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GB 31604.8-2021 (GB31604.8-2021)

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GB 31604.8-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
Food safety national standard - Food contact materials and products - Determination of total migration
ISSUED ON: SEPTEMBER 07, 2021
IMPLEMENTED ON: MARCH 07, 2022
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 One -- Determination of overall migration in water-based food simulants,
chemical alternative solvents ... 4 
2 Principle ... 4 
3 Reagents and materials ... 4 
4 Instruments and equipment... 5 
5 Analysis steps ... 5 
6 Expression of analysis results ... 7 
7 Precision ... 11 
Part Two -- Determination of total migration in olive oil ... 11 
8 Principle ... 11 
9 Reagents and materials ... 12 
10 Instruments and equipment... 14 
11 Analysis steps ... 14 
12 Expression of analysis results ... 20 
13 Precision ... 23 
Annex A Suitability Judgment ... 25 
Annex B Confirmation of moisture-sensitive specimens and adjustment of
moisture content -- Vacuum drying method ... 26 
Annex C Confirmation of moisture-sensitive specimens and adjustment of
moisture content -- Constant humidity method ... 28 
Annex D Typical chromatogram ... 30 
National Food Safety Standard - Food Contact
Materials and Articles Determination of Overall
Migration
1 Scope
This Standard specifies the methods for determination of overall migration for
food contact materials and articles.
This Standard is applicable to the determination of overall migration for food
contact materials and articles.
Part One -- Determination of overall migration in
water-based food simulants, chemical alternative
solvents
2 Principle
The specimen uses water-based food simulants and chemical alternative
solvents [such as n-hexane, isooctane, 95% (volume fraction) ethanol solution,
n-heptane]. Perform migration test under selected migration test conditions.
Evaporate and dry the soaking liquid obtained from the migration test. After
deducting the corresponding blanks, the total amount of all non-volatile
substances migrated from the specimen to water-based food simulants and
chemical substitute solvents is obtained.
3 Reagents and materials
Unless otherwise specified, the reagents used in this method are analytically
pure, and the water is grade two water specified in GB/T 6682.
3.1 Reagents
3.1.1 Absolute ethanol (C2H6O).
3.1.2 Acetic acid (C2H4O2).
chemical substitute solvents
Wash and drain the evaporating dish before use. Dry for 2h in a 100°C±5°C
electric heating constant temperature drying oven. Then weigh it after cooling
for 0.5h in a desiccator. Repeat drying, cooling, and weighing until constant
weight (that is, the difference in mass between the two weighings does not
exceed 0.5mg). The last weighed mass is the mass of the empty evaporating
dish.
Take an empty evaporating dish with constant weight. Add 200mL of the
soaking solution obtained from the migration test to it (if the evaporating dish
specification is < 200mL, it needs to be evaporated to dryness in batches).
Place it in a water bath that is not higher than the boiling point of each soaking
solution 10°C and evaporate to dryness. Use filter paper or dust-free wipes to
absorb the water droplets on the bottom of the evaporating dish (no paper fibers
remain at the bottom of the evaporating dish). Then put the evaporating dish in
a 100°C±5°C electric heating constant temperature drying box to dry for 2h.
Take it out. Cool in a desiccator for 0.5h. Weigh it. Repeat drying, cooling, and
weighing until constant weight. The last weighed mass is the mass of the
evaporating dish with specimen evaporation residue. The mass of the
evaporating dish with the evaporation residue of the specimen minus the mass
of the empty evaporating dish is the mass of the soaking solution residue for
the specimen determination.
5.3 Determination of trichloromethane extract
The determination steps are applicable to food contact materials and articles
that require the detection of chloroform extracts in the product standard.
Add 20mL of chloroform to the residue obtained in 5.2. Wetting the residue. Use
the filter paper to filter. Collect the filtrate into an evaporating dish with constant
weight. Then use 20mL of chloroform to extract the residue twice respectively.
Use a little chloroform to rinse the filter paper. The filtrate is incorporated into
the evaporating dish. Steam to dry according to step 5.2. Obtain the mass of
the residue extracted with chloroform from the soaking solution for the
specimen determination.
