(a) DPV graphs of: 1.9, 5.0, 8.0, 25, 45, 65, 80, 95, 110, 125, 145 μM (from 1 to 11) RC in the presence of 20 μM HQ and CC. Insert: Linear relationship of the peak current vs. the concentration of RC; (b) DPV graphs of: 0.9, 4.0, 8.0, 15, 40, 55, 70, 85, 100, 115, 130, 150 μM (from 1 to 12) CC in the presence of 20 μM HQ and RC. Insert: Linear relationship of the peak current vs. the concentration of CC; (c) DPV graphs of: 0.9, 5.0, 15, 40, 60, 85, 105, 130, 150 μM (from 1 to 9) HQ in the presence of 20 μM CC and RC. Insert: Linear relationship of the peak current vs. the concentration of HQ.