Low-Substituted Hydroxypropyl Cellulose [9004-64-2]

This product is low-substituted 2-hydroxypropyl ether cellulose. It is prepared by alkalization of cellulose followed by etherification with propylene oxide under high temperature conditions, then neutralization, recrystallization, washing, drying, crushing, and sieving. Calculated on the dried basis, it contains 5.0% to 16.0% of hydroxypropoxy groups (—OCH?CHOHCH?).     

【Characteristics】This product is a white or almost white powder; odorless, tasteless.

Loss on drying  When dried at 105°C to constant weight, the loss in weight is not more than 8.0% (General Chapter 0831). Residue on ignition  Take 1.0g of the product, carry out the test as directed (General Chapter 0841); the residue is not more than 1.0%. Heavy metals  Using the residue obtained in the test for Residue on ignition, carry out the test as directed (General Chapter 0821, Method II); the content of heavy metals is not more than 20 parts per million.

 Iron salts  Take 1.0g of the product, ignite as directed under Residue on ignition, add 5ml of hydrochloric acid to the residue, heat on a water bath to dissolve, add water to make 25ml, and mix well; take 5.0ml, carry out the test as directed (General Chapter 0807); the color produced is not deeper than that of a control solution prepared with 2.0ml of standard iron solution (0.010%).     Arsenic salts  Take 1.0g of the product, add 1.0g of calcium hydroxide, mix, add a small amount of water, stir evenly, dry, then heat gently to carbonize, and ignite at 500–600°C until completely ashed. Allow to cool, add 8ml of hydrochloric acid and 23ml of water, carry out the test as directed (General Chapter 0822, Method I); it complies with the requirement (0.0002%).    

【Assay】  Hydroxypropoxy  Determine as directed under the test for Methoxy, Ethoxy, and Hydroxypropoxy Groups (General Chapter 0712). If the second method (volumetric method) is used, take about 0.1g of the product, accurately weighed, and determine as directed. 

【Category】Pharmaceutical excipient, disintegrant, and filler.

【Storage】Preserve in a tightly closed container.