Cetrimonium Bromide
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Hexadecyltrimethylammonium bromide [57-09-0].
»Cetrimonium Bromide contains not less than 96.0percent and not more than 101.0percent of hexadecyltrimethylammonium bromide,calculated as C19H42BrN,on the dried basis.
Packaging and storage—
Preserve in well-closed containers.Store at room temperature,and avoid excessive heat and freezing.Protect from moisture.
USP Reference standards á11ñ—
USP Cetrimonium Bromide RS.
Appearance of solution—
Transfer 2.0g of Cetrimonium Bromide to a 100-mLflask,dissolve in and dilute with previously boiled and cooled water to volume:the solution is clear and colorless.
Identification—
A:
Transfer 250mg of it to a 25-mLvolumetric flask,and dissolve in and dilute with alcohol to volume.Determine the absorbance in a 1-cm cell with a suitable spectrophotometer,after correcting for the blank:between 260nm and 280nm,the absorbance is not greater than 0.05.
B:
Dissolve about 5mg of it in 5mLof phosphate buffer pH8.0.Add a strip of methyl green–iodomercurate paper.After 5minutes,the solution shows a more intense greenish-blue color than a blank solution prepared at the same time in the same manner.
C:
Transfer 2.0g of it to a 100-mLflask,dissolve in and dilute with previously boiled and cooled water to volume:the solution froths copiously when shaken.
D:
Thin-Layer Chromatographic Identification Test á201ñ.
Test solution:
a solution in water containing about 20mg of Cetrimonium Bromide per mL.
Sodium acetate solution—
Transfer 135g of sodium acetate trihydrate to a 500-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.
Developing solvent:
a mixture of acetone,Sodium acetate solution,and methanol (20:35:45).
Procedure—
Proceed as directed in the chapter.Remove the plate from the developing chamber,and dry the plate in a current of hot air.Allow to cool.Expose the plate to iodine vapor,and examine in daylight:the principal spot obtained from theTest solution is similar in position,color,and size to that obtained from the Standard solution.
E:
Asolution of it meets the requirements of the tests forBromide á191ñ.
Microbial limits á61ñ—
The total aerobic microbial count is not more than 1000cfu per g.The total combined molds and yeasts count is not more than 10cfu per g.
Acidity or alkalinity—
To 50mLof the solution obtained in the Appearance of solutiontest add 0.1mLof bromocresol purple TS.Not more than 0.1mLof 0.1Nsodium hydroxide or 0.1Nhydrochloric acid is required to change the color of the indicator.
Loss on drying á731ñ—
Dry about 1.0g of it at 105
for 2hours:it loses not more than 2.0%of its weight.
for 2hours:it loses not more than 2.0%of its weight.
Residue on ignition á281ñ:
not more than 0.5%,determined on 1.0g.
Limit of amines and amine salts—
Dissolve 5.0g of Cetrimonium Bromide in 30mLof a mixture of 1Nhydrochloric acid VSand methanol (1:99,v/v),and add 100mLof isopropyl alcohol.Pass a stream of nitrogen slowly through the solution.Gradually add 15.0mLof 0.1Ntetrabutylammonium hydroxide VS,recording the potentiometric titration curve.If the curve shows two inflection points,the volume of titrant added between the two points is not greater than 2.0mL.
Assay—
Transfer 2.0g of Cetrimonium Bromide,accurately weighed,to a 100-mLvolumetric flask,and dissolve in and dilute with water to volume.Transfer 25.0mLof this solution to a separatory funnel,and add 25mLof chloroform,10mLof 0.1Nsodium hydroxide VS,and 10.0mLof a freshly prepared solution of potassium iodide (1in 20).Shake well,allow to separate,and discard the chloroform layer.Wash the aqueous layer with three 10-mLportions of chloroform,and discard the washings.Transfer the aqueous layer to a stoppered conical flask,add 40mLof hydrochloric acid,allow to cool,and titrate with 0.05Mpotassium iodate VSuntil the deep brown color is almost discharged.Add 2mLof chloroform,and continue the titration,shaking vigorously,until the color of the chloroform layer no longer changes.Perform a blank titration on a mixture of 10.0mLof a freshly prepared solution of potassium iodide (1in 20),20mLof water,and 40mLof hydrochloric acid,and make any necessary correction.Each mLof 0.05Mpotassium iodate is equivalent to 36.45mg of Cetrimonium Bromide (C19H42BrN).
Auxiliary Information—
Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 2985
Pharmacopeial Forum:Volume No.30(3)Page 970
Phone Number:1-301-816-8251