An instrument used to determine the water content of a sample.
SOP FOR OPERATION1.0. PURPOSE :To provide a procedure for the operation of Karl Fisher titrator.
2.0. SCOPE :Applicable to Karl Fisher titrator.
MAKE & MODEL : Lasco, KFTA.
3.0. RESPONSIBILITY:
3.1. Officer-Quality Control
3.2. Executive-Quality Control
4.0. ACCOUNTABILITY:Manager-Quality Control
5.0. DEFINITION:An instrument used to determine the water content of a sample.
A Macro Karl Fischer Instrument uses standardized volumetric solution to
determine the amount of moisture in samples, and is used when the expected result is between 1 mg to 100 mg of water. A Micro Karl Fischer Instrument uses an electrical current (coulometry) for determination of moisture in samples, and is used when the expected result is between 10 μg to
10 mg of water.
6.0. PROCEDURE:6.1. Ensure the calibration status is valid.
6.2. Ensure the instrument is clean and free from dust.
6.3. Switch on the instrument by using switch provided on rear side of left. Green LED ‘O’ will glow.
6.4. Fix KFR bottle by screwing on the plastic cap, operate bellow, holding vertically and closing the “T” joint connection tube. Air pressure in
KFR bottle increases and lifts KFR to fill burette, when level crosses ‘0’ mark remove finger, Zero level gets automatically.
6.5. Place magnetic stirring paddle slowly by sliding in to the reaction vessel and fix the burette by lifting the burette by lifting the burette
assembly.
6.6. Pour about 20ml of methanol into the reaction vessel.
6.7. Connect jack wire to reaction vessel and electrode terminals marked ‘e’ rear
side on the instrument.
6.8. Switch on stirrer, set required speed by using regulator, wait for 10 to 15seconds for uniform stirring.
6.9. Add KFR by drops into reaction vessel by operating burette valve. Until pre end point. Yellow LED glows ‘P’ is nearing end point
indication.
6.10. Now add KFR by drops slowly giving 10-20 seconds between additions until
Red LED ‘E’ glows continuously for 30seconds it indicate the end point of the titration. ( Neutralisation of methanol)
6.11. Fill the burette, weigh a 1ml syringe with needle with a small quantity of
Distilled water and add 25-100mg into the reaction vessel and close the stopper. Start magnetic stirrer, titrate up to end point.(ie. RED LED glows for 30secs.). Note the burette reading and calculate the water equivalent of KFR by using the following calculation.
F = M/A
Where, M à mg in water,
A à Volume of KFR consumed.
Repeat the same and take mean.
6.12.
Weigh the sample in the plastic spoon add to the reaction vessel, fill the burette and start the stirrer, wait until samples dissolves. Add KFR up to end point and note the burette reading, and calculate the water content by using the following formula.
% of water content = B X F X 100 / W
Where, B - Volume of KFR consumed.
F - Factor
W - Weight of sample in mg.
6.13. After completion of analysis remove the KFR bottle from the plastic cap and fix the methanol bottle. Drain KFR from the burette and fill methanol and wash the reaction vessel.
6.14. Switch OFF the instrument and clean the place.
7.0. REFERENCES:Instrument Manual