2 QO PHYSIOLOGICAL CHEMISTRY 



13. The Determination of Epinephrin (Adrenalin) in the Adrenal 

 Glands. 1 Principle. It has not yet been found possible to determine 

 adrenalin in the blood by chemical methods. In the adrenals it may be 

 determined by the method given below. 



The method is based upon the quantitative production of blue 

 color when a solution of adrenalin is treated with phosphotungstic 

 acid. Uric acid and other substances likewise give the reaction but 

 can be disregarded when the determination is made upon adrenal 

 glands. 



Procedure. Rub the weighed gland thoroughly in a mortar with fine sand 

 and N/io hydrochloric acid. The mixture is then rinsed into an Erlenmeyer 

 flask with more N/io acid and water, using in all about 15 c.c. of the acid for each 

 2 grams of gland and about three times as much water. Heat to boiling to dis- 

 solve the epinephrine. Then add 5 c.c. of 10 per cent sodium acetate solution for 

 each 15 c.c. of hydrochloric acid present and heat again to boiling. Transfer 

 the whole mixture (except the sand) to a volumetric flask (capacity 100 c.c. for 

 each 2 grams of gland) and make to mark with water. Filter. Pipette 5 c.c. of 

 the clear extract into a 100 c.c. measuring flask and i c.c. of a fresh uric acid 

 solution containing i mg. of uric acid into another 100 c.c. flask. To each flask 

 add 2 c.c. of uric acid reagent (see Folin and Denis' method for uric acid, 

 page 274) and 20 c.c. of saturated sodium carbonate solution. Allow to stand 

 for two to three minutes, dilute to the mark, shake thoroughly, and compare 

 in the usual manner in a Duboscq colorimeter with the uric acid standard set 

 at 20 mm. Calculate as if the solution contained uric acid, and divide the 

 result by three to obtain the equivalent in epinephrine which gives three times as 

 much color as an equal weight of uric acid. 



Nephelometric Methods 



The Nephelometer. The nephelometer is an instrument for 

 measuring the density of precipitates and thus determining the amount 

 of any substance which can be obtained in the form of a suitable 

 suspension. It is somewhat similar in form and principle to a color- 

 'imeter. It differs from the latter in that the light which reaches the 

 eye is not transmitted light, which, on the contrary, is excluded, but 

 light reflected from the particles of the suspension. The brightness 

 of the two fields is compared instead of their colors. It is adapted 

 particularly for the determination of substances that in very dilute 

 solution may be precipitated in the form of suspensions which do not 

 agglutinate appreciably in the time required for making readings 

 (10-20 minutes). The method has been adapted to the determination 

 of proteins in digestion mixtures, milk, urine, etc.; 2 nucleic acids; 3 



1 Folin, Cannon, and Denis: Jour. Biol. Chem., 13, 477, 1913. 



2 Kober: Jour. Biol. Chem., 13, 485, 1913; Jour. Am. Ch. Soc., 35, 1585, 1913; Folin 

 and Denis: Jour. Biol. Chem., 18, 273, 1914. 



3 Kober and Graves: Jour. Am. Chem. Soc., 36, 1304, 1914. 



