konduktivitymetry

Konduktivitymetry is the measurement of a material's ability to conduct electric current, typically in liquids such as water and electrolyte solutions. The measured quantity, conductivity, reflects the concentration and mobility of ions and is used as an indicator of ionic content, purity, salinity, and process control.

Principle: An alternating current is applied between electrodes in contact with the test sample. The resulting current is proportional to conductance. Conductance G equals the reciprocal of resistance R. Conductivity κ is related to G by κ = G · K, where K is the cell constant determined by the geometry of the electrode arrangement. Temperature influences ionic mobility, so temperature compensation is commonly applied.

Instrumentation and methods: Modern conductivity meters use two-electrode or four-electrode cells to minimize polarization; four-electrode designs reduce electrode polarization errors. Readings are often reported as direct conductivity (S/m or mS/cm) and may be accompanied by temperature (°C). Calibration typically uses standard potassium chloride solutions with known conductivity at a reference temperature, often 25°C.

Applications: Konduktivitymetry is widely used in water quality testing (drinking water, wastewater, process water), soil salinity assessment, agriculture, food and beverage processing, chemical production, and industrial process control. It also supports monitoring electrolyte content in biological and biomedical contexts.

Limitations and considerations: Measurements depend on electrode condition and sample temperature; fouling, polarization, and air bubbles can affect accuracy. The method assumes homogeneous, conductive samples and can be less reliable for non-ionic species or non-aqueous solvents. High ionic strength and complex mixtures may require temperature correction and calibration adjustments.

See also: Electrical conductivity, cell constant, impedance spectroscopy, conductivity sensors.