Conductometers

A conductometer, or conductivity meter, is an instrument used to measure the electrical conductivity of a liquid, a property that reflects the concentration of ions and thus the solution’s ionic strength. Conductivity depends on temperature and can be used to infer salinity, total dissolved solids, or quality in water samples. Most meters display conductivity κ in siemens per meter or millisiemens per centimeter, derived from the conductance G of a cell with a defined geometry through the relation G = κK, where K is the cell constant.

A typical conductivity meter applies an alternating current between two electrodes, usually platinum, to minimize electrode polarization. The measured conductance is converted to conductivity using the cell constant, which depends on electrode area and the gap between electrodes. Some meters use four-electrode configurations to further reduce polarization errors. Modern instruments often include automatic temperature compensation, reporting conductivity at a reference temperature (commonly 25 °C).

Types range from portable handheld meters for field work to benchtop instruments in laboratories. There are specialized versions for ultra-pure water, high-salinity brines, or microconductivity measurements in micromhos per centimeter. Calibration relies on standard solutions with known conductivities, such as potassium chloride standards, and regular verification is recommended.

Conductometers are widely used in environmental monitoring, drinking-water analysis, pharmaceutical and food industries, and process control to monitor water quality, electrolyte strength, or reaction progress. Limitations include sensitivity to temperature, electrode fouling or coating, sample turbidity, and chemical incompatibilities with electrode materials. Accurate results require proper calibration, appropriate cell geometry, thorough cleaning, and, when needed, correction for temperature effects.