URINE 553 



compound. Glucose and certain other interfering substances are re- 

 moved by precipitation with copper sulphate and calcium hydroxide. 

 Preservatives other than toluene or copper sulphate should not be used. 



Procedure. Removal of Glucose and other Interfering Substances from 

 Urine. 



Place 25 c.c. of urine in a 250 c.c. measuring flask. Add 100 c.c. of water, 

 50 c.c. of copper sulphate solution l and mix. Then add 50 c.c. of 10 per cent 

 calcium hydroxide suspension, shake, and test with litmus. If not alkaline, add 

 -nore calcium hydroxide. Dilute to the mark and let stand at least one-half 

 hour for glucose to precipitate. Filter through a dry folded filter. This procedure 

 will remove up to 8 per cent of glucose. Urine containing more should be diluted 

 enough to bring the glucose down to 8 per cent. The copper treatment is de- 

 pended upon to remove interfering substances other than glucose, and should 

 therefore never be omitted, even when glucose is absent. The filtrate may be 

 tested for glucose by boiling a little in a test-tube. A precipitate of yellow 

 cuprous oxide will be obtained if the removal has not been complete. A slight 

 precipitate of white calcium salts always forms, buJt does not interfere with the 

 detection of the yellow cuprous oxide. 



Determination of Total Acetone Bodies (Acetone, Acetoacetic Acid, and 

 /3-hydroxybutyric Acid.) Place in a 500 c.c. Erlenmeyer flask 25 c.c. of urine 

 filtrate. Add 100 c.c. of water, 10 c.c. of 50 per cent sulphuric acid, and 35 

 c.c. of the 10 per cent mercuric sulphate. Or hi place of adding the water and 

 reagents separately, add 145 c.c. of the "combined reagents." Connect the flask 

 with a reflux condenser having a straight condensing tube of 8 or 10 mm. dia- 

 meter and heat to boiling. After boiling has begun, add 5 c.c. of the 5 per cent 

 dichromate through the condenser tube. Continue boiling gently 11/2 hours. 

 The yellow precipitate which forms consists of the mercury sulphate-chromate 

 compound 2 of the preformed acetone, and the acetone which has been formed 

 by decomposition of acetoacetic acid and by oxidation of the 0-hydroxybutyric 

 acid. It is collected in a Gooch or "medium density" alundum crucible, washed 

 with 200* c.c. of cold water, and dried for an hour at 110. The crucible is 

 allowed to cool in room ah* (a desiccator is unnecessary and undesirable) and 

 weighed. Several precipitates may be collected, one above the other, without 

 cleaning the crucible. As an alternative to weighing, the precipitate may be dis- 

 solved and titrated as described below. 



Determination of Acetone and Acetoacetic Acid. The acetone plus the 

 acetoacetic acid, which completely decomposes into acetone and CO 2 on heat- 



1 Solutions Required. 20 per cent copper sulphate 200 grams of CuSO^sHjO dissolved 

 in water and made up to i liter. 



10 per cent mercuric sulphate 73 grams of pure red mercuric oxide dissolved in i 

 liter of H 2 SO4 of 4 N. concentration. 



50 volume per cent sulphuric acid 500 c.c. of sulphuric acid of 1.83 5 specific gravity, 

 diluted to i liter with water. Concentration of H 2 SO4 must be readjusted if necessary 

 to make it 17.0 N by titration. 



10 per cent calcium hydroxide suspension mix 100 grams of Merck's fine light "rea- 

 gent" Ca(OH) 2 with i liter of water. 



5 per cent potassium dichromate 50 grams K 2 Cr 2 O7 dissolved in water and made 

 up to i liter. 



Combined reagents for total acetone body determination i liter of the above 50 

 per cent sulphuric acid, 3.5 liters of the mercuric sulphate, 10 liters of water. 



*This contains about 77 per cent mercury and in the absence of chromate has approximately 

 one of the following formulas: 3HgSO 4 .5HgO.2(CH,) 2 CO or 



