Membranes (Dec 2021)

Solid-Contact Potentiometric Anion Sensing Based on Classic Silver/Silver Insoluble Salts Electrodes without Ion-Selective Membrane

  • Chunxian Liao,
  • Lijie Zhong,
  • Yitian Tang,
  • Zhonghui Sun,
  • Kanglong Lin,
  • Longbin Xu,
  • Yan Lyu,
  • Dequan He,
  • Ying He,
  • Yingming Ma,
  • Yu Bao,
  • Shiyu Gan,
  • Li Niu

DOI
https://doi.org/10.3390/membranes11120959
Journal volume & issue
Vol. 11, no. 12
p. 959

Abstract

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Current solid potentiometric ion sensors mostly rely on polymeric-membrane-based, solid-contact, ion-selective electrodes (SC-ISEs). However, anion sensing has been a challenge with respect to cations due to the rareness of anion ionophores. Classic metal/metal insoluble salt electrodes (such as Ag/AgCl) without an ion-selective membrane (ISM) offer an alternative. In this work, we first compared the two types of SC-ISEs of Cl− with/without the ISM. It is found that the ISM-free Ag/AgCl electrode discloses a comparable selectivity regarding organic chloride ionophores. Additionally, the electrode exhibits better comprehensive performances (stability, reproducibility, and anti-interference ability) than the ISM-based SC-ISE. In addition to Cl−, other Ag/AgX electrodes also work toward single and multi-valent anions sensing. Finally, a flexible Cl− sensor was fabricated for on-body monitoring the concentration of sweat Cl− to illustrate a proof-of-concept application in wearable anion sensors. This work re-emphasizes the ISM-free SC-ISEs for solid anion sensing.

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