Copolymer of Vinylimidazole/Vinylpyrrolidone  
PVI/PVP  
ビニルイミダゾール・ビニルピロリドン共重合体  
 
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/v inylpyrrolidone . When Copolymer of Vinylimidazole/  Vinylpyrrolidone  is 
used in grape juice used for wine production, this additive is considered to be us ed in 
grape wine.  
The Copolymer of Vinylimidazole/Vinylpyrrolidon e 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 Vinylimi dazole/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 w avenumbers.  
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) . Attachment  (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 substance s  Not more than 1%.  
Weigh 1 g of Copolymer of Vinylimidazole/Vinylpyrrolidon e, 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 t hrough 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 m g of imidazole, 3.2 mg of 1,3 -
divinylimidazolin -2-one, 1 6 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 org anic 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 tempera ture: 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  appea rs 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 fu sed 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 fo r 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 measur e 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 i njection.  
Injection method: Splitless.  
 
Imidazole   C3H4N2  [288-32-4]  White to light yellow crystal s 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 us ed 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 C 3H4N2 
 
2-Pyrrolidone  C4H7NO   [616-45-5]  A colorless to pale yellow, clear liquid or wh ite 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 pea k 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) coated 
with 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 th en 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 10 0 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 temperatu re: 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  
 
 
ビニルイミダゾール ・ビニルピロリドン共重合体  
105 
 
 
 
 
 
75 
 
 
 
 
%T  50 
 
 
 
 
25 
 
 
 
 
0 
4000   
3000   
2000   
1500  
Wavenumber [cm-1]  
1000   
600