Flow-injection on-line electrochemical separation/determination of ions using a two-step oil/water-type flow cell system.

A flow system for electrochemical separation and detection of ions was constructed by connecting two oil/water (O/W)-type flow cells, in which a long polarizable O/W interface was formed at the inner surface of a porous poly(tetrafluoroethylene) (PTFE) tube. Using this system, acetylcholine and choline ions, whose ion-transfer potentials are different by only 60 mV, could be separated and determined simultaneously. It was thus shown that the present flow system is promising for the electrochemical flow separation/detection of ions and, in principle, also for electrochromatographic separation of ions.