Indirect Determination of Multivalent Ions Using an Ion-selective Electrode

Abstract

A multivalent ion can indirectly be determined in terms of a potentiometric analysis of an excess of a monovalent precipitant ion using an appropriate monovalent ion-selective electrode.
The precision of indirect method is described in relation to that of potential reading and that of added amount of precipitant. The optimum amount of monovalent precipitant was determined by the solubility products of the precipitates and by the precision of determination. on the basis of potential reading. The effect of added amount on the precision of determina- tion was discussed. Theoretical calculation showed that the precision of determination in terms of indirect calibration curve method is higher than that in terms of direct calibration curve method as the precision of potential reading decreases. The precision of indirect determination of sulphide ion based on portentiometry of silver ion using silver ion-selective electrode is statistically higher than that of direct determination of sulphide ion using sulphide ion-selective electrode.