Fabrication of an all-solid-state ammonium ion– selective electrode by a two-step process using cyclic voltammetry

• Main Authors: Benoudjit, Abdelmohsen, Abd-Wahab, Firdaus, Wan Salim, Wan Wardatul Amani
• Format: Conference or Workshop Item
• Language: English
• Published: MDPI 2020
• Subjects: TD169 Environmental protection; TP248.13 Biotechnology
• Online Access: http://irep.iium.edu.my/84243/7/84243_Fabrication%20of%20an%20all-solid-state%20ammonium%20ion%E2%80%93%20selective%20electrode.pdf; http://irep.iium.edu.my/84243/; https://www.mdpi.com/journal/biosensors/special_issues/IECB2020_SI#published
• Institution: Universiti Islam Antarabangsa Malaysia

Ammonium ions (NH4+) are one of the indicators of water quality; high ammonium concentration [NH4+] in water can cause eutrophication and affect aquatic biota and can cause cell death in the central nervous system of human beings. However, current ion-selective electrodes used for water-quality monitoring are bulky, require frequent calibration owing to membrane fouling, and cannot be integrated into mobile sensor platforms. We fabricated an all-solid-state ion-selective electrode for ammonium ion (NH4+ISE) using a two-step process; first is electropolymerization deposition on the electrode using a solution of 3,4-ethylenedioxythiophene (EDOT), sodium polystyrene sulfonate (NaPSS), and o-phenylenediamine (OPD) resulting in a solid-state transducer on screen-printed carbon electrodes (SPCEs), and the second is electropolymerization of OPD as ion-selective membrane (ISM) on top of the transducer. The electropolymerization deposition of the transducer and the ISM were simply achieved by using cyclic voltammetry (CV) with potential from 0.0 V to 0.8 V and 50 mVs-1 scan rate. The fabricated NH4+ISE can detect [NH4+] as low as 4.8×10-5 M, with a slope of 20 mV/decade (R2>0.99) and a linear range from 4.8×10-5 M to 0.1 M. These preliminary results provide an initial insight into the applicability of the simple two-steps fabrication process of the NH4+ISEs for scaling-up purposes, with the ability for miniaturization and integration to a mobile sensor platform.