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ACETOACETIC ACID. (9-OXYBUTYRIC ACID. 825
Detection of Acetone and Acetoacetic Acid 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 \vc 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 tV 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 lie diluted with water, or the concentration prevented
by the addition of water dropwise 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
0-Oxybutyric Acid, C
,
4H8 U3 ,
= CH? .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) D =— 24.12°
1
See also Salkowski, Pfluger’s Arch., 56.
* Hofmeister’s Beitnige, 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 0. Sammet, Zeitschr. f. physiol. Chem., 83.
8
Abderhalden’s Handbuch der biochemischen Arbeitsmethoden, Bd. 3.
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