Polyvinyl Acetate Dispersion
DEFINITION
Dispersion of polyvinyl acetate in water. It contains 25.0% to 30.0% of polyvinyl acetate. It may contain suitable surface active agents and stabilizers.
IDENTIFICATION
•  A. Place one drop of Dispersion on a glass plate and allow to dry. A clear and homogeneous film is formed.
•  B. Infrared Absorption
Analysis:  Place one drop of the Dispersion on a glass plate, and cover the test substance with a water-resistant crystal disk (silver chloride or KRS-51). Gently press on, and then remove the crystal disk. Dry the crystal disk in a drying chamber until a homogeneous film is formed.
Acceptance criteria:  The IR absorption spectrum of the film so formed exhibits maxima corresponding to the same wavelengths as those of a similar preparation of USP Polyvinyl Acetate Dispersion RS treated in the same manner.
ASSAY
•  Procedure
Sample:  1.5 g of Dispersion
Analysis:  Transfer the Sample to a 250-mL borosilicate glass flask fitted with a reflux condenser. Add 25.0 mL of 0.5 M alcoholic potassium hydroxide and a few glass beads. Attach the condenser and heat under reflux for 30 min. Add 1 mL of phenolphthalein TS, and titrate immediately (while still hot) with 0.5 N hydrochloric acid VS. Perform a blank determination under the same conditions (see Titrimetry 541, Residual Titrations.)
Calculate the saponification value, IS, by the formula:
Result = [Mr1 × (VB VT)] × N]/W
 Mr1 = = molecular weight of potassium hydroxide, 56.11 VB = = volume of 0.5 N hydrochloric acid consumed in the blank test (mL) VT = = volume of 0.5 N hydrochloric acid consumed in the actual test (mL) N = = exact normality of the hydrochloric acid W = = weight of the Dispersion taken for the test (g)
Calculate the percentage content of polyvinyl acetate using the following formula:
Result = F × (Mr2 × IS/Mr1) × 100
 F = = factor converting mg to g, 10-3 g/mg Mr2 = = molecular weight of vinyl acetate, 86.09 Mr1 = = molecular weight of potassium hydroxide, 56.11
Acceptance criteria:  The content of polyvinyl acetate is 25.0%–30.0%.
OTHER COMPONENTS
Stabilizers or Surface Active Agents
•  Povidone
[Note—Perform this test only if the Dispersion contains povidone. ]
Sample:  0.25 g
Analysis:  Perform nitrogen determination by sulfuric acid digestion on the Sample as directed in Nitrogen Determination 461, Method II.
Calculate the percentage content of povidone using the following formula:
Result = N/0.126
 N = = percentage content of nitrogen 0.126 = = percentage content, expressed as a decimal number, of nitrogen in vinylpyrrolidone
Acceptance criteria:  The content of povidone is NMT 4.0%.
IMPURITIES
Inorganic Impurities
Sample:  1.0 g of Dispersion
Analysis:  Heat a silica crucible to redness for 30 min, allow to cool in a desiccator, and weigh. Evenly distribute the Sample in the crucible and weigh. Dry the crucible at 100 to 105 for 1 h and ignite in a muffle furnace at 600 ± 25, until the test substance is thoroughly charred. Continue the experiment as directed under Residue on Ignition 281 on the residue obtained, beginning with “Moisten the sample with a small amount (usually 1 mL) of sulfuric acid…”
Acceptance criteria:  NMT 0.5%
Organic Impurities
•  Procedure 1: Limit of Vinyl Acetate
Solution A:  Acetonitrile, methanol, and water (5:5:90)
Solution B:  Acetonitrile, methanol, and water (45:5:50)
Mobile phase:  See the gradient table below.
Time
(min)
Solution A
(%)
Solution B
(%)
0 100 0
2 100 0
40 85 15
42 0 100
48 0 100
51 100 0
Standard solution:  Transfer 50 mg of vinyl acetate to a 100-mL volumetric flask, dissolve in and dilute with methanol to volume, and mix well. Dilute 5.0 mL of the solution with Solution A to 100 mL. Dilute 10.0 mL of this solution with Solution A to 100 mL. The Standard solution contains about 2.5 µg/mL of vinyl acetate. [Note—This solution should be analyzed within 1 h when stored at room temperature. ]
System suitability solution:  Transfer 50 mg of vinyl acetate and 50 mg of 1-vinylpyrrolidin-2-one to a 50-mL volumetric flask, add 10 mL of methanol, sonicate or gently shake the flask to dissolve the materials. Dilute with Solution A to volume. Dilute 10 mL of this solution with Solution A to 100 mL. Dilute 5 mL of this solution with Solution A to 100 mL. The System suitability solution contains about 5 µg/mL each of vinyl acetate and 1-vinylpyrrolidin-2-one.
