What reagent is used for Karl Fischer titration?
Aquastar® Reagents for Volumetric Karl Fischer Titration The volumetric Karl Fischer titration method is used to determine water content by adding iodine containing titrant to the sample, which is then dissolved or dispersed in a suitable solvent.
What is Karl Fischer reagent and how it is prepared?
The principle of Karl Fischer titration is based on the oxidation reaction between iodine and sulphur dioxide. Water reacts with iodine and sulphur dioxide to form sulphur trioxide and hydrogen iodide. An endpoint is reached when all the water is consumed.
What is pyridine free KF reagent?
The pyridine-free Karl Fischer reagent consists of two solutions, a dissolving agent and a titrating agent. The dissolving agent contains sulfur dioxide and a pyridine substitute in a solvent and is used for taking up the sample to be investigated with respect to its water content.
Why is imidazole used in Karl Fischer?
The use of imidazole instead of pyridine is greatly improving the speed of the KF reaction. When using these modern reagents, the speed, time and accuracy of the Karl Fischer reaction is influenced by the medium used in the titration vessel.
What is the pH of Karl Fischer reagent?
between pH 5.5 and 8
The optimum pH range of the sample solution for efficient Karl Fischer titration is between pH 5.5 and 8.
What is KF water factor?
The water equivalence factor, F in mg of water per ml of the reagent is given by the expression 0.1566 w/v, where w is the weight, in mg, of the sodium tartrate and v is the volume, in ml, of the reagent required.
What is KF reaction?
The KF reaction is based upon the oxidation of sulfur dioxide by iodine with the consumption of water in a buffered solution: I2 + 2H2O + SO2 -> 2HI + H2SO4. The titration reaches its endpoint when the titrating agent has achieved a volume sufficient to react the total amount of water in the sample.
What is Karl Fischer test?
Karl Fischer (KF) Titration is a technique for the determination of moisture content. It is a process based on the reaction of iodine with water. The KF method is one of the few techniques that will measure water content and not be affected by other volatiles.
Why is platinum electrode used in KF?
Principles of Karl Fischer titration The color change that signals the end point of the reaction is caused by the detection of excess iodine at the double platinum electrode which acts as the indicator, following the consumption of all the water in the sample which leads to the cessation of the reaction.
Why is dry methanol used in KF?
Dry methanol is the most commonly used medium in the titration vessel, however it is an unbuffered solvent. Hydranal-Methanol Rapid contains accelerators for the KF reaction and reduces titration times significantly.
What is KF instrument?
Karl Fischer titration is a classic titration method in chemical analysis that uses coulometric or volumetric titration to determine trace amounts of water in a sample. It was invented in 1935 by the German chemist Karl Fischer.
Why we use sodium tartrate in Karl Fischer?
Sodium tartrate dihydrate is the volumetric standard for Karl Fischer titration. Under normal conditions, it is stable and non-hygroscopic. Sodium tartrate dihydrate has a stoichiometric water content of 15.66% and is primarily used for titer determination in volumetry.
What is water content by KF?
KF has a high accuracy and precision, typically within 1% of available water, e.g. 3.00% appears as 2.97–3.03%. Although KF is a destructive analysis, the sample quantity is small and is typically limited by the accuracy of weighing.
What is formula for KF standardization?
6.4 The standardization is accepted when two determinations agree within 0.5% relative. 6.5 The factor F (mg H2O/ml KF reagent´) is calculated as: ; ; Page 2 a = g sodium tartrate dihydrate ml = ml KF reagent.
What is the pH of DMF?
In its anhydrous state, DMF is a relatively neutral solvent with a pH of 6.3, which, upon exposure to water, undergoes hydrolysis to produce formic acid (FAH) and dimethylamine (DMA).