KF Coulometre
At bestemme lavt fugt- og vandindhold i prøver er ikke et problem for disse coulometre.
Coulometrisk Karl Fischer-titrering er den ideelle metode til at bestemme lavt fugt- og vandindhold i prøver (0,001 til 1 % vandindhold). Vores udvalg af coulometre dækker ethvert behov og kan kombineres med KF ovnmetoden til svære prøver.
- Nøjagtig og pålidelig bestemmelse af sporniveau vandindhold i området fra 0,001 til 1 %
- Forskellige versioner tilgængelige, fx stand-alone eller computerstyret
- Vanskelige prøver kan let analyseres med ovnmetode
- Overholdelse med FDA Regulation 21 CFR Part 11 og EudraLex, bind 4, bilag 11
En række forskellige coulometre
Metrohm tilbyder forskellige coulometre for at opfylde dine krav. Kontakt os for at høre mere om vores coulometre.
| Coulometer | Funktioner |
|---|---|
| Titrando-coulometre |
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| Ti-Touch coulometer |
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| Eco Coulometer |
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| OMNIS Coulometer |
Brochure: OMNIS Coulometer and OMNIS Sample Robot Oven (8.000.5475, PDF, 2,8 MB)
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Prøveforberedelse og automatisering til coulometrisk KF-titrering
For vanskelige prøver, f.eks. faste prøver eller prøver, der ikke let opløses, kan du anvende KF-ovnmetoden. I denne metode opvarmes prøven i en ovn indtil vandet frigives, og vanddampen overføres til titreringsbeholderen til måling.
Vi tilbyder både manuelle ovne og automatiske prøveskiftere med integrerede ovne for øget prøvegennemstrømning.
Hvorfor coulometrisk KF-titrering til bestemmelse af vandindhold?
En række standarder anbefaler coulometrisk Karl Fischer-titrering til bestemmelse af vandindhold:
| Standard | Navn |
|---|---|
| ASTM D890 | Standardtestmetode for vand i flydende fyrrekemikalier |
| ASTM D1123 | Standardtestmetode for vand i motorkølevæskekoncentrat ved KF-reagensmetoden |
| ASTM D1533 | Standardtestmetode for vand i isolerende væsker ved coulometrisk KF-titrering |
| ASTM D3401 | Standardtestmetoder for vand i halogenerede organiske opløsningsmidler og deres blandinger |
| ASTM D4928 | Standardtestmetode for vand i råolier ved Coulometric Karl Fischer-titrering |
| ASTM D5460 | Standardtestmetode for gummiblandingsmaterialer - Vand i gummiadditiver |
| ASTM D6304 | Standardtestmetode til bestemmelse af vand i petroleumsprodukter, smøreolier og additiver ved coulometrisk KF-titrering |
| ASTM D7923 | Standardtestmetode for vand i ethanol- og kulbrinteblandinger af Karl Fischer Titrering |
| ASTM E1064 | Standardtestmetode for vand i organiske væsker af Coulometric Karl Fischer Titratio |
| DIN EN ISO 12937 | Petroleumsprodukter - Bestemmelse af vand - Coulometrisk KF-titreringsmetode |
| ISO 10337 | Råolie - Bestemmelse af vand - Coulometrisk KF-titreringsmetode |
| UOP 481-10 | Vand i flydende kulbrinter og tunge kulbrinter med fordamper ved hjælp af coulometrisk titrering |
| USP | <921> Metode 1c |
| EP | 2.5.32 Vand: Mikrobestemmelse |
Coulometric Karl Fischer titrator – FAQs
What is coulometric Karl Fischer titration?
Coulometric titration is used to determine trace-levels of water in samples within a range of 10 µg to 200 mg water. However, larger amount of water (> 10 mg) require a lot of time and/or may exceed the water capacity of the KF reagent, which could lead to incorrect results.
The coulometric method uses electric current to generate the iodine that is needed for the Karl Fischer reaction. Metrohm KF Coulometers apply variable current strengths and pulse lengths, which allows precise "iodine addition" even in the region of the endpoint.
Learn more about coulometric KF titration in the application bulletin:
Coulometric water content determination according to Karl Fischer (AB-137, PDF, 228 KB)
Why is coulometric Karl Fischer titration used for water content determination?
Coulometric KF titration is a sensitive method suitable to determine low water contents between 0.001 and 1%. The coulometric method is an absolute method, meaning that there is no need for titer determination. In addition, a series of standards recommend coulometric Karl Fischer titration for water content determination:
| Standard | Name |
|---|---|
| ASTM D890 | Standard Test Method for Water in Liquid Pine Chemicals |
| ASTM D1123 | Standard Test Method for Water in Engine Coolant Concentrate by the KF Reagent Method |
| ASTM D1533 | Standard Test Method for Water in Insulating Liquids by Coulometric KF Titration |
| ASTM D3401 | Standard Test Methods for Water in Halogenated Organic Solvents and Their Mixtures |
| ASTM D4928 | Standard Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration |
| ASTM D5460 | Standard Test Method for Rubber Compounding Materials - Water in Rubber Additives |
| ASTM D6304 | Standard Test Method for Determination of Water in Petroleum Products, Lubricating Oils, and Additives by Coulometric KF Titration |
| ASTM D7923 | Standard Test Method for Water in Ethanol and Hydrocarbon Blends by Karl Fischer Titration |
| ASTM E1064 | Standard Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titratio |
| DIN EN ISO 12937 | Petroleum products - Determination of water - Coulometric KF titration method |
| ISO 10337 | Crude Petroleum - Determination of water - Coulometric KF titration method |
| UOP 481-10 | Water in Liquid Hydrocarbons, and Heavy Hydrocarbons by Vaporizer, using Coulometric Titration |
| USP | <921> Method 1c |
| EP | 2.5.32 Water: Micro Determination |
What is the difference between coulometric and volumetric titration?
The main difference between coulometric and volumetric Karl Fischer titration concerns titrant addition. In volumetric Karl Fischer titration, the titrant is added directly to the sample with a buret. Coulometric Karl Fischer titration features a generator electrode, which electrochemically generates the required iodine for the titration directly in the titration cell.
Metrohm offers titrator solutions that perform volumetric or coulometric titration on separate titrators as well as both volumetric and coulometric titration in a single instrument. Contact us to learn more.
What are the requirements for coulometric titration?
Requirements for coulometric titrations are the following:
- The process must take place with 100% current efficiency.
- No side reactions must occur.
- Oxidation or reduction must lead to a defined oxidation state.
Metrohm KF Coulometers meet these requirements with commercially available reagents.