What is the Karl Fischer Titration Method?

Karl Fischer titration is an advanced form of bench chemistry that yields an extremely accurate reading of water concentration in a range of sample types. It is prized highly for its ability to distinguish water across the broadest possible range; from 100% down to 100 parts per million. The range of applications for Karl Fischer testing is subsequently expansive.

How Karl Fischer Titration is Conducted

Karl Fischer Titration follows one of two easily replicable processes: Coulometric titration or volumetric titration. Both are principally similar. First, a sample of interest is combined with an anode solution that promotes oxidation. This solution typically comprises an alcohol base, sulfur dioxide (SO₂), and a homogenous halogen like pryidine.

A platinum cathode is immersed in a cell filled with the anode solution and a current is induced. The cathode consumes sulfur dioxideand produces iodine (I₂) which subsequently reacts with water stoichiometrically. Generally, a single mole of iodine is consumed per mole of water. A second electrode detects a voltage differential which gives a precise electrochemical readout of water content.

The endpoint of Karl Fischer titration is largely what differentiates coulometric from volumetric techniques. In a coulometric determination of water content, the percentage is determined electrochemically. Whereas, in volumetric methods, you would determine the end point potentiometrically.

Recognized Applications of the Karl Fischer Titration Method

Arguably the most reliable and precise water content testing method available, Karl Fischer titration covers a broad scope of application areas. Here is a brief selection:

• Clothing and textile manufacturers working with wool, silk, and cotton commonly conduct Karl Fischer Titration to identify unwanted water and to remove any signs of moisture which could be damaging to the materials.
• Wood and paper producers who have a vested interest in the control of water content also rely on the test to eradicate high volumes of the substance.
• Applications can even be seen in the construction industry where strength and durability of building materials such as cement depend heavily on the perfect mix of materials to achieve the right balance of concrete-making consistency.

Karl Fischer Titration with RQM+ Lab Services

At RQM+ Lab Services,  we leverage Karl Fischer titration to quickly and selectively determine moisture content in a wide range of sample types with outstanding accuracy and precision. If you would like to learn more about testing water content with us, why not contact a member of the RQM+ Lab Services, team today?