| Research Abstract |
The development and application of ion-selective electrodes continue to be an area of focus. In this study, special attention was paid to develop organic ammonium ion-selective membrane electrodes, because there are many drugs having the amino group in their molecules. First, we constructed biogenic amine-sensitive membrane electrode using the combinations of appropriate solvent mediators and a lipophilic ion-exchanger, sodium tetrakis [3,5-bis (2-methoxyhexafluoro-2-propyl) phenyl] borate. It was found solvent mediators, such as thiophosphate esters with a P=S group, generally strengthened response to organic ammonium ions including histamine, and markedly suppressed responses to inorganic cations, such as Na^+ and K^+, suggesting that hydrogen bonding between the NH_3^+ group of organic ammonium ions and the negatively polarized sulfur atom in the P=S group would enhance such responses. We applied the histamine electrode constructed using prothiofos, one of the compounds containing a
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P=S group, to determine histamine release from mast cells. The histamine concentrations determined agreed well with those determined by an established fluorimetric assay.
Second, we constructed a triethylammonium-sensitive membrane electrode using sodium tetrakis [3,5-bis (2-methoxyhexafluoro-2-propyl) phenyl] borate as an ion-exchanger and benzyl 2-nitrophenyl ether as a solvent mediator and applied it for the determination of the pH difference across a cell membrane. The method is based on monitoring of the pH gradient-induced uptake of triethylammonium in situ. In experiments using liposomes, the uptake of triethylammonium into liposomes was quantitatively induced according to the pH difference across the liposomal membrane. The transmembrane pH difference in Escherichia coli cells and the light-induced formation of the pH difference across the envelop vesicles of Halobacterium halobium were successfully determined by the present method.
We described here only two results. Other results can be seen through references described in the back of this report. Less
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