Voltammetric vs. potentiometric sensing of dopamine: Advantages and disadvantages, novel cell designs, fundamental limitations and promising options

• A novel multisensor tubular flow-through unit and “barrel” type electrochemical cell for small volume samples are developed.
• The tubular unit is suitable for dopamine potentiometric sensing however an ionophore with higher selectivity is needed.
• “Barrel” type 3-electrode cell allows for dopamine sensing down to 10−7 M in 200 μl samples.
• Cyclic voltammetry and impedance data suggest that diffusion is the limiting stage of dopamine oxidation.

Advantages and disadvantages of voltammetric vs. potentiometric sensing of dopamine are discussed. The study is focused on the measurements in small sample volumes, rather than on the selectivity to dopamine. For the potentiometric sensing, a novel flow-through tubular unit is developed. For voltammetric measurements with bare gold and platinum electrodes, miniature cylinder cells with the volume of 200 μl are developed. The CV and impedance data suggest that the dopamine diffusion to the electrode surface is the limiting stage of the whole electrode process which hinders measurements without stirring. It is shown that use of micro electrode arrays allows overpassing this limitation.