Studies on the Fluorescence Reaction between Nucleic Acid and the Complex of Cobalt(II) with 5-(3-Fluoro-4-chlorophenylazo)-8-sulfonamidoquinoline and Its Applications

Based on the enhancement of the fluorescence intensity of the complex of 5-(3-fluoro-4-chlorophenylazo)-8-sulfonamidoquinoline (FCPBSQ) with Co2+ by nucleic acid in the presence of Tween 80 and in the weakly basic medium, a fluorescence method for the determination of nucleic acid was proposed. The calibration graphs for the determination of denatured calf thymus DNA (ct DNA), fish sperm DNA (fs DNA), and yeast RNA (yt RNA) were obtained in concentration ranges 0.050–4.0, 0.10–3.0, and 0.050–3.0 μg/ml with limits of detection of 0.010, 0.030, and 0.020 μg/ml, respectively. The method has been satisfactorily used for the determination of DNA in wheat cell extraction and ct DNA, fs DNA, and yt RNA in synthetic samples. Investigations on the binding mode by the Scatchard plots method suggested that both intercalation and electrostatic binding modes existed in this system.