D-Xylose
C5H10O5
Mol. Wt. 150.13
D-xylose
〔58-86-6〕
Content
D-Xylose,
when dried, contains 98.0−101.0% of D-xylose (C5H10O5).
D-Xylose
Description
occurs as colorless to white crystals or as a white crystalline
powder. It is odorless and has a sweet taste.
Identification
(1)
Add 2−3 drops of D-Xylose solution (1 → 20) to 5 ml of
boiling Fehling's TS. A red precipitate is formed.
(2)
Dissolve 1 g of
D-Xylose
in 25 ml of freshly boiled and cooled water. The
solution is dextrorotatory.
(3)
To 1 g of D-Xylose, add 3 ml of water, dissolve while warming, add 3 ml of a
mixture of diluted hydrochloric acid (1 → 3) and a solution of diphenylamine in
ethanol (1 → 40) (5 : 2), and heat in a water bath for 5 minutes. A yellow to light
orange color develops.
(4)
Dissolve 0.5 g of
D-Xylose
in 20 ml of water, add 30 ml of phenylhydrazine
hydrochloride−sodium acetate TS and 10 ml of diluted acetic acid (1 → 20), heat in a
water bath for about 2 hours to form a precipitate, and recrystallize the precipitate
from water. The melting point is 160−163℃.
Purity
(1)
Clarity and color of solution
Colorless, almost clear (4.0 g, water 20
ml).
(2)
Free acid
Weigh 1.0 g of
D-Xylose,
dissolve in 10 ml of freshly boiled and
cooled water, add 1 drop of phenolphthalein TS, and add 1 drop of 0.2 mol/l sodium
hydroxide. The color of the solution is pink.
(3)
Sulfate
Not more than 0.005% as SO4.
Test Solution Weigh 1.0 g of D-Xylose, and dissolve in 30 ml of water.
Control Solution 0.10 ml of 0.005 mol/l sulfuric acid.
(4)
Heavy metals
Not more than 10 µg/g as Pb (2.0 g, Method 1, Control
solution Lead Standard Solution 2.0 ml).
(5)
Arsenic
Not more than 4.0 µg/g as As2O3 (0.50 g, Method 1, Apparatus B).
(6)
Other saccharide
Weigh 0.5 g of
D-Xylose,
and dissolve in water to make
1,000 ml. Use this solution as the test solution. Measure 0.1 ml of the test solution, and
perform Paper Chromatography, using a n-butanol−pyridine−water mixture (6 : 4 : 3)
as the developing solvent, without a control solution. Only one pink spot is observed.
For the filter paper, use a No. 2 filter paper for chromatography. Stop the development
when the solvent front rises about 15 cm above the point where the test solution was
applied, and mark the position of the front. Air-dry the filter paper, develop with the
same developing solvent, and stop the development when the solvent front reaches the
point marked above. Repeat the procedure once more, spray with a color reagent, dry
at 100−125℃ for 5 minutes, and observe from above in daylight. Prepare the color
reagent as follows: Weigh 0.93 g of aniline and 1.66 g of phthalic anhydride, and
dissolve in 100 ml of water saturated n-butanol.
Loss on Drying
Not more than 1.0% (105℃, 3 hours).
Residue on Ignition
Assay
Not more than 0.05% (5 g).
Weigh accurately about 1 g of D-Xylose, previously dried, dissolve in water
to make exactly 500 ml, measure exactly 10 ml of this solution, transfer into a flask
with a ground-glass stopper, add 50 ml of sodium metaperiodate solution (1 → 400),
exactly measured, add 1 ml of sulfuric acid, and heat in a water bath for 15 minutes.
After cooling, add 2.5 g of potassium iodide, shake well, allow to stand in a dark and
cold place for 15 minutes, and titrate with 0.1 mol/l sodium thiosulfate (indicator:
starch TS). Perform a blank test in the same manner, and make any necessary
correction.
1 ml of 0.1 mol/l sodium thiosulfate = 1.8766 mg of C5H10O5