RESUMO
The use of autologous blood transfusions by endurance athletes has remained one of the most difficult doping practices to detect. The implementation of the Athlete's Biological Passport by some sporting bodies has proved to be effective; however, the analysis relies on the long-term monitoring of numerous biological markers, looking for abnormal variations in a number of biological markers to indicate doping. This work introduces an approach to identify autologous blood transfusions by examining the red blood cells (RBCs) directly. By using high-speed capillary electrophoretic separations, the relative distribution of the sizes of the RBCs in a sample can be established in under 3 min, following the preparation of the cells. As RBCs that have been stored for transfusions undergo vesiculation, the relative size of the transfused cells differs from the native cells. The capillary electrophoretic separation allows for a rapid examination of this distribution and the changes that are seen when transfused RBCs are mixed with native cells. In this work, the effectiveness of this approach is demonstrated in the identification of simulated (in vitro) autologous blood transfusions performed with blood samples from three highly trained cyclists; it was possible to rapidly identify when as little as 5 % of the RBCs in the sample were from a simulated autologous transfusion.