HYDRANAL COULOMETRIC TITRATION
Coulometric Karl Fischer titrations normally require two reagent solutions: an anolyte (the solution in the anodic compartment) and a catholyte (the solution in the cathodic compartment).
Hydranal-Coulomat A-type or E-type reagents are used as anolytes. The anolytes contain iodide and a sulfur dioxide/imidazole buffer in suitable solvents. Hydranal-Coulomat C reagents are used as catholytes.
Coulometric reagents based on different solvent compositions serve to support the broad variety of samples analyzed, i.e. Hydranal-Coulomat Oil contains methanol, xylene and chloroform for titration in oils.
The methanol-free Hydranal-Coulomat AK and Hydranal NEXTGEN Coulomat A-FA versions contribute to the titration of ketones and other methanol sensitive samples by suppressing negative side effects.
Furthermore, some working techniques are aided by special reagents i.e. the use of Karl Fischer oven by Hydranal Coulomat AG-Oven or the titration of lithium-ion battery electrolytes with Hydranal-Coulomat A-FA and C-FA.
Advantages of Hydranal-Coulometric reagents include:
• Easy to use
• High accuracy for trace amounts of water
• Stable conditions of the titration vessel
• Broad product range
• Special compositions to support difficult sample-types
• Long shelf life (up to five years)
Coulometric cells
There are two different types of coulometric cells: those with and those without a diaphragm. The diaphragm separates the anode chamber from the cathode chamber.
Oxidation of I- to I² occurs at the anode, whereas the reduction of protons to H² occurs at the cathode. For cells without a diaphragm, the anodic and cathodic compartments are not separated and only one reagent, the anolyte, is needed. Though the latter coulometric cell may seem more convenient to use, the cell with diaphragm achieves the highest accuracy down to the trace range of water. Our recommendation for samples that dissolve well in methanol is Hydranal-Coulomat AG. A cell with diaphragm requires, additionally, Hydranal-Coulomat CG as catholyte.
PRODUCT: 34807
PRODUCT NAME: Hydranal™-Coulomat A
DESCRIPTION: Anolyte preferred for cells with diaphragm*
PACKAGING: 500 mL
PRODUCT: 34836
PRODUCT NAME: Hydranal™-Coulomat AG
DESCRIPTION: Anolyte suitable for cells with and without diaphragm
PACKAGING: 500 mL; 1 L
PRODUCT: 34433
PRODUCT NAME: Hydranal™ NEXTGEN Coulomat AG-FI
DESCRIPTION: Anolyte suitable for cells with and without diaphragm, free of Imidazole
PACKAGING: 500 mL
PRODUCT: 34471
PRODUCT NAME: Hydranal™ NEXTGEN Coulomat A-FA
DESCRIPTION: Anolyte for coulometric Karl Fischer titration of ketones and Li-ion battery electrolytes, preferred for cells with diaphragm, acetonitrile-based, free of alcohols (free of CMR substances)
PACKAGING: 500mL
PRODUCT: 34843
PRODUCT NAME: Hydranal™-Coulomat AG-H
DESCRIPTION: Anolyte for titration of long-chained hydrocarbons, preferred for cells with diaphragm*
PACKAGING: 500 mL
PRODUCT: 34739
PRODUCT NAME: Hydranal™-Coulomat AG-Oven
DESCRIPTION: Anolyte for determination with Karl Fischer oven, suitable for cells with and without diaphragm
PACKAGING: 500 mL
PRODUCT: 34820
PRODUCT NAME: Hydranal™-Coulomat AK
DESCRIPTION: Anolyte for titration of ketones, preferred for cells with diaphragm*
PACKAGING: 500 mL
PRODUCT: 34868
PRODUCT NAME: Hydranal™-Coulomat Oil
DESCRIPTION: Anolyte for titration of oils, preferred for cells with diaphragm*
PACKAGING: 100 mL; 500 mL
PRODUCT: 34726
PRODUCT NAME: Hydranal™-Coulomat E
DESCRIPTION: Anolyte based on ethanol, suitable for cells with and without diaphragm
PACKAGING: 500 mL
PRODUCT: 34810
PRODUCT NAME: Hydranal™-Coulomat AD
DESCRIPTION: Anolyte preferred for cells without diaphragm
PACKAGING: 500 mL
PRODUCT: 34840
PRODUCT NAME: Hydranal™-Coulomat CG
DESCRIPTION: Catholyte
PACKAGING: 10 × 5 mL ampoules
PRODUCT: 34470
PRODUCT NAME: Hydranal™ NEXTGEN Coulomat C-FA
DESCRIPTION: Catholyte for coulometric Karl Fischer titration of ketones and Li-ion battery electrolytes, acetonitrile-based, free of alcohols (free of CMR substances)
PACKAGING: 10 × 5 mL ampoules
PRODUCT: 34821
PRODUCT NAME: Hydranal™-Coulomat CG-K
DESCRIPTION: Catholyte for titration of ketones
PACKAGING: 10 × 5 mL ampoules
*In theory all Hydranal™-Coulomat anolytes may be used with either type of generator electrode: with or without a diaphragm. However, the anolytes which contain a co-solvent in addition to methanol show increased recoveries when used with a diaphragmless generator electrode. Therefore we recommend using a diaphragm generator electrode when working with a co-solvent containing anolyte. This will require the use of the appropriate catholyte.
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