Copolymer of Vinylimidazole/Vinylpyrrolidone PVI/PVP

Standards for Use
Permitted for use in grape juice used for wine production and grape wine only.
Shall be used at not more than 0.50 g/L in grape wine as copolymer of vinylimidazole/vinylpyrrolidone. When Copolymer of Vinylimidazole/ Vinylpyrrolidone is used in grape juice used for wine production, this additive is considered to be used in grape wine.
The Copolymer of Vinylimidazole/Vinylpyrrolidone used shall be removed before the completion of the final product.
Compositional Specifications
Substance Name Copolymer of Vinylimidazole/Vinylpyrrolidone
Definition
Copolymer of Vinylimidazole/Vinylpyrrolidone is produced by polymerization of 1-vinylimidazole and 1-vinyl-2-pyrrolidone, with a ratio of 9 : 1, in the presence of
crosslinking agent 1,3-divinylimidazolin-2-one at a level of less than 2%.
Content
Copolymer of Vinylimidazole/Vinylpyrrolidone, when calculated on the dried basis,contains 26.0–29.0% of nitrogen (N = 14.01).
Description Copolymer of Vinylimidazole/Vinylpyrrolidone occurs as a white to
yellowish-white powder.
Identification Determine the absorption spectrum of Copolymer of Vinylimidazole/Vinylpyrrolidone as directed in the Disk Method under Infrared
Spectrophotometry, and compare with the Reference Spectrum. Both spectra exhibit similar intensities of absorption at the same wavenumbers.
Purity
(1) Lead Not more than 2 μg/g as Pb (2.0 g, Method 1, Control Solution: Lead Standard Solution 4.0 mL, Flame Method).

(2) Arsenic Not more than 2 μg/g as As (0.50 g, Method 3, Standard Color: Arsenic Standard Solution 2.0 mL, Apparatus B).
(3) Water-soluble substances Not more than 0.5%.
Weigh 10 g of Copolymer of Vinylimidazole/Vinylpyrrolidone, add it to 100 mL of water,shake, and allow to stand for 24 hours. Filter by suction through a membrane filter (2.5–
3.0 μm pore size). Then, filter the filtrate by suction through a membrane filter (0.8 μm pore size), evaporate on a water bath to dryness, and weigh the residue.
(4) Acetic acid/ethanol-soluble substances Not more than 1%.
Weigh 1 g of Copolymer of Vinylimidazole/Vinylpyrrolidone, add 500 mL of a solution of 15 g of acetic acid and 50 mL of ethanol (95) in 500 mL of water, shake, and allow to stand for 24 hours. Filter the filtrate by suction through a membrane filter (2.5–3.0 μm pore size). Then, filter the filtrate by suction through a membrane filter (0.8 μm pore size), evaporate on a water bath to dryness, and weigh the residue.
(5) Organic impurities
Imidazole Not more than 50 μg/g.
1,3-Divinylimidazolin-2-one Not more than 2 μg/g.
1-Vinylimidazole Not more than 10 μg/g.
1- Vinyl-2-pyrrolidone Not more than 5 μg/g.
2-Pyrrolidone Not more than 50 μg/g.
Test Solution Weigh 2.0 g of Copolymer of Vinylimidazole/Vinylpyrrolidone, add exactly 1 mL of the internal standard solution, add 24 mL of acetone, and stir for 4 hours with a stirrer. Allow to stand, filter, and use the filtrate as the test solution.
Internal Standard Solution Use a solution of benzonitrile in acetone (1 in 4000).
Standard Solution Weigh separately 80 mg of imidazole, 3.2 mg of 1,3-divinylimidazolin-2-one, 16 mg of 1-vinylimidazole, 8.0 mg of 1-vinyl-2-pyrrolidone, and 80 mg of 2-pyrrolidone in a 200-mL volumetric flask, and add acetone to make 200 mL.
Use the solution as the standard solution.
Control Solution Measure exactly 1 mL of the standard solution and 4 mL of the internal standard solution, and add acetone to make100 mL.
Procedure Analyze 1 μL each of the test solution and the control solution by gas chromatography using the operating conditions given below. Determine the peak area ratio of each organic impurity to benzonitrile for the test solution and the control solution.
The peak area ratio of each organic impurity to benzonitrile from the test solution is not greater than the peak area ratio of the corresponding organic impurity to benzonitrile from the control solution.
Operating Conditions
Detector: Nitrogen phosphorous detector.
Column: A fused silica tube (0.25 mm internal diameter and 30 m length) coated with a 0.5-μm thick layer of polyethylene glycol for gas chromatography.
Column temperature: Raise the temperature at a rate of 5°C/minute from 160°C to 210°C, and then maintain at 210°C for 7 minutes.
Injection port temperature: 220°C.
Detector temperature: 250°C.
Carrier gas: Helium.
Flow rate: Adjust so that the peak of benzonitrile appears 4–5 minutes after
injection and the peak of each organic impurity is separated.
Injection method: Split.
Split ratio: 1 : 10.
Loss on Drying Not more than 5.0% (140°C, 1 hour).
Ash Not more than 0.3% (800°C, 6 hours).
Assay Weigh accurately about 10 mg of Copolymer of Vinylimidazole/Vinylpyrrolidone,and proceed as directed in the Semi-micro Kjeldahl Method under Nitrogen
Determination. Determine the nitrogen content on the dried basis.
Reagents, Solutions, and Other Reference Materials
Benzonitrile C7H5N [100-47-0] A colorless, clear liquid.
Purity Related substances Prepare a test solution by dissolving 40 mg of benzonitrile in 25 mL of acetone. Prepare a control solution by diluting exactly 1 mL of the test solution with acetone to make exactly 50 mL. Analyze 1.0 μL each of the test solution and the control solution by gas chromatography using the operating conditions below. Continue the chromatography for two times the retention time of the main peak and measure the peak areas. The sum of the areas of all the peaks, excluding the main peak and solvent peaks, from the test solution is not greater than the area of the main peak from the control solution.
Operating conditions
Detector: Flame-ionization detector.
Column: A fused silica tube (0.25 mm internal diameter and 30 m length) coated with a 0.5-μm thick layer of polyethylene glycol for gas chromatography.
Column temperature: Raise the temperature at a rate of 5°C/minute from 160°C to 210°C, and then maintain at 210°C for 7 minutes.
Injection port temperature: 220°C.
Detector temperature: 250°C.
Carrier gas: Helium.
Flow rate: Adjust so that the peak of benzonitrile appears 4–5 minutes after injection.
Injection method: Split.
Split ratio: 1 : 10.
1,3-Divinylimidazolin-2-one C7H10N2O [13811-50-2]
Melting point 65–71°C.
Purity Related substances Prepare a test solution by mixing 6 mg of 1,3-divinylimidazolin-2-one with 2 mL of ethyl acetate. Prepare a control solution by diluting exactly 0.5 mL of the test solution with ethyl acetate to make exactly 10 mL. Analyze 2.0 μL each of the test solution and the control solution by gas chromatography using the operating conditions below. Continue the chromatography for 1.5 times the retention time of the main peak and measure the peak areas. The sum of the areas of all the peaks,excluding the main peak and solvent peaks, from the test solution is not greater than the area of the main peak from the control solution.
Operating conditions
Detector: Flame-ionization detector.
Column: A fused silica tube (0.25 mm internal diameter and 30 m length) coated with a 0.25-μm thick layer of 5% diphenyl/95% dimethylpolysiloxane for gas chromatography.
Column temperature: Maintain the temperature at 60°C for 5 minutes, raise at a rate of 15°C/minute to 280°C, and then maintain at 280°C for 1 minute.
Injection port temperature: 150°C.
Detector temperature: 250°C.
Carrier gas: Helium.
Flow rate: Adjust so that the peak of 1,3-divinylimidazolin-2-one appears 11–13 minutes after injection.
Injection method: Splitless.
Imidazole C3H4N2 [288-32-4] White to light yellow crystals or powder. Very soluble in water and in methanol.
Content Not less than 98.0%.
Melting point 88–92°C.
Assay Weigh accurately about 0.1 g of imidazole, add 50 mL of acetic acid for nonaqueous titration, and titrate with 0.1 mol/L perchloric acid. To confirm the endpoint,use a potentiometer with a glass indicator electrode and silver-silver chloride reference electrode. A combined electrode can also be used for the indicator and reference electrodes. Separately, perform a blank test to make any necessary correction.
Each mL of 0.1 mol/L perchloric acid = 6.808 mg of C3H4N2
2-Pyrrolidone C4H7NO [616-45-5] A colorless to pale yellow, clear liquid or white to pale yellow lumps or powder.
Melting point 22–27°C.
Purity Related substances Prepare a test solution by dissolving 1 g of 2-pyrrolidone in 10 mL of methanol. Prepare a control solution by diluting exactly 1 mL of the test solution with methanol to make exactly 50 mL. Analyze 1.0 μL each of the test solution and the control solution by gas chromatography using the operating conditions below.

