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GB 31604.56-2023 English PDF (GB31604.56-2023)

GB 31604.56-2023 English PDF (GB31604.56-2023)

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GB 31604.56-2023: National food safety standard - Food contact materials and products - Determination of laurolactam migration

This Standard specifies the method for determining the migration amount of laurolactam in food contact materials and products. This Standard is applicable to the determination of the migration amount of laurolactam in polyamide food contact materials and products. Method one -- Liquid chromatography
GB 31604.56-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standards -- Food Contact Materials
and Products -- Determination of Migration Amount of
Laurolactam
ISSUED ON: SEPTEMBER 06, 2023
IMPLEMENTED ON: MARCH 06, 2024
Issued by: National Health Commission of the People's Republic of China; State Administration for Market Regulation.
Table of Contents
1 Scope ... 3
2 Principle ... 3
3 Reagents and materials ... 3
4 Instruments and equipment ... 5
5 Analysis steps ... 5
6 Expression of analysis results ... 7
7 Precision ... 9
8 Other ... 9
9 Principle ... 10
10 Reagents and materials ... 10
11 Instruments and equipment ... 11
12 Analysis steps ... 12
13 Expression of analysis results ... 14
14 Precision ... 14
15 Other ... 14
Annex A Chromatogram of laurolactam standard solution ... 16
National Food Safety Standards -- Food Contact Materials
and Products -- Determination of Migration Amount of
Laurolactam
1 Scope
This Standard specifies the method for determining the migration amount of laurolactam in food contact materials and products.
This Standard is applicable to the determination of the migration amount of laurolactam in polyamide food contact materials and products.
Method one -- Liquid chromatography
2 Principle
After the migration test of food contact materials and products, liquid chromatography is used for testing. Among them, water-based, acidic, ethanol-containing food simulants and chemical alternative solvents of 95% (volume fraction) ethanol are directly injected after filtration. Oil-containing food simulants are filtered and injected after liquid-liquid extraction and solid-phase extraction. The chemical alternative solvent isooctane is injected by filtration after solvent removal and reconstitution with acetonitrile. Use retention time to qualitative determination. Use external standard method for quantification.
3 Reagents and materials
Unless otherwise stated, the reagents used in this method are analytically pure, and the water is grade one water specified in GB/T 6682.
3.1 Reagents
3.1.1 Acidic, ethanol-containing, grease-containing food simulants and chemical alternative solvents: The reagents used are in accordance with the regulations of GB 5009.156.
3.1.2 Acetonitrile (C2H3N): chromatographically pure.
3.1.3 Formic acid (CH2O2): chromatographically pure.
3.1.4 Ammonia water: the mass fraction of ammonia is 25%~28%.
3.1.5 Absolute ethanol (C2H6O).
3.2 Reagent preparation
3.2.1 Formic acid-water solution: measure 5.0 mL of formic acid and 95 mL of water, and mix well.
3.2.2 Ammonia-acetonitrile solution: measure 2.0 mL of ammonia, 8.0 mL of water and 90 mL of acetonitrile, and mix well.
3.2.3 Formic acid-acetonitrile-water solution: measure 20 mL of acetonitrile and 80 mL of water; pipette 100 μL of formic acid; mix well.
3.3 Standard product
Laurolactam standard product (C12H23NO, CAS: 947-04-6, also known as laurolactam or azacyclotridecane-2-one): purity ≥98%, or certified by the country and awarded as a standard material certificate of reference material.
3.4 Standard solution preparation
3.4.1 Laurolactam standard stock solution (1000 mg/L): Weigh 100 mg (accurate to 0.1 mg) of laurolactam standard product. Dissolve in absolute ethanol and adjust the volume to 100 mL. Shake well. Transfer the solution to a brown glass container. Store at 4°C away from light. Validity period is 3 months.
3.4.2 Laurolactam standard intermediate solution (200 mg/L): Pipette 5.0 mL of laurolactam standard stock solution into a 25 mL volumetric flask. Dilute to volume with absolute ethanol. Shake well. Transfer the solution to a brown glass container. Store at 4°C away from light. Validity period is 3 months.
3.4.3 Aqueous, acidic, ethanol-containing food simulants or 95% (volume fraction) ethanol standard working solution: Pipette 0.50 mL, 1.0 mL, 2.5 mL, 5.0 mL, and 10 mL of laurolactam standard intermediate solution into 100 mL volumetric flasks. Dilute to volume with corresponding aqueous, acidic, ethanol-containing food simulant or 95% (volume fraction) ethanol. Prepare standard working solutions with concentrations of 1.0 mg/L, 2.0 mg/L, 5.0 mg/L, 10 mg/L and 20 mg/L, respectively. Prepare when needed.
