The interaction between safranine T(ST) and yeast DNA was studied by means of UV absorption and fluorescence spectrometry. The wavelengths of fluorescence excitation and emission of ST were 520 nm and 570 nm, respectively. The maximum absorption of UV spectrum was at 520 nm. Two kinds of interaction between ST and DNA, intercalation and electrostatic interaction, were conformed. The binding site size in DNA base pairs was 14.5±1.5 and the apparent binding constant was (2.81±0.11)×10 4 mol -1·L. The fluorescence quenching constant of DNA to ST was (1.52±0.19)×10 4 mol -1·L. A novel fluorescence analysis for DNA determination was presented and the effects of experimental conditions on the fluorescence quenching were discussed.