5.4 Blank test
Treat water-based food simulants, chemical alternative solvents, and
chloroform that are not in contact with food contact materials and articles
according to 5.1, 5.2, and 5.3. Obtain the residue mass of the blank soaking
solution and the residue mass of the blank soaking solution extracted with
chloroform.
X6 - Total migration of product contact materials and articles after chloroform
extraction, in milligrams per square decimeter (mg/dm2);
F - Under foreseeable use cases, the ratio between the area of food contact
materials and articles that actually contact the food and the mass of the food
(S/V), in square decimeter per kilogram (dm2/kg). The density of various liquid
foods is usually calculated as 1kg/L. Convert its volume into the corresponding
food mass. When the actual S/V is known, F is the maximum S/V under the
foreseeable use case. When the actual S/V is unknown, F uses 6dm2/kg, that
is, 6dm2 of food contact materials and articles contact 1kg of food.
6.3 Correction of results
When GB 31604.1 stipulates the correction factor for fat-containing food
simulants, the determination results of the chemical solvent substitution test
shall be divided by the corresponding correction factor.
6.4 Expression of results
The calculation result of the total migration amount is expressed as the
arithmetic mean of the two parallel determination results obtained under the
repeatability condition. The calculation result is accurate to one decimal place.
7 Precision
When the total migration result is ≤ 10.0mg/dm2 or 60.0mg/kg, the difference
between the two independent determination results obtained under
repeatability conditions and the arithmetic mean shall not exceed 1.0mg/dm2 or
6.0mg/kg. The determination result after applying the correction factor shall also
meet this requirement.
When the total migration result is > 10.0mg/dm2 or 60.0mg/kg, the difference
between the two independent determination results obtained under
repeatability conditions and the arithmetic mean shall not exceed 10% of the
arithmetic mean. The determination result after applying the correction factor
shall also meet this requirement.
Part Two -- Determination of total migration in olive oil
8 Principle
The specimen uses olive oil as a food simulant. The migration test is carried
out under the selected conditions. The total migration is determined by the
(accurate to 0.1g) potassium hydroxide and dissolve it in 500mL of methanol.
Mix well.
9.2.3 Saturated sodium sulfate solution: Weigh 50g (accurate to 0.1g) of
anhydrous sodium sulfate in a 250mL beaker. Add 100mL of water on the
electric hot plate and boil to dissolve. After cooling to room temperature, use a
funnel equipped with qualitative filter paper to filter into a breaker.
9.2.4 Sulfuric acid solution (430g/L): Weigh 215g (accurate to 0.1g) of sulfuric
acid. Add slowly to a beaker containing about 300mL of water. Stir while adding.
After the solution has cooled to room temperature, transfer to a 500mL
volumetric flask. Wash the beaker with a small amount of water 2 to 3 times.
Combine the washing liquid into the volumetric flask. Use water to set volume.
Prepare it when it is required. When the temperature is 20°C±5°C, the solution
is placed in a closed moisture content adjustment container. Maintain a
moisture content adjustment environment with a relative humidity of 50% ± 5%.
9.2.5 Sulfuric acid solution (70g/L): Weigh 35g (accurate to 0.1g) of sulfuric acid.
Add slowly to a beaker containing about 300mL of water. Stir while adding. After
the solution is cooled to room temperature, transfer to a 500mL volumetric flask.
Wash the beaker with a small amount of water 2 to 3 times. Combine the
washing liquid into the volumetric flask. Use water to set volume. Prepare it
when it is required. When the temperature is 20°C±5°C, the solution is placed
in a closed moisture content adjustment container. Maintain a moisture content
adjustment environment with a relative humidity of 80% ± 5%.
9.3 Standard product
Heptadecanoic acid triglyceride (C54H104O6, CAS number: 2438-40-6): Purity
≥98%, or standard material certified by the country and awarded with a standard
material certificate.
9.4 Preparation of standard solution
9.4.1 Internal standard solution (2.0mg/mL)
Accurately weigh 1.0g (accurate to 0.1mg) of heptadecanoic acid triglyceride.
