Computer approach to ion-selective electrode potentiometry by two standard additions and subtractions methods through ionic strength calibration

Abstract

The effect of ionic strength in standard additions and subtractions methods has been utilised for determining an unknown concentration using an ion-selective electrode without prior calibration of the electrode. In the simplest instance, only two standard additions or subtractions are required. An initial value of unknown concentration or electrode slope is first assumed to solve the equations repeatedly. This method gives greater accuracy than the methods which are used at present. The method was used to evaluate the unknown concentration and electrode slope. The blank solution has the same ionic strength as the standard solution in the two standard additions method. In the two standard subtractions method, a suitable blank solution is chosen. The effectiveness of computer iterative solution of the two standard additions method is demonstrated on a lead sample.