Since the first anti-doping tests in the 1960s, the analytical aspects of the testing remain challenging. The evolution of the analytical process in doping control is discussed in this paper with a particular emphasis on separation techniques, such as gas chromatography and liquid chromatography. These approaches are improving in parallel with the requirements of increasing sensitivity and selectivity for detecting prohibited substances in biological samples from athletes. Moreover, fast analyses are mandatory to deal with the growing number of doping control samples and the short response time required during particular sport events. Recent developments in mass spectrometry and the expansion of accurate mass determination has improved anti-doping strategies with the possibility of using elemental composition and isotope patterns for structural identification. These techniques must be able to distinguish equivocally between negative and suspicious samples with no false-negative or false-positive results. Therefore, high degree of reliability must be reached for the identification of major metabolites corresponding to suspected analytes. Along with current trends in pharmaceutical industry the analysis of proteins and peptides remains an important issue in doping control. Sophisticated analytical tools are still mandatory to improve their distinction from endogenous analogs. Finally, indirect approaches will be discussed in the context of antidoping, in which recent advances are aimed to examine the biological response of a doping agent in a holistic way.
1.1. History of doping control analyses The fight
against drug abuse in sports has continuously improved since doping control
began in the 1960s . Various analytical
strategies have been used to detect doping agents in the urine samples of
athletes. Anti-doping analyses, first used gas chromatography (GC)
nitrogen-selective detection (nitrogenflame ionization detection; NFID) to
screen for stimulants in more than two thousand urine samples during the 1972 Olympic
Games in Munich . Immunoassays have also been
used in some laboratories as a screening procedure, but the results have to be confirmed
by chromatography due to the lack of specificity .
In 1983 at the IX Pan American Games higher degree of selectivity and
sensitivity was obtained by the introduction of benchtop quadrupole GC coupled
to mass spectrometry (GC–MS) . During the
previous decade, liquid chromatography coupled to mass spectrometry in
single-stage or tandem mode (LC–MS(/MS)) has become an attractive alternative
for doping control analysis due to the development of atmospheric pressure
ionization (API) sources. The demand for more sensitive and specific methods to
detect a higher number of commonly used doping agents continues to grow .