KF titration is a classic titration method that uses coulometric or volumetric titration to determine the moisture content of a sample. Karl Fischer (KF) reagents for analytical techniques developed by chemist Karl Fischer Accurately measure the moisture content of gases, liquids and solids.

What is the KF reaction?

Karl Fischer titration is a widely used analytical method to quantify the moisture content in various products.The rationale behind it is based on Bunsen reaction of iodine and sulfur dioxide an aqueous medium.

What is the principle of KF?

The principle of Karl Fischer titration is Completely based on the oxidation reaction between sulfur dioxide and iodine. Water reacts with sulfur dioxide and iodine to form hydrogen iodide and sulfur trioxide. It reaches an end point when all the water is consumed.

What are pyridine-free KF reagents?

A substantially pyridine-free Karl Fischer reagent that can be used for sure Water, including solubilizers containing sulfur dioxide and a pyridine substitute in a Karl Fischer solvent, and titrants containing iodine in a Karl Fischer solvent, where the pyridine substitute is a base or basic…

What’s the use of Karl Fischer?

Karl Fischer (KF) titration is a redox reaction that uses Water consumption during the reaction to measure the amount of water in the sample. It is the reference method for moisture determination due to its specificity, accuracy and speed of measurement. It occurs in organic solvents.

Karl Fischer titration

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39 related questions found

What is the limit of the KF factor?

The relative standard deviation between the two mean KF factors for water and DST measured continuously shall not be more than 3.0% [Average of two factors (2 with water and 2 with DST) to be considered for calculation.]

What are the advantages of Karl Fisher moisture determination?

The advantage of the Coulomb Karl Fischer method is that Ability to accurately measure small amounts of moisture. The sensitivity of these instruments is as low as 0.1 microgram (µg) water. This method is typically used for samples with less than 1% moisture or less than 200 micrograms of moisture.

What is the formula for KF normalization?

6.4 Standardization was accepted when the relative agreement between the two assays was within 0.5%. 6.5 Factor F (mg H2O/ml KF ​​reagent´) is calculated as follows: ; page 2 a = g sodium tartrate dihydrate ml = ml KF ​​​​. 6.6 Selection of titrant and solvent according to standardization 6. … The result must be between 99.0 and 101.0 %.

What is the KF test?

The water content was determined by Karl Fischer analysis. Karl Fischer Titration (KF) A method in analytical chemistry that uses coulometric, volumetric, or oven titration to determine the amount of water in a sample at trace to percent levels.

Why do we use DST in KF calibration?

DST is the main standard and is stable below 150 degrees Celsius. It is easy to release free water molecules when reacting with KF reagent. This DST contains 15.66% water molecules, so we can easily calculate and standardize the KF reagent.

How does KF titration work?

Karl Fischer titration principle

The water content is then calculated based on the amount of reagent added.The titration cell must be kept away from atmospheric moisture and the sample unresponsive with KF reagent. …when there is an excess of iodine, the reaction has reached the end point.

Which base is used in Karl Fischer reaction?

The bases commonly used in Karl Fischer titrations are Pyridine, and primary amines such as imidazole can also be used. The alkyl sulfites are then oxidized by iodine to alkyl sulfates, and it is this oxidation reaction that consumes the water used for water content determination.

How does the Coulomb KF work?

in coulometric Karl Fischer titration Iodine is produced by electrolysis. Determine the amount of iodine added to the sample by measuring the current required for the electrochemical production of iodine. When reacting with water, brown iodine is reduced to colorless iodide.

How to calculate the water content in KF?

The water equivalence factor, F, in mg water/ml reagent, is given by the expression 0.1566 w/vwhere w is the weight of sodium tartrate in mg and v is the volume of reagent required in ml.

Does Karl Fischer measure bound water?

Karl Fischer titration Efficiently quantify even tight « bindings », and is generally considered a better moisture analysis method than loss on drying. In fact, this extra water, measured using Karl Fischer, is often referred to as « bound » water.

What is the difference between Lod and moisture content?

The moisture content is determined by Karl Fischer titration, which consists of only water, the moisture content. … the loss on drying (LOD) is determined by Heat the sample below its melting point In an oven, it includes all volatiles, including water content and solvents.

What is the KF water factor?

How is the Karl Fischer factor calculated?The water equivalent factor F is determined according to the formula 0.1566 xw/v in mgs H2O/ml reagentwhere W is the weight of sodium tartrate in mgs and V is the volume of reagent in ml.

Why is KF used for DO measurement?

KFC selective for water, because the titration reaction itself consumes water. Conversely, the measurement of dry mass loss will detect the loss of any volatile species. The volumetric KF can easily measure samples up to 100%, but for analytes with water content below 0.05%, a large amount of sample is required, which is impractical.

What are the main disadvantages of Karl Fischer titration?

Manual volumetric KF Titration needs to be reloaded for each determination Hence high solvent consumption. When manual volumetric KF titration is applied to starch-containing materials, the margin of error is relatively large.

What does Coulomb method mean?

Wikipedia, the free encyclopedia.Coulomb method Determines the amount of substances converted during the electrolysis reaction by measuring the amount of electricity (in coulombs) consumed or produced. It can be used to accurately measure electric charge, and amperage can even be used to define the coulomb method.

What is the difference between a KF and a coulomb counter?

The main difference between the two is that Volumetric method, the titrant is added directly to the sample via the burette. In contrast, with the coulometric method, the titrant is generated electrochemically in the titration cell. The water level measured by the coulometric method is much lower than the volume method.

Why does KF use disodium tartrate dihydrate?

Sodium tartrate dihydrate is a volume standard for Karl Fischer titration. Under normal conditions, it is stable and not hygroscopic.Sodium tartrate dihydrate has a stoichiometric water content of 15.66% and is mainly used in For potency determination in volumetric methods.

What is a Karl Fischer solution?

As shown in the following formula (1), the Karl Fischer method uses a Karl Fischer reagent that reacts quantitatively and selectively with water to measure the moisture content.Karl Fischer reagent by Iodine, Sulfur Dioxide, Bases and Solvents, such as alcohol. I2+SO2+3Base+ROH+H2O ⇒ 2Base+HI+Base+HSO4R…..(1)

How do you calibrate KF?

Use a syringe to accurately weigh approximately 0.005 to 0.05 g (5 to 50 mg) of water and enter the weight in grams. 5. Press « Run » key Make the red light on at the « BUSY » position. Press the « RUN » key again to start the titration.