GB 31604.46-2023 PDF in English
GB 31604.46-2023 (GB31604.46-2023) PDF English
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National food safety standard - Food contact materials and products - Determination of free phenol and migration
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| GB 31604.46-2016 | English | 70 |
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Method for analysis of hygienic standard of epoxy phenolic coatings for inner wall of food cans
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Standards related to (historical): GB 31604.46-2023
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GB 31604.46-2023: PDF in English GB 31604.46-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Food Contact Materials
and Products - Determination of Free Phenol and Migration
ISSUED ON: SEPTEMBER 6, 2023
IMPLEMENTED ON: MARCH 6, 2024
Issued by: National Health Commission of the People’s Republic of China;
State Administration for Market Regulation.
Table of Contents
Foreword ... 3
1 Scope ... 4
Part 1 - Determination of Free Phenol ... 4
2 Principle ... 4
3 Reagents and Materials ... 4
4 Instruments and Equipment ... 5
5 Analytical Procedures ... 6
6 Expression of Analysis Results ... 6
7 Precision ... 7
8 Others ... 7
Part 2 - Determination of Free Phenol Migration ... 7
9 Principle ... 7
10 Reagents and Materials ... 7
11 Instruments and Equipment ... 10
12 Analytical Procedures ... 10
13 Expression of Analysis Results ... 12
14 Precision ... 15
15 Others ... 15
Part 3 - Determination of Phenol Migration ... 15
16 Principle ... 15
17 Reagents and Materials ... 15
18 Instruments and Equipment ... 17
19 Analytical Procedures ... 18
20 Expression of Analysis Results ... 20
21 Precision ... 21
22 Others ... 22
Appendix A Schematic Diagram of Steam Distillation Apparatus ... 23
Appendix B Chromatogram of Phenol Standard Working Solution ... 24
National Food Safety Standard - Food Contact Materials
and Products - Determination of Free Phenol and Migration
1 Scope
This Standard specifies the method for the determination of food contact materials and products
- free phenol and the determination of migration.
In this Standard, Part 1 is applicable to the determination of free phenol in epoxy phenolic resin
coatings for food contact; Part 2 is applicable to the determination of free phenol migration in
food contact materials and products; Part 3 is applicable to the determination of phenol
migration in food contact materials and products.
Part 1 - Determination of Free Phenol
2 Principle
The free phenol in the specimen reacts with bromine to generate bromophenol. The remaining
bromine reacts with potassium iodide. The precipitated iodine is titrated with sodium thiosulfate.
In accordance with the consumption of sodium thiosulfate solution, calculate the content of free
phenol.
3 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are all analytically pure, and
the water is Grade-1 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Hydrochloric acid (HCl): mass fraction 36% ~ 38%.
3.1.2 Trichloromethane (CHCl3).
3.1.3 Ethanol (C2H6O).
3.1.4 Potassium iodide (KI).
3.1.5 Soluble starch [(C6H10O5)n].
3.1.6 Bromine water (Br2): content 3%.
3.1.7 Anhydrous sodium carbonate (Na2CO3).
3.1.8 Potassium bromide (KBr).
3.2 Preparation of Reagents
3.2.1 Potassium iodide solution (100 g/L): weigh-take 1.00 g of potassium iodide, use water to
dissolve it and dilute to 10 mL.
3.2.2 Starch indicator solution (10 g/L): weigh-take 1.0 g of soluble starch, add 5 mL of water
to adjust it to a paste, while stirring, add the paste to 90 mL of boiling water, and boil for 1 min
~ 2 min; cool and dilute to 100 mL. The usage period is 2 weeks.
3.3 Reference Materials
3.3.1 Sodium thiosulfate pentahydrate (Na2S2O3 5H2O, CAS No.: 10102-17-7): working
reference reagent, or a standard substance certified by the state and awarded a reference material
certificate.
3.3.2 Potassium bromate (KBrO3, CAS No.: 7758-01-2): working reference reagent, or a
standard substance certified by the state and awarded a reference material certificate.
3.3.3 Standard solution for volumetric analysis of bromine: a standard substance certified by
the state and awarded a reference material certificate.
