Ammonio Methacrylate Copolymer
»Ammonio Methacrylate Copolymer is a fully polymerized copolymer of acrylic and methacrylic acid esters with a low content of quaternary ammonium groups.The assay requirements differ for the two types as set forth in the accompanying table.
Ammonio methacrylate units,
dried basis (%)
Type Min. Max.
A 8.85 11.96
B 4.48 6.77
Packaging and storage— Preserve in tight containers at a temperature not exceeding 30.
Labeling— Label it to state whether it is Type Aor Type B.
Identification—
B: Pour a few mLof the solution prepared for the Viscositytest onto a polytef sheet,and allow the solvent to evaporate:a clear film results.
Viscosity á911ñ— Place 52.5g of isopropyl alcohol and 35.0g of acetone in a conical flask having a ground-glass joint.Add a quantity of Ammonio Methacrylate Copolymer,accurately weighed and equivalent to 12.5g of solids on a dried basis,while stirring until the polymer has dissolved completely.Equip a suitable rotational viscosimeter with an adapter system consisting of a measuring cylinder and a spindle.The measuring cylinder has an internal diameter of 2.762cm and a depth of 13.50cm;the spindle is 2.515cm in diameter,9.074cm in height,and has a shaft 0.40cm in diameter.Transfer 16mLof the solution into the measuring cylinder,and adjust the temperature of the solution and the adapter to 20±0.1.With the spindle rotating at 30rpm,immediately observe and record the scale reading.Convert the scale reading to centipoises by multiplying the reading by the constant for the viscosimeter,adapter system,and speed employed.The viscosity is not more than 15centipoises.
Loss on drying á731ñ— Dry it in vacuum at 80for 5hours:it loses not more than 3.0%of its weight.
Residue on ignition á281ñ: not more than 0.1%.
Limit of monomers—
Sodium perchlorate solution— Dissolve 3.5g of sodium perchlorate (NaClO4·H2O)in 100mLof water.
Mobile phase— Dilute phosphoric acid with water to obtain a solution having a pHof 2.0.Mix four volumes of this solution with one volume of methanol,filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography).
Standard solution— Dissolve 80mg of ethyl acrylate and 10mg of methyl methacrylate in 50mLof methanol.
Standard preparation— Dilute 1mLof the Standard solution with methanol to 100mL.Add 10mLof this solution to 5mLof Sodium perchlorate solution.
Test preparation— Dissolve 5g of Ammonio Methacrylate Copolymerin methanol,and dilute with the same solvent to 50mL.Add 5mLof Sodium perchlorate solution dropwise to 10mLof this solution while continuously stirring.Remove the precipitated polymer by centrifugation.Use the clear supernatant.
Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 202-nm detector and a 4.6-mm ×12-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the resolution,R,of the pair of analytes is not less than 1.0,and the relative standard deviation for replicate injections is not more than 2.0%for each analyte.
Procedure— Separately inject equal volumes (about 50µL)of the Standard preparationand the Test preparation into the chromatograph,record the chromatograms,and measure the responses for the major peaks.The capacity factors,k¢,for ethyl acrylate and methyl methacrylate are about 9.8and 11.3,respectively.Calculate the quantity,in mg,of ethyl acrylate in the portion of Ammonio Methacrylate Copolymer taken by the formula:
0.8(rU/rS),
in which rUand rSare the peak responses of ethyl acrylate obtained from the Test preparationand the Standard preparation,respectively.Calculate the quantity,in mg,of methyl methacrylate in the portion of Ammonio Methacrylate Copolymertaken by the formula:
0.1(rU/rS),
in which rUand rSare the peak responses of methyl methacrylate obtained from the Test preparationand the Standard preparation,respectively.Not more than 0.005%of methyl methacrylate and not more than 0.025%of ethyl acrylate are found.
Assay— Dissolve about 1g of Ammonio Methacrylate Copolymer Type A,or 2g of Type B,previously dried and accurately weighed,in a mixture of 96mLof glacial acetic acid and 4mLof water.Add 5mLof mercuric acetate TSand titrate with 0.1Nperchloric acid VS,determining the endpoint potentiometrically.Perform a blank determination and make any necessary correction.Each mLof 0.1Nperchloric acid is equivalent to 20.772mg of ammonio methacrylate (C9H18ClNO2)units.
Auxiliary Information— Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 2955
Pharmacopeial Forum:Volume No.30(5)Page 1666
Phone Number:1-301-816-8262