Basic Principles of Karl Fischer Moisture Analyzers

The Karl Fischer moisture analyzer, also called a trace moisture analyzer, is based on the quantitative reaction with Karl Fischer reagent of known water equivalent. It can determine any moisture in a sample (free water or water of crystallization). So what is the basic principle behind its operation?

The basic Karl Fischer principle requires a certain amount of water to participate in the oxidation of sulfur dioxide by iodine.

The reaction equations are as follows:

I2+SO2+3C5H5N+H2O2C5H5NHI+C5H5NSO3

C5H5NSO3+CH3OHC5H5·HSO4CH3

In the first step, water reacts; in the second, the product of the first step—the arsenite–arsenic trioxide complex—reacts with methanol to drive the first step forward.

The titration is performed by a dual platinum electrode powered at both ends, and the instrument controls titration using the current signal from the depolarized dual platinum electrode. When the solution contains only iodide and no free iodine, no current flows and the electrode polarizes. When the endpoint is reached (all water consumed), free iodine appears in the solution, depolarizing the electrode so the current suddenly rises: iodine is oxidized at one electrode and reduced at the other. The sample's water content is then calculated from the amount of Karl Fischer reagent consumed.

In fact, measurement with a Karl Fischer moisture analyzer is fairly simple. The instrument is accurate, easy to operate, practical, and safe.

There is much more on principles, operating methods, procedures, and maintenance tips. To learn more, the VicoMeter moisture analyzer website will continue to update for you, with more content available at https://www.weikemeituo.com/Halogen Moisture Analyzers_Karl Fischer Moisture Analyzers_Density Meters_Electronic Balances_Moisture Analyzers for Lithium Batteries, Wood, Wood Chips, Gases, Solids and Liquids—VicoMeter | Jiangsu Victor Instrument Meter Co., Ltd.!