Quercetin–La(III) complex for the fluorimetric determination of nucleic acids Original Research Article

The ternary fluorescent complexes of nucleic acids–quercetin–lanthanum(III) were studied. Nucleic acids in this study involve natural and thermally denatured calf thymus DNA (ctDNA), yeast DNA (yDNA) and yeast RNA (yRNA). In the pH range 7.8–8.3 (controlled by NH3–NH4Cl buffer) ternary fluorescent complexes are formed which give maximum emission at 470 nm when excited at 280 nm. Based on the fluorescence reactions sensitive fluorimetric methods for nucleic acids were proposed. Using optimal conditions, the calibration curves were linear in the range of 0.5–3.0 μg ml−1 for ctDNA, 0.5–4.0 μg ml−1 for yDNA and yRNA. The limits of determination (3σ) were 0.072 μg ml−1 for ctDNA, 0.142 μg ml−1 for yDNA and 0.307 μg ml−1 for yRNA, respectively. Six synthetic samples were determined with satisfaction.