Sample solution:  Transfer 250 mg of the Dispersion to a 10-mL volumetric flask, add about 4 mL of methanol, and sonicate. After cooling to ambient temperature, dilute with water to volume, and mix. Centrifuge at 4000 × g for 10 min, and pass through a 0.2-µm membrane filter. [Note—This solution should be analyzed within 1 h when stored at room temperature. ]
Chromatographic system
Mode:  LC
Detector:  UV 205 nm
Columns
Analytical column:  4.0-mm × 25-cm; 5-µm packing L1
Pre-column:  4.0-mm × 3-cm; 5-µm packing L1 may be used if a matrix effect is observed.
[Note—The matrix effect may result in poor reproducibility of the retention times and of the peak shapes. ]
Column temperature:  30
Flow rate:  1 mL/min
Injection size:  10 µL
System suitability
Sample:  System suitability solution
[Note—The relative retention times for vinyl acetate and 1-vinylpyrrolidin-2-one are 1.0 and 1.2, respectively. ]
Suitability requirements
Resolution:  NLT 5.0 between vinyl acetate and 1-vinylpyrrolidin-2-one
Relative standard deviation:  NMT 5.0% determined from the 1-vinylpyrrolidin-2-one peak
Analysis
Samples:  Standard solution and Sample solution
Acceptance criteria:  The response of the vinyl acetate peak from the Sample solution is NMT that of the vinyl acetate peak from the Standard solution, corresponding to NMT 100 ppm of vinyl acetate.
•  Procedure 2: Limit of Acetic Acid/Acetate
Mobile phase:  5 mM sulfuric acid
Standard solution:  0.3 mg/mL for each of acetic acid and citric acid in Mobile phase
Sample solution:  Transfer 200 mg of the Dispersion to a 10-mL volumetric flask, add about 8 mL of water, and sonicate for about 10 min. Cool to ambient temperature, and dilute with water to volume.
Chromatographic system
Mode:  LC
Detector:  UV 205 nm
Column:  4.6-mm × 25-cm; 5-µm packing L1
Column clean:  After each injection, rinse the column with a mixture of equal volumes of Mobile phase and acetonitrile.
Column temperature:  Ambient
Flow rate:  1 mL/min
Injection size:  20 µL
System suitability
Sample:  Standard solution
[Note—The relative retention times for acetic acid and citric acid are 1.0 and 1.2, respectively. ]
Suitability requirements
Resolution:  NLT 2.0 between acetic acid and citric acid
Relative standard deviation:  NMT 5.0% determined from the acetic acid peak
Analysis
Samples:  Standard solution and Sample solution
Acceptance criteria:  The response of the acetic acid peak from the Sample solution is NMT that of the acetic acid peak from the Standard solution, corresponding to NMT 1.5% of acetic acid.
SPECIFIC TESTS
•  Microbial Enumeration Tests 61 and Tests for Specified Microorganisms 62: The total aerobic microbial count does not exceed 1000 cfu/g, and the total combined molds and yeasts count does not exceed 100 cfu/g
•  pH 791: 3.0–5.5
Dry 1.0 g of the Dispersion at 110 for 5 h: it loses between 68.5% and 71.5% of its weight.
•  Coagulum Content
Sample:  100 g of Dispersion
Analysis:  Accurately weigh a stainless steel sieve having 45-µm openings or a suitable single-woven wire cloth with a mesh width of 45 µm, and filter the Sample 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 100–105.
Acceptance criteria:  The weight of the residue does not exceed 500 mg (0.5%).
•  Packaging and Storage: Preserve in tight containers at a temperature below 25. Protect from freezing.
•  Labeling: Label it to indicate the names and quantities of any added surface active agents and stabilizers.
USP Polyvinyl Acetate Dispersion RS

1  KRS-5 consists of 42% thallium(I) bromide and 58% thallium(I) iodine by molecular weight. Suitable disks of silver chloride and of KRS-5 are available from www.photonic.saint-gobain.com, www.almazoptics.com, and www.internationalcrystal.net.
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Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
1-301-816-8335
(EXC2010) Monographs - Excipients