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CO2 gas diffussion and exchange

  1. Jul 18, 2010 #1
    I have to pick the best cell culture vessel:
    For my experiments, the vessel initially contains 0% CO2. Then it's placed in an incubator set to 37 degreesC and 5% CO2. There is a 1 micron filter i can attach to a port in the vessel that can be 10mm wide or a .2 micron filter can be attached to a port that is 26mm wide. Experimentally the vessel with the 26mm port proves to be better as more cells survive--probably because CO2 diffuses quicker (I assume)--and 5%CO2 is necessary for the cells. I'm just not able to justify the result--can anyone please explain why this might be occuring based on any theories like brownian motion or bernoulli's principle maybe?? Basically I need some kind of an equation that justies that the volumetric flow rate is much faster/better in the vessel that has a 26mm port instead of the 10mm ports (regardless of the filter device--which probably acts as resistance).
     
  2. jcsd
  3. Jul 19, 2010 #2

    alxm

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    Insufficient information, really, since while you know the size of the holes, you don't know the % of hole area. (after all it wouldn't matter if the filter was huge if it only had one hole in it!) If you assume it's the same in both filters, then obviously the larger one will let gas through faster.

    It sounds a bit strange. I'd expect the gas concentration to equilibrate within minutes, whereas incubation times are on the order of 10-20h, aren't they? I'd expect the effect to be quite small.

    Either way, it'd really be easier to just measure the concentration over time. Surely if the CO2 concentration is so vital you must have some means of measuring it?
     
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