URINE 509 



expelled, after which dissolve it in about 10 c.c. of hot water and rinse the solu- 

 tion quantitatively through a plug of cotton or glass wool (to remove all metallic 

 lead) into a 500 c.c. volumetric flask. Add 20-25 c.c. of a saturated picric acid 

 solution and about 7-8 c.c. of a 10 per cent NaOH solution, which contains 5 

 per cent of Rochelle salt. 1 At the end of five minutes fill to the mark with water 

 and read in the colorimeter just as in the case of creatinine (see page 506). 



Calculation. Calculate the creatinine content of the solution in the same 

 manner as given under Creatinine (page 507) . From the value thus obtained sub- 

 tract the value for the creatinine content of the urine before dehydration. The 

 difference will be the creatine content of the original urine in terms of creatinine. 



Interpretation. Creatine occurs only in very small amounts in the 

 urine of normal adults, but is found in larger amounts in that of children 

 (10 to 50 mg. per day). Creatine ingestion in adults has little effect 

 on the urinary excretion. In fasting, the amount is markedly increased 

 (it may amount to 100 mg. or more per day). Creatine also appears 

 in the urine after high water ingestion. It is found in many pathological 

 conditions associated with malnutrition and disintegration of muscular 

 tissue, in fever, etc. Very large amounts have been found in cases of 

 carcinoma of the liver. 



2. Folin-Benedict and Myers Method. 2 To 20 c.c. of urine in a 50 c.c. volu- 

 metric flask, add 20 c.c. of normal hydrochloric acid and place the flask in an auto- 

 clave at a temperature of 117-120 C. for one-half hour. Add distilled water until 

 the volume of the acid-urine mixture is exactly 50 c.c., close the flask by means of 

 a stopper, and shake it thoroughly. Approximately neutralize 25 c.c. of this mix- 

 ture, introduce it into a 500 c.c. volumetric flask and determine its creatinine con- 

 tent according to Folin's Colorimetric Method (see page 506). 



For calculation and interpretation see the foregoing method. 



3. Method of Folin. 3 Water-bath Procedure. Heat 10 c.c. of urine with 5 c.c. 

 of normal hydrochloric acid on the boiling water-bath or at 9oC. for three hours. 

 The creatine is transformed into creatinine. Some darkening takes place but this 

 does not interfere because of the subsequent dilution. The mixture is made up to 

 50 c.c., 25 c.c. of this is taken, neutralized, and creatinine plus creatine determined 

 just as in the case of creatinine alone. The creatine is obtained by difference. 

 This procedure may be used for diabetic urines which is not the case with the auto- 

 clave procedure nor with the Benedict modification. It is perhaps not quite so 

 accurate as the autoclave procedure. 



4. Microchemical Modification of Folin. 4 By greatly diluting the urine the 

 time required for the conversion of creatine to creatinine is decreased, and picric 

 acid can be substituted for mineral acid. 



Procedure. Enough urine to give 0.7-1.5 mg. of creatinine is measured into 

 a weighed Erlenmeyer Jena flask (capacity 200 c.c.) ; 20 c.c. of saturated picric acid 

 solution, about 130 c.c. of water, and a few very small pebbles to promote even 

 boiling are added and the mixture is gently boiled, preferably over a micro-burner 



1 The Rochelle salt should be present to prevent any formation of turbidity, which 

 otherwise may occur, due to the presence of traces of dissolved lead. 

 - Benedict and Myers: Am. J. Phys., 18, 397, 1907. 



3 Folin: Zeitschr.f. physiol. Chem., 41, 222, 1904. 



4 Folin: Jour. Biol. Chem., 17, 469, 1914. 



