Ethylcellulose Aqueous Dispersion
»Ethylcellulose Aqueous Dispersion is a colloidal dispersion of Ethylcellulose in water.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of Ethylcellulose.It contains suitable amounts of Cetyl Alcohol and Sodium Lauryl Sulfate,which assist in the formation and stabilization of the dispersion.It may contain suitable antifoaming and antimicrobial agents.
Packaging and storage— Preserve in tight containers,and protect from freezing.
Labeling— The labeling states the ethoxy content of the Ethylcellulose and the percentage of Ethylcellulose.
Identification—
A: Transfer a small quantity to a silver chloride plate,and allow the water to evaporate:the IRabsorption spectrum of the residue in the 3600to 2600cm-1and 1500to 800cm-1regions exhibits maxima only at the same wave numbers as that of a film of USP Ethylcellulose RSprepared as directed in the test for Identification underEthylcellulose.
B: Transfer about 2mLto a 100-mm diameter petri dish so that the bottom of the dish is covered uniformly.Place the dish in an oven or on a hot plate to evaporate the water:a transparent film results.
C: Dissolve the film formed in Identificationtest Bin 20mLof chloroform.Inject 2µLof this solution into a gas chromatograph (see Chromatography á621ñ)equipped with a 2-mm ×1.8-m column that contains 10%liquid phase G1on support S1Amaintained at a temperature of 220and a flame-ionization detector.The temperatures of the injection port and the detector are maintained at about 250and 275,respectively.The retention time of the major peak following the solvent peak in the resulting chromatogram corresponds to that obtained from a similar solution of USP Cetyl Alcohol RS.
D: Methylene blue solution—To a 150-mLgraduated beaker containing 0.7mLof sulfuric acid and 5g of anhydrous sodium sulfate slowly add water to the 90-mLmark.Add methylene blue solution (3in 1000)to the 100-mLmark,and mix.
Procedure— To 1mLof Aqueous Dispersion in a 100-mLgraduated mixing cylinder add 9mLof water followed by 25mLof Methylene blue solution,and mix.Add 15mLof chloroform,and shake vigorously.Allow the two phases to separate:the lower phase is blue,indicating the presence of sodium lauryl sulfate.
Viscosity á911ñ— Use a rotational viscosimeter equipped with a low-viscosity adapter.Mix the Aqueous Dispersion,and pipet 20mLof it into the low-viscosity small sample adapter.Start the viscosimeter,and take readings after 60,90,and 120seconds at a temperature of 25±2and at a spindle speed that results in readings between 10%and 90%of full-scale.Multiply the average of the three readings by the factor specified for the spindle speed selected to obtain the viscosity in centipoises.The viscosity is not more than 150centipoises.
pHá791ñ: between 4.0and 7.0.
Loss on drying— Place about 10g of standard 20-to 30-mesh sand,previously dried for at least 30minutes at 60,into a tared petri dish.Add 5mLof Aqueous Dispersion,and again weigh.Dry at about 60to constant weight:it loses not more than 71.0%of its weight.
Organic volatile impurities,Method Vá467ñ: meets the requirements.
Solvent— Use dimethyl sulfoxide.
Assay— Determine the ethoxy content,as directed under Methoxy Determination á431ñ,using an accurately weighed portion of Ethylcellulose Aqueous Dispersion equivalent to about 25mg of ethylcellulose.Calculate the ethylcellulose content from the ethoxy content found and the ethoxy content of the Ethylcellulose as declared in the labeling.Each mLof 0.1Nsodium thiosulfate is equivalent to 0.7510mg of (–OC2H5).
Auxiliary Information— Staff Liaison:Justin Lane,B.S.,Scientific Associate
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3004
Phone Number:1-301-816-8323