3.4 Preparation of Standard Solutions
3.4.1 Sodium thiosulfate standard titration solution [c(Na2S2O3) = 0.1 mol/L]
Weigh-take 26 g of sodium thiosulfate (Na2S2O3 5H2O), add 0.2 g of anhydrous sodium
carbonate, dissolve it in 1,000 mL of water, and slowly boil it for 10 min; cool and place it in a
brown reagent bottle. Store it in the dark for 2 weeks, then, filter it. Before use, calibrate it in
accordance with GB/T 5009.1. Sodium thiosulfate standard titration solution of the same
concentration for volumetric analysis can also be used.
3.4.2 Brome standard solution [c (𝟏𝟐Br2) = 0.1 mol/L]
Weigh-take 3.0 g of potassium bromate and 25.0 g of potassium bromide, dissolve it in 1,000
mL of water, and evenly shake it. Before use, calibrate it in accordance with GB/T 5009.1.
Standard solution of the same concentration for volumetric analysis of bromine can also be
used.
4 Instruments and Equipment
4.1 Balance: with a division value of 0.01 g and 0.1 mg, respectively.
4.2 Steam distillation apparatus: see Appendix A for the schematic diagram; or automatic steam
distillation apparatus.
V2---the volume of sodium thiosulfate standard titration solution consumed by specimen
titration, expressed in (mL);
c---the actual concentration of sodium thiosulfate standard titration solution, expressed in
(mol/L);
V3---the constant volume of the distilled liquid, expressed in (mL);
m---the mass of the sample, expressed in (g);
V4---the volume of the distilled liquid transferred-taken during the titration, expressed in (mL).
The result shall retain 2 significant figures.
7 Precision
The absolute difference between the results of two independent determinations obtained under
repeatability conditions shall not exceed 5% of the arithmetic mean.
8 Others
In this method, the detection limit is 0.4 g/kg and the quantitation limit is 2.0 g/kg.
Part 2 - Determination of Free Phenol Migration
9 Principle
Under alkaline conditions (pH 9.0 ~ 10.5), free phenol reacts with 4-aminoantipyrine under the
catalysis of potassium ferricyanide to generate antipyrine dye. The antipyrine dye in water is
extracted with chloroform. Then, use a spectrophotometer to determine the absorbance value
of the test solution at 460 nm, compare it with the standard series to obtain the free phenol
content in the soaking solution, and further calculate the amount of free phenol migration. For
antipyrine dyes in other food simulants and alterative solvents, use a spectrophotometer to
determine the absorbance value of the test solution at 500 nm, compare it with the standard
series to obtain the free phenol content in the soaking solution, and further calculate the amount
of free phenol migration.
10 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are all analytically pure, and
the water is Grade-1 water specified in GB/T 6682.
10.1 Reagents
Take phenol into a distillation bottle with an air condenser, heat and distill it, and collect the
distillate at 182 C ~ 184 C. After cooling, the distillate shall be white. Store it in a brown
bottle and tightly store it in a cool and dark place. Accurately weigh-take 1.0 g (accurate to 0.1
mg) of refined white phenol into a 1 L volumetric flask, use water to dilute to the scale and
evenly mix it. In accordance with GB 8538-2016, calibrate it.
10.4.2 Standard intermediate solution (100 mg/L)
Use an appropriate amount of ethanol to dilute the calibrated standard stock solution (1,000
mg/L) to 100 mg/L. Store it in a refrigerator at 4 C and away from light. It shall remain valid
for 1 month.
10.4.3 Standard intermediate solution (10 mg/L)
Use an appropriate amount of water to dilute the calibrated standard stock solution (1,000 mg/L)
to 10 mg/L. Prepare it right before use.
10.4.4 Standard series of working solutions in aqueous solution
Respectively and accurately transfer-take 0 mL, 1.0 mL, 2.0 mL, 4.0 mL, 6.0 mL and 10.0 mL
of the standard intermediate solution (10 mg/L) into six 200 mL volumetric flasks; use water to
reach a constant volume to the scale and evenly mix them. The concentration of phenol in the
standard series of working solutions is respectively 0.00 mg/L, 0.05 mg/L, 0.10 mg/L, 0.20
mg/L, 0.30 mg/L and 0.50 mg/L.
