Application of Hematoxylin Multi-wall Carbon Nanotube Modified Carbon Paste Electrode as a Chemical Sensor for Simultaneous Determination of Dopamine and Acetaminophen

A hematoxylin multi-wall carbon nanotube modified carbon paste electrode (HMWCNT-CPE) was fabricated and the electrochemical behavior of dopamine (DA) was investigated on it, using cyclic voltammetry, chronoamperometry and differential pulse voltammetry as diagnostic techniques. A comparison of the data obtained from the electrocatalytic oxidation of DA at HMWCNT-CPE, MWCNT-CPE, and hematoxylin modified CPE (HMCPE) clearly shows that a combination of MWCNT and hematoxylin definitely improves the characteristics of DA electrocatalytic oxidation. The kinetic parameters such as the electron transfer coefficient, α, and the heterogeneous electron transfer rate constant, k′, for the oxidation of DA at the HMWCNT-CPE surface were determined using cyclic voltammetry. Differential pulse voltammetry (DPV) exhibits two linear dynamic ranges (2.0×10-1 μM to 8.0 μM and 8.0 μM to 1000.0 μM) and a detection limit of 6.0×10-2 μM for DA. In DPV, HMWCNT-CPE could separate the oxidation peak potentials of DA and acetaminophen (AC) present in the same solution though, at the unmodified CPE, the peak potentials were indistinguishable. The sensitivity of the modified electrode for DA determination in the absence and presence of AC is the same. It indicates the fact that simultaneous or individual measurement of DA and AC is possible without any interference. Low cost and simplicity, wide linear range, good reproducibility, and stability are the important advantages of this modified electrode. Finally, the modified electrode was successfully applied to the determination of DA and AC in pharmaceutical preparations.