Use of Highly Hydrophobic Ionic Liquids for Ion-selective Electrodes of the Liquid Membrane Type

Naoya NISHI, Hiroshi MURAKAMI, Yukinori YASUI, Takashi KAKIUCHI
2008 Analytical Sciences  
The phase-boundary potential at the interface between an aqueous KCl solution (W) and a hydrophobic room-temperature ionic liquid (RTIL), trioctylmethylammonium bis(nonafluorobutylsulfonyl)imide ([TOMA + ][C 4 C 4 N -]), containing dicyclohexano-18-crown-6 (DCH18C6), shows the nernstian response to K + in W within a polarized potential window of 500 mV between [TOMA + ][C 4 C 4 N -] and W, demonstrating that hydrophobic RTILs can be used as a nonvolatile ionic medium for liquid-membrane
more » ... id-membrane ion-selective electrodes. The complex formation constant of K + with DCH18C6 in [TOMA + ][C 4 C 4 N -] is estimated to be on the order of 10 9 from the upper detection limit using a partition equilibrium model in the presence of a neutral ionophore. The response time of the phase-boundary potential is ~20 min. Gelled [TOMA + ][C 4 C 4 N -] also shows the nernstian response to K + , although the upper limit is lower probably due to a change in the solvent properties from the non-gelled [TOMA + ][C4C4N -]. The response time of the gelled [TOMA + ][C4C4N -] is ~5 min, shorter than that of the non-gelled [TOMA + ][C4C4N -].
doi:10.2116/analsci.24.1315 pmid:18845893 fatcat:gseap5azgnbtfdyag4kxmdjvti