Thermometric Titration - The Missing Piece in the Titration Puzzle

Thermometric titration is a highly versatile titration method because one sensor can be used for various kinds of applications. The temperature sensors (Thermoprobes) are neither specific to any ion type nor does their performance depend on the electrochemical properties of the sample solution. They require almost no maintenance and can be used immediately without any conditioning. Thermometric Titration can solve application problems that potentiometry cannot or at least not with satisfying reproducibility:

• Free Fatty Acids (FFA) in edible oils or phosphate in fertilisers can be determined even at low levels with high reproducibility and without cross interference of other ions.
• Etching acid mixtures containing phosphoric acid can be titrated in aqueous media.
• Two different analytes (e.g. sulfate and total acid) can be determined in two consecutive titrations without changing the sensor and sample solution.

In all cases the titration can be carried out without any special sample preparation and the results are usually obtained very fast. In a thermometric titration, reagent solution (titrant) is added to the sample at a constant rate until the endpoint is reached. The latter can be recognised by a break in the titration curve obtained by plotting the amount of titrant added to the sample versus the temperature. The second derivative of the temperature curve yields the endpoint. Since the temperature sensor has a response time of 0.3 s and a resolution of10–5 K, even small enthalpy changes are reliably monitored.

With the 859 Titrotherm Metrohm offers a well proven system for thermometric titration and provides applications for many industries.