Voltammetric Method for the Determination of Lactic Acid Using a Carbon Paste Electrode Modified with Cobalt Phthalocyanine

Abstract

A non-enzymatic lactic acid sensor was fabricated by a carbon paste electrode (CPE) modified with cobalt phthalocyanine (CoPC). The electrochemical behavior of CoPC modified electrode in lactic acid solutions was characterized by cyclic voltammetry. Results showed that the modified electrode exhibits good catalytic activity for the oxidation of lactic acid at 1.18 V versus saturated Ag/AgCl reference electrode. It had an operational pH range of 3.6-1.6 and showed the linear dynamic range from 11.9 mM to 188 mM of lactic acid at pH 2.0 with good reproducibility. The detection limit was found to be 1.54 mM (3σ). Our study also found that ascorbic acid, malic acid, EDTA, oxalic acid, and citric acids were the interfering species to the electrode while melonic acid, maleic acid, fumeric acid, and stearic acid showed no interference effect on the electrode performance.