10.4.5 Standard series of working solutions in 4% (volume fraction) acetic acid solution
Respectively and accurately transfer-take 0 mL, 0.125 mL, 0.50 mL, 1.00 mL, 1.50 mL and
3.00 mL of the standard intermediate solution (100 mg/L) into six 50 mL volumetric flasks; use
4% (volume fraction) acetic acid solution to reach a constant volume to the scale and evenly
mix them. The concentration of phenol in the standard series of working solutions is
respectively 0.00 mg/L, 0.25 mg/L, 1.00 mg/L, 2.00 mg/L, 3.00 mg/L and 6.00 mg/L.
10.4.6 Standard series of working solutions in 10% (volume fraction) ethanol solution
Respectively and accurately transfer-take 0 mL, 0.125 mL, 0.50 mL, 1.00 mL, 1.50 mL and
3.00 mL of the standard intermediate solution (100 mg/L) into six 50 mL volumetric flasks; use
10% (volume fraction) ethanol solution to reach a constant volume to the scale and evenly mix
them. The concentration of phenol in the standard series of working solutions is respectively
0.00 mg/L, 0.25 mg/L, 1.00 mg/L, 2.00 mg/L, 3.00 mg/L and 6.00 mg/L.
10.4.7 Standard series of working solutions in isooctane
Respectively and accurately transfer-take 0 mL, 0.25 mL, 0.50 mL, 1.00 mL, 1.50 mL and 3.00
mL of the standard intermediate solution (100 mg/L) into six 50 mL volumetric flasks; use
isooctane to reach a constant volume to the scale and evenly mix them. The concentration of
phenol in the standard series of working solutions is respectively 0.00 mg/L, 0.50 mg/L, 1.00
aminoantipyrine solution and 1.0 mL of potassium ferricyanide solution. Each time a reagent is
added, thoroughly shake it; let it stand for 10 min, and reserve it for testing.
If the soaking solution is colored or turbid, take 50.0 mL of the soaking solution into a
distillation bottle, add a few glass beads, heat and distill it. When about 90% of the total volume
has been distilled, stop distillation. After slightly cooling, add 10 mL of water to the distillation
bottle and continue distillation, until 50 mL of distilled liquid is collected. Transfer-take all the
distilled liquid into a conical flask, follow the operation after “add 7.20 g of sodium carbonate”
in the previous paragraph to obtain the test solution.
12.2.3 Treatment of 10% (volume fraction) ethanol soaking solution and 20% (volume
fraction) ethanol soaking solution
Transfer-take 50.0 mL of the soaking solution into a conical flask, and successively add 1.0 mL
of ammonium chloride buffer solution, 1.0 mL of 4-aminoantipyrine solution and 1.0 mL of
potassium ferricyanide solution. Each time a reagent is added, thoroughly shake it; let it stand
for 10 min, and reserve it for later testing.
If the soaking solution is colored or turbid, take 50.0 mL of the soaking solution into a
distillation bottle, add a few glass beads, heat and distill it. When about 90% of the total volume
has been distilled, stop distillation. After slightly cooling, add 10 mL of water to the distillation
bottle and continue distillation, until 50 mL of distilled liquid is collected. Transfer-take all the
distilled liquid into a conical flask, follow the operation after “successively add 1.0 mL of
ammonium chloride buffer solution” in the previous paragraph to obtain the test solution.
12.2.4 Treatment of 50% (volume fraction) ethanol soaking solution and 95% (volume
fraction) ethanol (chemical alternative solvent) soaking solution
Transfer-take 10.0 mL of the soaking solution into a conical flask, add 40.0 mL of water, and
evenly mix it. In accordance with 12.2.3, conduct the treatment to obtain the test solution.
If the soaking solution is colored or turbid, take 10.0 mL of the soaking solution into a
distillation bottle, add 40.0 mL of water and a few glass beads, heat and distill it. When about
90% of the total volume has been distilled, stop distillation. After slightly cooling, add 10 mL
of water to the distillation bottle and continue distillation, until 50 mL of distilled liquid is
collected. Transfer-take all the distilled liquid into a conical flask, follow the operation after
“successively add 1.0 mL of ammonium chloride buffer solution” in 12.2.3 to obtain the test
solution.
12.2.5 Treatment of isooctane (chemical alternative solvent) soaking solution
Transfer-take 50.0 mL of the soaking solution into a separatory funnel, add 50.0 mL of water
and evenly mix it. Shake it for 2 min, let it stand to obtain stratification. In accordance with
12.2.3, conduct the treatment. Take the aqueous layer (lower layer) solution and filter it through
a nylon filter membrane; reserve it for later testing.
