A Comparison of Plasma Protein Fractions by Kjeldahl and Biuret Analysis and Refractive Index Measurements

In electrophoretic studies of serum and plasma the concentration of protein in the various fractions is often expressed in absolute values. These are commonly obtained by calculation from the percentage distribution of the components and the total protein content of the serum or plasma. Although this practice is widespread there is no assurance that the values obtained reflect a true measure of the protein content of the individual components. It is readily apparent from the divergent results obtained by the technique of paper electrophoresis that the major components of serum contain varying concentrations of protein, lipids and carbohydrates and exhibit a varying response to protein dyes