Electrocatalytic Oxidation of Dopamine and Ascorbic Acid on Carbon Paste Electrode Modified with Nanosized Cobalt Phthalocyanine Particles: Simultaneous Determination in the Presence of CTAB

Metallophthalocyanine (MPc) and its derivatives are well known as electrocatalysts to catalyze oxidation or reduction of some species, such as cysteine, nitric oxide. Their nanosized particles may display the potential optics, electronic, catalytic and structural properties. In this paper, carbon paste electrodes modified with nanosized cobalt phthalocyanine particles (denoted as Nano-CoPc-CPE) are fabricated. The electrocatalytic oxidation of dopamine (DA) and ascorbic acid (AA) on the Nano-CoPc-CPE was investigated by means of cyclic voltammetry. Nano-CoPc particles perform good electrocatalytic activity to DA and AA. The anodic peak potentials of DA and AA were separated with good sensitivity in the presence of cetyltrimethylammonium bromide (CTAB). The DA and AA can be simultaneously determined by using differential pulse voltammetry. On optimal conditions, the good linear response to DA and AA was observed in the range of 3.0×10−6–1.0×10−4 M and 5.0×10−6–3.0×10−4 M with the correlation coefficient of 0.9983 and 0.9978, respectively. Moreover, 100-fold AA did not interfere in the determination of DA. This method has been used to simultaneously determine DA and AA concentration in mixed drug samples with satisfactory results.