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Amino Methacrylate Copolymer
» Amino Methacrylate Copolymer is a fully polymerized copolymer of (2-dimethylaminoethyl) methacrylate, butyl methacrylate, and methyl methacrylate. It contains not less than 20.8 percent and not more than 25.5 percent of dimethylaminoethyl groups (C4H10N), calculated on the dried basis.
Packaging and storage— Preserve in tight containers, and store at a temperature not exceeding 25.
Color of solution— The absorbance of the Test solution prepared in the test under Viscosity, determined in a 1-cm cell at 420 nm in a suitable spectrophotometer, is not greater than 0.300. Use water as the blank.
Identification—
B: Pour 1 mL of the Test solution prepared in the test under Viscosity onto a glass plate and allow the solvent to evaporate: a clear, colorless film results.
Viscosity 911—
Test solution— Dissolve 12.5 g in a mixture of 35.0 g of acetone and 52.5 g of isopropyl alcohol. [note—Reserve a portion of this solution for the Color of solution test.]
Procedure— 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 2.762 cm and a depth of 13.50 cm; the spindle is 2.515 cm in diameter, 9.074 cm in height, and has a shaft 0.40 cm in diameter. Transfer 16 mL of the Test solution into the measuring cylinder, and adjust the temperature of the solution and the adapter to 20 ± 0.1. With the spindle rotating at 30 rpm, immediately observe and record the scale reading. Convert the scale reading to centipoises by multiplying the reading by the constant for the viscosimeter, the adapter system, and the speed employed. The viscosity is between 3 and 6 centipoises.
Loss on drying 731— Dry it at 110 for 3 hours: it loses not more than 2.0% of its weight.
Residue on ignition 281: not more than 0.1%.
Limit of monomers—
test 1, limit of butyl methacrylate and methyl methacrylate—
pH 2.0 Phosphate buffer (0.0625 M)— Prepare an aqueous solution containing 8.9 g of anhydrous dibasic sodium phosphate and 8.5 g of monobasic potassium phosphate per L. Adjust with phosphoric acid to a pH of 2.0.
Mobile phase— Prepare a mixture of methanol and pH 2.0 Phosphate buffer (0.0625 M) (55:45).
Standard solution— Prepare a solution in acetonitrile having a concentration of about 1000 µg per mL each of butyl methacrylate and methyl methacrylate. Dilute 1.0 mL of the solution to 250.0 mL with water, and mix.
Test solution— Dissolve about 1.0 g of Amino Methacrylate Copolymer, accurately weighed, in pH 2.0 Phosphate buffer (0.0625 M), and dilute with pH 2.0 Phosphate buffer (0.0625 M) to 50.0 mL, and mix.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 205-nm detector and a 4.6-mm × 12-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the resolution, R, between butyl methacrylate and methyl methacrylate is not less than 10; and the relative standard deviation for replicate injections is not more than 3.0%.
Procedure— Separately inject equal volumes (about 50 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in µg, of each monomer in the portion of Amino Methacrylate Copolymer taken by the formula:
50C(rU / rS)
in which C is the concentration, in µg per mL, of each monomer in the Standard solution; and rU and rS are the peak responses of each monomer obtained from the Test solution and the Standard solution, respectively: not more than 0.1% of each monomer is found.
test 2, limit of 2-dimethylaminoethyl methacrylate—
Monobasic potassium phosphate solution (0.025M)— Prepare an aqueous solution containing 3.4 g of monobasic potassium phosphate per L.
Mobile phase— Prepare a mixture of Monobasic potassium phosphate solution (0.025M) and tetrahydrofuran (75:25).
Standard solution— Prepare a solution in tetrahydrofuran having a concentration of about 200 µg per mL of (2-dimethylaminoethyl) methacrylate. Dilute 2.0 mL of the solution to 50.0 mL with tetrahydrofuran, and mix.
Test solution— Dissolve about 1.0 g of Amino Methacrylate Copolymer, accurately weighed, in tetrahydrofuran, dilute with tetrahydrofuran to 50.0 mL, and mix.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 215-nm detector and a 4.6-mm × 12-cm column that contains packing L8. The flow rate is about 2 mL per minute. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 50 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the response for the major peak. Calculate the quantity, in µg, of (2-dimethylaminoethyl) methacrylate in the portion of Amino Methacrylate Copolymer taken by the formula:
50C(rU / rS)
in which C is the concentration, in µg per mL, of the monomer in the Standard solution; and rU and rS are the peak responses of (2-dimethylaminoethyl) methacrylate obtained from the Test solution and the Standard solution, respectively: not more than 0.1% is found.
Assay— Dissolve 0.20 g in a mixture of 4 mL of water and 96 mL of glacial acetic acid, and mix. Titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically (see Titrimetry 541). One mL of 0.1 N perchloric acid is equivalent to 7.21 mg of dimethylaminoethyl groups (C4H10N).
Auxiliary Information— Staff Liaison : Hong Wang, Ph.D., Scientist
Expert Committee : (EM205) Excipient Monographs 2
USP31–NF26 Page 1072
Pharmacopeial Forum : Volume No. 31(4) Page 1137
Phone Number : 1-301-816-8351