3.4.4 Standard working solution of oil-containing food simulants: Weigh 2 g (accurate to 0.01 g) of olive oil. Add 20 μL, 30 μL, and 50 μL of laurolactam standard intermediate solution and 20 μL and 40 μL of laurolactam standard stock solution, respectively. Mix well. Prepare standard working solutions with concentrations of 2.0 mg/kg, 3.0 mg/kg, 5.0 mg/kg, 10 mg/kg and 20 mg/kg. Prepare when needed. Before putting on the machine, follow 5.1.3 to process it simultaneously with the soaking solution of oil-containing food simulants.
5.1.3 Fat-containing food simulants test solution
Weigh 2 g (accurate to 0.01 g) of the oil-containing food simulant soaking solution into a 15 mL centrifuge tube. Add 4.0 mL of acetonitrile. Vortex and extract for 10 min. Centrifuge at 8500r/min for 2 min. Take the supernatant. Repeat extraction of soaking liquid once. Combine the two extracts. Concentrate to approximately 0.5 mL with nitrogen blowing at 45°C. After reconstitution with 4.0 mL of formic acid-aqueous solution, transfer to a mixed cation solid-phase extraction cartridge activated with 3.0 mL of acetonitrile, pure water, and formic acid-aqueous solution. Elute with 3.0 mL of formic acid-water solution and acetonitrile in sequence. Elute with 3.0 mL of ammonia- acetonitrile solution. The eluate is blown dry with nitrogen at 45°C. Add 1.0 mL of formic acid-acetonitrile-water solution. Vortex for 1 min to reconstitute. Filter with microporous membrane for measurement.
5.1.4 Isooctane test solution
Pipette 1.0 mL of the isooctane soaking solution obtained from the migration test. Blow dry with nitrogen at 45°C. Add 1.0 mL of acetonitrile to dissolve the residue. Filter with microporous membrane for measurement.
5.1.5 Preparation of blank test solution
Food simulants and chemical alternative solvents that are not in contact with food contact materials and products are processed according to 5.1.2, 5.1.3 and 5.1.4 to obtain a blank test solution.
5.2 Instrument reference conditions
The instrument reference conditions are as follows:
a) Chromatographic column: C18 column; column length is 250 mm; column inner diameter is 4.6 mm; particle size is 5 μm, or a chromatographic column with equivalent performance;
b) Mobile phase: acetonitrile and water (50+50, volume ratio);
c) Flow rate: 1.0 mL/min;
d) Injection volume: 20 μL;
e) Column temperature: 25℃;
f) Detection wavelength: 210 nm.
5.3 Preparation of standard curve
Determine the standard working solution according to the instrument reference conditions listed in 5.2. Draw a standard curve with the concentration of laurolactam in the standard working solution as the abscissa and the corresponding peak area as the ordinate. The reference chromatogram of laurolactam standard solution is shown in Figure A.1 of Annex A.
5.4 Determination of test solution
Measure the food simulant test solution and blank test solution according to the instrument reference conditions listed in 5.2. Use the retention time to determine the peak area of the target substance. Obtain the concentration of laurolactam in the test solution according to the standard curve. Calculate the migration amount of laurolactam according to Chapter 6. The deviation between the retention time of the chromatographic peak of the food simulant test solution and the retention time of the chromatographic peak of the standard working solution shall be within the range of ±2.5%.
The test solution can be diluted according to specific circumstances so that the measured value is within the linear range of the standard curve.
6 Expression of analysis results
6.1 Calculation of migration amount of laurolactam in food simulants
The migration amount of laurolactam in food simulants is calculated according to formula (1).
Where,
X1 - The migration amount of laurolactam in food simulants, in milligrams per liter (mg/L) or milligrams per kilogram (mg/kg);
c - The content of laurolactam in the food simulant test solution, in milligrams per liter (mg/L) or milligrams per kilogram (mg/kg);
c0 - The content of laurolactam in the blank test solution, in milligrams per liter (mg/L) or milligrams per kilogram (mg/kg);
N - The dilution factor.
6.2 Calculation of specific migration amounts of laurolactam in food contact materials and products
6.2.1 Calculation of specific migration amount of laurolactam in non-sealed food contact materials and products (expressed in mg/kg)
simulants and chemical alternative solvents 95% (volume fraction) ethanol and isooctane is 0.5 mg/L. The limit of quantitation is 1.0 mg/L. The method detection limit of laurolactam in oil-containing simulants is 1.0 mg/kg. The limit of quantification is 2.0 mg/kg.
The detection limit and quantitation limit of the specific migration amount of laurolactam in food contact materials and products are based on the method detection limit and quantification limit of laurolactam in food simulants. Conversion is performed according to Chapter 6.
