Potentiometric determination of nitrate ions by the dilution method with ion-selective electrodes

A potentiometric method of determining nitrate ions with ion-selective electrodes is proposed, based on the n-fold dilution procedure followed by adding a standard solution until the initial potential value is attained. The concentration to be determined is estimated without using any electrochemical characteristics of the electrode system. The detection limit for nitrate ions is 8 x 10(6) M. The method makes it possible to determine nitrate ions in the presence of a 200-fold excess of chloride ions with an error of no higher than 10%.