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$14 URINE.
ment and with sufficient practice very exact results can be obtained by
this method. The value of this procedure consists in the rapidity with
which the determination can be made. In using instruments specially
constructed for clinical purposes the accuracy is less than with the less
expensive fermentation test. Under such circumstances, and as the
estimation by means of polarization can be performed with exactitude
only by specially trained chemists, it is hardly worth while to give this
method in detail, and the reader is referred to handbooks for hints in the
use of the apparatus.
Hasselbach and Lindhard 1
have recently suggested a method for the
quantitative estimation of sugar which is based on the decolorization of an alkaline
safranin solution in the presence of sugar.
Fructose (levulose). Levogyrate urines containing sugar have been
noted by several investigators, although the nature of the sugar was not
well known to the earlier observers. In recent years several positively
authentic cases of levulosuria have been described, and also cases of
diabetes have been found where fructose exists in the urine besides glucose.
Reports on this subject do not agree, however.2
Fructose may be detected as follows: The urine is levorotatory, and
the levorotatory substance ferments with yeast. The urine gives the
ordinary reduction tests and the ordinary phenylglucosazone. With
methylphenylhydrazine it gives the characteristic fructose methyl-
phenylosazone, and it also gives Seliwanoff’s reaction on heating
after the addition of an equal volume of hydrochloric acid and a little
resorcin. With this test it must be remarked that too lengthy or too
strong heating must not be applied, since other carbohydrates may also
give the reaction (see page 218 and the works of Rosin and Umber 3
).
In the presence of fructose a red coloration appears. After cooling it
can be neutralized with soda and shaken out with amyl alcohol, (Rosin)
or with acetic ether (Borchardt). The amyl alcohol removes a red
pigment which gives a band in the spectrum between E and b and on
stronger concentration also a band in the blue at F. The acetic ether
in the presence of fructose becomes yellow, and this is more characteristic
according to Borchardt than Rosin’s method, which has certain
fallacies. The simultaneous presence of nitrites and indican disturbs
the test, and in this case first remove the nitrous acid by boiling the
urine, acidified with acetic acid or hydrochloric acid for one minute. In
order to remove other disturbing pigments, Malfatti suggests the
oxidation of the urine with a little hydrochloric acid and potassium
permanganate. Jolles 4
has suggested a method for detecting fructose
besides glucose by means of a diphenylamine solution.
1
Bioch. Zeitschr., 27.
*See Borchardt, Zeitschr. f. physiol. Chem., 55 and 60; W. Voit, ibid., 58 and 61;
Adler, Pfluger’s Arch., 139.
a
Umber, Salkowski’s Festschrift, Berlin, 1904; Rosin, ibid., and Zeitschr. f.
physiol. Chem., 38.
4
Rosin, 1. c; Borchardt, 1. c; Malfatti, Zeitschr. f. physiol. Chem., 58; Jolles
and Mauthner, Chem. Centralbl., 1910, 1, 483.
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