pH METER Cleaning SOP



1.0  OBJECTIVE:
To lay down the procedure for cleaning of pH meter and activation of pH electrode.
2.0  SCOPE:
This shall be applicable to the pH meter of Quality Control Laboratory.
3.0  RESPONSIBILITY:
3.1  Technical Assistant/ Helper.
3.2  Q.C Analyst.
4.0  ACCOUNTABILITY:
4.1  Manager-Quality Control.
5.0  MATERIAL AND EQUIPMENT:
5.1  pH meter.
5.2  Clean dry cloth
5.3  Purified water.
5.4  De-ionized water.
5.5  Detergent.
5.6  Dilute KCl solution.
5.7  Storage solution (e.g. buffer pH 5.00/5.01).
5.8  Lint-free tissue paper.
6.0  PROCEDURE:
6.1  Switch OFF the instrument from ON/OFF button and main supply.
6.2  Clean the apparatus with the help of clean dry cloth.
6.3  Electrode cleaning: Electrodes, which are mechanically intact, can often be restored to normal performance by one or combination of the following procedure:
6.3.1        Salt deposits: Dissolve the deposit by immersing the electrode in purified water for 10 to 15min. Then thoroughly rinse with de-ionized water.
6.3.2        Oil/grease films: Wash electrode pH bulb in a little detergent and water. Rinse electrode tip with de-ionized water.
6.3.3        Clogged reference junction: Heat a dilute KCl solution to 60-80oC. Place the sensing portion of the pH electrode into the heated KCl solution for approximately 10min. Allow the electrode to attain room temperature while immersed in some unheated KCl solution.
6.3.4        Electrode activation: In case of dehydration / electrode showing sluggish response, the bulb can be rehydrated by immersing the electrode in an ideal storage solution (e.g. buffer pH 5.00/5.01) for 1-2 hr. If this fails, proceed for the electrode rejuvenation.
6.4  Clean the electrodes before and after use.
6.5  And store the electrode in storage solution or pH buffer 5.00/5.01 or 7.00/7.01 buffer solution when not in use.
6.6  Storage:
6.6.1        Always keep the electrode bulb wet, preferably in the pH 5.00/5.01 buffer. Raw water is also acceptable storage media, but avoid storage in de-ionized water
6.6.2        During handling of the pH meter, check if electrode is broken, replace the same with new electrode and enter the details in “Instrument Usage Log Book” of pH meter.
6.7  Electrode rejuvenation: If the electrode fail to give appropriate result during calibration, the same shall be rejuvenated as mentioned below:
6.7.1        Dip and stir the electrode in ethyl alcohol for 5min.
6.7.2        Leave the electrode in purified water for 15min.
6.7.3        Dip and stir the electrode in concentrated acid (e.g. Hydrochloric acid, sulphuric acid) for 5min.
6.7.4        Leave the electrode in purified water for 15min.
6.7.5        Dip and stir the electrode in strong base (sodium hydroxide) for 5min.
6.7.6        Leave for 15min in raw water.
6.7.7        Test with standard calibration buffer solution.
6.7.8        If the electrode still fails to restore the normal electrode response, the electrode rejuvenation steps 6.7.3 to 6.7.6 shall be repeated.
6.7.9        If the response does not improve, then the electrode has completed its useful life and same shall be replace with a new electrode.
6.7.10    Record the electrode rejuvenation details.
6.8  For refill electrode:
6.8.1        Refill the reference chamber with fresh electrolyte. Allow the electrode to stand upright for 1 hour.
6.8.2        To minimize clogging and ensure a quick response time, the glass bulb and the junction should be kept moist not allowed to dry out.
6.8.3        Replace the solution in the protective cap with a few drops of storage solution or, in its absence, filling solution.
6.9  Precautions:
6.9.1        Avoid rubbing or wiping the electrode bulb.
6.9.2        Rinse the electrode with distilled water and gently blot it dry with a lint-free tissue.
6.9.3        During transport, tiny bubbles of air may form inside the glass bulb affecting proper functioning of electrode. These can be removed by “shaking down”.
6.9.4        Never store the electrodes in distilled or de-ionized water.
7.0  REVISION LOG:
Revision No.
Effective Date
Reason
00

New SOP

8.0  REFERENCES:
8.1  Not Applicable.
9.0  ANNEXURES:
Annexure 1: Cleaning Record of pH meter (Cleaning Equipment Log Book).




Annexure: 1
 Cleaning Record of pH meter (Cleaning Equipment Log Book).
Cleaning Record of Electronic Analytical weighing balance PGW 453i Adam
Date
Cleaned by
Checked by
Remarks 























































































10.0    ABBREVIATIONS:
Abbreviation
Expanded Form
SOP
Standard operating procedure
&
And
No.
Number  
Ltd.
Limited
Q.C
Quality control
QCEC
Quality control equipment cleaning
Sr.#
Serial number
B.P
British pharmacopoeia
KCl
Potassium chloride
e.g.
Example
Min
Minute
oC
Degree centigrade
Hr
Hour


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