Determining Minute Quantities of Nitrogen. 91 



Morphine Test. 

 Blood Sugar. 



Per Cent. 



Time. 



Example I. 



Example II. 



Control Day. 



Test Day. 



Control Day. 



Test Day. 



12.00 



O.180 



O.180 



0.IS6 



O.ISO 



12.30 



O.182 



0.202 



O.132 



0-135 



1. 00 



0.182 



0.2l6 



0.I3S 



O.140 



2.00 



O.176 



0.180 



0.I3S 



0.128 



3-00 



O.180 



O.179 



O.138 



O.123 



162 (1340) 



A method for determining minute quantities of nitrogen in 

 nitrogenous substances. 



By Theodore Kuttner (by invitation). 



[From the Department of Physiological Chemistry, Mt. Sinai 



Hospital.} 



When an alkaline mixture containing phenol and NH 3 or NH 2 

 groups is oxidized by a hypochlorite, a blue-colored solution results. 

 This color is produced in the cold in mixtures of proper concentra- 

 tion, while mixtures of more dilute solutions give no color or only 

 a very faint blue. Upon heating the mixtures, those containing 

 the minutest trace of the above-mentioned groups develop a color, 

 while the color of the more concentrated ones deepens considerably 

 in intensity. The latter varies in direct proportion to the amount 

 of the NH3 and amino acid group present. 



This reaction is made the basis of colorimetric methods for 

 the estimation of incoagulable nitrogen, urea and ammonia nitro- 

 gen in blood, urine and other biological fluids, and for the estima- 

 tion of certain substances containing amino groups such as albu- 

 men, arsphenamin (salvarsan), etc. The estimation is carried out 

 by comparison with a suitable set of standards or in a colorimeter 

 against a known standard. 



In estimating incoagulable nitrogen of the blood, the method 

 briefly is as follows: the proteids are precipitated either by the 

 addition of 2.5 per cent, trichloracetic acid to 10 times the volume 



