1. Karl Fischer coulometric titration normally requires two reagent solutions
- An anolyte (the solution in the anode compartment) and a catholyte (the solution in the cathode compartment). Hydranal Coulomat reagent type A or type E is used as the anolyte. Anolytes contain iodide and a sulfur dioxide/imidazole buffer in a suitable solvent. Hydranal Coulomat CG reagent is used as the catholyte.
- Coulometric reagents based on different solvent components are used to support many types of samples being analyzed, for example Hydranal Coulomat Oil containing methanol, xylene and chloroform for titration in oils, or methanol-free Hydranal Coulomat AK for ketone titration. Moreover, some working techniques are supported by special reagents, for example using the Karl Fischer oven of Hydranal Coulomat AG-Oven or using the diaphragmless cell of Hydranal Coulomat AD.
2. Coulometric cells
- There are two different types of coulometric cells: those with and those without a diaphragm. The diaphragm separates the anode compartment from the cathode compartment. The oxidation of I⁻ to I² takes place at the anode, while the reduction of protons to H2 takes place at the cathode.
- For diaphragmless cells, the anode and cathode compartments are not separated and only a single reagent, the anolyte, is needed. Although the second coulometric cell appears more convenient to use, cells with a diaphragm achieve the highest accuracy (down to a trace range of water).
3. Advantages of HYDRANAL coulometric reagents
- Easy to use
- High accuracy for water content
- Stable conditions of the titration vessel
- Wide product range
- Long shelf life (up to 5 years)
4. Reagents for the Hydranal Coulomat line coulometric method
- 34807 Hydranal Coulomat A: Anolyte preferred for cells with a diaphragm*. Bottle specification: 500ML
- 34836 Hydranal Coulomat AG: Anolyte suitable for cells with and without a diaphragm. Bottle specification: 500ML & 1L
- 34843 Hydranal Coulomat AG-H: Anolyte for titrating long-chain hydrocarbons, preferred for cells with a diaphragm*. Bottle specification: 500ML
- 34739 Hydranal Coulomat AG-Oven: Anolyte for determination with the Karl Fischer oven, suitable for cells with and without a diaphragm. Bottle specification: 500ML
- 34820 Hydranal Coulomat AK: Anolyte for titrating ketones, preferred for cells with a diaphragm*. Bottle specification: 500ML
- 34868 Hydranal Coulomat Oil: Anolyte for titrating oils, preferred for cells with a diaphragm*. Bottle specification: 100ML & 500ML
- 34726 Hydranal Coulomat E: Ethanol-based anolyte, suitable for cells with and without a diaphragm. Bottle specification: 500ML
- 34810 Hydranal Coulomat AD: Anolyte preferred for diaphragmless cells. Bottle specification: 500ML
- 34840 Hydranal Coulomat CG: Reagent for Karl Fischer coulometric titration (cathode solution). Bottle specification: 10x5ml/box
- 34821 Hydranal Coulomat CG-K: Catholyte for titrating ketones. Bottle specification: 10x5ml/box
* In theory, all Hydranal-Coulomat anolytes can be used with either of the two generator electrode types: with or without a diaphragm. However, anolytes containing co-solvents other than methanol show increased recovery when used with the diaphragmless generator cell. Therefore, we recommend using the diaphragm generator electrode when working with anolyte-containing solvents. This will require the use of a suitable catholyte.
PacificLAB is proud to be the official supplier of chemical products and Hydranal reagents (brand Honewell Fluka) in Vietnam. The Hydranal catalog is always diverse, goods are always in stock, and delivery service is attentive. In particular, pricing is extremely competitive. Customers can refer to the details of the products we supply at the following link: