庫侖式卡爾費雪 ( Karl Fischer ) 滴定法是測定樣品中低水份和含水量（0.001 至 1% 的水含量）的理想方法。我們的庫侖式系列可以滿足任何要求，並且可以與 KF 烘箱法結合用於困難樣品。
- 準確可靠地測定 0.001 至 1 % 範圍內的微量水含量
- 可提供各種庫侖式水份儀版本，例如，單獨使用或使用電腦控制
- 使用烘箱法可以輕鬆分析困難的樣品
- 符合 FDA 法規 21 CFR Part 11 和 EudraLex、Volume 4、Annex 11
庫倫式水分測定儀的種類
Metrohm 提供各種庫侖式水份測定儀來滿足您的需求，聯繫我們以了解有關我們庫侖式水份測定儀的更多資訊。
| 庫侖式水份測定儀 | 特色 |
|---|---|
| Titrando 庫倫式水份測定儀 |
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| Ti-Touch 庫倫式水份測定儀 |
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| Eco 經濟型庫倫式微量水份儀 |
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庫侖式 KF 滴定的樣品前處理和自動化
對於難處理的樣品，例如固體樣品或不易溶解的樣品，您可以應用 KF 烘箱法。在此方法中，樣品在烘箱中加熱直至水份被釋放，水蒸氣被轉移到滴定容器中進行測量。
我們提供手動烘箱和帶有整合烘箱的自動進樣器，以提高樣品處理量。
為什麼用庫侖式 KF 滴定測定水含量 ?
以下一系列標準推薦使用庫侖法卡爾費雪滴定進行含水量測定 :
| 標準 | 名稱 |
|---|---|
| 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 |
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.