Ring‐disc Microelectrodes towards Glutathione Electrochemical Detection

An alternative approach for space‐resolved glutathione (GSH) detection using a ring‐disc microelectrode and an appropriate electroactive probe (acetaminophen) is reported. Acetaminophen is electrochemically oxidized at one of the electrodes and a fraction of the reaction product (N‐acetyl‐p‐quinoneimine) diffuses to the other, where it is detected. The collection efficiency value is dependent on the concentration of glutathione in solution, which consumes N‐acetyl‐p‐quinoneimine during its transit from the disc to the ring. Collection efficiency values close to 100 % were obtained by confining the electroactive species in a gap (<2 μm) that resembles a thin layer cell in a SECM configuration. The proposed indirect method was used to image the transport of GSH across an impermeable membrane in a SECM experiment. The method proved to be useful as a proof of concept for space‐resolved GSH electrochemical detection and a topography independent electrochemical image was acquired.