Method two -- Liquid chromatography-tandem mass
spectrometry
9 Principle
After the migration test of food contact materials and products, liquid chromatography- tandem mass spectrometry is used for detection. Among them, water-based, acidic, ethanol-containing food simulants and chemical alternative solvents of 95% (volume fraction) ethanol are directly injected after filtration. Oil-containing food simulants are filtered and injected after liquid-liquid extraction and solid-phase extraction. The chemical alternative solvent isooctane is injected by filtration after solvent removal and reconstitution with acetonitrile. Retention time and relative ion abundance ratio are used for qualitative determination. Use external standard method for quantification. 10 Reagents and materials
Unless otherwise stated, the reagents used in this method are analytically pure, and the water is grade one water specified in GB/T 6682.
10.1 Reagents
Same as 3.1.
10.2 Solution preparation
Same as 3.2.
10.3 Standard product
Same as 3.3.
10.4 Standard solution preparation
10.4.1 Laurolactam standard stock solution (1000 mg/L): same as 3.4.1.
10.4.2 Laurolactam standard intermediate solution (10 mg/L): Pipette 1 mL of laurolactam standard stock solution into a 100 mL volumetric flask. Dilute to volume with absolute ethanol. Shake well. Transfer the solution to a brown glass container. Store at 4°C away from light. It is valid for 3 months.
10.4.3 Laurolactam standard intermediate solution (1.0 mg/L): Pipette 1 mL of laurolactam standard stock solution into a 10 mL volumetric flask. Dilute to volume with absolute ethanol. Shake well. Transfer the solution to a brown glass container. Store at 4°C away from light. It is valid for 3 months.
10.4.4 Aqueous, acidic, ethanol-containing food simulants and 95% (volume fraction) ethanol standard working solution: Accurately pipette 0.30 mL, 0.50 mL, 1.0 mL, 5.0 mL and 10 mL of laurolactam standard intermediate solution (1.0 mg/L) into 100 mL volumetric flasks. Dilute to volume with corresponding aqueous, acidic, ethanol- containing food simulants or 95% (volume fraction) ethanol. Prepare 0.003 mg/L, 0.005 mg/L, 0.010 mg/L, 0.050 mg/L, and 0.10 mg/L standard working solutions. Prepare when needed.
10.4.5 Standard working solution of oil-containing food simulants: Pipette 12 μL, 20 μL, and 40 μL of laurolactam standard intermediate solution (1.0 mg/L) and 10 μL and 20 μL of laurolactam standard intermediate solution (10 mg/L) respectively. Add to 2 g (accurate to 0.01 g) of oil-containing food simulant. Mix well. Prepare 0.006 mg/kg, 0.010 mg/kg, 0.020 mg/kg, 0.050 mg/kg, and 0.10 mg/kg standard working solutions. Prepare when needed. Before putting on the machine, follow 12.1 to synchronize with the oil-containing food simulant soaking solution.
10.4.6 Iso-octane standard working solution: Pipette 0.30 mL, 0.50 mL, 1.0 mL, 5.0 mL and 10 mL of laurolactam standard intermediate solution (1.0 mg/L) into 100 mL volumetric flasks, respectively. Dilute to volume with isooctane. The concentrations of the standard working solutions are 0.003 mg/L, 0.005 mg/L, 0.010 mg/L, 0.050 mg/L, and 0.10 mg/L, respectively. Prepare when needed. Before putting on the machine, process it simultaneously with the isooctane soaking solution according to 12.1. 11 Instruments and equipment
11.1 Liquid chromatography-tandem mass spectrometer: equipped with electrospray ion source (ESI).
11.2 Adjustable pipette: the measuring range is 10 μL~100 μL and the measuring range is 100 μL~1000 μL.
11.3 Analytical balance: division is 0.0001 g (0.1 mg) and 0.01 g.
11.4 Organic microporous filter membrane: 0.45 μm.
11.5 Vortex mixer.
11.6 Centrifuge.
11.7 Nitrogen concentration device.
11.8 Solid phase extraction device.
11.9 Mixed cationic solid-phase extraction cartridge or equivalent purification column: 150 mg/6 mL.
12 Analysis steps
12.1 Sample preparation
Same as 5.1.
12.2 Instrument reference conditions
12.2.1 Liquid chromatography conditions
The reference conditions for liquid chromatography are as follows:
a) Chromatographic column: C18 chromatographic column; column length is 100 mm; column inner diameter is 2.1 mm; particle size is 1.7 μm, or a column with equivalent performance;
b) Mobile phase: A is an aqueous solution containing 0.1% (volume fraction) formic acid; B is an acetonitrile solution containing 0.1% (volume fraction) formic acid; the elution gradient is shown in Table 1;
c) Flow rate: 0.3 mL/min;
d) Column temperature: 40℃;
e) Injection volume: 2 μL.

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