Requires about
50 mg to 300 mg
of material. Avoids contamination of the oven and titration cell: minimal side reaction effects. Significantly reduces sample preparation steps. Significantly enhances sample throughput, accuracy and repeatability of results.
How do you make Karl Fischer reagent?
Prepare a solution by mixing 670 mL of methanol and 170 mL of pyridine. Now, add 125 g of iodine to the solution and cool it. Then, take a 250 mL graduated cylinder and add 100 mL of pyridine to it.
How do you calculate Karl Fischer factor?
How do you calculate Karl Fischer factor? The water equivalence factor F is determined according to the formula
0.1566 x w / v in mgs of H2O per ml of reagent
, where W is the sodium tartrate weight in mgs, and V is the reagent volume in ml.
What is the limit of KF factor?
Standardization is valid, if
concentration should be not less than 5 mg and not more than 7mg
. The relative Standard deviation between two average KF factors of water and DST determined consecutively should not be more than 3.0 % [Average of two factors (2 with water and 2 with DST) to be considered for calculation.]
What electrode is KF titration?
The most advanced KF titration technology uses a
double platinum electrode
for electrochemical indication of the end point, but visual and photometric indicators are also used.
What is KF reagent?
As shown in Formula (1) below, the Karl Fischer method uses Karl Fischer reagent, which
reacts quantitatively and selectively with water, to measure moisture content
. Karl Fischer reagent consists of iodine, sulfur dioxide, a base and a solvent, such as alcohol.
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.
What is pyridine free KF reagent?
An essentially pyridine-free Karl Fischer reagent useful in the determination of water, comprises
a dissolving agent containing sulfur dioxide and a pyridine substitute in a Karl Fischer solvent, and a titrating agent containing iodine in a Karl Fischer solvent
, wherein the pyridine substitute is an alkali or alkaline …
How do you calculate water factor?
The water equivalence factor F, in mgs of H
2
O per ml of reagent, is calculated according to the formula
0.1566 x w/v
, where W is the weight in mgs of sodium tartrate and V is the volume in ml of the reagent.
What is moisture content formula?
Calculate the moisture content on a wet-weight basis using the following formula:
Moisture content (%) = W2 – W3 x 100
.
W2-W1
. where, W1 = weight of container with lid; W2 = weight of container with lid and sample before drying; and W3 = weight of container with lid and sample after drying.
Why methanol is used in KF titration?
Most liquid samples dissolve in methanol, which is the usual solvent in Karl Fischer determinations.
To determine the total amount of water
, the sample must dissolve completely. Other solvents can be added to methanol in specific proportions to liberate the water more efficiently.
Why dry methanol is used in KF titration?
Methanol is typically used
as the working medium in the titration cell
. One-component volumetric reagents are easier to handle, and are usually less expensive than two-component reagents.
What is KF 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 DST is used for KF calibration?
Answer. 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
.
How do you clean a generator electrode?
How do you clean KF generator electrodes?
Immerse the diaphragm or the electrode surface in nitric acid, and boil with a hot stirrer. Drain out the chromate inside the cell, and rinse it with pure water for 2 to 3 times until yellowish color disappears. Clean the inner burette with methanol or with alcohol.
What is Karl Fischer water content?
The advantage of the Coulometric Karl Fischer method is the capability to accurately measure small amounts of moisture. Sensitivity of these instruments is as low as 0.1 microgram (μg) of water. This method is
normally used for moisture content below 1% or for samples where the moisture is less than 200 micrograms
.
Does Karl Fischer measure bound water?
Karl Fischer titrations are effective at quantifying even the tightly “bound”
, and are often considered a better moisture analysis method than loss on drying. In fact, this extra water that is measured using Karl Fischer is often referred to as the “bound” water.
What is drift in KF?
Simply put, drift is
background moisture that the Karl Fisher titrator is detecting
. What is background moisture? Well, it is moisture that the Karl Fisher titrator (specifically the detector electrode) is detecting inside the vessel -that’s not coming from your sample.
