Simultaneous determination of ascorbic acid, epinephrine, and uric acid by differential pulse voltammetry using poly(3,3′-bis[N,N-bis(carboxymethyl)aminomethyl]-o-cresolsulfonephthalein) modified glassy carbon electrode

A selective and stable poly(3,3′-bis[N,N-bis(carboxymethyl)aminomethyl]-o-cresolsulfonephthalein) modified glassy carbon electrode was prepared using the electrochemical polymerization technique for the simultaneous determination of ascorbic acid (AA), epinephrine (EP), and uric acid (UA). The modified electrode showed an excellent electrocatalytic activity for AA, EP, and UA oxidations and for accelerated electron transfer between the electrode and the substances. The separation potentials of the oxidation peak potentials for EP–AA and EP–UA were about 180 mV and 130 mV, respectively. Calibration curves in the ranges 1.0–2000 μmol L−1, 0.20–175 μmol L−1, and 0.020–2000 μmol L−1 were obtained for AA, EP, and UA, respectively. The lowest detection limits (S/N = 3) were 0.4 μmol L−1, 0.03 μmol L−1, and 0.009 μmol L−1 for AA, EP, and UA, respectively. The proposed procedure was also successfully applied for the simultaneous detection of AA, EP, and UA in injectable medicine, blood plasma, and urine samples.