Measure Water Content in Lyophilized Vaccines with Karl Fischer Titration

This application describes the titration method to determine the water content of lyophilized pharmaceutical products by automated coulometric titration using a Karl Fischer titrator and an InMotion™ Autosampler.

By downloading this application package, you will receive a PDF of the application note as well as the required data for the LabX™ titration software method.

What Is Lyophilization? 

Lyophilization is a dehydration process typically used to preserve material by freezing the material. The reduced surrounding pressure allows the frozen solvent to sublime directly from the solid phase to the gas phase. After this drying process, the final residual water content in the product is very low, around 1% to 4%.

Why Perform Lyophilization?

A significant proportion of active pharmaceutical ingredients are unstable in liquid formulations, and thus, they need to be stored in the solid form. To achieve this, drugs are lyophilized in order to remove water from the formulations. This lyophilized powder is easier to transport and has an increased shelf life.

Role of Karl Fischer Titration

Lyophilized samples need to ensure the water content present in them is below the permissible limit. Karl Fischer (KF) titration is commonly used to determine the water content in the samples. In a KF titration, the amount of water is calculated from the amount of iodine consumed in order to reach the endpoint of the following reaction.

CH₃OH + SO₂ + 3 RN + H₂O + I₂ → 2 [RNH]I + [RNH]SO₄CH₃

In coulometric KF titration, the iodine is generated by an electrochemical reaction in the cell. For more information on the basics, methods, and techniques of Karl Fischer titration, review our Karl Fischer Titration Guides.

Please note, this product is not intended for medical use.