Controlled-Current Coulometry: Coulometric Titration

Coulometric titration measures an analyte's quantity in solution using a standard reagent that interacts with the analyte and is generated electrolytically by a constant current.

A galvanostat provides the regulated current, and the standard reagent's precursor is in excess, ensuring 100% current efficiency.

In a typical titration cell, the working electrode generates the reagent within the test solution, which then reacts with the analyte.

The auxiliary or counter electrode, which completes the electrical circuit, remains isolated from the bulk solution to prevent interference from its reaction products.

In some cases, instead of isolating the counter electrode, the reagent is produced externally in an isolated generation cell before being added to the titration cell.

In coulometric titration, electricity initially flows through the cell for long periods, gradually decreasing as it nears chemical equivalence, like dispensing less and less fluid from a burette.

The end point is identified by the reagent reacting with the detector circuit, and the amount of analyte is calculated using the current and time required to complete the titration.