Fig. 3. The optimization of the concentrations of DNA (A) and pH effects (B) in the presence of 500 nM Hg²⁺ ions. In (A), the spectrum of each concentration of DNA used was described by full line (without Hg²⁺ ions) and dot-dashed line (with Hg²⁺ ions). The concentration of DNA: red: 0.1 μM, green: 0.2 μM, yellow: 0.5 μM, blue: 1 μM, pink: 2 μM, black: 5 μM and cyan: 10 μM. In (B), the spectrum of each pH used was described by full line (without Hg²⁺ ions) and dot-dashed line (with Hg²⁺ ions). Red: 6.0, green: 6.5, yellow: 7.0, blue: 7.4, pink: 8.0.