Ligand-sensitized fluorescence of Tb3+ in Tb3+–dibutylphosphate complexes: Application for the estimation of DBP

The fluorescence of Tb3+ is sensitized by complexation with dibutylphosphate (DBP) and tri-n-butylphosphate (TBP). The excitation maximum for the Tb3+–DBP complex occurs at 218.5 nm, while that for the Tb3+–TBP complex is observed at 228.0 nm. Both complexes yield Tb3+ fluorescence at 548 nm. The difference in the excitation maxima for the two complexes has been used to advantage for the estimation of DBP in the presence of TBP. DBP is the main degradation product of TBP in the PUREX process and the method described in this work can thus serve as a useful analytical tool in monitoring the quality of the TBP in the process. This method has been shown to be applicable for the estimation of DBP when present to an extent of 0.1–10% of TBP, in TBP/dodecane solutions.