Stability of sodium carbonate buffer

[Han]

"Peter Ellis" <pjie2 at cam.ac.uk> wrote in news:462og9F93lfgU1
@individual.net:

> Stacy Ferguson wrote:
>>
>> Bicarbonate breaks down to CO2 and water. While this is reversible,
>> CO2 doesn't stay in solution easily (if it did, you could just leave
>> an open bottle of Coke in the fridge indefinitely) and that throws
>> off the equilibrium. When I'm using carbonate buffers frequently, I
>> just have a fresh batch made every 1-2 weeks.
> 
> Freezing it should stop the evaporation, no?
> 
> Peter 
> 
I think that freezing drives off the dissolved gas, so pfft, buffering 
gone.  In hematology, the reactivity of platelets is often measured in 
plasma (soft spin of blood, rbc and white cells go down, platelets stay in 
plasma, use this platelet-rich plasma, PRP).  After a few hours of opening 
and closing the tube with PRP, some/much of the dissolved CO2 is lost, the 
buffering of the PRP goes awry (I think losing CO2 will acidify), and 
platelet reactivity is greatly diminished.  To prevent/delay this, we blow 
5% CO2 in air over the plasma.

-- 
Best regards
Han 
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