Comparison of the pH of serum and plasma.

Abstract

While the experiments reported above were being carried out, Hirsch 1 stated that serum is more acid than plasma. In a later paper 2 , however he reported data throwing doubt on the accuracy of his previous conclusion. In order to determine whether there was any difference between the pH of serum and of plasma of dog's blood, electrometric and colorimetric pH determinations were done on both, Cullen's 3 colorimetric method was used. We found no difference between the serum and plasma pH, electrometrically determined. The correction in Cullen's method, however, is slightly greater for serum than for plasma as stated by Cullen.