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Abstract
A fluorescence probe, safranine T (ST), was proposed for the investigation of DNA. ST is a fluorescent cationic dye. Its fluorescence intensity decreased significantly in the presence of DNA. Evidence showed that the fluorescence quenching was due to the formation of a complex between dye and DNA which is less fluorescent than the free dye. Steady-state anisotropy measurements demonstrated that ST bound to DNA and resulted in an increase in anisotropy. The calibration graphs for the determination of Calf thymus DNA (CT DNA) and fish sperm DNA (FS DNA) were obtained. Good linear dependency of F0/F on the concentration of DNA was observed with the concentration ranging from 8.3 ng /ml to 15.0 μg / ml for CT DNA and from 14.0 ng / ml to 16.0 μg / ml for FS DNA. The LOD were 8.3 ng /ml and 14.0 ng / ml for CT DNA and FS DNA, respectively. The relative standard deviations were 1.44 % and 0.92 % for 4.0 μg / ml and 0.40 μg / ml of CT DNA, respectively, and 1.52% and 1.12% for 4.0 μg / ml and 0.50 μg / ml of FS DNA, respectively.