Quartz crystal microbalance sensor using ionophore for ammonium ion detection

Yasuhiro Kosaki, Kosuke Takano, Daniel Citterio, Koji Suzuki, Seimei Shiratori

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Ionophore-based quartz crystal microbalance (QCM) ammonium ion sensors with a detection limit for ammonium ion concentrations as low as 2.2.M were fabricated. Ionophores are molecules, which selectively bind a particular ion. In this study, one of the known ionophores for ammonium, nonactin, was used to detect ammonium ions for environmental in-situ monitoring of aquarium water for the first time. To fabricate the sensing films, poly(vinyl chloride) was used as the matrix for the immobilization of nonactin. Furthermore, the anionic additive, tetrakis (4-chlorophenyl) borate potassium salt and the plasticizer dioctyl sebacate were used to enhance the sensor properties. The sensor allowed detecting ammonium ions not only in static solution, but also in flowing water. The sensor showed a nearly linear response with the increase of the ammonium ion concentration. The QCM resonance frequency increased with the increase of ammonium ion concentration, suggesting a decreasing weight of the sensing film. The detailed response mechanism could not be verified yet. However, from the results obtained when using a different plasticizer, nitrophenyl octyl ether, it is considered that this effect is caused by the release of water molecules. Consequently, the newly fabricated sensor detects ammonium ions by discharge of water. It shows high selectivity over potassium and sodium ions. We conclude that the newly fabricated sensor can be applied for detecting ammonium ions in aquarium water, since it allows measuring low ammonium ion concentrations. This sensor will be usable for water quality monitoring and controlling.

Original languageEnglish
Pages (from-to)563-567
Number of pages5
JournalJournal of Nanoscience and Nanotechnology
Issue number1
Publication statusPublished - 2012


  • Ammonium ion
  • Ionophore
  • Liquid phase
  • Nonactin
  • Quartz crystal microbalance
  • Sensor

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • Biomedical Engineering
  • General Materials Science
  • Condensed Matter Physics


Dive into the research topics of 'Quartz crystal microbalance sensor using ionophore for ammonium ion detection'. Together they form a unique fingerprint.

Cite this