Ionic Liquid Salt Bridge in Dilute Aqueous Solutions

Abstract

A new type of salt bridge composed of a hydrophobic room-temperature ionic liquid, recently proposed (T. T. Yoshimatsu, Bull. Chem. Soc. Jpn., 2006, 79, 1017), has been shown to be satisfactorily usable in dilute aqueous solutions of submillimolar range. A stable phase-boundary potential has been demonstrated between an ionic liquid, 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) ] and water is maintained constant over more than four orders of magnitude change in the concentration of an aqueous electrolyte solution. The ionic-liquid salt bridge is a superior alternative to salt bridges based on equitransferent electrolytes in practical applications, particularly, the potentiometry of samples of low ionic strengths, such as potentiometric pH measurements of rainwater.

Mutual Solubility of Hydrophobic Ionic Liquids and Water in Liquid-Liquid Two-phase Systems for Analytical Chemistry

“…From an electroanalytical chemistry viewpoint, hydrophobic ILs are promising for modifying the electrode surface, [98][99][100][101][102][103][104][105][106] preparing membranes for ion-selective electrodes, [107][108][109][110][111] salt bridges, [112][113][114] and other potentiometric as well as voltammetric sensors. 115 A remarkable growth in the number of papers dealing with carbon paste and other carbon electrodes impregnated with ILs attests the strong interest to apply ILs for electroanalytical chemistry.…”

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

“…One possible reason for the deviation at low concentrations is the shift of the potential of the Ag/AgCl/W interface from the expected one due to low Cl -concentrations. 10 Another reason for the deviation is the dissolution of AgCl in W from the Ag/AgCl electrode to produce Ag + ions in W behaving as interfering ions to K + . The AgCl dissolution occurs when the Cl -concentration is lower than or compatible with 13 mM, the solubility of AgCl in water.…”

“…8 The partition is useful when the phase-boundary potential formed by the partitioning of the RTIL is desirable as in the application of the RTILs to salt bridges. [9][10][11] However, the partition of RTIL-constituting ions should be minimized when the RTILs are used as so-called plasticizers or ion exchangers of the liquid-membrane ISEs. Several attempts have been made to use ILs as a component of the liquid-membrane ISEs.…”

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

“…The 0.05 mol kg -1 citrate buffer solution (pH 3.78 at 25 C) 10 was prepared by dissolving 11.41 g of KH2C6H5O7 (Kanto Chemical Co., Inc., 98%) in pure water and diluting it to 1.000 ± 0.0004 dm 3 . A 3.33 mol dm -3 potassium chloride solution (Horiba, 300) was used.…”

“…Recently, a new salt bridge using a hydrophobic ionic liquid has been proposed [1][2][3] as an alternative to the conventional KCl salt bridge (KClSB). The ionic liquid salt bridge (ILSB) is promising for solving most problems inherent to the conventional KClSB, such as the contamination of samples, the requirement of frequently renewing the KCl solution, clogging of the junction, and the dependence of the liquid junction potential (LJP) on the type of the junction.…”