titrimetrie

Titrimetrie, or titrimétrie analytique, is a quantitative method in analytical chemistry that determines the amount of a substance in a sample by reacting it with a solution of known concentration, called the titrant. The reaction proceeds to a defined endpoint, which is detected by an indicator or by instrumental measurements such as pH, conductivity, or current. From the known concentration and volume of titrant used, the amount of analyte can be calculated using the stoichiometry of the reaction.

Titrimetry encompasses several major types, including acid–base titrimetry, redox titrimetry, complexometric titrimetry (for example with EDTA), and precipitation titrimetry. Detection methods vary and may include colorimetric indicators, potentiometry (measuring pH or redox potential), conductometry, or amperometry. Modern practice often employs automatic or semi-automatic titrators to improve precision and reproducibility.

Calculation in titrimetry relies on the stoichiometric relationship between titrant and analyte. If the balanced reaction is aA + bB → products, and titrant B is added in volume V_T at concentration C_T, then the moles of B added are C_T × V_T. At the equivalence point, the moles of A present are (a/b) × (C_T × V_T). The concentration of analyte in the sampled volume V_A is C_A = [(a/b) × (C_T × V_T)] / V_A. In a simple 1:1 reaction, this reduces to C_A = (C_T × V_T) / V_A.

Titrimetry is widely used in pharmaceuticals, environmental analysis, food chemistry, and clinical laboratories to quantify acids, bases, oxidants and reductants, metal ions, and complexing agents with relatively rapid and inexpensive procedures.