Metrohm is offering its 859 Titrotherm system for thermometric titration, suitable for applications in many industries.
Thermometric titration is a versatile titration method because one sensor can be used for various 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 is suitable for use in applications where potentiometry cannot perform with satisfying reproducibility.
For example, thermometric titration can determine free fatty acids (FFA) in edible oils or phosphate in fertilisers, 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 (for example sulphate 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 quickly.
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 0.3s and a resolution of 10-5K, even small enthalpy changes are reliably monitored.
