Color Reaction of Aromatic Aldehyde with Serum Protein and Its Application to the Determination of Serum Total Globulin Concentration

The reaction of four aromatic aldehydes including p-dimethylaminobenzaldehyde (p-DMABA) with serum protein has been studied. The aromatic aldehydes gradually reacted with serum globulin with the irradiation of a fluorescent lamp at room temperature to form a colored product with an absorption maximum at about 520 to 635 nm with high molar absorptivity, while only slightly reacting with serum albumin. The reaction rate increased as the intensity of light increased, and at about 3000 luxes the reaction completed within 45 min after the reaction started. Of the four aromatic aldehydes evaluated, the colored product of p-DMABA indicated the most excellent spectral characteristics. Based on these results, this aromatic aldehyde was applied to the detemination of the serum total globulin concentration. The measurement values by the proposed method, using a g-globulin solution as a standard material, correlated well with those by the method of Goldenberg and Drewes using glyoxylic acid (r = 0.983), the combined biuret-BCG method (r = 0.949) and moderately with the combined biuret-cellulose acetate electrophoresis method (r = 0.899).