Packaging and storage—
Preserve in well-closed containers. No storage requirements specified.
Identification—
A:
Dissolve 1.4 g of Sorbitol Solution in 75 mL of water. Transfer 3 mL of this solution to a 15-cm test tube, add 3 mL of freshly prepared catechol solution (1 in 10), mix, add 6 mL of sulfuric acid, mix again, and gently heat the tube in a flame for about 30 seconds: a deep pink or wine color appears.
B:
The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.
pH 
791
:
between 5.0 and 7.5, in a 14% (w/w) solution of Sorbitol Solution in carbon dioxide-free water.
Residue on ignition 281:
not more than 0.1%, calculated on the anhydrous basis, determined on a 2-g portion, accurately weighed.
Reducing sugars—
To an amount of Sorbitol Solution, equivalent to 3.3 g on the anhydrous basis, add 3 mL of water, 20.0 mL of cupric citrate TS, and a few glass beads. Heat so that boiling begins after 4 minutes, and maintain boiling for 3 minutes. Cool rapidly, and add 40 mL of diluted acetic acid, 60 mL of water, and 20.0 mL of 0.05 N iodine VS. With continuous shaking, add 25 mL of a mixture of 6 mL of hydrochloric acid and 94 mL of water. When the precipitate has dissolved, titrate the excess of iodine with 0.05 N sodium thiosulfate VS using 2 mL of starch TS, added towards the end of the titration, as an indicator. Not less than 12.8 mL of 0.05 N sodium thiosulfate VS is required, corresponding to not more than 0.3% of reducing sugars, on the anhydrous basis, as glucose. The amount determined in this test is not included in the calculated amount under Other Impurities.
Limit of nickel—
Test solution—
Dissolve 20.0 g of Sorbitol Solution in diluted acetic acid, and dilute with diluted acetic acid to 100.0 mL. Add 2.0 mL of a saturated ammonium pyrrolidine dithiocarbamate solution (containing about 10 g of ammonium pyrrolidine dithiocarbamate per L) and 10.0 mL of methyl isobutyl ketone, and shake for 30 seconds. Protect from bright light. Allow the two layers to separate, and use the methyl isobutyl ketone layer.
Blank solution—
Prepare as directed for Test solution, except to omit the use of the Sorbitol Solution.
Standard solutions—
Prepare as directed for Test solution, except to prepare three solutions by adding 0.5 mL, 1.0 mL, and 1.5 mL of nickel standard solution TS.
Procedure—
Set the instrument to zero using the
Blank solution. Concomitantly determine the absorbances of the
Standard solutions and the
Test solution at least three times each, at the wavelength of maximum absorbance at 232.0 nm, with a suitable atomic absorption spectrophotometer (see
Spectrophotometry and Light-Scattering 851) equipped with a nickel hollow-cathode lamp and an air–acetylene flame. Record the average of the steady readings for each of the
Standard solutions and the
Test solution. Between each measurement, aspirate the
Blank solution, and ascertain that the reading returns to zero. Plot the absorbances of the
Standard solutions and the
Test solution versus the added quantity of nickel. Extrapolate the line joining the points on the graph until it meets the concentration axis. The distance between this point and the intersection of the axes represents the concentration of nickel in the
Test solution. Not more than 1 µg per g, calculated on the anhydrous basis, is found.
Assay—
Mobile phase, Resolution solution, Standard preparation, and Chromatographic system—
Proceed as directed in the
Assay under
Sorbitol.
Assay preparation—
Accurately weigh about 0.12 g of Sorbitol Solution, dissolve in and dilute with water to about 20 g. Accurately record the final solution weight, and mix thoroughly.
Procedure—
Proceed as directed in the
Assay under
Sorbitol. Calculate the percentage of
D-sorbitol (C
6H
14O
6) in the portion of Sorbitol Solution taken by the formula:
100(CS / CU)(rU / rS),
in which
CS is the concentration, in mg per g, of
USP Sorbitol RS in the
Standard preparation; CU is the concentration, in mg per g, of Sorbitol Solution in the
Assay preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
