Methacrylic Acid Copolymer
Type A or Type B: Poly(methacrylic acid, methyl methacrylate);
Methacrylic acid–methyl methacrylate copolymer
[25086-15-1].
Type C: Poly(methacrylic acid, ethyl acrylate);
Methacrylic acid–ethyl acrylate copolymer[25212-88-8].
(meth'' a kril' ik as' id koe pol' i mer).
(Any article currently titled Methacrylic Acid Copolymer, Type A or Type B, will be officially titled Methacrylic Acid and Methyl Methacrylate Copolymer after December 1, 2015. Any article currently titled Methacrylic Acid Copolymer, Type C, will be officially titled Methacrylic Acid and Ethyl Acrylate Copolymer after December 1, 2015. After December 1, 2015, the Methacrylic Acid Copolymer monograph will no longer be valid.)
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Type A or Type B: Poly(methacrylic acid, methyl methacrylate);
Methacrylic acid–methyl methacrylate copolymer
[25086-15-1].Type C: Poly(methacrylic acid, ethyl acrylate);
Methacrylic acid–ethyl acrylate copolymer
[25212-88-8].DEFINITION
Methacrylic Acid Copolymer consists of methacrylic acid and methyl methacrylate monomers arranged in a random distribution or consists of methacrylic acid and ethyl acrylate monomers arranged in a random distribution. It may contain suitable surface-active agents. The Assay and Viscosity requirements differ for the three types, as described in the table below.
| Methacrylic Acid Units, Dried Basis (%) |
Viscosity mPa·s |
|||
|---|---|---|---|---|
| Type | Min. | Max. | Min. | Max. |
| A | 46.0 | 50.6 | 60 | 120 |
| B | 27.6 | 30.7 | 50 | 200 |
| C | 46.0 | 50.6 | 100 | 200 |
IDENTIFICATION
• B. Procedure:
It meets the requirements of the test for Assay.
ASSAY
• Procedure:
Sample:
1 g, previously dried
Analysis:
Dissolve the Sample in 100 mL of neutralized acetone and titrate with 0.1 N sodium hydroxide VS, determining the endpoint potentiometrically (see Titrimetry 
541
). Each mL of 0.1 N sodium hydroxide is equivalent to 8.609 mg of methacrylic acid (C4H6O2) units.
541). Each mL of 0.1 N sodium hydroxide is equivalent to 8.609 mg of methacrylic acid (C4H6O2) units.
Acceptance criteria
Type A:
46.0%–50.6%
Type B:
27.6%–30.7%
Type C:
46.0%–50.6%
IMPURITIES
Inorganic Impurities
• Residue on Ignition 281:
NMT 0.1% for Types A and B; NMT 0.4% for Type C
281:
NMT 0.1% for Types A and B; NMT 0.4% for Type C
• Heavy Metals, Method II 231:
NMT 20 ppm
231:
NMT 20 ppm
Organic Impurities
• Procedure: Limit of Monomers
Phosphate buffer:
Prepare an aqueous solution containing 17.8 g/L of anhydrous dibasic sodium phosphate and 17.0 g/L of monobasic potassium phosphate. Adjust with phosphoric acid to a pH of 2.0. This buffer has a concentration of 0.125 M.
Sodium perchlorate solution:
35 mg/mL of sodium perchlorate. 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 for Type A or Type B:
Dissolve 0.05 g of methacrylic acid and 0.05 g of methyl methacrylate in 5 mL of butanol, and add methanol to exactly 100 mL. Transfer 1.0 mL of this solution to a 100-mL volumetric flask. Dilute with methanol to volume. Mix 3.0 mL of this solution with 10.0 mL of Phosphate buffer. This solution contains 1.15 µg/mL each of methacrylic acid and methyl methacrylate.
Standard solution for Type C:
Dissolve 0.01 g of methacrylic acid and 0.01 g of ethyl acrylate in 5 mL of butanol, and add methanol to exactly 100 mL. Transfer 1.0 mL of this solution to a 100-mL volumetric flask. Dilute with methanol to volume. Mix 5.0 mL of this solution with 5.0 mL of Sodium perchlorate solution. This solution contains about 0.5 µg/mL each of methacrylic acid and ethyl acrylate.
Sample solution for Type A or Type B:
Transfer 1 g of Methacrylic Acid Copolymer, Type A or Type B, to a 50-mL volumetric flask, dilute with methanol to volume, and mix. Add 3 mL of this solution dropwise, while continuously stirring, to a beaker that contains 10.0 mL of Phosphate buffer. Remove the precipitated polymer to obtain a clear supernatant by centrifugation (e.g., NLT 5000 × g for NLT 5 min). Use the clear supernatant.
