Ionic liquid salt bridge based on tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide for stable liquid junction potentials in highly diluted aqueous electrolyte solutions

A moderately hydrophobic ionic liquid, tributyl(2-methoxyethyl)phosphonium bis(pentafluoroethanesulfonyl)amide ([TBMOEP+][C2C2N-]), shows a very stable liquid junction potential upon contact with an aqueous solution whose ionic strength is as low as 1 mu mol dm(-3). The stability with the maximum excursion of the potential within +/- 0.5 mV for 30 min is very promising for accurate determination of pH and other single ion activities potentiometrically. (C) 2010 Elsevier B.V. All rights reserved.