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Determination of Water Content in Powdered Milk by Karl Fischer Titration (CAT#: STEM-PPA-0127-YJL)

Introduction

The water content has a strong influence on the physico-chemical stability of milk powder during storage and distribution. Additionally technological functionalities like dissolution or wettability can also be affected by the water content. The oxidative stability of milk powder varies with the water content. Legislation imposes strict limits as milk powder or dried milk is an important commodity in international trade.




Principle

Karl Fischer titration is used as a reference method for many substances and is a chemical analysis method based on the oxidation of sulfur dioxide by iodine in methanol hydroxide solution. Titration can be performed by volumetric or coulometric methods.
According to the volumetric method, an iodine-containing Karl Fischer solution is added until the first signs of iodine excess appear. Iodine turnover was determined by the volume of the burette containing iodine Karl Fischer solution.
In the coulometric procedure, reacted iodine is generated directly in the titration cell by electrochemical oxidation of iodide ions until traces of unreacted iodine are detected. Faraday's law can be used to calculate the amount of iodine produced by the required charge.

Applications

Food industry; Petroleum industry

Procedure

1. Pre-titrate the instrument.
2. Weigh the sample.
3. Pour the sample into the titration vessel.
4. Stir until the sample dissolves, and titrate to the end point with Karl Fischer titrant.
5. Enter the sample mass and record the moisture determination.

Materials

• Sample Type: Liquids, solids, slurries, even gases