ON A RAPID CLINICAL METHOD FOR DETERMINING THE 

 AMMONIA COEFFICIENT OF URINES. 



Raymond F. Bacon. 

 (From the Chemical Laboratory, Bureau of Science.) 



The ammonia coefficient of a urine is a number corresponding to the 

 percentage of the total nitrogen which is present as ammonia or am- 

 monium salts. The normal urine of adult human beings has an am- 

 monia coefficient of 4.1 to 4.64 per cent. This amount may increase in 

 various pathologic conditions until half of the nitrogen in the urine is 

 excreted as ammonia and ammonium salts. Such a condition indicates 

 very serious disturbances in the metabolism of the patient. 



The present methods of determining ammonia in the urine are 

 quite tedious; they require a rather long process and considerable 

 apparatus. The usual method employed is the distillation of the urine 

 vrith a mild alkali (magnesia, sodium carbonate, etc.), the evolved 

 ammonia being absorbed in standard acid and the amount determined 

 by simple titration. The total nitrogen is estimated by the Kjeldahl 

 method or less accurately from a determination of the urea in the urine 

 by decomposition with an alkaline hypobromite. A certain amount of 

 urea is always decomposed by the alkali in the distillation method; this 

 entails the appplication of a correction to the resiilts as obtained by the 

 above process. The value of this correction is usually determined, after 

 the ammonia has been distilled in the manner given above, by adding 

 sufficient water to the liquid to bring it up to the original volume, and 

 redistilling under the same conditions and for the same length of time. 

 If the distillation is carried oiit in vacuo to avoid the decomposition of 

 urea by alkalies, great trouble is often experienced because of the foaming 

 of the urine. It is absolutely impossible to distill some albuminous urines 

 in vacuo because of the foaming of the alkaline liquids. The method 

 which I propose is sufficiently accurate for clinical purposes, requires 

 no elaborate apparatus, the actual manipulation requires about three 

 minutes and the whole determination is finished in about thirty minutes. 

 I propose to determine the ratio of ammonia to urea plus ammonia ; this, 

 for clinical purposes, represents a sufficiently close approximation to the 

 true ammonia coefficient. The method does not result in a high degree of 



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