Physiological Buffers—They Keep You Alive

An important diagnostic analysis is the CO2/HCO3 balance in blood. This ratio is related to the pH of the blood by the Henderson-Hasselbalch equation (7.45)  

The HC03 concentration may be determined by titrimetry (Experiment 8), or the total carbon dioxide content (HCO3 + dissolved CO2) can be determined by acidification and measurement of the evolved gas. If both analyses are performed, the 

The C02/HC03 balance can be assessed from measuring two of the parameters in Equation (7.88). 

The partial pressure, pco, of CO2 may also be measured (e.g., using a CO2 electrode), in which case [H2CO3] O.SOpco,- Then, only pH or [HCOs ] need be determined. 

Note that these equilibria and Equation 7.88 hold although there are other buffer systems in the blood. The pH is the result of all the buffers and the [HCO3 ]/ H2CO3] ratio is set by this pH. 

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