A new sensor for thermometric titrations

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 H3BO3in 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 pK values of some well established weak acids such as, acetic acid (4.77), phosphoric acid (pK1 = 2.18, pK2 = 7.20 and pK3 = 12.32) as well as for a very weak acid of uncertain pK values H3BO3 (pK1 = 9.20, pK2 = 12.7 and pK3 = 13.80). The sensor was also examined for kinetic catalytic determination of iron(III) in water, milk and pharmaceuticals.