Zeta potentials in nonaqueous media: how to measure and control them

The effect of traces of water in nonaqueous solvents on the zeta-potential is overrated, and the role of impurities in presumably pure organic solvent s is often overlooked. Oxides can serve as potentiometric sensors to determ ine the concentration and nature of impurities. Even in very inert solvents the countercharge in solution must exist. Small ions are stabilized by hom oconjugation and by amphiphilic nonionic compounds. The electrokinetic phen omena of the second kind are more common in nonaqueous solvents and they le ad to very high absolute values of mobility at high field strengths. (C) 19 99 Elsevier Science B.V. All rights reserved.