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This standard replaces GB/T 23296.11-2009 Food Contact Materials - Determination of Ethylene Oxide and Propylene Oxide in Plastics - Gas Chromatography.
The following main changes have been made with respect to GB/T 23296.11-2009 (the previous edition):
——This standard is renamed as National Food Safety Standard - Food Contact Materials and Articles - Determination of Ethylene Oxide and Propylene Oxide in Plastics;
——"Headspace gas chromatography-mass spectrometry" for determination of ethylene oxide and propylene oxide is added.
National Food Safety Standard
Food Contact Materials and Articles
Determination of Ethylene Oxide and Propylene Oxide in Plastics
1 Scope
This standard specifies determination method of ethylene oxide and propylene oxide in food contact materials and articles.
This standard is applicable to determination of ethylene oxide and propylene oxide in plastic food contact materials and articles.
Method I Headspace Gas chromatography-mass Spectrometry
2 Principle
Extract ethylene oxide or propylene oxide in the sample with N, N-dimethyl acetamide (DMAC), conduct headspace sample injection, separate ethylene oxide or propylene oxide and ethyl ether (internal standard) and other components in chromatographic column, examine by mass spectrometry detector and carry out quantative determination by internal standard method.
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.
3.1 Reagents
N,N-dimethyl acetamide (DMAC for short, C4H9NO, CAS No.: 127-19-5): chromatographically pure, peak area of impurity with the same retention time as ethylene oxide or propylene oxide in chromatogram shall not exceed 1%.
3.2 Standard product
3.2.1 Ethylene oxide (C2H4O, CAS No.: 75-21-8): with purity ≥99%, or reference material approved and awarded with reference material certificate by the State.
3.2.2 Propylene oxide(C3H6O, No.: 200-879-2): with purity ≥99%, or reference material approved and awarded with reference material certificate by the State.
3.2.3 Ethyl ether (C4H10O, CAS No.: 60-29-7): with purity≥99.5%, or reference material approved and awarded with reference material certificate by the State. Peak area of impurity with the same retention time as ethylene oxide or propylene oxide shall not exceed 1%.
3.3 Preparation of standard solution
3.3.1 Ethylene oxide standard stock solution
Weigh 50 mg (accurate to 0.0001 g) ethylene oxide, dissolve with DMAC, scale the volume to 50mL and prepare into stock solution with concentration of 1 mg/mL. Seal preserve in dark place at 4℃, with the valid period of 2 months.
3.3.2 Propylene oxide standard stock solution
Weigh 50 mg (accurate to 0.0001 g) propylene oxide, dissolve with DMAC, scale the volume to 50 mL and prepare into stock solution with concentration of 1 mg/mL. The storage conditions of the solution are as specified in 3.3.1.
3.3.3 Ethylene oxide and propylene oxide mixed standard intermediate solution
Measure 5 mL DMAC into 50 mL volumetric flask, respectively pipet 2.0 mL ethylene oxide standard stock solution (3.3.1) and 1.0 mL propylene oxide standard stock solution (3.3.2) into the volumetric flask, scale the volume with DMAC and obtain ethylene oxide and propylene oxide mixed standard intermediate solution. In the solution, concentrations of ethylene oxide and propylene oxide are 40.0 μg/mL and 20.0 μg/mL respectively. The storage conditions of the solution are as specified in 3.3.1.
3.3.4 Ethylene oxide and propylene oxide mixed standard solution
Pipet 5.0 mL DMAC into six 10 mL volumetric flasks respectively with graduated pipette, respectively pipet 25 μL, 50 μL, 100 μL, 250 μL, 500 μL and 1,000 μL ethylene oxide and propylene oxide mixed standard intermediate solution (3.3.3) into these six volumetric flasks with microinjector and scale the volume with DMAC. The concentrations of ethylene oxide are 0.1 μg/mL, 0.2 μg/mL, 0.4 μg/mL, 1.0 μg/mL, 2.0 μg/mL and 4.0 μg/mL, and those of propylene oxide are 0.05 μg/mL, 0.1 μg/mL, 0.2 μg/mL, 0.5 μg/mL, 1.0 μg/mL and 2.0 μg/mL. The storage conditions of the solution are as specified in 3.3.1.
3.3.5 Ethyl ether internal standard stock solution
Weigh 50 mg (accurate to 0.0001 g) ethyl ether into 50 mL volumetric flask containing 5 mL DMAC, scale the volume with DMAC and prepare into stock solution with concentration of 1 mg/mL. The storage conditions of the solution are as specified in 3.3.1.
3.3.6 Ethyl ether internal standard intermediate solution
Measure 5 mL DMAC into 10 mL volumetric flask, pipet 2.5 mL ethyl ether internal standard stock solution (3.3.5) into the volumetric flask with graduated pipette, scale the volume with DMAC and obtain ethyl ether internal standard intermediate solution. The concentration of this solution is 250.0 μg/mL. The storage conditions of the solution are as specified in 3.3.1.
4 Instruments and Apparatus
4.1 Gas chromatography - mass spectrometer: equipped with electron bombardment ion source (EI) and headspace automatic sample injector.
4.2 Microinjector: 10 μL, 100μL and 1,000 μL.
4.3 Headspace bottle: 20mL; equipped with aluminium cap and butyl rubber or silicone resin rubber isolation pad whose side contacting sample shall be coated with polytetrafluoroethylene.
4.4 Analytical balance: with sensibility of 0.0001g .
4.5 Mechanical oscillator.
5 Analysis Steps
5.1 Specimen treatment
As for specimens that can be dissolved in DMAC, directly weigh them; as for specimens that are not dissolved in DMAC, weigh them as early as possible after crushing them into fragments with particle size less than 1 mm× 1mm with freezing grinder or scissor or other cutting tools and they cannot be heated or softened during cutting.
5.2 Preparation of specimen solution
Weigh 1.0 g±0.1 g specimen (5.1) into headspace bottle, pipet 5.0 mL DMAC into the headspace bottle with graduated pipette, add 10 μL ethyl ether internal standard intermediate solution (3.3.6) with microinjector and seal with cap as early as possible. Oscillate headspace bottle with oscillator at frequency of one time every two seconds till specimen dissolution as for specimen that can be dissolved in DMAC and 4 h for DMAC that is not dissolved in DMAC. If sample concentration exceeds linear range, properly dilute the sample with DMAC before adding internal standard solution to make its concentration within the linear range.
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Instruments and Apparatus
5 Analysis Steps
6 Expression of Analysis Result
7 Accuracy
8 Other
9 Principle
10 Reagents and Materials
11 Instruments and Apparatus
12 Analysis Steps
13 Expression of Analysis Result
14 Accuracy
15 Other
Annex A Standard Chromatogram of Ethylene Oxide and Propylene Oxide
