Study on the luminescence behavior of lanthanide ions with luminol by flow injection chemiluminescence analysis

This work first described the linear quenching of LnIII (including LaIII, CeIII, PrIII, NdIII, SmIII, EuIII, GdIII, TbIII, DyIII, HoIII, ErIII, TmIII, YbIII and LuIII) on luminol-dissolved oxygen chemiluminescence system and possible quenching mechanism by flow injection analysis. The general equation of the decrement of CL intensity with LnIII concentration, ΔI=AlnCLn+B, was given and the interaction model of LnIII with luminol, lg[(I0−I)/I]=rlg[Ln]+lgK, was established. The sensitive factor A was found to be linear with the physical parameters (Z, γ±, Eo and ΔHhyd). By plotting A against Z, it could be seen light lanthanides (LL) and heavy lanthanides (HL) presented a good symmetry. The results showed that the reaction of LnIII with luminol was a spontaneous process by the electrostatic force with the association constants K at 106-107 level. The binding constants KD (about 104-105) and the number of binding sites n (about 1) of LnIII (LaIII, EuIII, GdIII, TbIII and LuIII) to bovine serum albumin were first given by FI-CL, and the binding ability of LnIII followed the pattern: LaIII