Improved direct colorimetric method for the determination of total serum globulins

1. A direct, fast, and efficient manual method is described for determining total serum globulins. The procedure is based on the reaction of tryptophan residues with glyoxylic acid in the presence of an oxidizing agent to produce a highly colored 4-carboline derivative. 2. A single, odorless reagent is employed and Beer's law is obeyed up to at least 7 g/100 ml of globulin at 565 nm. 3. Results of parallel assays demonstrate good agreement between our method and a reference cellulose acetate electrophoretic method and poor agreement with a HABA dye binding method.