A. Differential pulse voltammograms for the iodine coated electrode in PBS containing (A) (blue) 0.05 mM dopamine, (red) 0.05 mM dopamine + 0.5 mM ascorbic acid, and (green) 0.05 mM dopamine + 2.5 mM ascorbic acid. B. (blue) 0.05 mM dopamine, (green) 0.05 mM dopamine + 0.1 mM uric acid and (orange) 0.05 mM dopamine + 1.75 mM uric acid.