Electrochemical Behaviour Study and Sensitive Determination of Dopamine on Cathodically Pretreated Boron-doped Diamond Electrode

An unmodified and cathodically pretreated boron-doped diamond (BDD) electrode was used as a sensitive electrochemical sensor for the determination of dopamine (DA) using differential pulse (DPV) and square-wave voltammetry (SWV). Cyclic voltammetric studies indicated a quasi-reversible behaviour of DA in acetate buffer solution at pH 3 with well-defined oxidation and reduction peak at +0.66 and +0.07 V vs. Ag/AgCl/3 M KCl, respectively. The electrode reaction of DA was shown to be a two-electron diffusion-controlled process. With optimized experimental parameters, the current response of DA was proportionally linear in the concentration range from 0.3 to 100μM and 0.7 to 100μM with low detection limits of 0.09 and 0.04μM as well as good repeatability (relative standard deviation of 3.5 and 3.3 %) for DPV and SWV, respectively. The influence of possible interfering compounds was also studied. The practical applicability of the developed method was demonstrated on the determination of DA in model human urine and water samples, with results similar to those obtained by a spectrophotometric method. The proposed electrochemical methodology is simple, inexpensive and rapid with no need of tedious sample pretreatment. In this way, BDD electrode may represent an efficient alternative to widely used modified electrodes in the determination of DA.