12.3 Blank Test
17.1.2 Absolute ethanol (C2H6O).
17.1.3 95% ethanol.
17.1.4 Isooctane (C8H18).
17.1.5 Olive oil: chemically pure, in line with the requirements of GB 5009.156.
17.1.6 Methanol (CH4O): chromatographically pure.
17.1.7 Acetonitrile (C2H3N): chromatographically pure.
17.2 Preparation of Reagents
17.2.1 Water-based food simulants: prepared in accordance with the stipulations of GB
5009.156.
17.2.2 80% methanol solution: measure-take 80 mL of methanol and 20 mL of water, and evenly
mix it.
17.3 Reference Material
Same as 10.3.
17.4 Preparation of Standard Solutions
17.4.1 Standard stock solution (1,000 mg/L)
Same as 10.4.1.
17.4.2 Standard intermediate solution (100 mg/L)
Accurately transfer-take 1.00 mL of the standard solution (1,000 mg/L) into a 10 mL volumetric
flask, use methanol to dilute it and reach a constant volume, and evenly mix it. Store it in a
refrigerator at 4 C away from light. It shall remain valid for 1 month.
17.4.3 Standard intermediate solution (10 mg/L)
Accurately transfer-take 0.50 mL of the standard solution (1,000 mg/L) into a 50 mL volumetric
flask, use methanol to dilute it and reach a constant volume. Prepare it right before use.
17.4.4 Standard series of working solutions of water-based food simulants
Respectively and accurately transfer-take 0.01 mL, 0.05 mL, 0.10 mL, 0.30 mL and 0.60 mL of
the standard intermediate solution (100 mg/L) into five 10 mL volumetric flasks. Use 4%
(volume fraction) acetic acid solution to reach a constant volume. Thus, standard working
solutions with a mass concentration of 0.10 mg/L, 0.50 mg/L, 1.00 mg/L, 3.00 mg/L and 6.00
mg/L are obtained.
The preparation of standard working solutions of water, 10% (volume fraction) ethanol solution,
20% (volume fraction) ethanol solution, and 50% (volume fraction) ethanol solution is carried
out in accordance with the preparation method of 4% (volume fraction) acetic acid solution
standard working solution.
17.4.5 Standard series of working solutions of oil and fat food simulants
Respectively and accurately weigh-take 5.0 g (accurate to 0.01 g) of olive oil into 5 stoppered
glass centrifuge tubes, and respectively add 0.015 mL, 0.05 mL, 0.10 mL, 0.15 mL and 0.30
mL of the standard intermediate solution (100 mg/L). Conduct vortex mixing to respectively
obtain standard working solutions of 0.30 mg/kg, 1.00 mg/kg, 2.00 mg/kg, 3.00 mg/kg and 6.00
mg/kg.
17.4.6 Standard series of working solutions of isooctane
Respectively and accurately transfer-take 0.10 mL, 0.50 mL, 1.00 mL, 3.00 mL and 6.00 mL of
the standard intermediate solution (10 mg/L) into five 10 mL volumetric flasks and use 80%
methanol solution to reach a constant volume. Thus, standard working solutions with a mass
concentration of 0.10 mg/L, 0.50 mg/L, 1.00 mg/L, 3.00 mg/L and 6.00 mg/L are respectively
obtained.
17.4.7 Standard series of working solutions of 95% (volume fraction) ethanol
Respectively and accurately transfer-take 0.02 mL, 0.10 mL, 0.20 mL, 0.40 mL and 0.60 mL of
the standard intermediate solution (100 mg/L) into five 10 mL volumetric flasks and use 95%
(volume fraction) ethanol solution to reach a constant volume. Thus, standard working solutions
with a mass concentration of 0.20 mg/L, 1.00 mg/L, 2.00 mg/L, 4.00 mg/L and 6.00 mg/L are
respectively obtained.
17.5 Materials
17.5.1 Hydrophilic PTFE filter membrane: polytetrafluoroethylene (PTFE), with a pore size of
0.45 m.
