1.0 OBJECTIVE
To lay down a procedure for operation & calibration of Karl Fischer apparatus.
2.0 RESPONSIBILITY
Chemist/Executive
3.0 ACCOUTABILITY
Manager Quality Control
4.0 PROCEDURE
4.1 CONTROLS ON THE PANEL
Ø A main switch is provided on the back side. This switch put the instrument "ON”. It will be indicated by the "Red" pilot on the panel.
Ø Screen shows :
METTLER TOLEDO
DL 31
VERSION 1.8
Ø General cleaning :
Ø Ensure that glass vessel is cleaned and dried.
Ø Push PUMP key & F3 . Fill specially dried Methanol in glass vessel by pushing Blue bottom above the instrument panel.
Ø Press ‘RUN’ key & F3 key . Iinstrument automatically neutralize the methanol with Karl Fisher Reagent.
Ø Select ‘Method No’ from the display shown using (Δ) (Ñ) keys ,then Press F3 key .
Ø After completion of neutralization ,display
DRIFT CONC SAMPLE.
Ø For Drift calculation press F1key. After completion of Drift display apears
DRIFT CONC SAMPLE.
Ø Select ‘CONC’ from the display & Press F3 key.
Ø Display shows ‘KF standard ,Di-Na tartrate’. Change Di-Na tartrate by Distilled Water 3696 and then press F3 key twice.
Ø Press ‘Setup’ key and set the time 30 seconds for dissolving distilled water.
Ø Add accurately weighed 10 mg of distilled water 3696 in the neutralized Methanol and enter the weight of distilled water in Grams, then press F3 key twice.
Ø When titration is completed the instrument will automatically print concetration of the Karl Fisher Reagent.
Ø Repeat the operation 4.1.12 to 4.1.13 twice . Calculate the average concetration.
Ø Press ‘RESET’ key and ‘SETUP’ key .Then press F3 key.
Ø Press F2 key and enter average concetration of the Karl Fisher Reagent.
4.2 DETERMINATION OF WATER CONTENT FOR A GIVEN SAMPLE :
- For easily soluble substances :
Ø Set the time for 10 seconds.
Ø Press ‘Reset’ key ,then press ‘Run’ key and F3 key. Pretitration is started .
Ø After completion of pretitration , the display shows
DRIFT CONC SAMPLE
Ø Press F3 key, the display shows
ABC SELECT OK
Ø Enter sample identification by using ‘ABC’ key.
Ø Now add sample in titration vessel.
Ø Enter sample weight in Grams and press F3 key twice.
Ø After completion of tiration , the results of water content of sample in % is printed automatically.
4.3.2 For not easily soluble substances:
Ø Press ‘Reset’ key and ‘setup’ key.
Ø Set the time for 30 seconds.
Ø Press ‘Reset’ key ,then press ‘Run’ key and F3 key. Pretitration is started .
Ø 4.3.2..4 After completion of pretitration , the display shows
DRIFT CONC SAMPLE
Ø Press F3 key, the display shows
ABC SELECT OK
Enter sample identification by using ‘ABC’ key.
Ø Now add sample in titration vessel.
Ø Enter sample weight in Grams and press F3 key twice.
Ø After completion of tiration , the results of water content of sample in % is printed automatically.
4.4. SIZE OF THE SAMPLE :
Select a samples size, which contains 5.00 to 10.00 mgs of water.
The following table will serve as a guide for samples size.
Expected moisture content Range of sample size
Bellow 1.0%. Above 500 MG
1.0% to 5.0% 300 to 500 MG
5.0% to 10.0% 200 to 300 MG
Above 10% 100 to 200 MG
4.4.1 PRECAUTIONS
Ø When a liquid sample is to be added by a syringe, always take some more volume and then inject the desired volume.
Ø Clean syringes and needless the Use dry them.
Ø While testing various samples of which the moisture contents are roughly known, test the sample having lowest moisture first and then go on to the next in order to avoid contamination.
Ø If moisture content of samples are unknown and very small sample to obtain pilot reading and then adjust the size of sample accordingly. Keep next sample ready and if some time is lapsed between two titration. Press START, get to the end point then add sample immediately. This will eliminate the error due to lapse of time.
Ø Rinse the syringes with the sample itself 2.3 times and then take the test sample. This will remove the moisture from syringe if any.
4.5 CALIBRATION :
Ø Neutralize the water in methanol by Karl Fischer titrator.
Ø Weigh accurately 100 mg of sodium tartrate dihydrate as a standard. Add into the titration flask and titrate. Record the volume required for the sample.
Ø Take three reading and record obtained results by karl fisher titrator.
Ø Calculate the average water equivalent factor of karl Fischer reagents.
Ø Standard value of titrer factor is 6.0 limit : ± 0. 5.
4.6 FREQUENCY : Every month.
Quality assurance is the best service one can provide to their customers.Here few tricks are enlisted in this post which can help people who engaged in the business of service providing.
ReplyDeleteHi,
ReplyDeleteWant to get our Karl Fischer titrator through a NABL accredited Calibration Lab/Agency.
Do you know of any such lab in Hyderabad or other place