How to establish and use high-ionic-strength pH standards

Detn. of accurate transference parameters in concd. aq. NH4Cl solns. has allowed acquisition of a set of pH-metric stds. of ionic strengths up to 7.2 mol kg-1. Use of these high-ionic-strength stds. together with better salt bridges (viz. CsCl instead of KCl) in the high pH-metric cell contributes to effective zeroing of the high residual liq. junction potentials expected when measuring sample solns. of high ionic strengths (esp. highly acidic or highly alk.). Subsidiary cond. measurements on the sample solns. are recommended to help attainment of the condition of equality of ionic strength with the std. ref. soln.