Comparison of boron-doped diamond and glassy carbon electrodes for determination of procaine hydrochloride

The electrochemical oxidation of procaine hydrochloride (PC·HCL, 2-diethylaminoethyl 4-aminobenzoate hydrochloride) was investigated at as-deposited boron-doped diamond (ad-BDD) electrode, anodically oxidized BDD (aoBDD) electrode and glassy carbon (GC) electrode using cyclic voltammetry (CV). Well-defined cyclic voltammograms were obtained for PC·HCL oxidation with high signal-to-background (S/B) ratio, low tendency for adsorption, good reproducibility and long-term stability at ad-BDD electrode, demonstrating its superior electrochemical behavior and significant advantages in contrast to ao-BDD and GC electrode. At 100 μM PC·HCL, the voltammetric S/B ratio was nearly one order of magnitude higher at an ad-BDD electrode than that at a GC electrode. In a separate set of experiments for oxidation of 100 μM PC·HCL, 96%, 92% and 84% of the initial oxidation peak current was retained at the ad-BDD, ao-BDD and GC electrode, respectively, by stirring the solution after the tenth cycle. The current response was linearly proportional to the square root of the scan rate within the range 10-1000 mV s^-1 in 10 μM PC·HCL solutions, indicating that the oxidation process was diffusion-controlled with negligible adsorption at an ad-BDD surface. The good linearity was observed for a concentration range from 5 to 200 μM with a linear equation of y = 0.03517x + 0.65346 (r = 0.999), and the detection limit was 0.5 μM for oxidation of PC·HCL at the adBDD electrode. The ad-BDD electrode could maintain 100% of its original activity after intermittent use for 3 months.