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This standard replaces SN/T 2333-2009 Food Contact Materials - Polymer - Determination of Vinyl Acetate in Food Simulants - Gas Chromatography-Mass Spectrometry.
The following main changes have been made with respect to SN/T 2333-2009:
——This standard is renamed as National Food Safety Standard - Food Contact Materials and Articles - Determination of Migration of Vinyl Acetate;
——Quantitative method is modified, i.e., internal standard method is replaced by external standard method.
National Food Safety Standard
Food Contact Materials and Articles
Determination of Migration of Vinyl Acetate
1 Scope
This standard specifies the determination method of migration of vinyl acetate in food contact materials and articles.
This standard is applicable to the determination of migration of vinyl acetate in food contact materials and articles.
2 Principle
Leach the vinyl acetate in the specimen with food simulant soak solution, scale the volume with acetone, and finally carry out the gas chromatographic determination and the quantative determination by external standard method. Once detected, the sample shall be confirmed by gas chromatography-mass spectrometry.
3 Reagents and Materials
Unless otherwise specified, analytically-pure reagents and Class-I water (defined in GB/T 6682) are adopted for the purpose of this method. Containers and transfer appliances in test shall not be made of plastic materials.
3.1 Reagents
3.1.1 Acetone (C3H6O): free of vinyl acetate.
3.1.2 Methanol (C2H4O).
3.1.3 Water-based, acidic, alcoholic and oil-based food simulants: the reagents adopted shall be in accordance with the requirements of GB 31604.1.
3.2 Reagent preparation
3.2.1 Water-based, acidic, alcoholic and oil-based food simulants: prepare according to GB 5009.156.
3.2.2 Methanol-water solution (1+1): measure 100 mL methanol and 100 mL water, then mix them well.
3.3 Standard product
Vinyl acetate (C4H6O2, CAS No.: 108-05-4): with purity≥99%, or reference material approved and awarded with reference material certificate by the State.
3.4 Preparation of standard solutions
3.4.1 Vinyl acetate standard stock solution (1000 mg/L): accurately weigh 10 mg (accurate to 0.01 mg) vinyl acetate standard in 10mL volumetric flask, dilute with acetone to the scale, and keep it sealed at -10℃.
3.4.2 Vinyl acetate standard intermediate solution (100 mg/L): pipet 1.0 mL vinyl acetate stock solution into 10mL volumetric flask, dilute with acetone to the scale, and prepare on the day of use.
4 Instruments and Apparatus
4.1 Gas chromatograph: equipped with FID detector.
4.2 Gas chromatograph-mass spectrometer: equipped with EI ion source.
4.3 Analytical balance: with sensibility of 0.1 mg and 0.01 g.
4.4 Microinjector: 10 μL, 50 μL and 1000μL.
4.5 Ultrasonator.
4.6 0.2 μm nylon membrane syringe filter.
5 Analysis Steps
5.1 Sample migration test
Carry out migration test in accordance with the requirements of GB 5009.156 and GB 31604.1 for the sample, and obtain the food simulant test solution. If the obtained food simulant test solution fails to be used for the next test immediately, it shall be kept in dark place in 4℃ refrigerator.
The food simulant test solution obtained shall be cooled or recovered to room temperature before being used for the next test.
5.2 Preparation of water-based, acidic, alcoholic and oil-based food simulants standard working solutions
Accurately pipet 0 mL, 0.01 mL, 0.05 mL, 0.1 mL, 0.5 mL and 1.0 mL vinyl acetate standard intermediate solution into 10mL volumetric flasks, scale the volume with acetone to obtain the standard working solutions with the concentrations of vinyl acetate as 0.00 mg/L, 0.1 mg/L, 0.5 mg/L, 1.0 mg/L, 5.0 mg/L and 10.0 mg/L respectively. Prepare the corresponding water-based, acidic, alcoholic and oil-based food simulants standard working solutions respectively in the same way.
5.3 Reference conditions of gas chromatography instrument
Reference conditions of gas chromatography instrument are listed below:
a) Chromatographic column: DB-5 quartz capillary column with length of 30 m, inside diameter of 0.32 mm and film thickness of 0.25 μm, or equivalent;
b) Temperature programming: 35℃ (maintain for 5 min), rise to 50℃ at a rate of 5℃/min, rise to 250℃ (for 2 min) at a rate of 40℃/min.
c) Temperature of injection port: 250℃;
d) Sample injection mode: split injection (10:1), with sample injection amount of 1 μL;
e) Detector temperature: 300℃;
f) Flow rate of carrier gas (N2): 0.5 mL/min;
g) Hydrogen flow rate: 30 mL/min;
h) Air flow rate: 400 mL/min.
5.4 Determination
5.4.1 Specimen determination
Take clean and dry 25 mL volumetric flask, add 1 g (accurate to 0.0001 g) simulated food soak solution which has been subject to migration test, dilute with acetone to the scale, and mix sufficiently well for standby.
Pipet a certain amount of the above test solution with microinjector, inject it into the gas chromatograph, determine twice respectively according to the above gas chromatography conditions, and see Figure A.1 for the gas chromatogram of vinyl acetate.
5.4.2 Blank test
The blank test refers to the parallel operation which is carried out according to the same analysis steps, reagents and consumption, except without addition of the specimen.
6 Expression of Analysis Results
Obtain the concentration of vinyl acetate in specimen solution from the standard curve, and calculate the migration according to GB 5009.156 to obtain the migration of vinyl acetate in food contact materials and articles. The calculation result is accurate to two decimal places.
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Instruments and Apparatus
5 Analysis Steps
6 Expression of Analysis Results
7 Confirmatory Test
8 Accuracy
9 Other
Annex A Gas Chromatogram of Vinyl Acetate
Annex B Reference Conditions for Confirmation by Gas Chromatography - Mass Spectrometry
Annex C Chromatogram - Mass Spectrogram of Vinyl Acetate
