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This standard replaces SN/T 2200-2008 Food Contact Materials - Pulp, Paper and Board - Determination of 7 Specified Polychlorinated Biphenyls (PCBs)
The following changes have been made with respect to SN/T 2200-2008 (the previous edition):
——This standard is renamed as "National Food Safety Standard - Food Contact Materials and Articles - Determination of Polychlorobiphenyls (PCBs) in Food Contact Paper".
——The type of polychlorobiphenyls for determination is added (PCB 118 is added).
——The pretreatment process is modified.
National Food Safety Standard
Food Contact Materials and Articles
Determination of Polychlorobiphenyls (PCBs) in Food Contact Paper
1 Scope
This standard specifies the determination method for polychlorobiphenyls in food contact paper through gas chromatography or gas chromatography-mass spectrometry.
As for this standard, Method I is gas chromatography and Method II is gas chromatography-mass spectrometry, which are applicable to the determination of 8 polychlorobiphenyls in all kinds of food contact paper.
Method I Gas Chromatography
2 Principle
Polychlorobiphenyls in single-layer food contact paper are extracted with mixed solution of n-hexane and methylene chloride through oscillation in water bath or with accelerated solvent extraction instrument while those in composite food contact paper are extracted with accelerated solvent extraction instrument. Extracting solution, after being concentrated and subjected to sulphonation treatment by using concentrated sulfuric acid, is detected with gas chromatograph equipped with electron capture detector and quantitatively determined 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
3.1.1 n-hexane(C6H14): chromatographically pure.
3.1.2 Methylene chloride (CH2Cl2).
3.1.3 Acetonitrile (CH3CN): chromatographically pure.
3.1.4 Concentrated sulfuric acid (H2SO4): guaranteed reagent.
3.2 Preparation of reagents
3.2.1 Mixed solution of n-hexane and methylene chloride (1+1): measure 100mL of n-hexane and 100mL of methylene chloride and mix them uniformly.
3.3 Standard products
2,2′,5-trichloro diphenyl (PCB 18), 2,4,4′-trichloro diphenyl (PCB 28), 2,2′,5,5′-tetrachlorobiphenyl (PCB 52), 2,2′,4,5,5′-pentachlorobiphenyl (PCB 101), 2,3′,4,4′,5-pentachlorobiphenyl (PCB 118), 2,2′,3,4,4′,5′-hexachlorobiphenyl (PCB 138), 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153), 2,2′,3,4,4′,5,5′-heptachlorobiphenyl (PCB 180) and internal standard substances 2,2′,3,3′,4,4′,5,5′,6,6′-decachlorobiphenyl (PCB 209): standard products with purity ≥98% or reference materials approved and awarded with reference material certificate by the State; see Table A.1 for relevant information of 8 polychlorobiphenyls and internal standard substances.
3.4 Preparation of standard solution
3.4.1 Polychlorobiphenyl and internal standard substance standard stock solution: accurately weigh a proper amount of polychlorobiphenyl standard product, and respectively prepare it into solution with concentration of 200 mg/L with n-hexane; seal and preserve it at -18℃, with storage time of 12 months.
3.4.2 Mixed standard working solution: accurately pipet a right amount of standard stock solutions of 8 polychlorobiphenyls respectively, dilute them level by level with n-hexane to get 1.00 mg/L mixed standard working solutions, seal and preserve them at -18℃, with the storage time of 3 months.
3.4.3 Internal standard substance working solution: accurately pipet proper amount of internal standard substance (PCB 209) standard stock solution, and prepare it into 1.00 mg/L solution with n-hexane; seal and preserve it at -18℃, with the storage time of 3 months.
3.4.4 A series of mixed standard solutions: pipet a proper amount of mixed standard working solution and internal standard substance working solution, prepare them into a series of mixed standard solutions with concentration of 0.0050 mg/L, 0.010 mg/L, 0.025 mg/L, 0.050 mg/L, 0.100 mg/L and 0.200 mg/L respectively (the concentration of the internal standard substance in all cases is 0.050 mg/L); prepare immediately before use.
3.5 Materials
3.5.1 Polyamide filter membrane: 0.22 μm.
3.5.2 Chromosorb G: premium grade; CAS No.: 68855-54-9; heated for 4 h in 400℃ muffle furnace prior to use.
4 Instruments and Apparatus
4.1 Gas chromatograph (GC): equipped with electron capture detector.
4.2 Water bath oscillator.
4.3 Accelerated solvent extraction instrument (ASE).
4.4 Balance: with a sensibility of 0.01g and 0.00001g.
4.5 Centrifuger: rotation speed≥5,000 r/min.
4.6 Rotary evaporator.
4.7 Nitrogen blowing concentrator.
4.8 Vortex oscillator.
5 Analysis Steps
5.1 Sampling
Sample according to GB/T 450 or GB/T 740; after sampling, wrap the sample with aluminium foil to prevent the sample changing before test.
5.2 Sample preparation
Take a portion of representative sample (about 100g) and scissor it into fragments with size smaller than 5mm×5mm, and mix them uniformly; after sampling, wrap the samples with aluminium foil to protect them from pollution.
5.3 Specimen extraction
5.3.1 Extraction in water bath through oscillation (applicable to single-layer food contact paper)
Weigh about 2g (accurate to 0.01 g) of sample and put it into 50mL glass centrifugal tube with stopper, add into 100 μL of PCB 209 quantitative internal standard substance working solution (1.00 mg/L), oscillate it to mix uniformly; add 25mL of n-hexane and methylene chloride solution, extract in 40℃ water bath through oscillation for 1h, with the oscillating speed of 200 r/min; transfer the extracting solution to a 100mL obconical flask. Add 20mL of n-hexane and methylene chloride solution into the residue, and extract again in water bath through oscillation for 1h. Merge all the extracting solutions, and have it concentrated by rotary evaporator in 40℃ water bath until it is nearly dry.
5.3.2 Accelerated solvent extraction (applicable to single-layer food contact paper and composite food contact paper)
Weigh about 2g (accurate to 0.01g) of sample, add 100 μL of PCB 209 quantitative internal standard substance working solution (1.00 mg/L), mix it uniformly with 4 g of diatomite, load it into stainless steel extraction pool on whose bottom the glass-fiber filter paper is laid (before loading the specimen, load a layer of diatomite (about 2g) first on the extraction pool bottom), and then load the diatomite to fill the stainless steel extraction pool, screw on the cover, put it on the extraction pool tray of accelerated solvent extraction instrument and extract. See Table 1 for accelerated solvent extraction conditions; after completion of extraction, transfer the extracting solution into a 100mL obconical flask, and have it concentrated by rotary evaporator in 40℃ water bath until it is nearly dry.
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 Relevant Information of 8 Polychlorobiphenyls and the Internal Standard Substance
Annex B Gas Chromatogram for Standard Solutions of 8 Polychlorobiphenyls and the Internal Standard Substance
Annex C Characteristic Ion of 8 Polychlorobiphenyls and Internal Standard Substance
Annex D Total Ion Current Chromatogram of Gas Chromatography-mass Spectrometry for the Standard Solutions of 8 Polychlorobiphenyls and Internal Standard Substance
