Packaging and storage—
Preserve in well-closed containers. Store between 5
and 25
, with excursions permitted up to 30
. Do not freeze.
Viscosity 
911
—
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 and 9.074 cm in height, and has a shaft that is 0.40 cm in diameter. Mix the Ethyl Acrylate and Methyl Methacrylate Copolymer Dispersion, pipet 16 mL into the measuring cylinder, and adjust the temperature of the Ethyl Acrylate and Methyl Methacrylate Copolymer Dispersion 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 not more than 50 centipoises.
Residue on ignition 281—
Using mild heating conditions (e.g., steam bath, sand bath) to avoid loss of material, evaporate the Ethyl Acrylate and Methyl Methacrylate Copolymer Dispersion to dryness prior to ignition: not more than 0.4% residue is obtained, calculated on the undried basis.
Limit of monomers—
Sodium perchlorate solution—
Dissolve 3.5 g of sodium perchlorate in 100 mL of water.
pH 2.0 Phosphoric acid—
Dilute phosphoric acid with water to obtain a solution having a pH of 2.0.
Mobile phase—
Prepare a mixture of
pH 2.0 Phosphoric acid and methanol (80 : 20), filter, and degas. Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard solution—
Prepare a solution in tetrahydrofuran having a concentration of about 2 µg per mL each of ethyl acrylate and methyl methacrylate. To 10.0 mL of this solution add 5.0 mL of a Sodium perchlorate solution, and mix. Dilute 5.0 mL of the mixture to 10.0 mL with water, and mix.
Test stock solution—
Dissolve 1.0 g of Ethyl Acrylate and Methyl Methacrylate Copolymer Dispersion with tetrahydrofuran, and dilute with the same solvent to 50 mL.
Test solution—
To 5.0 mL of Sodium perchlorate solution add 10.0 mL of the Test stock solution, dropwise, while stirring continuously. Centrifuge and filter the clear supernatant. Dilute 5.0 mL of the clear supernatant with water to 10.0 mL, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 200-nm detector and a 4.6- × 120-mm 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 ethyl acrylate and methyl methacrylate is not less than 2.0; and the relative standard deviation for replicate injections is not more than 2.0% for each analyte.
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 Ethyl Acrylate and Methyl Methacrylate Copolymer Dispersion taken by the formula:
10C(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 for the monomer obtained from the
Test solution and the
Standard solution, respectively: not more than 0.01% of total monomers is found.
Coagulum content—
Accurately weigh a stainless steel sieve having 125-µm openings, and filter 100 g of Ethyl Acrylate and Methyl Methacrylate Copolymer Dispersion through it. Wash the sieve with distilled water until a clear filtrate is obtained, and dry the sieve to constant weight at 105
: the weight of the residue does not exceed 1000 mg (1%).
