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National food safety standard - Food contact materials and products - Determination of migration of benzoic acid, phthalic acid and trimellitic acid in food
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| GB 31604.21-2016 | English | 85 |
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National food safety standard - Food contact materials and articles - Determination of migration of terephthalic acid
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GB 31604.21-2025: National food safety standard - Food contact materials and products - Determination of migration of benzoic acid, phthalic acid and trimellitic acid in food
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GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard - Food contact materials and
articles - Determination of migration amount of benzoic
acid, benzenedicarboxylic acid and benzenetricarboxylic
acid
Issued on: SEPTEMBER 02, 2025
Implemented on: MARCH 02, 2026
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
2 Principle... 4
3 Reagents and materials... 4
4 Instruments and equipment... 7
5 Analytical procedure... 8
6 Expression of analytical results... 10
7 Precision... 12
8 Others... 13
Annex A Information on benzoic acid, benzenedicarboxylic, and benzenetricarboxylic
acid standard substances... 14
Annex B Liquid chromatography reference chromatograms of benzoic acid,
benzenedicarboxylic acid, and benzenetricarboxylic acid... 15
National food safety standard - Food contact materials and
articles - Determination of migration amount of benzoic
acid, benzenedicarboxylic acid and benzenetricarboxylic
acid
1 Scope
This Standard specifies the liquid chromatography method for the determination of
migration amount of benzoic acid, 1,2-benzenedicarboxylic acid (also known as
phthalic acid), 1,3-benzenedicarboxylic acid (also known as isophthalic acid), 1,4-
benzenedicarboxylic acid (also known as terephthalic acid), 1,3,5-benzenetricarboxylic
acid (also known as trimesic acid), 1,2,4-benzenetricarboxylic acid (also known as
trimellitic acid), and 1,2,3-benzenetricarboxylic acid (also known as hemimellitic acid)
in food contact materials and articles.
This Standard applies to the determination of migration amount of benzoic acid,
phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, trimellitic acid, and
hemimellitic acid in food contact plastic materials and articles, food contact paper and
paperboard materials and articles, adhesives for food contact materials and articles, and
paintings and coatings for food contact.
2 Principle
After migration tests on food contact materials and articles according to GB 31604.1
and GB 5009.156, the target analytes in olive oil and isooctane soaking solutions are
extracted with 50 % (volume fraction) ethanol solution or acetonitrile solution (5+1);
the ethanol volume fraction is diluted by 95 % (volume fraction) ethanol soaking
solution to below 50 %; other soaking solutions are directly injected for determination.
The target analytes are separated by liquid chromatography, determined by ultraviolet
detector or diode array detector, and quantified using the external standard method.
3 Reagents and materials
Unless otherwise specified, all reagents used in this method are of analytical grade, and
the water is grade 1 water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Glacial acetic acid (C2H4O2).
to the mark with water, and mix well. The mass concentrations of trimesic acid in the
obtained standard series working solutions are 0.031 mg/L, 0.10 mg/L, 0.25 mg/L, 0.50
mg/L, 0.75 mg/L, and 1.0 mg/L, respectively. The mass concentrations of the other 6
types of target analytes are 0.375 mg/L, 1.2 mg/L, 3.0 mg/L, 6.0 mg/L, 9.0 mg/L, and
12 mg/L, respectively. Prepare fresh before use. When the mass concentrations of
benzoic acid and phthalic acid in the sample solution exceed the above linear range,
accurately transfer 1.0 mL, 2.0 mL, 3.0 mL, 4.0 mL, 5.0 mL, and 6.0 mL of the mixed
standard intermediate solution C into six 10 mL volumetric flasks, respectively, dilute
to the mark with water, and mix well. The mass concentrations of the 7 types of target
analytes in the obtained standard series working solutions are 10 mg/L, 20 mg/L, 30
mg/L, 40 mg/L, 50 mg/L, and 60 mg/L, respectively. Prepare fresh before use.