Place in a 100mL beaker. Add cyclohexane to dissolve. Transfer to a 500mL
volumetric flask. Wash the beaker 3 times with cyclohexane. The washing liquid
is combined into the volumetric flask. Use cyclohexane to set volume. Store in
a refrigerator at 4°C. The validity period is 1 month.
9.4.2 Olive oil standard stock solution (100mg/mL)
Weigh 5.0g of blank olive oil obtained from migration test (accurate to 0.1mg).
Place in a 50mL beaker. Add n-heptane to dissolve. Transfer to a 50mL
volumetric flask. Wash the beaker 3 times with n-heptane. The washing liquid
multiple products. The number of specimens is determined according to the
following purposes:
a) Migration test: At least 3 specimens of disposable products; At least 3
specimens per set of specimens for repeated use of articles;
b) Volatile matter determination: 2 specimens;
c) Suitability judgment (see Annex A): 2 specimens;
d) Surface area determination: 1 specimen;
e) Confirmation of moisture sensitivity: 2 specimens.
11.2 Suitability Judgment
Take 2 specimens to determine the suitability of the method according to the
steps described in Annex A. If the previous test has confirmed the suitability of
the method, it can omit the steps in Annex A.
11.3 Weighing of the initial mass of the specimen
Determine whether the specimen is moisture sensitive according to the steps
described in Annex B or Annex C. If the previous test has confirmed that the
specimen is a non-moisture-sensitive specimen, it can omit the steps in Annex
B or Annex C.
If the specimen is a non-moisture sensitive specimen, directly weigh the initial
mass. If the specimen is moisture sensitive, after adjusting the moisture content
according to the steps described in the relevant appendix, the initial mass of
the specimen is obtained. If the specimen adopts the steps described in Annex
C to adjust the moisture content and cannot reach a constant weight within 5d,
use Annex B to adjust the moisture content.
11.4 Migration test
The migration test of food contact materials and articles shall be conducted in
accordance with the requirements of GB 31604.1 and GB 5009.156. For
reusable articles, test on 3 sets of specimens prepared from the same batch of
test specimens. Each group of specimens differs only in the migration test time.
The migration test time of the first group of specimens is the migration test time
determined according to the requirements of relevant standards. The migration
test time of the second group of specimens is twice that of the first group. The
migration test time of the third group of specimens is 3 times that of the first
group. The number of parallel specimens for migration test should meet the
requirements of 11.1a).
11.5 Weighing the final mass of the specimen
Remove the specimen from the olive oil as soon as possible after the migration
test is completed. Cool to room temperature. Place the specimen between two
filter papers or dust-free wipes. Lightly press it. Suck off the olive oil on the
surface of the specimen. Repeat the pressing steps until no oil spots appear on
the paper. No paper fibers shall remain on the surface of the specimen. For
non-moisture sensitive specimens, directly weigh the final mass. After adjusting
the moisture content of the moisture-sensitive specimen in the same way as in
11.3, weigh the final mass.
11.6 Determination of the volatile matter of the specimen
Prepare 2 parallel specimens according to the steps described in 11.1. Obtain
the initial mass of the specimen according to the steps described in 11.3. Except
that no olive oil is added, carry out the migration test according to the steps
described in 11.4. For non-moisture sensitive specimens, directly weigh the
final mass. After adjusting the moisture content of the moisture-sensitive
specimen in the same way as in 11.3, weigh the final mass.
The mass of volatile matter per unit area of each parallel specimen is calculated
by dividing the difference between the initial mass and the final mass of the
specimen by the corresponding sampling area. If the moisture content of the
specimen is adjusted according to the steps described in Annex B, this step can
be omitted.
11.7 Blank test
Follow the steps in 11.4 to dispose of olive oil that is not in contact with food
contact materials and articles. Use it to prepare olive oil standard stock solution.
11.8 Determination of the absorption of olive oil by the specimen
11.8.1 The first extraction of olive oil
The extraction solvent is selected according to the main polymer material of the
food contact surface of the food contact material and the article. When the main
material is the specimen of non-polar polymer (such as polyethylene,
polypropylene), use N-pentane. When the main material is a specimen of polar
polymer (such as polyethylene terephthalate), use a mixed solution of n-
pentane-ethanol (95+5).
