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GB 31604.22-2016 PDF in English


GB 31604.22-2016 (GB31604.22-2016) PDF English
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GB 31604.22-2016English70 Add to Cart 0-9 seconds. Auto-delivery. Method for analysis of hygienic standard of products of foamed polystyrene for food packaging Valid
Standards related to (historical): GB 31604.22-2016
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GB 31604.22-2016: PDF in English

GB 31604.22-2016 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National Food Safety Standard - Food Contact Materials and Articles - Determination of Dichlorodifluoromethane in Products of Foamed Polystyrene ISSUED ON. OCTOBER 19, 2016 IMPLEMENTED ON. APRIL 19, 2017 Issued by. National Health and Family Planning Commission of the PRC Table of Contents Foreword . 3  1 Scope .. 4  2 Principles . 4  3 Reagents and materials .. 4  4 Instruments and equipment . 5  5 Analytical procedures . 5  6 Analysis results expression . 6  7 Precision. 7  8 Others . 7  Appendix A Gas chromatogram of dichlorodifluoromethane standard solution 8  National Food Safety Standard - Food Contact Materials and Articles - Determination of Dichlorodifluoromethane in Products of Foamed Polystyrene 1 Scope This Standard specifies the method for determination of dichlorodifluoromethane in products of foamed polystyrene. This Standard applies to the determination of dichlorodifluoromethane in products of foamed polystyrene. 2 Principles According to relevant gas law, PLACE the sample in a sealed equilibration flask; and USE a solvent to dissolve. At a certain temperature, dichlorodifluoromethane diffuses. When it reaches an equilibration, TAKE the head space gas and INJECT it into gas chromatograph for determination. 3 Reagents and materials Unless otherwise stated, the reagents used in this method are analytically pure. The water is the Grade II water specified in GB/T 6682. 3.1 Reagents 3.1.1 N, N-dimethylacetamide (C4H9NO). chromatographically pure. 3.2 Standard Dichlorodifluoromethane (CCl2F2) (CAS Number. 75-71-8). The purity>99%. 3.3 Preparation of standard solutions 3.3.1 Standard stock solution of dichlorodifluoromethane (100 μg/mL). Accurately WEIGH 1 mg (accurate to 0.01 mg) of dimethylacetamide standard in a 10 mL brown volumetric flask; USE N, N-dimethylacetamide to dissolve and dilute to volume; and MIX well. At 4 °C, STORE it for 1 year. c) Inlet temperature. 250 °C; d) Detector temperature. 300 °C; e) Carrier gas. nitrogen; the purity is greater than or equal to 99.999%. Constant current mode; flow rate. 1.0 mL/min; f) Injection volume. 1.0 mL, split injection; the split ratio is 20.1; g) Make-up gas. nitrogen, 60 mL/min. 5.3 Making of standard curve ADD 3 mL of N, N-dimethylacetamide in each of 5 equilibration flasks; CAP the plugs; USE a microsyringe to take 0 μL, 3 μL, 15 μL, 30 μL, 150 μL, 300 μL of standard working solution of dichlorodifluoromethane (1 μg/mL) and INJECT into the flasks through rubber plug; gently SHAKE well and PUT in a constant temperature water bath at 65 °C to equilibrate for 15 min. The standard curve concentrations are 0 ng/mL, 1 ng/mL, 5 ng/mL, 10 ng/mL, 50 ng/mL,100 ng/mL. Respectively TAKE 1 mL of the head space gas and INJECT into gas chromatograph; TAKE the dichlorodifluoromethane content as the abscissa; TAKE the peak area as the ordinate and DRAW standard curve. The gas chromatogram of dichlorodifluoromethane standard solution is as shown in Figure A.1. 5.4 Determination of sample solution Manually or automatically INJECT the head space gas, which contains 1 mL of the sample, into gas chromatograph to determine; and OBTAIN the peak area. According to the standard curve, OBTAIN the content of dichlorodifluoromethane in the sample solution. At the same time, CARRY out blank test. 6 Analysis results expression The content of dichlorodifluoromethane in the sample is calculated according to the equation (1). Where. X - The content of dichlorodifluoromethane in the sample, in micrograms per kilogram (mg/kg); ......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.