Selective determination of dopamine in the presence of uric acid and ascorbic acid by N,N′-bis(indole-3-carboxaldimine)-1,2-diaminocyclohexane thin film modified glassy carbon electrode by differential pulse voltammetry

Abstract

In this study N,N′-bis(indole-3-carboxaldimine)-1,2-diaminocyclohexane (ICDACH) was deposited on the glassy carbon (GC) electrode to fabricate a new sensor and used for the determination of dopamine. Deposition of ICDACH was performed by cyclic voltammetry scanning from 0.6V to 1.7V at a sweep rate of 100mVs−1 for 25 cycles in 1mM ICDACH solution. The prepared electrode was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), contact angle measurement (CAM), profilometry and X-ray photoelectron spectroscopy (XPS). The proposed electrode demonstrated an electrocatalytical effect on the oxidation of dopamine (DA) in the presence of 200μM uric acid (UA) and 50μM ascorbic acid (AA) using differential pulse voltammetry (DPV) method. The oxidation peak currents increased linearly with two concentration intervals of DA at pH 7 phosphate buffer. One of them is 0.60–11.8μM and the other is 11.8–90.0μM. The oxidation peaks of DA, UA and AA could be well separated because the oxidation of AA is inhibited on the modified electrode. Also the separation of DA and UA peak potentials are large enough for DA detection. Therefore, DA could be measured individually in the presence of UA and AA. The limit of detection (LOD) was found as 0.186μM (at a signal-to-noise ratio of 3). The suggested electrode was applied for the determination of DA in dopamine hydrochloride injection and human urine sample with sufficient precision and accuracy.