Refractometric methods for determining total protein

Abstract

A rapid refractometric method for determining horse serum protein was described, in which the refractometric change, taking place during heat coagulation (pH 4.6), served as a quantitative measure of the amt. of protein in soln. This method was used for total protein detn. of horse serum, plasma and horse protein solns., the salt content of which was not exactly known. For solns. containing from 0.2 to 10% protein the results were in close agreement with gravimetric protein figures. For calculation the refractometric increment constant a = 0.00185 for horse protein was used. A simple pressure device was described for carrying out heat coagulation at 100[degree], avoiding evaporation of water. Reiss''s method for determining serum protein by means of a single refractometer reading was worked out for horse sera in the form of a graphic method. It gave for routine purposes satisfactory agreement with gravimetric methods.