methylated tretoquinol, tretoquinol sulphate and O-methylated tretoquinol sulphate could be also identified in human urine after administration. The longest-lasting urinary metabolite of tretoquinol currently known, O-methylated tretoquinol, is also likely to be a useful marker in doping controls.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".