Complexation of europium(III) with organic ligands and in human body fluids studied by TRLFS

An(III) exhibit very high radioactivity and therefore pose a great health risk for humans in case of accidental release/incorporation. Their metabolism and speciation in body fluids is not yet fully known and our studies shall help to adress this lack of knowledge. Ln(III) are used in radiological medicine e.g. as contrast agents and exhibit similar physico-chemical properties as An(III) but no radioactivity. Therefore Ln(III) are often used as analogs for An(III). In the present study the complexation of Eu(III) with different organic ligands, which are components of natural biofluids, as well as its speciation in natural human urine samples were investigated. Results show, that Eu(III) speciaition in urine samples with lower pH is dominated by citric acid complexation while in samples with higher pH inorganic complexes are formed.