The Determination of Dopamine Using Glassy Carbon Electrode Pretreated by a Simple Electrochemical Method

In this study, the pretreated glassy carbon electrode (GCE) was prepared by electrochemical oxidation firstly at +1.75 V for 300 s, and then by electrochemical reduction at –1.75 V for 300 s in 0.1 mol L–1 pH 7.0 phosphate buffer solution (PBS) and used for the determination of dopamine (DA) by cyclic voltammetry (CV). The pretreated GCE gives 100-fold greater current responses for dopamine compared with unpretreated GCE. The effect of pH, pretreated mode, scan rate and concentration of dopamine on the peak current was investigated, and the results indicated that the peak current of dopamine is the highest in 0.1 mol L–1 pH 7.0 PBS and the electrode reaction corresponds to a rate-controlled process. The peak current of the anodic peak and the concentration of dopamine hydrochloride is linear in the range of 1.0 × 10–7 – 9.0 × 10–6 mol L–1 and 1.2 × 10–5 – 8.0 × 10–5 mol L–1 with correlation coefficients of 0.9973 and 0.9980, and the detection limit is 3.0 × 10–8 mol/L. It has been successfully applied to the determination of dopamine in dopamine hydrochloride injection with recoveries ranging from 98 to 103%. The proposed method possesses the distinct advantages of simple, appropriate for operation, good reproducibility and cheap instrument.