The sensitivity of pH electrode become worser. In my research pH maintenance is very important. Even I was dipped the electrode in KCL solution the electrode showing same problem. Please anyone tell how to rectify this problem.
Abima Samuel, to reactivate a pH electrode there are several options that you can implement one after the other as you notice that the previous option does not work. This is because the severity of the treatment increases as you go from option 1 to 3. It is important to note that the last two treatments use hazardous substances that must be handled very carefully in a suitable and resistant container.
1 - Immerse the electrode in a 0.1 M hydrochloric acid solution for 24 hours. Subsequently rinse with plenty of high purity deionized water. If the response does not improve, re-immerse the electrode in 0.1 M HCl for an additional 24 h. If this does not work, then try option 2.
2 - Immerse the electrode in a 10% solution of NH4HF2 (ammonium bifluoride) for 1 min, rinse with plenty of water and re-inspect its performance. If operation is not restored, try step 3.
3 - Immerse the electrode in 5% HF solution for 10 to 15 seconds, rinse with plenty of water, rinse quickly in 5 M hydrochloric acid solution, then rinse with plenty of water. Recheck operation. If electrode operation has not been restored, it is time to replace the electrode.
Regards
Dear Friend, Please keep your Electrode in Saturated Potassium Chloride for 24 Hours and use, how you are storing electrode also important, for Cleaning the electrode you use above steps every time rinsing with Deionized water is very important, try the above method and give your comments
Regards,
kantharao
Improving the sensitivity of the pH electrode is rather impossible. You need to buy a new electrode
The treatment procedure used to reactivate the pH (combination) electrode depends on the nature of the contaminants adsorbed/deposited on the glass membrane and the diaphragm of the reference electrode system. In addition to “general purpose” procedures (including slight etching of the glass layer) described by Javier Ernesto Vilaso Cadre, some specific treatments may be effective for removing particular contamination. For example, in biological/clinical applications, poor performance of the electrode is often caused by proteins contamination. In this case, the treatment with a solution of 1% pepsin in 0.1M HCl (for several hours) is recommended, since pepsin as a proteolytic enzyme breaks down proteins into smaller peptides.
Recommendations for regular care and maintenance of pH electrode probes (not the sealed variety):
- Flushing (completely empty and refill) electrolyte solution (usually 3M to 4M depending on manufacturer) KCl Reference Solution monthly.
- For best results, always keep the pH bulb wet, preferably in a storage solution or in pH 4 buffer with ~1/100 parts 4M potassium chloride (KCl) added.
Potential remedies for electrodes with slow and/or out-of-spec calibration slopes:
- Cleaning a blocked diaphragm, which is the porous ceramic junction that creates an electrolytic interface between the inner conducting system and the sample by allowing ions from the electrolyte solution to flow into the sample.
- Rehydration of a dehydrated electrode, which can result from being left out of solution and/or long exposure to non-ionic solutions (flour in de-ionized water is an ion-deficient media that can dehydrate the electrode membrane)
- Regeneration of the electrode using a reactivation solution (NH4HF2)
Cole-Parmer recommends the following methods for restoration:
o Method 1: Soak the electrode in a 0.4 M of HCl (hydrochloric acid) for 10 minutes (Mettler-Toledo recommends 0.1M HCl for 12 hours), then rinse the electrode with deionized or distilled water. This should remove any organic protein from the glass electrode and the surface of the reference electrode, as well as rehydrating the electrode membrane.
o Method 2: Soak the electrode in a 3.8 or 4.0 M KCl (potassium chloride) solution heated to 50°C for one hour. Allow the KCl solution to cool down to room temperature, then rinse the electrode with deionized or distilled water. This will open and clean the reference electrode of all contaminants.
o Method 3: Soak the electrode in a pH 4 buffer solution, heated to 50°C for one hour. Allow the buffer to cool down to room temperature, then rinse the electrode with deionized or distilled water. This will open and clean the reference electrode.
o Method 4: After each use, rinse the electrode in 0.5 N or 1% HCl. If you have a buildup of oil or protein contaminants, try soaking the electrode in a warm detergent and water solution. Degreasing dishwashing detergents or stain-removing prewash pretreatments are ideal for this (any brand will work). An overnight soak may be needed if buildup is heavy. Then rinse the electrode in deionized or distilled water and soak for 10 minutes in 1% HCl. Rinse the electrode again in deionized or distilled water and then calibrate using pH buffers. If the electrode calibrates to buffers, it can be used in tests. When the electrode cannot be calibrated, even after attempts to clean it, it must be replaced.
o Method 5: For protein removal, soak the electrode in a contact lens enzymatic cleaner solution overnight. The enzymes will remove proteins from glass and plastic.
- After any of these special cleaning procedures, remember to drain/refill the reference electrolyte. Soak the electrode in storage solution for at least 10 minutes prior to use. If these steps fail to restore normal electrode response, the electrode will need to be replaced.
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