Aquastar® Reagents for Coulometric Karl Fischer Titration

Coulometric Karl Fischer titration is preferred for very low levels of water content, or for moisture determination of expensive substances, or small samples. With our Aquastar range of coulometric Karl Fischer reagents, precise moisture content can be determined from below 10.000 ppm down to 10 ppm. Coulometric reagents are available for titration cells both with and without diaphragms. Whatever your application, the high quality of Aquastar coulometric reagents will ensure accurate and reproducible results.

Principle of Coulometric Karl Fischer Titration

Coulometric Karl Fischer titration is an absolute method. The iodine required for the reaction is produced itself in the titration cell by anodic oxidation at the generator electrode. In comparison to volumetric titration, the iodine titrant required for the titration is electrochemically generated in the titration cell itself by anodic oxidation of iodide at the generator electrode. Water content is determined by measuring the current needed for oxidation until the reaction is completed. The measuring cell for coulometric determination consists of anode and cathode compartments which may be separated by a diaphragm.


The Karl Fischer Titration Process

  • Elimination of ambient moisture in the titration cell
  • Elimination of traces of water in the Karl Fischer solvent
  • Elimination of adherent moisture in the titration cell (wall; electrode, stopper)

  • Test if the instrument & electrode is working correctly to obtain accurate results
Sample determination
  • Sample needs to be completely dissolved or dispersed in a suitable solvent
  • Complete extraction of the water from the sample


Aquastar Coulometric Reagents

Our Karl Fischer coulometric reagents have been used for accurate and reproducible water determination for over 40 years. Our full range of reagents include the convenient CombiCoulomat reagents which have the advantage that even in diaphragm cells, only one reagent is required. This simplifies the application and excludes any mistakes.

In addition, separate reagents for anode and cathode cell, as well as reagents for the fritless cell are also available. All our coulometric reagents are chloroform free. For oil samples, solvents such as xylene, toluene or decanol can be added.


  • Fast analysis, fast pre-titration
  • For samples with low water content
  • Distinct endpoint to ensure confidence in results
  • Reliable and consistent high quality for reproducible results
  • Only one reagent necessary when using CombiCoulomat frit

Aquastar CombiCoulomat fritless

Designed for the Karl Fischer coulometric titration without a diaphragm, our Aquastar CombiCoulomat fritless can also be used for cells with a diaphragm in both the anode and cathode cells.

Aquastar CombiCoulomat frit

A reagent designed for the coulometric cell with a frit for a fast and precise determination of very low water contents, it can also be used for both anode and cathode cell.

Aquastar Coulomat A-NC / Aquastar Coulomat C-NC

Cells with a diaphragm require reagents for each cell. Aquastar Coulomat C-NC, and A-NC are available if separate anolyte and catholyte reagents are preferred.


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