Amendment to the Ordinance for Enforcement of the Food Sanitation Act  and the 
Specifications and Standards for Food s, Food Additives , Etc . 
 
The government of Japan will designate Copolymer of 
Vinylimidazole/Vinylpyrrolidone  as an authorized food additive  and establish 
compositional specifications  and use standards for this additive . 
 
Background  
Japan prohibits the sale of food additives that are not designated by the Minister of 
Health, Labour and Welfare (hereinafter referred to as “the Minister”) under Article 
12 of the Food Sanitation Act (Act No. 233 of 1947; hereinafter referred to as “the 
Act”). In addition, when specifications or stand ards for food additives are stipulated 
in the Specifications and Standards for Foods , Food Additives , Etc. (Public Notice of 
the Ministry of Health and Welfare No. 370, 1959) , Japan prohibits the sale  of those 
additives unless they meet the specifications or the standards  pursuant to Article 13 
of the Act . 
 
In response to a request from the Minister, the Committee on Food Additives of the 
Food Sanitation Council under the Pharmaceutical Affairs and Food Sanitation 
Council (hereinafter referred to as “the Committee”)  has discussed the adequacy of 
the designation of Copolymer of Vinylimidazole/Vinylpyrrolidone  as a food additive. 
The conclusion of the Committee  is outlined below.  
 
Outline of conclusion  
The Minister  should designate Copolymer of Vinylimidazol e/Vinylpyrrolidone  as a 
food additive unlikely to cause harm to human health pursuant to Article 12 of the 
Act and should establish compositional specificatio ns and use standards for this 
additive pursuant to  Article 1 3 of the Act (see Attachment  for the details ). 
  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 (draft)  
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/Vinylpyrrolidon e used shall be removed before the 
completion of the final product.  
 
Compositional Specifi cations (draft)  
Substance Name  Copolymer of Vinylimidazole/Vinylpyrrolidone  
Definition  
Copolymer of Vinylimidazole/Vinylpyrrolidone is produced by polymerization of 1-
vinylimidazole and 1-vinyl-2-pyrrolidon e, 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 
Spectroph otometry, 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 of 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, f ilter 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/Vinylpyrrolidone, add 500 mL of a solution 
of 15 g of acetic acid  and 50 mL of et hanol (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, f ilter 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-pyrrolidon e Not more than 5  μg/g. 
2-Pyrrolidon e Not more than 50  μg/g. 
 
Test Solution   Weigh  2.0 g of  Copolymer of Vinylimidazole/Vinylpyrrolidone,  
add exactly 1 mL of 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 s olution 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, 16 mg of 1 -vinylimidazole , 8.0 mg of 1-vinyl-2-pyrrolidon e, 
and 80 mg of  2-pyrrolidon e 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 portions 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 impurit y to benzonitrile for the test solution and the 
control solution.  The peak area ratio of  each organic impurit y to benzonitrile  from  
the test solution is not greater  than the peak area ratio  of the  corresponding  organic 
impurit y 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  from 160°C to 210°C at a rate of 
5°C/minute, 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 impurit y is separated . 
Injection method: Split.  
Split ratio : 1 : 10. 
Loss on Drying   Not more than 5.0% (1 40°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 dissolv ing 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 o f 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 from 160°C to 210°C at a rate of 
5°C/minute, 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. T he 
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 to 
280°C at a rate of 15°C/m inute, 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   C3H4O2  [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 accurat ely 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 C 3H4N2 
 
2-Pyrrolidon e  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 dissolv ing 1 g of 2-
pyrrolidon e 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 o f 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  to 
190°C at a rate of 10°C/minute, 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-pyrrolidon e 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 dissolv ing 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 f rom 160°C to 210°C at a rate of 
5°C/minute, 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