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cleared on a B sample

Dave_1Dave_1 Posts: 9,512
edited March 2012 in Pro race
by the EPO test. Serious.

Luis Mansilla has been cleared of doping charges after his B-sample came back negative, the head of the Chilean cycling federation has said. Mansilla can now resume his preparations for the London Olympics, where he is expected to feature on both the track and road teams.

Mansilla had tested positive for EPO after stage 5 of the 2012 Tour of Chile in January, which he lead for eight stages and in which he won two stages.

"The legal department of the International Cycling Union (UCI) sent us this morning the lab report which details that Luis Mansilla's B sample was negative.This means that no banned substances," Miguel Carrillo told the Chilean news website emol.com.

He added that the report “did not explain the reassign” for the first positive result.

"With the news, it is confirmed that Mansilla is released and can continue to compete without major problems."

Mansilla, also speaking with emol.com, said that the positive doping control left him very angry. “There was much damage, my family suffered a lot because they did not know what to do. I could not believe it, and every time I remembered, I was angry.”

With the news of the negative B sample, he is ready to put it all behind him. “Now I only have to prepare for the Olympics,” he said. He wants “to give satisfaction to my country. On the bike I've always tried to do my best and I've given everything. Obviously I want to do well and show that at this moment I am one of the best cyclists in the country.”

http://www.cyclingnews.com/news/mansill ... e-b-sample

Posts

  • B3rnieMacB3rnieMac Posts: 384
    Who uses EPO these days?
  • squiredsquired Posts: 1,216
    A negative doesn't mean it wasn't in his sample. It can just mean that there wasn't enough to constitute a positive. The first sample might have been just above the threshold. It seems that many people over the years have been obviously doping in terms of the results of their samples, but not to a degree that is sufficient to be "positive".

    I think Marion Jones had something similar a few years back. Positive A sample and negative B. There would have been a similar press release afterwards. Later on of course she was proven to be dirty. In the case of this guy who knows. Mind you, given the margins required to test positive in the first place I doubt he is whiter than white.
  • PokerfacePokerface Posts: 8,640
    The only thing I don't understand is... how can one sample be below the threshold and one above? I mean - you pee in a cup and then pour it into two bottles. It's the same urine and neither sample is more or less diluted than the other. Assuming the testing protocol is the same for both samples.

    Does it degrade over time or something? That might explain why the B sample had 'less' in it when tested several weeks/months later.
  • graeme_s-2graeme_s-2 Posts: 3,382
    Pokerface wrote:
    The only thing I don't understand is... how can one sample be below the threshold and one above? I mean - you pee in a cup and then pour it into two bottles. It's the same urine and neither sample is more or less diluted than the other. Assuming the testing protocol is the same for both samples.

    Does it degrade over time or something? That might explain why the B sample had 'less' in it when tested several weeks/months later.
    Presumably there's a margin of error in the process. I've no idea what units of measurement are used, but if for example anything above a 1 is a failed test, and the test is accurate to +/- 0.2, then the A sample could come out at 1.1 as a fail and the B sample at 0.9 as acceptable.
  • esspeebeeesspeebee Posts: 174
    Pokerface wrote:
    The only thing I don't understand is... how can one sample be below the threshold and one above? I mean - you pee in a cup and then pour it into two bottles. It's the same urine and neither sample is more or less diluted than the other. Assuming the testing protocol is the same for both samples.

    Does it degrade over time or something? That might explain why the B sample had 'less' in it when tested several weeks/months later.
    Any quantitative chemical test (which is what we're dealing with here: how much of whatever substance is present?) will have a reasonably well-known margin of error; none of them can give an exact answer with any degree of certainty, only that (for example) there's a 95% probability that it's within 5% of this value.

    If one sample comes back positive and the other negative (which after all just mean "above a defined threshold" and "below that threshold") it could just mean that the actual value is so close to the line that the test can't give an answer with any degree of confidence. In one case the random error took it above the line, and in the other case the random error went the other way and took it below the line. In that situation, you just can't know which side of the 'positive' threshold the real value was, and have to give the benefit of the doubt.
  • No_Ta_DoctorNo_Ta_Doctor Posts: 10,098
    The real question is why we even heard there was a +ve on the A sample before the rider claimed hi right to have his B sample tested.
    “Road racing was over and the UCI had banned my riding positions on the track, so it was like ‘Jings, crivvens, help ma Boab, what do I do now? I know, I’ll go away and be depressed for 10 years’.”

    @DrHeadgear

    The Vikings are coming!
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