Potentiometric titrations is a titration method to measure the concentration of solute in a given solution by measuring the potential between two electrodes based on principle acid-base titrations, redox reaction or precipitation titrations. It offers fast and simple measurements compare to manual visual color change titration.
Principle
The potential difference between the two electrodes by addition of titrant or change in the concentration of ions is the basis of the potentiometric titration. Where the indicator electrode measures this potential difference.
Types of Potentiometric Titration
There are four types of titrations can be performed by potentiometric titration –
Acid-Base Titration
This type of potentiometric titration is used to determine the concentration of a given acid/base by using a standard solution whose concentration is known. It depends on the neutralization reaction of acids and bases.
Redox Titration
A type of titration based on a redox reaction between an analyte and titrant. Potentiometric titration was first used for redox titration.
Complexometric Titration
In this type of potentiometric titration, the concentration of metal ions are determined in the analyte by use of complex-forming reactions. Where a colored complex is formed and indicate the end point of the titration.
Precipitation Titration
In this type of titration, an insoluble precipitate is formed with a reaction between the given analyte and the titrant.
Components of Potentiometry
A potentiometry includes the reference electrode, with a known potential, constant over time and independent of the composition of the solution containing the analyte in which it is immersed, and an indicator electrode, whose response depends on the concentration of the analyte, and finally an instrument for measuring potential.
Potentiometry together with conductibility, coulometry, electrogravimetry, polarography, amperometry, etc. are part of electrochemical techniques or electroanalyticals.
Application
- Potentiometric titration is widely used in pharmaceutical analysis as below -
- To determine the assay of small-molecule active pharmaceutical ingredients (APIs), intermediates, and raw materials.
- For the analysis of cyanide, ammonia etc., in water or wastewater.
