A titration is used to determine precisely the concentration Cunknown (supposedly unknown) of a chemical compound Eint also called analyte, in a solution.
During the titration, a chemical reaction occurs: therefore it is a destructive dosing method (the chemical we want to dose is modified by the reaction).
The nature and concentration of the different chemicals in the solution evolve during the titration. To determine Cunknown , we follow the variation of the signal S, given by the measuring instrument. The variation of the signal S depends on the volume of chemical reacting with the analyte we want to dose. A significant variation of the signal is observed at the moment when the last traces of the analyte are consumed.
Several measuring device can be used (spectrophotometer, spectrofluorimeter, pH-meter, potentiometer, electrical conductivity meter, etc.) using the corresponding signals (absorption, fluorescence intensity, pH, potential, conductivity, etc.). In certain cases, Cunknown can be determined without the use of an instrument but using the differences in colour between the analyte and one of the products of the reaction. A coloured indicator can also be added to the solution, and this indicator is capable of changing colours when the signal changes greatly (pH, potential, fluorescence intensity). We are talking about a colorimetric titration. Only these types of titration methods will be presented here.