A Guide on Karl Fischer Titrations

‘What is the principle of Karl Fischer titration?’ is an important question in Chemistry. Karl Fischer titration is a systematic procedure. Experts use it for measuring water content in various types of samples. These samples can be solid, liquid, or gaseous in nature. 

Karl Fischer, a chemist, is credited with creating this procedure. The basis of this method is a reagent. This reagent reacts with water, thereby converting it into a non-propitious chemical. Read this article to understand what the principle of Karl Fischer titration is. Here, we will understand how to calculate the Karl Fischer factor and, finally, we shall see why Karl Fischer titration is used in pharmaceutical analysis.

How does it work?

Before we learn the principle of Karl Fischer titration, let’s first pay attention to its working. The consumption of H2O and I2 occurs in a typical Karl Fischer titration. The ratio of both these constituents here is 1:1. After consuming all the H2O content, the titration’s indicator electrode can detect excessive I2.

In the sample, the calculation of the H2O amount is based on the following:

• I2 concentration in the reagent
• The reagent quantity whose consumption takes place in the process

What is the principle of Karl Fischer’s titration?

The process takes place between SO2 and I2. This is in accordance with the Karl Fischer titration.

In Karl Fischer’s titration, the reaction of the following constituents takes place:

• I2
• SO2
• H2O

The chemical equation for the reaction of the above constituents is as follows:

I2 + SO2 + H2O → 2HI + SO3

How to calculate the Karl Fischer factor?

If you are already familiar with the principle of Karl Fischer titration, you know that it is a moisture content determination technique. The basis of this technique is the iodine reaction with water. A unique quality of Karl Fischer titration is that it is not impacted by other volatiles while measuring water content,

Sodium tartrate dihydrate refers to the Karl Fischer titration volumetric standard. In normal circumstances, Sodium tartrate dihydrate has the following qualities:

• Stable
• Non-hygroscopic

The stoichiometric water content of sodium tartrate dihydrate is 15.66%, and it is primarily used for determining titer in volumetry.

The determination of water takes place by a pyridine-free Karl Fischer reagent. This reagent involves the following:

• A dissolving agent containing sulphur dioxide in a Karl Fischer solvent
• A pyridine substitute in a Karl Fischer solvent
• A titrating agent containing iodine in a Karl Fischer solvent

The important point is that the pyridine substitute above is of an alkali or alkaline nature.

The formula for the calculation of the H2O uniformity factor F is below:

 0.1566w/v

This takes place in mgs of water per reagent’s ml

Here,

• W is representative of the C4H4Na2O6 weight in mgs
• V is representative of the volume in ml of the reagent

Note: C4H4Na2O6 given above is sodium tartrate

Why is Karl Fischer’s titration used in pharmaceutical analysis?

Karl Fischer titration is a titrimetric method that experts commonly use in the pharmaceutical industry. Its usage in pharmaceutical analysis is to determine water content in various types of substances, chemicals, or drugs.

Determination of water content is a significant factor in ensuring the excellence of the product. It is also important to ensure the product’s physical and chemical characteristics.

Conclusion

In chemistry, ‘what is the principle of Karl Fischer titration?’ is an important question. It is a systematic procedure by which experts can quantify water content in various types of samples. In Karl Fischer’s titration, the reaction of H2O, SO2, and I2 takes place. Its chemical equation is I2 + SO2 + H2O → 2HI + SO3. This titration is very useful in the pharmaceutical industry as it can determine water content in various types of chemicals or drugs.