Calibration

The conductivity σ can be deduced from the G measurement, provided that the cell constant k is known. It is therefore necessary to determine this constant, because its value can change over time, especially due to the absorption of analytes, which tends to reduce the active surface area. Therefore we must proceed to a calibration phase by means of a standard solution, whose conductivity is tabulated for each temperature: this is often a KCl solution at 0.1 mol.L^-1. In practice, the experimenter adjusts the constant k constant in order to display on screen the value of conductivity tabulated at the temperature of the study. Once it is calibrated, the value of σ is directly read on the electrical conductivity meter.

Conductivity values for a KCl solution at 0.1 mol.L^-1

Experimentally, we proceed as follows:
1- Place the conductivity cell in a standard solution of KCl at 0.1 mol.L^-1
2- Select the appropriate temperature.
3- Press the Cal button to start the calibration process. Change the value of the cell constant k to obtain the value of 𝜎 suitable for the measuring temperature.
4- Confirm the value of k. The electrical conductivity meter then displays 𝜎 and is ready to be used.
5- Rinse the cell in distilled water.