A new sensor for thermometric titrations

Abstract

A new thermometric sensor, which is a transistor (OC71), has been introduced to follow thermometric titrations successfully to clear end points. The sensor was suitable in both normal and differential modes of titration. It is possible to titrate down to 1.32 μmol of HCl and 26.4 μmol of H 3BO 3in a final 20 ml solution with accuracy and precision of 1%, 2.2% and 1.4%, 2.2%, respectively. The sensor, in association with a pH glass electrode, was used for the determination of p K values of some well established weak acids such as, acetic acid (4.77), phosphoric acid (p K 1 = 2.18, p K 2 = 7.20 and p K 3 = 12.32) as well as for a very weak acid of uncertain p K values H 3BO 3 (p K 1 = 9.20, p K 2 = 12.7 and p K 3 = 13.80). The sensor was also examined for kinetic catalytic determination of iron(III) in water, milk and pharmaceuticals.