kompleksomeetriline

Kompleksomeetriline, or complexometric, refers to a class of analytical techniques in which metal ions are quantified by forming stable complexes with a chelating agent, most commonly ethylenediaminetetraacetic acid (EDTA). In a typical complexometric titration, the sample containing metal ions is treated with the ligand, and the amount of ligand required to complex the metal ions is measured, providing a measure of the metal content.

The method relies on the formation of strong, selective metal–ligand complexes. The metal–ligand equilibrium is described by stability (formation) constants, which depend on factors such as pH, temperature, and the presence of competing ions. pH control is crucial because it influences metal speciation and the binding strength of the chelating agent. Masking agents may be used to suppress interference from certain ions and to reveal others.

A key practical aspect is endpoint detection. Endpoints are typically determined with metal indicators that change color when all metal ions have been complexed by the titrant, or by instrumental methods such as potentiometry or spectrophotometry. Common indicators include Eriochrome Black T, calcein, and murexide, each suitable for different metal ions and pH ranges.

Applications of complexometric titration are broad. It is widely used to determine water hardness (primarily Ca2+ and Mg2+), total metal contents in environmental samples, and concentrations of trace metals in pharmaceuticals, foods, and cosmetics. The method is valued for its versatility, accuracy, and ability to handle mixtures of metals, though it requires careful control of pH and potential interferences to achieve reliable results.