Turbidimetric Method for the Determination of Serum Globulin Using the Autoanalyzer.

An automatic procedure for the determination of globulin in serum or plasma is described. This method is based on the measurement of the turbidity which develops when serum is mixed with 27-4% sodium sulphate solution. The method gives good agreement with the salt fractionation technique (Majoor, 1946) and shows a high degree of precision. The differential estimation of serum proteins constitutes an important fraction of the work in most chemical pathology departments and the automation of these analyses would result in a great saving of time. While there are several adequate methods available for the measurement of total protein (Stevens, 1959; Failing, Buckley, and Zak, 1960), none of the procedures proposed for the albumin estimation has gained wide acceptance. These latter methods depend on the dye-binding capacity of albumin which has been shown to be influenced by a number of substances, e.g., drugs or heparin (Niall and Owen, 1961). In our hands, none of them has given consistent results and has shown poor agreement with the salt-fractionation technique of Majoor. For these reasons, experiments were begun to find, if possible, a more satisfactory method of albumin/globulin determination. In the course of these, it was discovered that the turbidity produced by mixing serum with 27-4% sodium sulphate varied in a linear manner with globulin content. This observation is the basis of the method to be described.