RTMcFadden said:
Specific Gravity doesn't really factor into it, provided they use the whole sample. The first step of the analytical process is to concentrate the sample by filtering, which removes the water. From my experience, SG is used as an integrity check during sample collection. Once had a guy on parole, with mandated drug testing, provide a sample that failed SG. First bad sign. Second bad sign was that it wouldn't freeze. The sample turned out to be Pine-Sol.
I think BroDeal is on to something here. By capturing less that the total void volume from the time of injection, or by using an aliquot of the sample collected, you reduce the overall amount of drug available for detection. So even with a concentration step, you limit your detectability. In addition, from the information I've read, the clearance of rEPO by the kidneys is not well understood, so there may be an issue there.
Specific Gravity (and pH) are checked during the sample collection process by the Doping Control Officer as a "field check" to ensure that the sample hasn't been manipulated. This takes places after the sample has been collected, split into two (the "A" and the "B"), and sealed in the actual transport vessels.
The DCO checks both the pH the SG of the residual urine left in the collection vessel to ensure it falls w/in whatever the WADA parameters are. If it doesn't, the DCO is supposed to compel the athlete to provide a new sample (even if it takes three more hours of waiting for the athlete to rehydrate and urinate again), and the DCO is expected to be even more vigorous in observing the sample provision to prevent corruption of the process...
For those of you who've never been drug-tested for sport, there is an accurate guide, with pictures,
here. (ignore the irony of the sport providing the info
)
As I'm not traveling or competing now, but am still in the USADA RTP for OOC testing, and the UCI whereabouts pool, I still get tested. The same DCO has conducted all of my sample collections, and I have to say that he's a well-trained, unflappable, professional. The guy is a PhD-holding professor at a local university, and handles all of the local OOC tests (there are a few other elite athletes in various Olympic movement sports living and training in Western PA who occasionally get selected for control). One time, though, during the '08 Olympics, actually, I had a supervisor from Colorado Springs come out along with a DCO-in-training...holy awkward. lol