Cullen's colorimetric method for the determination of the pH of blood plasma.

Abstract

In experiments on hemorrhage, Cullen's 1 colorimetric method for the determination of the pH of plasma was found unreliable even for comparative studies. The correction of 0.35 for dogs'plasma, necessary to convert the colorimetric readings of pH at 20°, to the electrometric pH at 38°, varied especially after hemorrhage, from 0.42 to 0.19.

Hastings and Sendroy 2 stated that Cullen's correction disappears if the colorimetric determinations are made at 38° instead of 20°. In a single experiment where this procedure was also used, the corrections became less, but did not disappear, and the variations noted above persisted.