3.4.5.2 Mixed standard working solution series E (applicable to quantitative
analysis of target analytes in other food simulants and chemical substitute solvents)
Accurately transfer 0.10 mL, 0.125 mL, 0.40 mL, 1.0 mL, 2.0 mL, 3.0 mL, and 4.0 mL
of mixed standard intermediate solution B into seven 10 mL volumetric flasks, dilute
to the mark with water, and mix well. The mass concentrations of trimesic acid in the
obtained standard series working solutions are 0.025 mg/L, 0.031 mg/L, 0.10 mg/L,
0.25 mg/L, 0.50 mg/L, 0.75 mg/L, and 1.0 mg/L, respectively, and the mass
concentrations of the other 6 types of target analytes are 0.30 mg/L, 0.375 mg/L, 1.2
mg/L, 3.0 mg/L, 6.0 mg/L, 9.0 mg/L, and 12.0 mg/L, respectively. Prepare fresh before
use. When the mass concentrations of benzoic acid and phthalic acid in the sample
solution exceed the above linear range, accurately transfer 1.0 mL, 2.0 mL, 3.0 mL, 4.0
mL, 5.0 mL, and 6.0 mL of the mixed standard intermediate solution C into six 10 mL
volumetric flasks, respectively, dilute to the mark with water, and mix well. The mass
concentrations of the 7 types of target analytes in the obtained standard series working
solutions are 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L, 50 mg/L, and 60 mg/L, respectively.
Prepare fresh before use.
3.5 Materials
Filter membrane. Hydrophilic polytetrafluoroethylene, pore size 0.45 μm.
4 Instruments and equipment
4.1 Liquid chromatograph. Equipped with a UV detector or diode array detector.
4.2 Water bath shaker.
4.3 Vortex shaker.
4.4 Balance. Sensitivities of 0.01 g and 0.1 mg, respectively.
4.5 Centrifuge. Speed ≥ 3000 r/min.
4.6 Pipettes. Capacities of 100 μL, 1 mL, and 5 mL, respectively.
4.7 Rotary evaporator or nitrogen evaporator.
5 Analytical procedure
5.1 Migration test
Food contact materials and articles shall undergo 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 tested immediately, it can be stored at 0 ℃ ~ 4 ℃ protected
from light for no more than 3 days. If further test is to be performed, the soaking solution
shall be brought back to room temperature before use.
5.2 Treatment of soaking solution
5.2.1 Treatment of olive oil soaking solution
5.2.1.1 Benzenedicarboxylic acid and benzenetricarboxylic acid test solution.
Accurately weigh 5.0 g (to the nearest 0.01 g) of the olive oil soaking solution obtained
from the migration test into a 25 mL stoppered glass centrifuge tube, add 5.00 mL of n-
heptane and 4.00 mL of 50 % (volume fraction) ethanol solution sequentially, vortex at
1500 r/min for 15 min, centrifuge at 3000 r/min for 10 min, and collect the ethanol
solution on the lower layer and filter through a filter membrane, for later test.
5.2.1.2 Benzoic acid test solution. Accurately weigh 10.0 g (to the nearest 0.01 g) of
the olive oil soaking solution obtained from the migration test into a 25 mL stoppered
glass centrifuge tube, add 4.00 mL of acetonitrile solution (5+1), vortex at 1500 r/min
for 15 min, centrifuge at 3000 r/min for 10 min, take approximately 2 mL of the
supernatant and filter through a filter membrane, accurately transfer 1.00 mL of the
filtrate and add 1.00 mL of water, and mix well, for later test.
5.2.2 Treatment of isooctane soaking solution
5.2.2.1 Benzenedicarboxylic acid and benzenetricarboxylic acid test solution.
Accurately transfer 5.00 mL of the isooctane soaking solution obtained from the
migration test into a 25 mL stoppered glass centrifuge tube, add 4.00 mL of 50 %
(volume fraction) ethanol solution, vortex at 1500 r/min for 15 min, centrifuge at 3000
r/min for 10 min, and collect the ethanol solution on the lower layer and filter through
a filter membrane, for later test.
