The world's anti-doping laboratories primarily rely on high-resolution chromatography-mass spectrometry to analyze samples. This technique is a crucial method in analytical research, allowing scientists to understand the composition of samples and identify specific molecules.
According to international standards, anti-doping labs must have the ability to detect substances and their metabolites at a concentration of 1 nanogram per milliliter (ng/ml) or less. To put this in perspective, imagine dissolving a small amount of sugar that fits on the tip of a knife in an Olympic-sized swimming pool, which has a volume of approximately 2.5 million liters. In reality, labs can detect substances at even lower concentrations, around 0.1 to 0.05 ng/ml or less.
According to the World Anti-Doping Code, some doping samples can be stored for up to 10 years for possible re-analysis. This is due to the fact that science is constantly evolving, and it is possible that the effectiveness of tests will increase during the storage period. One advantage of using mass spectrometry for testing is that it can automatically detect new metabolites of banned substances in "old" samples, without the need for further testing.
This means that even if a substance was used in microdoses or over a long period of time and was not detected initially, it may still be found in a stored sample during re-testing.