Redokstitratatsioon

Redokstitratatsioon, or redox titration, is a quantitative analytical method used to determine the concentration of a substance that can undergo oxidation or reduction. In this technique, a solution containing the analyte is reacted with a standard redox reagent (titrant) under controlled conditions, and the amount of titrant required to reach the end point reflects the amount of analyte present.

The principle relies on a redox reaction between the analyte and the titrant. Endpoints are identified either by a redox indicator, which changes color at a specific redox potential, or by a potentiometric measurement using a reference and indicator electrode. In some cases, the endpoint is determined visually by a color change; in others, the potential of the solution is monitored until it stabilizes at the equivalence point.

Procedure typically involves preparing a sample of known volume, adjusting the reaction conditions (such as acidity), standardizing the titrant with a primary standard, and titrating until the endpoint is reached. The concentration of the analyte is then calculated from the titrant volume, its concentration, and the reaction stoichiometry. For example, a common titration uses permanganate in acidic solution to determine iron(II): MnO4− reacts with Fe2+ in a known stoichiometry, allowing calculation of Fe2+ concentration from the titrant volume.

Applications include water analysis, food and beverage testing, and pharmaceutical assays where redox-active species are involved. Advantages include broad applicability and clear endpoints under proper conditions; limitations involve potential interference from other redox-active species and the need for careful standardization and control of reaction conditions.