Complex formation of U(VI) with the amino acid L-threonine and the corresponding phosphate ester O-phospho-L-threonine

摘要

The complex formation of uranium(VI) with L-threonine and O-phospho-L-threonine was studied by time-resolved laser-induced fluorescence spectroscopy (TRLFS). An increase in fluorescence emission intensity and a corresponding red shift of the bands in the spectra compared to the free uranyl cation indicate a complex formation between UO22+ and the non- and phosphorylated amino acid L-threonine. The complex formation constants for a 1:1 and 1:2 complex in the case of L-threonine were determined to be log beta(111) = 10.33 +/- 0.26 at ionic strength I = 0.1 M. log beta(111) = 10.25 +/- 10.25 and log beta(122) = 19.94 +/- 10.24 at ionic strength I = 0.5 M. The calculated constants of the different 1:1 uranyl complexes with O-phospho-L-threonine are log beta(131) = 20.28 +/- 0.11, log beta(121) = 18.94 +/- 0.29 and log beta(111) = 15.02 +/- 0.23 at I = 0.1 M.