title: Stability of a Ag/AgCl reference electrode equipped with an ionic liquid salt bridge composed of 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl)-amide in potentiometry of pH standard buffers.
abstract: The stability of a Ag/AgCl reference electrode equipped with a gelled ionic liquid, 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl)amide (C(8)mimC(1)C(1)N), as a salt bridge, was examined in the potentiometry of pH standard solutions. The variation in the liquid junction potential (LJP) of the ionic liquid (IL)-type reference electrode, measured with respect to a double junction-type KCl reference electrode, was within 1 mV when one standard solution was replaced by another, except for the phthalate standard. The time course of the potential of the IL-type reference electrode showed a standard deviation of ±0.3 mV in all buffer solutions. The reproducible deviation of the potential of the IL-type reference electrode in the phthalate pH standard amounted to 5 mV. The deviation is due to the partition of the hydrogen phthalate in the C(8)mimC(1)C(1)N, influencing the phase boundary potential (PBP) across the interface between C(8)mimC(1)C(1)N and the phthalate standard. If a citrate standard is used instead of the phthalate buffer, the IL salt bridge works satisfactorily as a salt bridge for a reference electrode suitable for potentiometoric pH measurements.
authors.affiliation: R&D Center, HORIBA, Ltd, Kyoto 601–8510, Japan. manabu.shibata@horiba.com
authors.forename: Manabu
authors.initials: M
authors.lastname: Shibata
authors.forename: Mikito
authors.initials: M
authors.lastname: Yamanuki
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nomura
authors.forename: Takashi
authors.initials: T
authors.lastname: Kakiuchi
mesh_terms: D002021:Buffers; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D052578:Ionic Liquids / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D018030:Silver Compounds / Q000737:chemistry*; D013449:Sulfonamides / Q000737:chemistry*
chemical_list: C558474:1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl)amide; D002021:Buffers; D052578:Ionic Liquids; D012492:Salts; D018030:Silver Compounds; D013449:Sulfonamides; D012834:Silver; C037548:silver chloride