Add 10.0mL of internal standard solution (2.0mg/mL) and extraction solvent to
the collection bottle of the Soxhlet extractor. Add zeolite or glass beads to
prevent explosion boiling. Cut the specimen into suitable size. Wrap it with
qualitative filter paper or put it in a glass fiber sleeve barrel (including specimen
debris, particles generated during the cutting process). Put into Soxhlet
extractor. Perform reflux extraction for 7h~8h. Cycle at least 6 times per hour.
Make sure that the specimen is completely immersed in the solvent and kept
column, 30.0m×250μm×0.25μm, or analytical column with similar
performance;
b) Carrier gas: Nitrogen, flow rate is 1.0mL/min;
c) Inlet temperature: 280°C;
d) Injection mode: split injection, split ratio is 40:1;
e) Injection volume: 1.0μL;
f) Heating program: initial temperature is 180°C, heating up to 240°C at
20°C/min, and then heating up to 300°C at 80°C /min;
g) Detector temperature: 250°C;
h) Hydrogen flow rate: 35mL/min;
i) Air flow rate: 460mL/min;
j) Makeup gas: nitrogen, flow rate 25mL/min.
11.8.5.1.2 Polar column reference conditions
a) Chromatographic column: Polyethylene glycol quartz capillary column,
30.0m×250μm×0.25μm, or analytical column with similar performance;
b) Carrier gas: nitrogen, flow rate 1.0mL/min;
c) Inlet temperature: 220°C;
d) Injection mode: split injection, split ratio is 10:1;
e) Injection volume: 1.0μL;
f) Heating program: the initial temperature is 120°C, keep for 1min, and heat
to 220°C at 20°C/min, keep for 10min;
g) Detector temperature: 250°C;
h) Hydrogen flow rate: 30mL/min;
i) Air flow rate: 350mL/min;
j) Makeup gas: Nitrogen, flow rate is 20mL/min.
11.8.5.2 Production of standard curve
Accurately and respectively pipette 0.02mL, 0.10mL, 0.20mL, 0.50mL, 1.0mL,
2.0mL, 5.0mL of olive oil standard stock solution (100mg/mL) into seven 50mL
flasks. Then add 10.0mL of internal standard solution (2.0mg/mL) to each flask.
Spin to dry the solvent. Perform methyl esterification according to 11.8.2.2 to
obtain the test solution. The mass of the corresponding olive oil in each liquid
to be tested is calculated as 2.0mg, 10mg, 20mg, 50mg, 100mg, 200mg, and
500mg, respectively. Respectively draw the above-mentioned series of
standard test liquids and inject them into the gas chromatograph. Determine
according to 11.8.5.1 instrument reference conditions. See Annex D for a typical
chromatogram.
Use internal standard method to draw standard curve. The peak area ratio of
the fatty acid methyl ester in the standard test solution to the internal standard
peak is the ordinate. The corresponding olive oil mass is the abscissa. When
using a polar column, the ordinate is the ratio of the peak area of all fatty acid
methyl esters (C16:0, C16:1, C18:0, C18:1, C18:2) of olive oil to the peak area of the
internal standard. When a non-polar column is used, the ordinate is the ratio of
the sum of the C16 and C18 peak areas of olive oil to the peak area of the internal
standard.
When the migration test temperature is ≥100°C, or the migration test time is
≥10d, the standard curve is only suitable for the quantitative analysis of
specimens in the same detection period and the same migration test conditions
as the blank olive oil for migration test. Under other migration test conditions,
when the olive oil used is the same production batch, the standard curves under
different migration test conditions can replace each other.
11.8.5.3 Determination of the mass of olive oil absorbed by the specimen
According to the instrument reference conditions in 11.8.5.1, the test specimen
(11.8.2~11.8.4) is injected into the gas chromatograph for determination.
Calculate the mass of olive oil in the test specimen according to the standard
curve.
The total mass of olive oil absorbed by the specimen is the sum of the mass of
olive oil in each liquid to be tested obtained from 11.8.1 to 11.8.4.
