URINE 545 



contains the phenols from one-half the amount of urine analyzed. The actual 

 determination of phenols, both free and total, is made upon a twc -fifths portion 

 of this filtrate and this amount of filtrate contains the phenols from one -fifth 

 of the amount of urine analyzed. In the determination of free phenols the colored 

 solution is diluted to only half that of the standard while in the determination 

 of total phenols the dilution is the same as that of the standard. 

 Hence, 



RI 



= milligrams of free phenol 



R 2 X4 

 and 



R 2 X2 



= milligrams of total phenol 



in 2 c.c. or 4 c.c. of urine according to whether 10 c.c. or 20 c.c. of urine was 

 taken for analysis, when RI is taken as the reading obtained with the standard 

 solution, and R 2 is taken as the reading obtained with the unknown. 



Interpretation. By this method total phenol excretions of from 

 0.2-0.5 gram per day have been noted in normal individuals. These 

 results are much higher than figures previously obtained by other 

 methods. The free phenols varied from 0.1-0.3 gram per day. The 

 total phenol excretion appears to vary directly but not proportionately 

 with the protein intake. The amount of conjugated phenol indicates 

 the extent to which the phenols have been detoxicated. The excretion 

 of phenols is increased in gastro-intestinal disorders associated with 

 increased putrefaction. It is increased by the ingestion of phenols or 

 of benzene. 



Oxalic Acid 



SalkowsW-Autenrieth and Barth Method. Principle. The oxalic acid is pre- 

 cipitated by means of CaCl 2 . From the solution of this precipitate in hydrochloric 

 acid the oxalic acid is extracted with ether and reprecipitated as calcium oxalate. 



Procedure. Place the 24-hour urine specimen in a precipitating jar, add an 

 excess of calcium chloride, render the urine strongly ammoniacal, stir it well, and 

 allow it to stand 18-20 hours. Filter off the precipitate, wash it with a small 

 amount of water and dissolve it in about 30 c.c. of a hot 15 per cent solution of 

 hydrochloric acid. By means of a separatory funnel extract the solution with 150 

 c.c. of ether which contains 3 per cent of alcohol, repeating the extraction four or 

 five times with fresh portions of ether. Unite the ethereal extracts, allow them to 

 stand for an hour in a flask, and then filter through a dry filter paper. Add 5 c.c. 

 of water to the nitrate, to prevent the formation of diethyl oxalate when the solu- 

 tion is heated, and distil off the ether. If necessary, decolorize the liquid with 

 animal charcoal and filter. Concentrate the filtrate to 3-5 c.c., add a little calcium 

 chloride solution, make it ammoniacal, and after a few minutes render it slightly 

 acid with acetic acid. Allow the acidified solution to stand several hours, collect 

 35 



