Detail of GB 31604.12-2016

Introduction of GB 31604.12-2016

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. This standard replaces GB/T 23296.2-2009 Food Contact Materials - Polymer - Determination of 1 3-butadiene in Food Simulants - Gas Chromatography and GB/T 23296.3-2009 Food Contact Materials - Determination of 1 3-butadiene in Plastics - Gas Chromatography. The following changes have been made with respect to GB/T 23296.3-2009 (the previous edition): ——This standard is renamed as "National Food Safety Standard - Food Contact Materials and Articles - Determination of 1, 3-butadiene and Determination of Migration"; ——The determination for migration of 1, 3-butadiene in food contact materials and articles is added. National Food Safety Standard Food Contact Materials and Articles Determination of 1, 3-butadiene and Determination of Migration 1 Scope This standard specifies determination method of 1, 3-butadiene in food contact materials and articles and its migration in such materials and articles. This standard is applicable to the determination of 1, 3-butadiene in food contact materials and articles and its migration in such materials and articles. Determination of 1, 3-butadiene 2 Principle Dissolve or disperse the food contact materials and articles with N, N-dimethyl formamide in a headspace bottle, heat to make the to-be-tested constituent reach gas-liquid equilibrium and then pipet headspace air quantitatively to determine gas chromatography. Carry out the qualitative determination by retention time and quantitative determination by internal standard method with n-pentane as internal standard substance. 3 Reagents and Materials Class-I water (defined in GB/T 6682) is adopted for the purposes of this method. As for the containers and transferring tools in the test, those made of plastic material shall not be used. 3.1 Reagent N, N-dimethyl formamide (DMF): analytical reagent, for which no interference peaks shall occur within the range of retention time of 1, 3-butadiene and n-pentane. 3.2 Standard products 3.2.1 1,3-butadiene (C4H6, CAS No.: 106-99-0): 2,000μg/mL, the standard material approved and awarded with reference material certificate by the State. 3.2.2 n-Pentane (C5H12, CAS No.: 106-66-0): purity≥99.5% or the standard material approved and awarded with reference material certificate by the State. 3.3 Preparation of 1, 3-butadiene standard solution 3.3.1 1,3-butadiene standard stock solution: pipet 1.0mL of 1,3-butadiene standard product, transfer it into a 10mL volumetric flask, add N, N-dimethyl formamide to dilute it to the scale, then mix uniformly so that the concentration of 1,3-butadiene in this solution is 200μg/mL; keep the solution in dark place and preserve it at -20℃, the validity period is 3 months, or preserve it at -4℃, in which case the validity period is a week. 3.3.2 1,3-butadiene standard working solution: pipet 0.1mL, 0.2mL, 0.3mL, 0.4mL and 0.5 mL of 1,3-butadiene standard stock solutions respectively, transfer them into five 10mL volumetric flasks, add N, N-dimethyl formamide into each volumetric flask to dilute to the scale, then mix uniformly (per milliliter is equivalent to 2μg, 4μg, 6μg, 8μg and 10μg of 1,3-butadiene); prepare it on the day when it will be used. 3.4 Preparation of n-Pentane standard solution Prepare an n-Pentane standard solution (concentration: about 10 μg/mL) with N, N-dimethyl formamide according to the process similar to that in 3.3. 4 Instruments and Apparatus 4.1 Gas chromatograph: (with flame ionization detector). 4.2 Headspace automatic sample injector. 4.3 20mL headspace air bottle for determination, with polyvinyl fluoride-coated silicon rubber cap and aluminum cap. 4.4 Analytical balance: with sensitivity of 0.1mg. 4.5 10mL volumetric flask. 4.6 100μL microinjector. 5 Analysis Steps 5.1 Preparation of specimen Take 10g of food contact materials, grind with grinder or cut with scissors into fragment with particle size less than or equal to 0.2cm, mix uniformly and load in a clean container. 5.2 Test solution preparation Weigh 0.5g (to the nearest of 0.01g) of the sample, place it into the headspace bottle, add 5.0mL of the N, N-dimethyl formamide and then immediately seal the bottle with the cap; add 100μL of n-Pentane standard solution into the headspace bottle with the 100μL microinjector, then shake the bottle sufficiently so that the specimen in the bottle dissolves or disperses completely; carry out blank test simultaneously. 5.3 Reference conditions of instruments 5.3.1 Conditions of headspace sample injector Conditions of headspace sample injector are as follows: a) Equilibrium time: 30min; b) Furnace temperature: 80℃; c) Pressure: 138kPa; d) Pressure time: 2min; e) Injection time: 0.04min; f) Transfer line temperature: 85℃. 5.3.2 Gas chromatography conditions Gas chromatography conditions are as follows: a) Chromatographic column: polystyrene-divinyl benzene quartz capillary column (length: 30m; inside diameter: 0.32mm; film thickness: 10μm) or equivalent column; b) Column temperature programming: it is kept at 80℃ for 12min and then increased to 120℃ at 10℃/min and kept for 20min; c) Injection port temperature: 220℃; d) Detector temperature: 250℃; e) Flow rate of carrier gas (nitrogen): 50mL/min; f) Hydrogen flow rate: 10mL/min; g) Air flow rate: 400mL/min; h) Sample injection from injection port under constant pressure: 100kPa. 5.4 Preparation of calibration solution and plotting of calibration curve Take 5 headspace bottles and respectively add 100μL of n-Pentane standard solution into them, and add 1, 3-butadiene standard series solutions successively, after which, the 1,3-butadiene content in calibration solution is equivalent to 0.2μg, 0.4μg, 0.6μg, 0.8μg and 1.0μg respectively. Adjust the gas chromatograph to the optimal working state, place the headspace bottle with standard series into headspace sample injector, take the gas above solution into the gas chromatograph for determination to obtain corresponding chromatographic peaks of n-Pentane and 1, 3-butadiene. Plot the calibration curve with 1,3-butadiene content as the x-axis and the ratio of peak area of 1,3-butadiene to that of n-Pentane the as y-axis. The gas chromatogram of 1, 3-butadiene is detailed in Figure A.1.

Contents of GB 31604.12-2016

Foreword i 1 Scope 2 Principle 3 Reagents and Materials 4 Instruments and Apparatus 5 Analysis Steps 6 Expression of Analysis Results 7 Accuracy 8 Others 9 Principle 10 Reagents and Materials 11 Instruments and Apparatus 12 Analysis Steps 13 Expression of Analysis Results 14 Accuracy 15 Others Annex A Gas Chromatogram of 1,3-butadiene