How does clenbuterol testing work?

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As the tension rises over the potential different outcomes to Alberto Contador's positive for clenbuterol, Peter Van Eenoo, the head of WADA's only accredited anti-doping lab in Belgium at the University of Ghent, has discussed the ins and outs of testing for the banned substance with Cycling Weekly.

Van Eenoo refused to discuss specific cases, although his laboratory was reportedly the one which discovered Chinese rider Fiyu Li's positive for clenbuterol this spring.

(Cycling Weekly) CW: How does testing for clenbuterol work?

(Peter Van Eenoo) PVE: Through a combined detection method called GC-MS. Part of the process is gas chromatography [GC], which separates different elements, and the other part, mass spectrometry [MS], identifies them.

CW: Any major advances in the last few years on this process?

PVE: Not over the last two decades or so. Just that the instruments which we used have got a lot more sensitive. We're getting better at detecting it.

CW: Although there have been reports that only four labs in the world could have detected the levels found recently in Alberto Contador's urine...

PVE: That story can only be completely made up. Each WADA lab only knows their own results from tests, and although we do talk to each other, we don't know where the other results have come from, they're completely anonymous. I don't see how anybody can have said that.

CW: Could a positive for clenbuterol come from other causes than direct doping?

PVE: It's possible. Contaminated products or foodstuffs are possible causes too. But in my opinion, you have to bear in mind whether it's the first athlete or athlete number 10,000 who alleges a clenbuterol positive has been caused by a particular contaminated product.

An athlete is always responsible for what is in his body fluids. If there's a positive but there's a reason for a reduction in the suspension, like food contamination, then he or she will have his sentence reduced.

CW: Why is there no limit of detection (tolerance level) when testing for clenbuterol?

PVE: Because its effect is long-term and spread out, and there's no clear correlation between the clenbuterol an athlete takes and the effect it has. On top of that, clenbuterol only breaks down in the body very slowly.

So if I took a lot and you and tested me an hour later, I might have a lot left in my system.

But if you tested me in four or five days, it might still be there. Either way you wouldn't know what effect it had had. That's why clenbuterol is always a positive.

Related links

Contador considers quitting cycling due to doping scandal

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