Potentiometric determination of fluoride by a combination of continuous-flow analysis and the gran addition method

Abstract

A method is described for the determination of fluoride ion by continuous-flow analysis combined with the Gran addition method using an ion-selective electrode.

The Gran addition method is a reliable potentiometric technique and an advantage of its use is that, in addition to the determination of the free and total fluoride concentration in a complexed medium, the complexation rate is also measured. The drawback of the method is the difficulty in adjusting the peristaltic pumps, which is time consuming. However, this extra time is compensated for by the simultaneous determination of fluoride ion concentration and the complexation rate.

For concentrations of fluoride ion between 0.5 and 100 mg 1^–1, the precision is 5%.