CLINICAL STUDIES OF THE BLOOD VOLUME. IV. ADAPTATION OF THE METHOD TO THE PHOTOELECTRIC MICROCOLORIMETER

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Abstract
A photoelectric method, using the photoelectric micro colorimeter of Evelyn and Cipriani, of determining the dye concn. of blood serum samples in the plasma volume method of Gibson and Evans is described. The technique of obtaining blood samples and preparing scrum for colorimetry is the same as descr. in the original technique. Concn. of "Evans Blue" in serum is measured with a filter transmitting light in the region of 620 m[mu]. Photo-electric transmission values are converted to densities and used in the original formula for calculation of plasma volume. Correction for hemolysis of samples is made by using the density value obtained with a filter transmitting light in the region of 540 m[mu], in the original formula. Comparison of the spectrophotometric and photometric methods shows the latter to give results within [plus or minus]2.5% of those obtained with the former. The photometric method has the advantage over the spectrophotometric method of greater simplicity, speed, economy, and freedom from objective errors.