Henderson-Hasselbalch equation


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equation

 [e-kwa´zhun]
an expression of equality between two parts.
Henderson-Hasselbalch equation a formula for calculating the pH of a buffer solution such as blood plasma, pH = pKa + log [BA/HA]; [HA] is the concentration of a free weak acid; [BA] the concentration of the ionized form of this acid; pKa the acid dissociation constant, a measure of the ionization equilibrium of the acid.

Hen·der·son-Has·sel·balch e·qua·tion

(hen'dĕr-sŏn hahs'ĕl-bawlk),
a formula relating the pH value of a solution to the pKa value of the acid in the solution and the ratio of the acid and the conjugate base concentrations: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the conjugate base and [HA] is the concentration of the protonated acid. For the bicarbonate buffer system in blood, pH = pK' + log([HCO3-]/[CO2]). The value of pK' for blood plasma is 6.10 and includes the first dissociation constant of H2CO3, the relation between [H2CO3] and [CO2], and other corrections. The partial pressure of CO2 multiplied by its solubility in plasma at 38°C (0.0301 mM/mm Hg) is commonly substituted for [CO2]; for example, when the plasma bicarbonate concentration is 24 mEq/L and the PCO2 is 40 mm Hg, the pH value is 6.10 + log(24/0.0301 × 40) = 7.40.
[Lawrence J. Henderson, Karl Hasselbalch]

Hen·der·son-Has·sel·balch e·qua·tion

(hen'dĕr-sŏn hahs'ĕl-bawlk ĕ-kwā'zhŭn)
A formula relating the pH value of a solution to the pKa value of the acid in the solution and the ratio of the acid and the conjugate base concentrations: pH = pKa + log ([A-]/[HA]) where [A-] is the concentration of the conjugate base and [HA] is the concentration of the protonated acid.
[Lawrence J. Henderson, Karl Hasselbalch]

Hasselbalch,

Karl, Danish biochemist and physician, 1874-1962.
Henderson-Hasselbalch equation - see under Henderson

Henderson,

Lawrence J., U.S. biochemist, 1879-1942.
Henderson-Hasselbalch equation - a formula relating the pH value of a solution to the value of the acid in the solution and the ratio of the acid and the conjugate base concentrations.
References in periodicals archive ?
For these reasons, the application of the Henderson-Hasselbalch equation to the calculation of the plasma bicarbonate concentration is not straightforward and the physiological meaning of the plasma bicarbonate value estimated from the application of this equation to human plasma remains uncertain.
The other two variables in the Henderson-Hasselbalch equation, partial pressure of carbon dioxide ([PCO.sub.2]) and bicarbonate, had marked decreases in the first two minutes but there were no statistical differences between the fluid groups, P=0.16 and P=0.13 (Figures 2B and 2C).