Eliminating the interference of ascorbic acid on the measurement of uric acid using cyclic voltammogram of oxygen plasma treated screen-printed carbon electrodes

摘要

The cross-talking behavior of the voltammetric signals generated when trying to determine the concentration of uric acid (UA) in a solution that also includes a high concentration of ascorbic acid (AA) was first discussed and estimated. This cross-talking behavior, caused by the presence of high concentrations of AA in the solution, skews the measurements of UA concentration. A simple and easy-to-use fitting procedure was developed for the simultaneous measurement of the mixed AA and UA. The AA’s current signals, generated at the shoulder of the AA peak curve on the cyclic voltammgram (CV), increased the background currents of the UA’s oxidative peak, thus creating the cross-talking effect. The oxygen plasma-treated screen-printed carbon electrodes (OP-SPCE) could make the oxidative peaks of UA and AA on the CVs become more defined (0.35 V for UA and 0.10 V for AA). When using OP-SPCE, the degree of cross-talking decreased and became proportional to the concentration of AA with a linear regression equation of y = 0.0226x + 2.421. Since the oxidative peak currents of AA were not influenced by that of UA even at high concentrations of UA, the AA concentration can be determined. Then the UA concentration in a composition solution can be quantitatively and accurately analyzed by subtracting of the cross-talking response. By using the fitting procedure we have developed on the OP-SPCEs, excellent recovery rates (97.9 to 106%) and RSD of 1.35% were obtained for the measurement of UA, even in the presence of high concentrations of AA.