I noticed that some CO2 suppliers provide different range of puritz (from 99.0% to 99.99%).
I was wondering how much CO2 quality may impair or enhance reproducibility of cell culture experiments.
Thank you for sharing.
Hi!
I have always used 5% of CO2 to enhance the growth of cell culteres. I cultured C2C12, RD, myoblasts, THP1... all with 5% CO2.
(If I correctly interpreted your question).
You always maintain 5% CO2 . The effect in increasing the CO2 it may lead to the formation of carbonic acid
your medium is buffered with bicarbonate.
CO2 + H2O -> H2CO3 H+ + HCO3-
so, if you increase CO2, you will decrease the pH.
I don't know for your cells in particular, but usually cells are at 5% CO2
Thank you for your answers!
I edited the question hoping to get more input on the quality of the CO2 itself.
For information we also use 5% CO2 :)
The%CO2 is determined by the bicarbonat concentration. Many investigators incorrectly use 5% when 7.5-10% is required for buffering.
If the CO2 in use was only 99% pure, given that you use 5% CO2, the total volume of other gases would only be 0.05% of the total incubator gas content. With the degree of gas mixing that happens with each opening of an incubator and the ever changing content of incoming air, i cant imagine such a small % impurity could have any impact on cell culture.
Thank you Paul.
That is a good reflexion, but what is the composition of the 1% which is not CO2 and how much can it impaire the reproducibility of an experiment...
Still looking around for an answer, but still not convince to change gaz quality (in my case from 99.90% to 99.95%).
The composition of the 1% would really depend on the method of gas production employed by your supplier. The most commonly used method (as far as i am aware) is purification of CO2 from another output gas such as exhaust gases from chemical and petrochemical processes or natural gas. In those cases the most probable contaminants would be hydrocarbons but if you live in or close to a city then you can be pretty sure the air your breathing is already pretty contaminated with those already.
As correctly pointed out, the answer to your question is with your supplier.
If one wants to be really picky, he may also consider that the actual tank can be a source of contamination (possibly more than the 0.1% impurities in the gas). Some "Food-grade" CO2 supplier use coated tanks. At least, make sure you get newish tanks.
It is also a good idea to have a filter (for hydrocarbons and for particulates) upstream from your cultures.
In any case, consider that the 0.1% of impurities in your CO2 will most likely also include N2 and O2. The proportion of other contaminants will be very small. Unless it is something with a strong biological activity, it is unlikely to constitute a major problem. Of course, how careful you ought to be, also depends on what you are doing with your cells.
Some of the comments on CO2 equilibria above are rather peculiar; luckily it is not what you are interested in.
Thank you Paul and Mario!
Need to get a better discussion with the supplier!
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