17.5.2 Nylon filter membrane: with a pore size of 0.45 m.
18 Instruments and Equipment
18.1 Liquid chromatograph: equipped with a fluorescence detector.
18.2 Vortex oscillator.
18.3 Analytical balance: with a division value of 0.01 g and 0.1 mg, respectively..
18.4 Centrifuge: with a rotating speed 4,000 r/min.
18.5 Pipette: with a measuring range of 100 L, 1 mL and 5 mL, respectively.
19 Analytical Procedures
19.1 Preparation of Test Solutions
19.1.1 Migration test
Food contact materials and products shall be subject to migration test in accordance with the
requirements of GB 31604.1 and GB 5009.156. If the soaking solution obtained from the
migration test cannot be immediately tested, it can be stored at room temperature or a
refrigerator at 4 C, with a storage period of no more than 3 days. If the next step of test is
carried out, the soaking solution shall recover to room temperature before use.
19.1.2 Treatment of soaking solutions
19.1.2.1 Preparation of water-based food simulant test solutions
Transfer-take 1 mL ~ 2 mL of the soaking solution obtained in the migration test, filter it through
the hydrophilic PTFE filter membrane and reserve it for testing.
19.1.2.2 Preparation of oil and fat food simulant test solutions
Accurately weigh-take 5.0 g (accurate to 0.01 g) of the olive oil soaking solution obtained from
the migration test into a stoppered glass centrifuge tube, accurately transfer-take 10.0 mL of 80%
methanol solution into the centrifuge tube; at 2,500 r/min, conduct vortex oscillation for 5 min;
at 4,000 r/min, conduct centrifugation for 5 min; take the upper layer of solution, filter it through
the nylon filter membrane, and reserve it for later testing.
19.1.2.3 Treatment of isooctane (chemical alternative solvent) soaking solution
Accurately transfer-take 5.00 mL of the isooctane soaking solution obtained from the migration
test into a stoppered glass centrifuge tube, and accurately transfer-take 5.00 mL of 80%
methanol solution into the centrifuge tube. At 1,500 r/min, conduct vortex oscillation for 1 min;
at 4,000 r/min, conduct centrifugation for 5 min; take the lower layer of solution, filter it through
the nylon filter membrane, and reserve it for later testing.
19.1.2.4 Preparation of 95% (volume fraction) ethanol (chemical alternative solvent)
soaking solution
Accurately transfer-take 5.00 mL of the 95% (volume fraction) ethanol soaking solution
obtained from the migration test into a stoppered glass centrifuge tube, accurately transfer-take
5.00 mL of water into the centrifuge tube, and evenly mix it; filter it through the hydrophilic
PTFE filter membrane, and reserve it for later testing.
19.1.2.5 Preparation of blank test solution
In accordance with 19.1.1 and 19.1.2, handle the food simulants and chemical alternative
solvents that are not in contact with the food contact materials and products.
c---the content of phenol in the specimen soaking solution, expressed in (mg/L) or (mg/kg);
c0---the content of phenol in the blank soaking solution, expressed in (mg/L) or (mg/kg);
V---the volume or mass of the specimen soaking solution, expressed in (L) or (kg);
S---the area of contact between the specimen and the soaking solution in the migration test,
expressed in (dm2);
S0---the area of the sealed product that comes into contact with food during actual use, expressed
in (dm2);
V3---the mass of the food actually contained in the container of the sealed product, expressed in
(kg); the volume of various liquid foods is converted into the corresponding mass based on a
density of 1 kg/L.
The result shall retain 2 significant figures.
20.3 Calculation of Specific Phenol Migration in Food Contact Materials and
Products of Sealed Products (expressed in mg/PCS)
When the specific phenol migration in food contact materials and products of sealed products
is expressed in mg/PCS, calculate in accordance with Formula (7). It is necessary to indicate
the migration test method used and the contact area between a single sealed product and the
food simulant in the migration test.
Where,
X6---the specific migration of phenol, expressed in (mg/PCS);
c---the content of phenol in the specimen soaking solution, expressed in (mg/L) or (mg/kg);
c0---the content of phenol in the blank soaking solution, expressed in (mg/L) or (mg/kg);
V---the volume or mass of the specimen soaking solution, expressed in (L) or (kg);
n---the number of sealed products for soaking, expressed in (PCS).
The result shall retain 2 significant figures.
21 Precision
The absolute difference between the results of two independent determinations obtained under
repeatability conditions shall not exceed 10% of the arithmetic mean.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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