Di(2-ethylhexyl)phthalate metabolites as markers for blood transfusion in doping control: Intra-individual variability of urinary concentrations

To indicate homologous or autologous blood transfusion in sports drug testing, quantification of increased urinary concentrations of di(2-ethylhexyl) phthalate (DEHP) metabolites presents a promising approach; however, the possible intra-individual variation of the metabolite concentrations over time has not been well characterized.