ACETOACETIC ACID. 0-OXYBUTYRIC ACID. 825 



Detection' of Acetone and Acetoacetic Add in the Urine. Before test- 

 ing for acetone test for acetoacetic acid; as this acid gradually decom- 

 poses on allowing the urine to stand, the specimen must be as fresh as 

 possible. In the presence of acetoacetic acid the urine gives the above- 

 mentioned tests. In testing for acetone in the presence of acetoacetic 

 acid make the urine slightly alkaline and shake in a separatory funnel 

 with ether free from alcohol and acetone. Remove the ether and shake 

 it with water, which takes up the acetone, and test for acetone in the 

 watery solution. 



In the absence of acetoacetic acid the acetone may be tested for 

 directly in the urine; this may be done by FROMMER'S test or LEGAL'S 

 test. These tests, which are only approximate, are of value only when 

 the urine contains a considerable amount of acetone. 



For a more accurate test we distill at least 250 cc. of the urine faintly acidified 

 with sulphuric acid, care being taken to have a good condensation. Most of the 

 acetone is contained in the first 10-20 cc. of the distillate. A better result may 

 be obtained by distilling a large quantity of urine until about TO has been dis- 

 tilled off, acidify the distillate with hydrochloric acid, redistill and repeat this 

 .several times, collecting the first portion of each distillation. The final distillate 

 is used for the above reactions. 1 SALKOWSKI and BORCHARDT have called attention 

 to the fact that in the distillation of an acidified urine containing sugar for the 

 detection or estimation of acetone, a substance giving iodoform can be formed 

 from the sugar if the distillation is carried too far. According to BORCHARDT 2 

 the urine must therefore first be diluted with water, or the concentration prevented 

 by the addition of water dropAvise during distillation. 



The quantitative estimation of acetone (also that formed from the 

 acetoacetic acid) is done by distilling the urine after the addition of acetic 

 acid or a little sulphuric acid. The quantity of acetone in the distillate 

 can be determined, according to the HUPPERT-MESSINGER method, by 

 converting it into iodoform by means of potassium iodide and then titrat- 

 ing the quantity of iodine used in the formation of the iodoform. The 

 precipitation of the acetone as p-nitrophenylhydrazone-acetone by means 

 of p-nitrophenylhydrazine in acetic acid solution can also be used for 

 determining the acetone in the distillate (v. EKENSTEIN and BLANKSMA 

 and MOLLER). In regard to these methods we refer to. 3 EMBDEN and 

 SCHLIEP and FoLiN 4 have suggested methods for determining the quan- 

 tity of acetone and acetoacetic acid separately. In regard to these 

 estimations we must refer to the work of EMBDEN and ScHMiTz. 5 



/3-Oxybutyric Acid, C 4 H 8 03, = CH3.CH(OH).CH2.COOH, ordinarily 

 forms an odorless syrup, but may also be obtained as crystals. It is readily 

 soluble in water, alcohol, and ether. It is levorotatory ; (a)^ 24.12 



1 See also Salkowski, Pfliiger's Arch., 56. 



2 Hofmeister's Beitrage, 8. 



3 Hoppe-Seyler, Thierfelder, 8. Aufl., 617 and 618. 



4 Embden and Schliep, Centralbl. f. d. ges. Phys. u. Path. d. Stoffwechsel, 1907; 

 Folin, Journ. of biol. Chem., 3. In regard to the quantitative estimation of acetone 

 see also O. Sammet, Zeitschr. f. physiol. Chem., 83. 



6 Abderhalden's Handbuch der biochemischen Arbeitsmethoden, Bd. 3. 



