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

This work first described the linear quenching of Ln(III) (including La-III, Ce-III, pr(III), Nd-III, Sm-III, Eu-III, Gd-III, Tb-III, Dy-III, Ho-III, Er-III, Tm-III, Yb-III and Lu-III) on luminol-dissolved oxygen chemiluminescence system and possible quenching mechanism by flow injection analysis. The general equation of the decrement of CL intensity with Ln(III) concentration, Delta I=AlnC(Ln)+B, was given and the interaction model of Ln(III) with luminol, lg[I-o-I)/I]=rlg[Ln]+IgK, was established. The sensitive factor A was found to be linear with the physical parameters (Z, gamma (+/-), E-o and Delta H-hyd). 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 Ln(III) with luminol was a spontaneous process by the electrostatic force with the association constants K at 10(6)-10(7) level. The binding constants K-D (about 10(4)-10(5)) and the number of binding sites n (about 1) of Ln(III) (La-III, Eu-III, Gd-III, Tb-III and Lu-III) to bovine serum albumin were first given by FI-CL, and the binding ability of Ln(III) followed the pattern: La-III < Eu-III < Gd-III < Tb-III < Lu-III. (C) 2015 Elsevier B.V. All rights reserved.