The changing pH in cell culture environment can alter virtually every cellular process like metabolism, cell growth. Extracellular pH is slightly alkaline and typically 7.3-7.4, while intracellular pH is slightly lower at 7.2. Many organelles such as mitochondria maintain a slightly different pH from the cytoplasmic pH but if these differences are too great, there are dramatic functional consequences for the organelles. Since pH is one of the most important parameters of cell culture, pH electrodes are the key for pH control in fermentation.
Innova bioreactor fermenter uses premium imported pH electrodes to offer positive support in pH control: With drift-free measurement, measurement signals always keep stable after steam sterilization, autoclavation, and CIP cleaning.
What Should We Do Before Start?
1. Confirm there is no mechanical damage to the pH glass and shaft.
2. Bioreactor pH electrodes have a protective silicone seal covering the ceramic diaphragm; The seal covering must be removed with the enclosed blade.
3. Remove the hydration cap, and rinse it with distilled water to make sure there are no electrolyte crystals. the electrode should only be dabbed dry with a tissue after rinsing. Do not rub it as this may build up a static charge and lengthen the response time.
4. Confirm no air bubbles exist behind the pH glass and remove the air bubbles by gently swinging the electrode in a vertical plane.
4. Please refer to the instruction manual in order to install the electrode.
5. The electrode can be soaked in acid buffer (pH4.00) for several minutes before use, then wash the glass bulb with pure water, gently absorb the water of the glass bulb with absorbent paper, and then soak it in neutral buffer (pH6.86 or 7.00, etc.) for several minutes to activate the electrode. And then start the pH electrode calibration.
How to Calibrate pH Electrodes in Bioreactor Fermenter?
1. Unscrew the electrode cap and connect the controller pH electrode wire. Rotate slowly to remove the protective liquid sleeve and place it to prevent the protective liquid from spilling.
2. Rinse the surface of the pH electrode with pure water and dry the residual water with absorbent paper and soak it in the standard solution of 7.00 (immersion in the glass bulb). When the pH value on the controller is stable, click "Calibration" on the screen.
3. Rinse the surface of the pH electrode with pure water again and dry the residual water with absorbent paper. Then, soak the pH electrode in the standard solution of 4.00. when the pH value on the controller is stable, click "Calibration" on the screen.
4. The equipment automatically calculates the zero point and slope, the zero point is about 0.0, and the positive drift is in the range of 0.5. when the slope is 1 and the drift is ±0.2. When the pH electrode is calibrated, disconnect the connection line between the pH electrode and the controller. Carefully lay the calibrated pH electrode aside to prevent it from falling and smashing. After the fermenter is cleaned, the pH electrode is installed in the pH electrode port on the fermenter. If the slope is not in the normal range, it is necessary to detect whether it is caused by equipment problems, electrode, line aging, or calibration.
Notes for pH electrodes calibration:
1. Fresh buffer solution should be used for calibration. Do not use it if the buffer solution expires.
2. Put the electrode into the buffer solution for 1 minute before the follow-up operation.
3. After rinsing the electrode, dry the water with a soft paper towel, and do not rub the pH sensitive membrane.
4. The electrode calibration period is determined according to different use environments and accuracy requirements, and the appropriate calibration period is determined on the premise of ensuring accuracy.
How to Carry Out Daily Maintenance of Bioreactor pH Electrodes?
1. For general contamination: wash the electrode with water, 0.1mol/L NaOH or 0.1mol/L HCl for several minutes.
2. For grease or organic contamination: clean the electrode with acetone or ethanol for a few seconds.
3. For sulfide pollution (diaphragm blackening): treat with a diaphragm cleaning solution (thiourea/HCl), soak the glass bulb part in the solution(the diaphragm should be submerged in the solution) until the diaphragm is colorless (at least 1 hour), then soak in 3mol/L KCI for at least 12 hours, fully rinsed and recalibrated for use.
4. For protein contamination (diaphragm yellowing): treat with an electrode cleaning solution (gastrin/HCl), the glass bulb section was placed in the solution, ensuring that the diaphragm was submerged in the solution (at least 1 hour), then recalibrated after rinsed with distilled water.
5. Electrode regeneration: Treat with an electrode regeneration solution. but kindly note that regeneration can only extend electrode life to a limited extent.
How to store pH electrodes?
1. When the electrode is not used for a long time, it should be stored in 3mol/L KCI or 9816/ViscolytTM electrolyte.
2. The electrode cannot be stored dry for a long time, and the electrode cannot be stored with a dry medium attached to the surface. If the electrode is stored dry by mistake for several days, it should be soaked in normal storage electrolytes for several hours before use.
3. The electrode cannot be stored in distilled water.
Innova offers a large variety of lab equipment and has been committed to delivering the highest quality lab equipment to medical device companies and laboratories worldwide. To learn more, visit our website https://www.innovabiomed.com, or contact us via info@innobiomed.com.
