The power of increasingly sensitive analytical instruments

Via the AP: 

Katerina Nash, a mountain biker and cross-country skier who represented the Czech Republic in two Winter and three Summer Olympics, avoided a four-year doping sanction after minute traces of a banned substance showed up in her system. Authorities determined the substance got there through her skin during the messy struggles she faced in forcing medicine drops down the throat of her ailing dog, a Vizsla named Rubi.

...Nash lives in California and was tested by authorities from the U.S. Anti-Doping Agency. The results that showed up several days later at USADA offices raised eyebrows. A trace amount (0.07 billionths of a gram per milliliter) of a substance called capromorelin had shown up in Nash’s urine. Though the amount was minuscule, it was enough to trigger an adverse finding. And though capromorelin isn’t specifically mentioned on the banned list, it still falls in the category of “other” prohibited substances that are related to human-growth hormone.

Much as they had in a previous instance where an over-the-counter sunscreen was determined to have caused positive tests, members of the USADA science team went to work.

First, they discovered that capromorelin was present in a medicine called Entyce, which is given to boost the appetite of sick dogs. Then, USADA’s lead scientist, Dr. Matt Fedoruk, and others went about applying the medicine to their own skin. Within days, they were testing positive. It was the latest example of the pros and cons of anti-doping’s use of increasingly sensitive instruments that can detect minuscule traces of drugs.

I'm genuinely glad to see that USADA chemists seem to be quite good at detecting xenobiotics in athlete urine, and that there is some level of rationality and flexibility to their rules. (Apparently, WADA rules are not nearly so flexible.) 

(It's also pretty interesting to see how different molecules seem to wander into our bloodstream at different rates. I wouldn't have guessed that capromorelin could get past the skin barrier, but apparently it did.)