Karl Fischer titration Interview Related questions

Guide line
935 USP

Type Karl Fischer titration
Coloarimatry and volumetry titration

Colarimatry titration because use of a electromagnetic filed

Volumetric titration
There is a manually titration (classical method like In burette fill kf reagent and conical flask fill a Methanol see the end point straw yellow colour)

KF Reagent

It is a dark brown colour
Photosensitive
Moisture sensitive so after use cap would packed carefully
Store : Dry and dark place
Composite : Methanol,SO2,I2, pyridine or Imidazole

Reaction
SO2 + I2 + H2O = HI + SO3

SO3 + C5H5N = C5H5 N SO3

C5H5 N SO3 + C2H5 = C2H5 N SO3 C2H5

Volt use
15-20 V as on neutral
150 -200 V endpoint detection

Endpoint
Strow pale Yellow color

Indicator
Self indicator

Drift
Background Moisture call
Example vessel moisture

Role PH in Karl Fischer Reaction
Kf reaction depends on the pH value of the solvent. When pH is
between 5 and 8, the titration proceeds normally. However, when the pH is lower than 5,
titration speed is very slow. On the other hand, when pH higher is than 8, titration rate is fast, but
only due to an interfering esterification side reaction which produces water, resulting in an
vanishing endpoint. Thus, the optimal pH range for the Karl Fischer reaction is from 5 to 8, and
highly acidic or basic samples need to be buffered to bring the overall pH into that range.

More Q & A Found in given Link

Quality control (Q.C)

this is original webside to learn

potentiometric titration

What is the principle of karl fischer titration

the actual principle is depend on mothod of detection

that is two type method
1,coulometary method
2,volumatry method
both method are differ only in the delivery of iodine and,detection of water since we know one iodine molecules is consumed by one one molecule of water so if

we calculate how much iodine is reacted with water in sample then we can easily

calculate the amount of water(this is the principle of volumatry method)

the second method is differ that we provide iodine molecule by oxidation of 2 iodide ions by electric method.and the reaction is same as in above equation. we calculate iodine by the faraday principle that is amount of iodine that is oxidised is directly proprtional
to the amount of charge or electricity is consumed to convert iodide ions in to iodine

Why only Water & Sodium Tatrate Is Use For Calibration Of Karl Fischer Titrator?

DST is primary standard and it is stable up to 150 degree Centigrade. It release free water molecules easily when reacts with KF reagent.DST is easily soluble in methanol. This DST has 15.66% water molecules so we can easily calculate and standardize the KF reagent. We use the factorof DST the compound which has less than 1% of moisture.

Water i.e 100% water molecules. But we must use 100% pure water there should absent dissolved salts and anymore. This method is not 100% accurate like DST. So generally We use the factor of water for the compound which has more than 1% of moisture.1water molecule approximately equal to 5mg of KFR.

In Karl fisher titration what is medium select while sample contain CO or CHO

DIMETHYL FORMAMIDE
PYRIDINE

(HERE USING METHANOL MEDIUM ITS FORMS WATER MOLUCULE TO
YHIS SAMPLES BECAUSE THIS SAMPLES ARE KRTO GROUPS.)

Karl fisher determination of water Content

Quality Controle   || HPLC  || Analytical Method Validation   

 

It is colomatric titration Volumetric titration it is use in determination of water Content

factor limit 4 – 6

Calculation(F) = Water in mg /Kf Reagent ml

Monthly Calibration done by Di-sodium tart rate
Calculation = Br X F X 100/1000 X weaight of DST

Limit moisture 15.5 – 16.5 % w/w
Rsd Limit NMT 1 %

Apparatus :- Karl Fischer Volumetric titrator, consisting of a titration cell, dual platinum electrode, magnetic stirrer, dispensing buret and control unit. Many manufacturers of general purpose laboratory titrators offer optional accessories that allow their instrument to perform KF titrations

Reagents:-

I + so2 + pyridine Or Imidazol

(Material Safety Data Sheets (MSDS) for detailed information concerning toxicity, first aid procedures, and safety precautions for chemicals used in this test procedure.)

all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society

such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.

 

 

Why does Acetonitrile use in HPLC Method development?

Accuracy – Analytical method validation, hplc, pharmaceutical

Specificity -Analytical Method validation -pharmaceutical companies

What is different between ODS and BDS column in hplc?

What is Internal standard HPLC / GC- How to USE

HPLC COLUMN – FACTOR AFFECTS,During HPLC analysis