title: S,S,S-Tris(2-ethylhexyl) phosphorotrithioate as an effective solvent mediator for a mexiletine-sensitive membrane electrode.
abstract: 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 NaH2PO4/Na2HPO4 (pH 7.4), giving a detection limit of 2x10(-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.
authors.affiliation: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Tsushima, Okayama, 700-8530, Japan. katsu@pharm.okayama-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Katsu
authors.forename: Yumi
authors.initials: Y
authors.lastname: Tsunamoto
authors.forename: Nobumitsu
authors.initials: N
authors.lastname: Hanioka
authors.forename: Keiko
authors.initials: K
authors.lastname: Komagoe
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Masuda
authors.forename: Shizuo
authors.initials: S
authors.lastname: Narimatsu
mesh_terms: D000889:Anti-Arrhythmia Agents / Q000737:chemistry; D004566:Electrodes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008801:Mexiletine / Q000737:chemistry*; D015394:Molecular Structure; D063086:Organothiophosphates / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry; D012463:Saliva / Q000737:chemistry; D012680:Sensitivity and Specificity; D012997:Solvents / Q000737:chemistry*
chemical_list: D000889:Anti-Arrhythmia Agents; D063086:Organothiophosphates; C520219:S,S,S-tris(2-ethylhexyl) phosphorotrithioate; D012997:Solvents; D008801:Mexiletine; D010758:Phosphorus