S,S,S-Tris(2-ethylhexyl) phosphorotrithioate as an effective solvent mediator for a mexiletine-sensitive membrane electrode

Takashi Katsu, Yumi Tsunamoto, Nobumitsu Hanioka, Keiko Komagoe, Kazufumi Masuda, Shizuo Narimatsu

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


S,S,S-Tris(2-ethylhexyl) phosphorotrithioate proved to be an effective solvent mediator for constructing a mexiletine-sensitive membrane electrode in combination with an ion-exchanger, sodium tetrakis[3,5-bis(2-methoxyhexafluoro- 2-propyl)phenyl]borate. Among a series of phosphorus compounds containing phosphoryl (P=O) groups, this solvent mediator showed the highest sensitivity to mexiletine in phosphate-buffered physiological saline containing 0.15 mol L-1 NaCl and 0.01 mol L-1 NaH2PO 4/Na2HPO4 (pH 7.4), giving a detection limit of 2∈×∈10-6 mol L-1 with a slope of 58.8 mV decade-1. This is the best reported detection limit of any mexiletine-sensitive electrode developed to date. Owing to its high selectivity toward inorganic cations, the electrode was used to determine the level of mexiletine in saliva, the monitoring of which is quite effective for controlling the dose of this drug noninvasively. The mexiletine concentrations determined with the mexiletine-sensitive electrode compared favorably with those determined by high-performance liquid chromatography.

Original languageEnglish
Pages (from-to)2057-2064
Number of pages8
JournalAnalytical and Bioanalytical Chemistry
Issue number6
Publication statusPublished - Mar 2007
Externally publishedYes


  • Drug monitoring
  • Ion-selective electrode
  • Mexiletine determination
  • S,S,S-Tris(2-ethylhexyl) phosphorotrithioate
  • Solvent mediator

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry


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