Performance-enhancing drugs are substances that have the capability to improve performance in humans. In sports, those substances are sometimes referred to as endogenic aids and one highly popular reference is anabolic steroids or their precursors with the colloquial term “steroids.” Steroids are very common hormones in our bodies, steroids help build muscle tissue and increase body mass by acting like the body’s natural hormone “testosterone.”
Amphetamines were the first ‘effective’ performance-enhancing drugs, which were used widely by soldiers in World War II. Soon after, amphetamine abuse crossed over into sports in the early 1950s. These drugs minimized the uncomfortable sensations of fatigue during exercise and were therefore especially useful for endurance sports. Consequently, the first causalities of cyclists occurred a few years later. For instance, Knut Jensen and Tommy Simpson both died in the 1960s due to dehydration during a race while using performance-enhancing drugs. Performance-enhancing drugs have been banned for decades by the International Olympic Committee and the World Anti-Doping Agency. But how can we distinguish naturally-produced steroids in our bodies from their synthetic analogs?
With their isotope fingerprint. Most of the synthetic steroids are produced from C-3 plant material, for instance, wheat, soybeans, or barley. This plant material consists of a distinctive isotope signature. The isotope fingerprint, found in plants, for example, can vary according to plant type, but also according to region or rainfall. By eating those plants, carbon, hydrogen, and other elements are taken up by our bodies and converted into our own body tissue. Our own isotope fingerprint resembles therefore the fingerprint of our nutrition. Similarly, isotope fingerprints of our naturally produced steroids equal the isotope fingerprint of our body tissue. However, synthetic steroids do not! So, if the athlete is clean, stable isotope composition should remain identical among all steroids in his body. But if the athlete was taking synthetic testosterone, we will be able to see a difference in stable isotope value in the testosterone sample.
The analysis of testosterone misuses in sports is usually done with carbon isotopes (13C/12C). Here, samples of testosterone are collected from urine and analyzed after sample preparation. Isotope-ratio mass spectrometry (IRMS) is the analytical technique for stable isotope analysis in organic compounds. In contrast to the standard mass spectrometry, as in example quadrupole MS or Orbitrap MS, IRMS is capable of measuring the smallest differences in the isotope composition with high accuracy. And this is quite important since differences in isotope ratio occur in the per mill range. Therefore, too small to detect with a standard MS.
The IRMS is usually coupled to gas chromatography (GC) or liquid chromatography (HPLC) for prior separation of a compound mixture. Especially, this is useful for biological and environmental samples. Achieving the high accuracy isotope composition can only be measured after online compound conversion to a simple analyte gas — i.e. carbon to carbon dioxide. Carbon dioxide retains the isotopic information and is subsequently analyzed with IRMS with high precision.
Except for carbon, hydrogen also can be applied for metabolite research. Identification of steroid metabolites in complex matrices can be time-consuming and challenging due to the requirement to both identify and quantify hundreds of different compounds with limited prior knowledge of the metabolites. Here compound-specific stable isotope analysis can be used to provide insights into the metabolism of many compounds in plants, animals, and humans. Deuterium labeling of compounds has long been recognized as a valuable means to identify metabolites. GC-IRMS enables the compound-specific hydrogen isotope analysis at the natural abundance and deuterium enrichment. Find out more about IRMS research here.
Most people relate isotopes to radioactivity or contamination. But there are two types of isotopes around us: radioactive isotopes (non-stable) and stable isotopes. The word “stable” already indicates stable isotopes do not decay. So, no radioactivity and no threat. Looking at stable isotopes can tell us a story about a chemical compound, for instance, how or where was it formed. Isotopes can therefore be used in various disciplines — such as geology, forensics, environment, or food authentication — giving us a lesson about the origin, the path, and the fate of substances that we would like to investigate.
Application Note :
- Sally Jenkins “Winning, Cheating Have Ancient Roots,” Washington Post, Aug. 3, 2007
- Timothy Noakes, MD, DSc “Tainted Glory – Doping and Athletic Performance,” New England Journal of Medicine, Aug. 26, 2004