Abstract
Monitoring of the neurotransmitter, dopamine is an important task as dysregulation is a marker for numerous diseases. Electrochemical methods have shown promise but suffer from interferences, inadequate limits of detection, limited dynamic range, and electrode fouling. These issues were addressed with a composite electrode consisting of pseudo-graphitic particles (d < 80 μm) within a Nafion ink deposited on a glassy carbon substrate. The particle surfaces were chemically modified with benzoate functionalities. This surface-bound anionic group was able to suppress interference from ascorbate and urate, through charge repulsion. Additionally, this sensor shows no loss in signal from dopamine fouling both in cyclic (CV) and square-wave voltametric (SWV) studies. With CV the LOD was 1.44 μM with a sensitivity of 1.252 μA μM−1 cm2 and linear range of 5–1000 μM. Application of SWV gave 0.08 μM, 3.273 μA μM−1 cm2 and 0.1–100 μM for these quantities. This performance is maintained in the presence and absence of 1 mM concentrations of ascorbate and urate interferents. This combination of performance, fouling resistance, and insensitivity to interferences is unique in literature.