96 



Scientific Proceedings (126) 



47 (2007) 



Dinitrosalicylic acid as a reagent for blood sugar. 

 By JAMES B. SUMNER and V. ARVIN GRAHAM. 



[From the Department of Physiology and Biochemistry, Medical 

 School, Cornell University, Ithaca, New York.] 



The reagent 1 , in use at Ithaca since 1921 for the estimation of 

 sugar in normal and diabetic urine, has been applied to blood. 

 The blood proteins are perfectly precipitated by the addition to 



1 c.c. of blood, laked with 2 c.c. of water, of 4 c.c. of the neutral 

 sodium salt of dinitrosalicylic acid (2.94 per cent.), followed by 



2 c.c. of dilute sulphuric acid (0.40 N). Filtration is rapid. Ex- 

 cess of oxalate does not interfere. Three c.c. of the filtrate are 

 heated in a Folin sugar tube in boiling water for three minutes 

 to remove the dissolved oxygen. One c.c. of 3 per cent, sodium 

 hydroxide is then added. This last reagent is made up saturated 

 with sodium chloride to prevent oxygen from dissolving in it. 



The test tube is heated for 10 minutes more, cooled and diluted 

 to 25, 50, or 100 c.c. volume. The standard is prepared by heat- 

 ing 2 c.c. of a 0.015 per cent, glucose solution with 1 c.c. of neu- 

 tral 1.78 per cent, sodium dinitrosalicylate for 3 minutes, adding 

 1 c.c. of the alkali and heating for 10 minutes. 



The method is convenient; one standard will keep all day and 

 can be used with bloods containing from 50 to 300 mg. of sugar 

 per 100 c.c. 



1 Sumner, J. B., Jour. Biol. Chcm., 1921, xlvii, 5. 



