Highly sensitive simultaneous electrochemical determination of myricetin and rutin via solid phase extraction on a ternary Pt@r-GO@MWCNTs nanocomposite

Tursynbolat, Satar; Bakytkarim, Yrysgul; Huang, Jianzhi; Wang, Lishi

The effect of pH was investigated by DPVs in BR buffer solution containing 50 mM myricetin and rutin at different pH values (Fig. 6A) . As the pH increased (Fig. 6B) , oxidation peak currents of both myricetin and rutin increased until pH 3 and then decreased at higher pH values. Therefore, the optimum pH was determined to be 3. In Fig. 6C , as the pH increased, both oxidation peak potentials of myricetin and rutin negatively shifted with a good linear relationship between the oxidation peak potentials and pH. The linear equation for myricetin was E pa (V) ¼ À0.0702 pH þ 0.5398 (R 2 ¼ 0.9918) and for rutin E pa (V) ¼ À0.0632 pH þ 0.6997 (R 2 ¼ 0.9904). The slopes of the respective equations were 70.2 and 63.2 mV/pH, suggesting that both myricetin and rutin oxidation followed the Nernst equation requiring identical number of protons and electrons. Combined with previous reports [36, 37] , the myricetin and rutin oxidation mechanism involved the same number electron and proton transfer processes (Scheme 2).