Fast and sensitive coulometric signal transduction for ion-selective electrodes by utilizing a two-compartment cell

Authors：Han, Tingting; Song, Tao; Bao, Yu; Wang, Wei^*; He, Ying; Liu, Zhenbang; Gan, Shiyu^*; Han, Dongxue; Bobacka, Johan; Niu, Li

Source：Talanta, 2023, 262: 124623.

DOI：10.1016/j.talanta.2023.124623

• Coulometric response
• Amperometric response
• Ion -selective electrodes as reference electrode
• Two -compartment cell
• Electrochemical impedance spectroscopy

Here, we propose a fast and sensitive coulometric signal transduction method for ion-selective electrodes (ISEs) by utilizing a two-compartment cell. A potassium ion-selective electrode (K+-ISE) was connected as reference electrode (RE) and placed in the sample compartment. A glassy carbon (GC) electrode coated with poly(3,4-ethylenedioxythiophene) (GC/PEDOT), or reduced graphene oxide (GC/RGO), was connected as working elec-trode (WE) and placed in the detection compartment together with a counter electrode (CE). The two com-partments were connected with an Ag/AgCl wire. The measured cumulated charge was amplified by increasing the capacitance of the WE. The observed slope of the cumulated charge with respect to the change of the log-arithm of the K+ ion activity was linearly proportional to the capacitance of the GC/PEDOT and GC/RGO, estimated from impedance spectra. Furthermore, the sensitivity of the coulometric signal transduction using a commercial K+-ISE with internal filling solution as RE and GC/RGO as WE allowed to decrease the response time while still being able to detect a 0.2% change in K+ concentration. The coulometric method utilizing a two -compartment cell was found to be feasible for the determination of K+ concentrations in serum. The advan-tage of this two-compartment approach, compared to the coulometric transduction described earlier, was that no current passed through the K+-ISE that was connected as RE. Therefore, current-induced polarization of the K+- ISE was avoided. Furthermore, since the GCE/PEDOT and GCE/RGO (used as WE) had a low impedance, the response time of the coulometric response decreased from minutes to seconds.

• Institution
  广州大学