5.2.2.2 Benzoic acid test solution. Accurately transfer 10.0 mL of the isooctane soaking
solution obtained from the migration test to a 25 mL stoppered glass centrifuge tube,
add 4.00 mL of acetonitrile solution (5+1), vortex at 1500 r/min for 15 min, centrifuge
at 3000 r/min for 10 min, take approximately 2 mL of the lower layer solution and filter
5.4.6 UV detector or diode detector. For trimesic acid, trimellitic acid, hemimellitic
acid, phthalic acid, and isophthalic acid, the detection wavelength is 214 nm; for
benzoic acid and terephthalic acid, the detection wavelength is 230 nm. The acquisition
time for each detection wavelength is determined based on the retention time of each
target analyte.
5.5 Plotting of standard curve
Determine the mixed standard working solution according to the instrument reference
conditions listed in 5.4, to obtain the chromatograms of the target analytes in the
corresponding standard working solution. A standard curve is plotted with the mass
concentration of the target analyte in the standard working solution as the abscissa and
the corresponding chromatographic peak area as the ordinate to obtain the linear
equation. See Figure B.1 in Annex B for the chromatogram of the standard working
solution.
5.6 Determination of test solutions
5.6.1 Qualitative determination
Determine the sample test solution (5.2) and the mixed standard working solution (3.4.5)
according to the instrument reference conditions listed in 5.4.If the retention time of
the chromatographic peak of the analyte in the test solution deviates from the
chromatographic peak of the same target analyte in the standard working solution
within ±0.1 min, it is determined that the sample contains the corresponding analyte.
5.6.2 Quantitative determination
Determine the sample test solution (5.2) and the blank solution (5.3) according to the
instrument reference conditions listed in 5.4, to obtain the peak area of each target
analyte. Read the content ρ and ρ0 of each analyte in the sample test solution and the
blank solution from the corresponding standard curve, the content ρ0 of each target
analyte in the blank solution shall not be higher than the method detection limit
concentration.
6 Expression of analytical results
6.1 Calculation of conversion factor for soaking solution treatment process
The conversion factor, f, for the olive oil and isooctane soaking solution treatment
process is calculated according to formula (1).
where.
f - the conversion factor for the pretreatment process of soaking solution;
V0 - the volume of the extraction solution, in liters (L);
n - the dilution factor of the extraction solution, where the dilution factor for benzoic
acid is 2, and for all others it is 1;
m - the sampling volume of the soaking solution, in liters (L) or kilograms (kg).
6.2 Calculation of specific migration amounts of benzoic acid, benzenedicarboxylic
acid, and benzenetricarboxylic acid in food contact materials and articles
(expressed in mg/kg)
When the specific migration amount of benzoic acid, benzenedicarboxylic acid, and
benzenetricarboxylic acid in food contact materials and articles is expressed in mg/kg,
it is calculated according to formula (2).
where.
X1 - the specific migration amount of the target analyte, in milligrams per kilogram
(mg/kg);
ρ - the content of the target analyte in the sample solution, in milligrams per liter
(mg/L);
ρ0 - the content of the target analyte in the blank solution, in milligrams per liter
(mg/L);
f - the conversion factor for the pretreatment process of the target analyte in the
soaking solution. For olive oil and isooctane soaking solutions, f is calculated
according to formula (1); for other soaking solutions, no conversion is involved, and
the value of f is represented by 1;
V - the volume of the sample soaking solution in the migration test, in liters (L);
S - the area of contact between the sample and the soaking solution in the migration
test, in square decimeters (dm2);
F - the ratio of the actual contact area of food contact materials and articles to the
volume (mass) of food under foreseeable use (hereinafter referred to as actual S/V),
in square decimeters per kilogram (dm2/kg). For various liquid foods, the density is
usually calculated as 1 kg/L, and the volume is converted to mass to calculate the
actual S/V. When the actual S/V is known, F is the maximum S/V under foreseeable
use; when the actual S/V is unknown, F is taken as 6 dm2/kg, i.e., 6 dm2 of food
contact materials and articles contacting 1 kg of food.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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