nannan
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ways to measure CO2 or carbonate concentration
I'm carrying out a reaction between CO2 and Carbonate buffer in capillaries. i need to identify the concentration of either CO2 gas or Carbonate
ion. This detection should be on-line and without precipitates considering the small dimension of the capillary(1mm).Thank you very much.
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chemoleo
Biochemicus Energeticus
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The only way I can see this to work continuously is to do it spectrophotometrically - i.e. you want a dye or some compound that either HCO3- or CO2
binds to specifically, and whose absorption spectrum changes as a result of it.
That way you can figure the amount of bound versus unbound species.
The problem is that if something binds to a dye (hemoglobin, although not a dye in the usual sense, binds CO2 and produces a shift), you are removing
the HCO3-/CO2 irreversibly out of the equilibrium, and thus you are forcing the equilibrium to the right, causing more CO2 to be dissolved etc.
Whether this is a problem depends on the respective equilibrium constants.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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neutrino
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Adding an indicator may work if there’s nothing else acidic/basic in there, as the carbonate ion is weakly basic.
[Edited on 2-1-2005 by neutrino]
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BromicAcid
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Considering the small dimensions of a capillary, as you said, an ion selective electrode would be out of the question, to determine the concentration
of CO2 gas though you could use a gas sensing electrode, they are reasonably priced considering the accuracy of their measurements and wide range over
which they function.
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mick
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Measure the carbonate first and then convert the CO2 to carbonate and measure the total.
mick
On line Ph meter titation.
[Edited on 2-1-2005 by mick]
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