Friday, December 10, 2010

Operation And Calibration Of Karl Fischer Apparatus

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.

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