For samples with a water content greater than 0.1%. The amount of water is determined by volumetry, based on a redox reaction (Iodine/Iodide) sensitive to very low moisture levels.
Volumetric determination
In presence of a base and a solvent (i.e. imidazole and methanol)
I2 + SO2 + 2H2O ➝ 2HI + H2SO4
The amount of iodine consumed in the titration is proportional to the water content of the sample. The end point is detected by a double platinum polarized electrode.
There are two ways to perform this reaction: with one component reagents or with two components.
One component reagents
All the necessary reagents to perform the reaction (iodine, sulphur dioxide and imidazole) are present in the titrant reagent: AQUAMETRIC® Composite.
The media generally used with these reagents is dry methanol.
Main advantages:
- Easy to use: All in one
- Flexibility to select the appropriate solvent (as media) to extract the water from the sample
Two component reagents
The reagents to perform the reaction are separate in two components:
- AQUAMETRIC® Titrant: Contains iodine dissolved in methanol
- AQUAMETRIC® Solvent: Media that contains the rest of necessary compounds (imidazole and sulphur dioxide in methanol)
Main advantages:
- High stability and shelf life
- Faster titration and high accuracy