512692.fig.006a
(a)
512692.fig.006b
(b)
Figure 6: (a) Differential pulse voltammograms of different concentrationof DA (a–g; 0.2, 0.3, 0.4, 0.5, 0.5, 0.6, 0.7, 0.8 and  M in 0.2 M phosphate buffer solution of pH 7.0 in the presence of  M AA, and  M UA at poly(XO)/GPE. (b) Graph of anodic peak current versus different concentration of DA.