Application of zetametry to determine concentrations of acidic and basic impurities in analytical reagents.

The sign and magnitude of the ζ potential of mineral oxides in allegedly pure organic solvents (high-quality chemical reagents) depends on the concentration of acidic and basic impurities, chiefly organic acids and amines. "Zetametric titration" with HClO(4) makes it possible to estimate the concentration of basic impurities and offers an attractive alternative to other analytical methods. Titanium(IV) oxide has been chosen as the probe powder in view of its very low solubility and nearly neutral point of zero charge in aqueous systems. Some systems have a high buffer capacity and addition of acid and base has a minor effect on the ζ potential of titania. Specific adsorption of alkali metal cations on anatase can be also a significant problem.