Continue the chromatography for two times the retention time of the main peak and measure the peak areas. The sum of the areas of all the peaks, excluding the main peak and solvent peaks, from the test solution is not greater than the area of the main peak from the control solution.
Operating conditions
Detector: Flame-ionization detector.
Column: A fused silica tube (0.53 mm internal diameter and 30 m length) coatedwith a 1.0-μm thick layer of polyethylene glycol for gas chromatography.
Column temperature: Maintain the temperature at 80°C for 1 minute, raise at a
rate of 10°C/minute to 190°C, and then maintain at 190°C for 20 minutes.
Injection port temperature: A constant temperature of near 200°C.
Detector temperature: 250°C.
Carrier gas: Helium.
Flow rate: Adjust so that the peak of 2-pyrrolidone appears about 10 minutes after injection.
Injection method: Split.
Split ratio: 1 : 20.
1-Vinylimidazole C5H6N2 [1072-63-5] A colorless to light yellow liquid.
Purity Related substances Prepare a test solution by dissolving 100 mg of 1-vinylimidazole in 25 mL of acetone. Prepare a control solution by diluting exactly 1 mL of the test solution with acetone to make exactly 50 mL. Analyze 1.0 μL each of the test solution and the control solution by gas chromatography using the operating conditions below. Continue the chromatography for two times the retention time of the main peak and measure the peak areas. The sum of the areas of all the peaks, excluding the main peak and solvent peaks, from the test solution is not greater than the area of the main peak from the control solution.
Operating conditions
Detector: Flame-ionization detector.
Column: A fused silica tube (0.25 mm internal diameter and 30 m length) coated with a 0.5-μm thick layer of polyethylene glycol for gas chromatography.
Column temperature: Raise the temperature at a rate of 5°C/minute from 160°C to 210°C, and then maintain at 210°C for 7 minutes.
Injection port temperature: 220°C.
Detector temperature: 250°C.
Carrier gas: Helium.
Flow rate: Adjust so that the peak of 1-vinylimidazole appears 4–5 minutes after injection.
Injection method: Split.
Split ratio: 1 : 10.
Infrared Reference Spectrum
Copolymer of Vinylimidazole/Vinylpyrrolidone