Add the following:
Methacrylic Acid and Ethyl Acrylate Copolymer Dispersion
(Title for this monograph—to become official May 1, 2017)
(Prior to May 1, 2017, the current practice of labeling the article of commerce with the name Methacrylic Acid Copolymer Dispersion may be continued. Use of the name Methacrylic Acid and Ethyl Acrylate Copolymer Dispersion will be permitted as of May 1, 2012, but the use of this name will not be mandatory until May 1, 2017. The 60-month extension will provide the time needed by manufacturers and users to make necessary changes.)
DEFINITION
Methacrylic Acid and Ethyl Acrylate Copolymer Dispersion is an aqueous dispersion of Methacrylic Acid and Ethyl Acrylate Copolymer. It contains, on the basis of the calculated amount of dry substance in the Dispersion, NLT 46.0% and NMT 50.6% of methacrylic acid units. It may contain suitable surface-active agents.
IDENTIFICATION
•  A. Infrared Absorption 197K: Proceed as directed, except to use the residue obtained in the test for Loss on Drying as the sample.
•  B. It meets the requirements of the Assay.
ASSAY
•  Procedure
Sample:  2.5 g of the Dispersion
Titrimetric system 
Mode:  Direct titration
Titrant:  0.1 N sodium hydroxide VS
Endpoint detection:  Potentiometric
Analysis:  Dissolve the Sample in 100 mL of neutralized acetone. Titrate the solution as directed in Titrimetric system. Each mL of 0.1 N sodium hydroxide is equivalent to 8.609 mg of methacrylic acid (C4H6O2) units.
Calculate, on the dried basis, the percentage of methacrylic acid units in the portion of Dispersion taken:
Result = [V × N/W × (100 L)] × 860.9
V== volume of titrant consumed (mL)
N== normality of the titrant
W== weight of Dispersion taken (g)
L== percentage of the Loss on Drying value for the Dispersion
Acceptance criteria:  46.0%–50.6% based on the calculated amount of dry substance in the Dispersion
IMPURITIES
Inorganic Impurities 
•  Residue on Ignition 281: Using mild heating conditions (e.g., steam bath, sand bath) to avoid loss of material, evaporate the Dispersion to dryness prior to ignition: NMT 0.2% residue is obtained, calculated on the undried Dispersion basis.
•  Heavy Metals, Method II 231: Using mild heating conditions (e.g., steam bath, sand bath) to avoid loss of material, evaporate the Dispersion to dryness prior to wetting with sulfuric acid and ignition: the color of the solution from the Test Preparation is not darker than that of the solution from the Standard Preparation (20 ppm).
Organic Impurities 
•  Limit of Monomers
Sodium perchlorate solution:  Dissolve 3.5 g of sodium perchlorate in 100 mL of water. This solution has a concentration of 0.25 M.
Mobile phase:  Add phosphoric acid dropwise to water to obtain a solution having a pH of 2.0. Prepare a mixture of this acidified water and methanol (80:20), and degas.
Standard solution:  Dissolve 0.01 g of methacrylic acid and 0.01 g of ethyl acrylate in 5 mL of butanol, and add methanol to make exactly 100 mL. Transfer 1.0 mL of this solution to a 100-mL volumetric flask, and dilute with methanol to volume. Mix 5.0 mL of this solution with 5.0 mL of Sodium perchlorate solution, accurately measured. This solution contains about 0.5 µg/mL each of methacrylic acid and ethyl acrylate.
Sample solution:  Transfer a quantity of Dispersion, equivalent to 3 g of solids on the dried basis, to a 50-mL volumetric flask, dilute with methanol to volume, and mix. Add 5 mL of this solution dropwise while continuously stirring into a beaker that contains 5.0 mL of Sodium perchlorate solution, accurately measured. Remove the precipitated polymer by centrifugation (e.g., NLT 5000 × g for NLT 5 min). Use the clear supernatant.
Chromatographic system  
Mode:  LC
Detector:  UV 202 nm
Column:  4.0-mm × 12.5-cm; 7-µm packing L1
Flow rate:  2 mL/min
Injection size:  20 µL
System suitability 
Sample:  Standard solution
[Note—The relative retention times for methacrylic acid and ethyl acrylate are 1.0 and 2.6, respectively. ]
Suitability requirements 
Resolution:  NLT 2.0 between methacrylic acid and ethyl acrylate
Relative standard deviation:  NMT 5.0%, determined for each analyte
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of each monomer in the solid portion of the Dispersion taken:
Result = (rU/rS) × (C/W) × VF × D × F × 100
rU== monomer (methacrylic acid or ethyl acrylate) peak response from the Sample solution
rS== monomer (methacrylic acid or ethyl acrylate) peak response from the Standard solution
C== concentration of the monomer (methacrylic acid or ethyl acrylate) in the Standard solution (µg/mL)
W== solid weight of the Dispersion, calculated on the dried basis, taken to prepare the Sample solution (g)
VF== final volume of the Sample solution, 10 mL
D== dilution factor for preparation of the Sample solution, 10
F== conversion factor, 106 g/µg
Acceptance criteria:  NMT 0.01% of total monomers, based on the weight of the solid portion of the Dispersion taken
SPECIFIC TESTS
•  Coagulum Content: Weigh a stainless steel sieve having 90-µm openings or a suitable single-woven wire cloth with a mesh width of 90 µm, and filter 100 g of the Dispersion through it. [Note—Suitable single-woven wire cloth mesh meets the requirements set in ISO 9044. ] Wash the sieve or the cloth with distilled water until a clear filtrate is obtained, and dry the sieve or the cloth to constant weight at 110: the weight of the residue does not exceed 1000 mg (1%).
•  Loss on Drying 731: Dry a sample at 110 for 6 h: it loses 68.5%–71.5% of its weight.
•  Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62: The total aerobic microbial count does not exceed 103 cfu/g, and the total combined molds and yeasts count does not exceed 102 cfu/g.
•  pH 791: 2.0–3.0
•  Viscosity 911: Equip a suitable rotational viscometer with an adapter comprising a cylindrical spindle rotating within an accurately machined chamber (or tube).1 Mix the Dispersion, pipet the volume of test specimen recommended by the instrument manufacturer into the chamber (or tube), and ensure that the temperature of the test specimen is at 20 ± 0.1. The shear rate under the test condition is NLT 1 s1 and NMT 100 s1.2 Measure the apparent viscosity following the instrument manufacturer's directions.
Acceptance criteria:  The viscosity is between 2 and 15 mPa·s.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers. Store at controlled room temperature. Protect from freezing.
•  Labeling: The label indicates the name and amount of any substance added as a surface-active agent.
•  USP Reference Standards 11
USP Methacrylic Acid and Ethyl Acrylate Copolymer (1:1) RS (USP Methacrylic Acid Copolymer, Type C RS)
NF30

1  A commercial device is available from Brookfield as an ultra-low (UL) viscosity adapter. The adapter comprises a 0.4-cm diameter shaft, an accurately machined chamber (or tube) with an internal diameter of 2.8 cm and a depth of 13.5 cm, and a cylindrical spindle 2.5 cm in diameter and 9.1 cm in height.
2  The cylindrical spindle rotates at 30 rpm.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
1-301-816-8335
(EXC2010) Monographs - Excipients
61 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339
(GCM2010) General Chapters - Microbiology
62 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339
(GCM2010) General Chapters - Microbiology
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 1859
Pharmacopeial Forum: Volume No. 36(6) Page 1640