Derivative and differential potentiometric stripping analysis.

The theory of derivative and differential potentiometric stripping analysis has been presented. The latter term refers to the technique consisting in measuring the derivative of time with respect of potential as a function of potential. Good correlation has been found between the experimental data and the theoretical results. The selectivity of differential potentiometric stripping analysis has been analyzed by computer calculations as a function of the difference of half-wave potential and the valency of the ions and the concentration ratio of the latter. The experimental results were in good agreement with the calculated data. The selectivity of d.p.s.a. is greatly affected by the asymmetry of the d.p.s.a. function. The selectivity in the case of an interferring ion of more cathodic halfwave potential than that of the measured one was found to be higher with the present technique than with other voltammetric methods.