I'm using adipose tissue MSCs, and the culture is placed in a 37C, 5% CO2 incubator. The media is being 50% replaced when the lactate level is above 10 mM.
pH is being monitored using an external pH meter. The measurement itself is done quickly (to mitigate pH raise). However, I'm still experiencing a slow and gradual increase in pH (from 7.34 - 7.7 during a 14-days period)
The incubator works properly with the correct CO2 concentration.
Any help?
Are you using FBS in you culture? Check if you used a different LOT midway.
Since the pH is measured externally it might be that the pH is your incubator is steady and differences arise due to different elapsed times between the pH measurement. I usually collect the medium and if I can't measure it straight away, I put in a slightly open centrifuge tube and keep it in the incubator till measurement. The pH increases rapidly if left in contact with air.
Taking out medium and than measuring pH, will not give accurate pH since pH changes in minutes in air without 5%Co2. Also putting electrode in incubator in the medium is not a good idea also since pH should be measured at RT not at 37C.
Best way will be, you place fresh medium in incubator and compare the colour of fresh medium with your medium in culture after 24hrs in incubator, not outside the incubator. You can judge the difference in colour (I do not know if your medium has phenol red or it is a colourless medium)
If you can do so, add phenol red to the medium and use its color to monitor pH (it may already be there). This might be better than using an a electrode. Also keep a log book for the conditions that exist in your incubator such as temperature, CO2 level and perhaps a notation for the phenol red color as well as, something like a hemocytometer count to monitor cell growth. Its not clear how often the medium is being replaced, but it may be easier to just set a time interval, instead of using a lactate level.
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Biochemical Techniques
- Analytical Chemistry
- pH