I am running a batch experiment using penicillin bottles where I have bacteria growing for 21 days in a highly alkaline media (pH 10). I am measuring the CO2 and O2 content in the headspace over time, but I am specially interested in the CO2 production. Usually I can simply use the CO2 content measured with a gas-chromatographer (GC) but because of the pH of my media, the CO2 will be dissolved into my media. This I have seen in the sharp drop of pH over time as well.

I want then, to calculate the amount of CO2 that has dissolved into my media. I know I require Dalton's Law of partial pressures and Henry's constant/Law. The thing is that, I am a bit confused because as I measured the pressure inside my closed bottles, the pressure in these bottles became negative. So my calculations are returning a negative value for my concentration of gas in the solution. Furthermore, I do not know if the formulas I used (Dalton and Henry), take into consideration the pH of my aqueous media.

  • $\begingroup$ What salts are present in you media? Something like calcium will precipitate with carbon dioxide and removed from your system. $\endgroup$
    – Chris
    Commented Sep 14, 2023 at 9:03
  • $\begingroup$ It's just a TSB media adjusted with CAPS buffer. No precipitation was observed. $\endgroup$ Commented Sep 14, 2023 at 9:27


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