Sensitive electrochemical determination of oxalic acid in spinach samples by a graphene-modified carbon ionic liquid electrode

Abstract

In this paper, a new electrochemical oxalic acid (OA) sensor based on graphene (GR)-modified carbon ionic liquid electrode (CILE) was proposed. The GR nanosheets were deposited on the surface of CILE by electroreduction with graphene oxide as precursor and electrocatalytic oxidation of OA on GR/CILE was further investigated. As compared with that of bare CILE, the oxidation peak current of OA on GR/CILE were greatly improved with the decrease of the oxidation potential. Electrochemical parameters of the electrooxidation of OA were calculated. Under the selected conditions, the oxidation peak currents increased with OA concentration in the range from 8.0 μM to 6.0 mM with the detection limit as 0.48 μM (3σ). The proposed method exhibited higher sensitivity and wider linear range, which was applied to determination of OA concentration in spinach samples with satisfactory results.