A commonly used method for quantifying sodium in foodstuffs is to determine the counterion chloride using argentometric titration, the concentration of which can be used to deduce the sodium concentration from the 1:1 stoichiometry of sodium chloride. This method involves errors because sodium is not only present with chloride as the counterion. A new method for direct titration of sodium with thermometric endpoint detection solves this problem.
Thermometric titration shares with potentiometric titration the use of a sensor to detect the endpoint of the titration reaction. In the case of thermometric titration, however, the sensor is a fast responding thermometer. Hence, instead of measuring the electrochemical potential in the solution, this robust, highly sensitive thermometer tracks the reaction enthalpy, i.e., the temperature change in the solution.