Fluorimetric study of the interaction between human serum albumin and quinolones-terbium complex and its application

A highly sensitive spectrofluorimetric method is proposed for determination of human serum albumin (HSA) and some quinolone drugs. Using quinolones-terbium (Tb3+) complex as a fluorescent probe, in the buffer solution of pH 7.8, HSA can remarkably enhance the fluorescence intensity of the quinolones-Tb3+ complex at 545 nm and the enhanced fluorescence intensity of Tb3+ ion is in proportion to the concentration of HSA and quinolone drugs. Optimum conditions for the determination of HSA were also investigated. The linear ranges and limits of detection are 8.0 × 10−9 to 8.0 × 10−8 mol L−1, 4.20 × 10−9 mol L−1 (for HSA); 1.0 × 10−6 to 4.0 × 10−6 mol L−1, 1.87 × 10−8 mol L−1 (for norfloxacin) and 1.0 × 10−7 to 1.0 × 10−6 mol L−1, 4.82 × 10−8 mol L−1 (for enoxacine), respectively. This method is simple, practical and relatively free interference from coexisting substances, as well as much more sensitive than most of the existing assays.