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, Δ I = A ln C Ln + B, was given and the interaction model of Ln III with luminol, lg[( I 0 − I )/ I ]= r lg[Ln]+lg K, was established. The sensitive factor A was found to be linear with the physical parameters ( Z, γ ±, E o and Δ 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