A novel strategy for the simultaneous discrimination of dopamine and epinephrine by cyclic square wave voltammetry implemented with a customized potentiostat

Abstract

In this study, we report a rapid and efficient strategy by cyclic square wave voltammetry (CSWV), a novel voltammetric technique, to detect dopamine (DA) and epinephrine (EP) separately and simultaneously with an unmodified graphene-based integrated electrode. The CSWV method, with high sensitivity and capability of mechanistic study, is achieved by controlling an inexpensive modified open-source potentiostat (MOSP) that has a superior performance comparable to commercial benchtop electrochemical workstations. Based on the different intramolecular cyclization reaction rates of DA and EP depending on pH, the concentration of DA could be derived from the cathodic peak at +0.12 V, and the concentration of EP could be calculated from the negative cathodic peak at −0.26 V. The CSW voltammogram presented that the linear range of both DA and EP was 5–70 μM, with a detection limit of 2.14 μM and 1.94 μM (S/N = 3) at neutral pH, respectively. In addition, the cathodic currents of CSWV were 12.68 and 10.72 times higher than those of cyclic voltammetry (CV) and 1.53 and 1.24 times higher than those of cathodic square wave voltammetry (cSWV). The proposed method showed a strong anti-interference capability and can be applied to detect DA and EP in the real sample (calf serum sample), with a recovery rate in the range of 100.05–108.25%. The introduced electrochemical determination method can provide a promising application prospect for point-of-care testing (POCT) of neurotransmitters.