(a)
(b)
Figure 7: Scatchard plots of the interaction between thulium(III)-arsenazo III and DNA in different concentrations of AO. (a) Without NaCl; (b) with NaCl (pH = 7.40). cThulium (III)-arsenazo III = 8.30 × 10−6 mol/L; cDNA = 4.00 × 10−6 mol/L; cAO = 4.00 × 10−5 mol/L (10 μL per can); Rt = cThulium (III)-arsenazo III/cDNA; a, Rt = 0.00; b, Rt = 0.20; c, Rt = 0.40; d, Rt = 0.60.