The determination of dextran in blood and urine with anthrone reagent.

Klevas (1) determined dextran in blood by the Hagedorn-Jensen (2) copper reduction method, applied to filtrate prepared by the Somogyi technique (3), after acid hydrolysis of the filtrate for 6 hours. Hint and Thorsen (4) estimated dextran in blood by alkalinizing trichloroacetic acid filtrate, treating the filtrate with standard copper solution, and determining residual copper after 4 hours shaking. These methods are timeconsuming and cumbersome. A considerable advance in analytical technique was made by Bloom and Willcox (5) who applied the anthrone reaction of Dreywood (6) to dextran precipitated from solution by alcohol. In the Bloom and Willcox method the blood proteins are removed by boiling with 30 per cent KOH, a procedure that gave a blank value of 12.4 f 3.2 mg. per cent in normal subjects (5). Procedures in which the dextran in trichloroacetic acid filtrates of blood and urine is precipitated by alcohol and determined turbidimetrically have been published by Metcalf and Rousselot (7) and by Jacobsson and Hansen (8). Metcalf and Rousselot reported their method somewhat inaccurate at concentrations of 1 mg. per ml. but of satisfactory reliability at concentrations of 2 to 16 mg. per ml. The color formed when carbohydrate is treated with anthrone reagent is influenced by the temperature, the time of heating, and the concentration of sulfuric acid and anthrone used. These factors, also conditions for optimal precipitation of dextran by alcohol, have been studied, and a method has been developed for the determination of clinical dextran, average molecular weight 70,000, in blood and urine.