Hello everyone,
I'm currently trying to expand human cells in a 2L cell culture bag (plastic), but I have problems with the medium getting to acidic - even when no cells are involved - and the CO2 supply is cut of. For example: I introduce the medium - pump the bag and the pH drop starts immediately, within 15 min the indicator changes color and the internal pH sensor also shows strong decrease. I closed gas in/out exchanged the medium - the same happens - also if I only pump air which should push towards basic conditions its not making any difference.
Thanks in advance, hope someone has an idea what I'm doing wrong.
You did not identify which media you are using for what you describe but the media should contain a strong buffer such as Hepes which will help to prevent fluctuations in pH. A lot of medias contain sodium bicarbonate which also controls pH but it is not as strong of a buffer as Hepes. You can supplement the media with Hepes to a final concentration of 15mM.
Hello, thank you for the response - I the first try was with endothelial growth medium 2 - the next day I exchanged medium completely and also included HEPES at 10mM but still it was going acidic, also I tryed with DMEM were I got similar results.
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