A convenient spectroscopic method for the estimation of hemoglobin concentrations in cell-free solutions

Using a millimolar absorptivity of 7.12 +/- 0.09 at 523 nm, it is possible to estimate the total concentration of hemoglobin in solutions containing oxyhemoglobin, deoxyhemoglobin and methemoglobin in any combination. This estimate is independent of the pH in the range 6.0-10.0 and will provide concentrations comparable to that obtained by the conventional and more precise use of cyanomethemoglobin. This methodology should be of value for the determination of extracellular hemoglobin in vivo, as a means for determining the vascular half-life of stroma-free hemoglobin based blood substitutes.