Cellulose 2-hydroxyethyl methyl ether [9032-42-2].
» Hymetellose is a partly O-(methylated) and O-(2-hydroxyethylated) cellulose.
Packaging and storage— Preserve in well-closed containers. No storage requirements specified.
Labeling— Label it to indicate the viscosity of a solution (1 in 50) at 20.
A: Use the solution prepared in the test for Color of solution. Heat the solution in a water bath while stirring: at a temperature above 50, the solution becomes cloudy or a flocculent precipitate is formed. The solution becomes clear again on cooling.
B: Transfer 1 mL of the solution from Identification test A to a glass plate, and allow the water to evaporate: a thin film is formed.
C: To 10 mL of the solution from Identification test A, add 0.3 mL of 2 N acetic acid and 2.5 mL of tannic acid TS: a yellowish-white, flocculent precipitate is formed that dissolves in ammonia TS.
D: In a test tube about 160-mm long, thoroughly mix 1 g of Hymetellose with 2 g of finely powdered manganese sulfate. Introduce, to a depth of 2 cm into the upper part of the tube, a strip of filter paper impregnated with a freshly prepared Diethanolamine–sodium nitroprusside solution. Insert the tube 8 cm into a silicone-oil bath at 190 to 200. The filter paper becomes blue within 10 minutes. Perform a blank test.
Diethanolamine–sodium nitroprusside solution— Prepare a sodium nitroprusside solution (1 in 20) and adjust with 1 N hydrochloric acid to a pH of 9.8. Mix 11 mL of this solution with 1 mL of a diethanolamine solution (1 in 5) in water.
E: Dissolve 0.2 g of Hymetellose completely, without heating, in 15 mL of 70% sulfuric acid. Pour the solution while stirring into 100 mL of ice water, and dilute with ice water to 250 mL. Transfer 1 mL of this solution to a test tube, and while cooling in ice water, add dropwise 8 mL of sulfuric acid, and mix thoroughly. Heat in a water bath for exactly 3 minutes, and immediately cool in ice water. While the mixture is cold, carefully add 0.6 mL of ninhydrin TS, and mix well. Allow to stand at 25: a pink color is produced immediately and does not become violet within 100 minutes.
Color of solution— While stirring, add a portion equivalent to 1.0 g of the dried Hymetellose to 50 g of carbon dioxide-free water heated to 90. Allow to cool, adjust the weight of the solution to 100 g with carbon dioxide-free water, and stir until dissolution is complete. This solution is not more intensely colored than a solution prepared immediately before use by mixing 2.4 mL of ferric chloride CS and 0.6 mL of cobaltous chloride CS with Diluent to make 10 mL, and diluting 5 mL of this solution with Diluent to make 100 mL. Make the comparison by viewing the substance and the solution downward in matched color-comparison tubes against a white surface (see Color and Achromicity 631).
Diluent— Dilute 27.5 mL of hydrochloric acid to 1000 mL with water.
Clarity of solution—
Hydrazine sulfate solution— Transfer 1.0 g of hydrazine sulfate to a 100-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Allow to stand for 4 to 6 hours before use. [Caution—Hydrazine sulfate is highly toxic. Avoid skin contact. ]
Methenamine solution— Transfer 2.5 g of methenamine to a 100-mL glass-stoppered flask, add 25.0 mL of water, insert the glass stopper, and mix to dissolve.
Primary opalescent mixture— [note—This suspension is stable for 2 months. Mix before use, and do not use if it adheres to the container.] To the flask containing Methenamine solution, add 25.0 mL of Hydrazine sulfate solution, mix, and allow to stand for 24 hours.
Opalescence standard— [note—Use this suspension within 24 hours after preparation.] Transfer 15.0 mL of the Primary opalescent mixture to a 1000-mL volumetric flask, dilute with water to volume, and mix.
Reference suspension— Transfer 30.0 mL of the Opalescence standard to a 100-mL volumetric flask, dilute with water to volume, and mix.
Test solution— Use the solution from the test for Color of solution.
Procedure— Transfer a sufficient portion of the Test solution to a test tube of colorless, transparent, neutral glass with a flat base and an internal diameter of 15 to 25 mm to obtain a depth of 40 mm. Similarly transfer a portion of the Reference suspension to a separate matching test tube. Compare the Test solution and the Reference suspension in diffused daylight, viewing vertically against a black background (see Visual Comparison under Spectrophotometry and Light-Scattering 851). [note—The Test solution is to be compared to the Reference suspension five minutes after preparation of the Reference suspension.] The Test solution is not more opalescent than the Reference suspension.
Viscosity 911 While stirring, add a portion equivalent to 6.0 g of the dried Hymetellose to 150 g of carbon dioxide-free water heated to 90. Stir with a propeller-type stirrer for 10 minutes, place the flask in a bath of ice water, continue the stirring, and allow to remain in the bath of ice water for 40 minutes to ensure that dissolution is complete. Adjust the mass of the solution to 300 g, and centrifuge the solution to expel any entrapped air. Adjust the temperature of the solution to 20 ± 0.1, and determine the viscosity using a rotational viscosimeter with a shear rate of 10 per second: the apparent viscosity is not less than 75% and not more than 140% of the value stated on the label.
pH 791 Use the solution from the test for Color of solution: the pH is between 5.5 and 8.0.
Loss on drying 731 Dry about 1.0 g of Hymetellose at 105 to constant weight: it loses not more than 10.0% of its weight.
Residue on ignition 281: not more than 1.0%, determined on 1.0 g.
Chloride 221 Dilute 1.0 mL of the solution from the Color of solution test with water to 20 mL, and add 1 mL of nitric acid and 1 mL of silver nitrate TS. Mix, allow to stand for 5 minutes protected from direct sunlight, and compare the turbidity, if any, with that produced from a 10-mL aliquot of a control (prepared by diluting 0.71 mL of 0.020 N hydrochloric acid to 100 mL) in an equal volume of total solution containing the quantities of reagents used in the test (see Visual Comparison in the section Procedure under Spectrophotometry and Light-Scattering 851): any turbidity produced by the test specimen does not exceed that of the control preparation (0.5%).
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Monograph Hong Wang, Ph.D.
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