11.8.5.4 Determination of the change in the composition of the olive oil
absorbed by the specimen
When using a polar column, draw a standard curve based on the ratio of C16:0
to the peak area of the internal standard to the mass of olive oil. Calculate the
mass of olive oil extracted by the specimen each time. Draw a standard curve
based on the ratio of C18:1 to the peak area of the internal standard to the mass
of olive oil. Calculate the mass of olive oil extracted by the specimen each time.
The difference between the mass of the olive oil in the same test specimen
calculated by the two standard curves shall be ≤ 2mg/dm2. Otherwise, olive oil
is not suitable as the oily food simulant for this specimen. When using a non-
Where,
X12 - Total migration volume of food contact materials and articles of sealed
products, in milligrams per piece (mg/piece);
m5 - Initial mass of the specimen before the migration test, in milligrams (mg);
m6 - Final mass of the specimen after the migration test, in milligrams (mg);
m7 - Total mass of olive oil absorbed by the specimen after the migration test,
in milligrams (mg);
Xb - Average value of volatile matter per unit area of 2 specimens before and
after migration test, in milligrams per square decimeter (mg/dm2);
S - Area where the specimen is in contact with the olive oil, in square decimeters
(dm2);
n - Number of soaked and sealed products, in pieces.
12.4 Correction of results
When GB 31604.1 specifies the correction factor for fat-containing food
simulants, the determination results shall be divided by the corresponding
correction factor.
12.5 Expression of results
The calculation result of total migration is the arithmetic mean of 3 parallel
determination results. The calculation result is accurate to one decimal place.
12.6 Reusable products
For reusable products, the total migration of the three groups of specimens is
calculated according to 12.5, which are marked as M1, M2, and M3 in turn. The
total migration in the third cycle (i.e., M3-M2) is regarded as the result of the third
migration test. The total migration volume in the third cycle shall not be higher
than the total migration volume in the first cycle (i.e., M1) and the total migration
volume in the second cycle (i.e., M2-M1).
13 Precision
When the total migration result is ≤ 10.0mg/dm2 or 60.0mg/kg, the difference
between the three independent determination results obtained under
repeatability conditions and the arithmetic mean shall not exceed 3.0mg/dm2 or
20.0mg/kg. The determination result after applying the correction factor shall
also meet this requirement.
Annex A
Suitability Judgment
A.1 Application scope
This procedure is suitable for confirming whether the method described in Part
2 is suitable for the determination of the total migration of the test specimen in
olive oil.
A.2 Steps
A.2.1 Standard solution determination: Weigh 45mg~55mg of (accurate to
0.1mg) olive oil. Dissolve in n-heptane and transfer to a 10mL volumetric flask.
Set volume and mix well. Accurately pipette 0.50mL of solution into a 50 mL
flask. Then add 10.0mL of internal standard solution (2.0mg/mL) to the flask.
Spin the solvent to dryness. Obtain the test solution according to the steps
described in 11.8.2.2. Measure by gas chromatography.
A.2.2 Specimen solution determination: Take 2 specimens prepared according
to 11.1. Except without adding the internal standard solution, extract the
specimen according to the steps described in 11.8.1. Obtain the test solution
according to the steps described in 11.8.2. Measure by gas chromatography.
A.3 Conclusion
Take the sum of the peak areas of all fatty acid methyl esters in A.2.1 as the
ordinate. Take the mass of the corresponding olive oil as the abscissa. Connect
with the origin to draw a standard curve. Quantify the peaks appearing in the
chromatogram of the specimen extract in A.2.2. If the mass of fatty acid methyl
ester interference in the specimen extract is ≥2mg/dm2, the method described
in Part Two is not suitable for the determination of the total migration of the test
specimen in olive oil.
If a polar column is used, and it is found that the specimen extract interferes
with the C18:0 and/or C18:2 peaks, but does not interfere with other fatty acid
methyl ester chromatographic peaks, then it can be considered that the method
described in Part Two is suitable for the determination of the total migration
amount of the test specimen in olive oil. When drawing a standard curve using
a polar column according to 11.8.5.2, the ratio of the total peak area of the
undisturbed fatty acid methyl ester chromatogram to the peak area of the
internal standard is selected as the ordinate.
......
(Above excerpt was released on 2021-10-02, modified on 2022-02-20, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GB31604.8-2021