A novel voltammetric platform composed of poly(aminopyrazine), ZrO2 and CNTs for a rapid, sensitive and selective determination of ascorbic acid in pharmaceuticals and food samples

Abstract

An electrochemical platform based on a composite of poly(aminopyrazine) (PAP), zirconium oxide nanoparticles (ZrO2NPs) and carbon nanotubes (CNTs) was prepared. A GCE was first modified with CNTs and ZrO2NPs via a drop-casting technique. Then, the ZrO2NPs/CNTs/GCE system was immersed into an aqueous solution of 1 mM aminopyrazine (AP) containing 10 mM LiClO4 in a potential range of −1.5 V–1.5 V for 20 cycles to carry out the polymerization step. The composite layer was characterized by energy dispersive X-ray (EDX), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The proposed voltammetric platform (PAP/ZrO2NPs/CNTs on GCE) was applied for the electrooxidation of ascorbic acid (AA). Compared with ZrO2NPs/CNTs/GCE, CNTs/GCE and GCE, the proposed novel system (PAP/ZrO2NPs/CNTs/GCE) presented an effective catalytic activity for the oxidation of AA with a large enhancement in the current response. The procedure has also enabled a large peak to peak separation between AA and tryptophan (TRP). A linear dynamic current response was obtained for the concentrations of AA in the range of 1.0 × 10−6 - 2.95 × 10−4 M with a detection limit of 3.5 × 10−7 M. The quantification of AA in pharmaceuticals and mixed fruit juices has successfully been performed by PAP/ZrO2NPs/CNTs/GCE.