Sample solution for Type C:
Transfer 3 g of Methacrylic Acid Copolymer, Type C, to a 50-mL volumetric flask, dilute with methanol to volume, and mix. Add 5 mL of this solution dropwise, while continuously stirring, to a beaker that contains 5.0 mL of Sodium perchlorate solution. Remove the precipitated polymer to obtain a clear supernatant 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 analytical column; 7-µm packing L1
Flow rate:
2 mL/min
Injection size:
20 µL
For Type A or Type B
System suitability
Sample:
Standard solution for Type A or Type B
[Note—The relative retention times for methacrylic acid and methyl methacrylate are 1.0 and 2.8, respectively. ]
Suitability requirements
Resolution:
NLT 2.0 between methacrylic acid and methyl methacrylate
Relative standard deviation:
NMT 5.0%
Analysis
Samples:
Standard solution for Type A or Type B and Sample solution for Type A or Type B
Calculate the percentage of each monomer (methacrylic acid or methyl methacrylate) in the portion of Methacrylic Acid Copolymer Type A or Type B taken:
Result = (rU/rS) × (C/W) × VF × D × F × 100
| rU | = | = monomer (methacrylic acid or methyl methacrylate) peak response from the Sample solution for Type A or Type B |
| rS | = | = monomer (methacrylic acid or methyl methacrylate) peak response from the Standard solution for Type A or Type B |
| C | = | = concentration of the monomer (methacrylic acid or methyl methacrylate) in the Standard solution for Type A or Type B (µg/mL) |
| W | = | = weight of Methacrylic Acid Copolymer Type A or Type B taken to prepare the Sample solution for Type A or Type B (g) |
| VF | = | = final volume of the Sample solution for Type A or Type B, 13 mL |
| D | = | = dilution factor for preparation of the Sample solution for Type A or Type B, 16.7 |
| F | = | = conversion factor, 10 6 g/µg |
Acceptance criteria:
NMT 0.05% for the total amount of monomers
For Type C
System suitability
Sample:
Standard solution for Type C
[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%
Analysis
Samples:
Standard solution for Type C and Sample solution for Type C
Calculate the percentage of each monomer (methacrylic acid or ethyl acrylate) in the portion of Methacrylic Acid Copolymer Type C taken:
Result = (rU/rS) × (C/W) × VF × D × F × 100
| rU | = | = monomer (methacrylic acid or ethyl acrylate) peak response from the Sample solution for Type C |
| rS | = | = monomer (methacrylic acid or ethyl acrylate) peak response from the Standard solution for Type C |
| C | = | = concentration of the monomer (methacrylic acid or ethyl acrylate) in the Standard solution for Type C (µg/mL) |
| W | = | = weight of Methacrylic Acid Copolymer Type C taken to prepare the Sample solution for Type C (g) |
| VF | = | = final volume of the Sample solution for Type C, 10 mL |
| D | = | = dilution factor for preparation of the Sample solution for Type C, 10 |
| F | = | = conversion factor, 106 g/µg |
Acceptance criteria:
NMT 0.01% for the total amount of monomers
SPECIFIC TESTS
• Viscosity 911
911
Analysis:
Place 254.6 g of isopropyl alcohol and 7.9 g of water in a test flask. Add a quantity of Methacrylic Acid Copolymer, equivalent to 37.5 g of solids on the dried basis, while stirring by means of a magnetic stirrer. Close the flask, and continue stirring until the polymer has dissolved completely. Adjust the temperature to 20 ± 0.1
. Equip a rotational viscometer with an accessory.1 The shear rate under the test condition is NLT 1 s-1 and NMT 100 s-1. Follow the instrument manufacturer's directions to measure the apparent viscosity.
. Equip a rotational viscometer with an accessory.1 The shear rate under the test condition is NLT 1 s-1 and NMT 100 s-1. Follow the instrument manufacturer's directions to measure the apparent viscosity.
Acceptance criteria
Type A:
60–120 mPa·s
Type B:
50–200 mPa·s
Type C:
100–200 mPa·s
• Loss on Drying 731:
Dry a sample at 110 for 6 h: it loses NMT 5.0% of its weight.
731:
Dry a sample at 110 for 6 h: it loses NMT 5.0% of its weight.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers. Store at controlled room temperature.
• Labeling:
Label it to state whether it is Type A, B, or C. The labeling also indicates the name and quantity of any added surface-active agent.
• USP Reference Standards 11
11
USP Methacrylic Acid Copolymer, Type A RS
USP Methacrylic Acid Copolymer, Type B RS
USP Methacrylic Acid Copolymer, Type C RS
1
A suitable accessory is available from Brookfield Engineering as the LV1 spindle, a cylindrical spindle 1.9 cm in diameter and 6.5 cm high attached to a shaft 0.3 cm in diameter. The spindle rotates at 30 rpm at an immersion depth of 8.15 cm.
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 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1858
Pharmacopeial Forum: Volume No. 35(4) Page 905