Salt bridges for minimization of liquid junction potentials in different solvent media

Some recent applications of salt bridges for aq. and aq.-org. solvent mixts. are presented. The main cause of high residual liq. junction potentials, and of consequent intrinsic errors, in direct potentiometric electroanal. (pIon and pH measurements) is the inadequacy of the salt bridge selected for insertion in the operational cell. Salt bridges with RbCl, CsCl and KCl were compared. The decreasing order of equitransference in aq. solns. was RbCl, CsCl, KCl. The order was not kept in alc./water mixts. KCl improved its equitransference with increasing proportion of alc., while it was reverse for CsCl. The soly. of KCl sharply decreased with increasing alc. contents. NaCl, which had a poor equitransference in aq. solns., greatly improved its equitransference with increasing percentages of alc., and at ≈80% of alc. it behaved as good as CsCl.