GB 5009.205-2024 National food safety standard - Determination of toxic equivalent quantity of dioxins and their analogues in foods
National food safety standard - Determination of toxic equivalent quantity of dioxins and their analogues in foods
1 Scope
This standard specifies the determination methods for the content and toxic equivalent quantity (TEQ) of 17 types of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) (collectively referred to as “PCDD/Fs”) and 12 types of dioxin-like polychlorinated biphenyls (DL-PCBs) in foods (see Table A.1 of Annex A).
“Method I: Isotope dilution - Gas chromatography - Magnetic sector high resolution mass spectrometry” is applicable to the determination of 17 PCDD/Fs and 12 DL-PCBs and their TEQ in foods.
“Method II: Isotope dilution - Gas chromatography - Triple quadrupole mass spectrometry” is applicable to the determination of 17 PCDD/Fs and 12 DL-PCBs and their TEQ in meat and meat products, aquatic animals and their products, milk and dairy products, eggs and egg products and oils.
Method I: Isotope dilution - Gas chromatography - Magnetic sector high resolution mass spectrometry
2 Principle
After extraction, purification and concentration, the specimen is determined by gas chromatography-magnetic sector high resolution mass spectrometer (GC-HRMS) and quantified by stable isotope dilution method. The TEQ of PCDD/Fs and DL-PCBs in the specimen are calculated by multiplying the toxic equivalency factor (TEF) of each target compound with the measured content and accumulating.
3 Reagents and materials
3.1 Reagents
Unless otherwise stated, reagents used in this method are all analytically pure, and water is of Grade 1 as specified in GB/T 6682.
3.1.1 Acetone (C3H6O): pesticide residue grade.
3.1.2 n-hexane (C6H14): pesticide residue grade.
3.1.3 Toluene (C7H8): pesticide residue grade.
3.1.4 Cyclohexane (C6H12): pesticide residue grade.
3.1.5 Dichloromethane (CH2Cl2): pesticide residue grade.
3.1.6 Methanol (CH3OH): chromatographic grade.
3.1.7 n-nonane (C9H20): ≥99%.
3.1.8 Ethyl acetate (CH3COOCH2CH3): pesticide residue grade.
3.1.9 Anhydrous sodium sulfate (Na2SO4): guaranteed reagent.
3.1.10 Concentrated sulfuric acid (H2SO4): guaranteed reagent.
3.1.11 Sodium hydroxide (NaOH): guaranteed reagent.
3.1.12 Silver nitrate (AgNO3): guaranteed reagent.
3.1.13 Diatomite for extraction: with bulk density of 18.0 g/100 mL ~ 36.0 g/100 mL (such as EXtrelut NT or equivalent products).
3.1.14 Gel chromatographic packing: polystyrene gel, 38 μm ~ 75 μm (e.g. Bio-Beads S-X3 or equivalent products).
3.1.15 Silica gel: 75 μm ~ 250 μm.
3.1.16 Alkaline aluminium oxide: 63 μm ~ 200 μm (e.g. EcoChromTM MP Alumina B-Super I or equivalent products).
3.1.17 Florisil: 150 μm ~ 250 μm.
3.1.18 Activated carbon: 150 μm to 180 μm (e.g. Carbopack C, Supelco 10258 or equivalent products).
3.1.19 Diatomite for purification: 26 μm (e.g. Celite 545 AW, Supelco 20199-U or equivalent products).
3.2 Reagent preparation
3.2.1 Activated silica gel: Wash the silica gel with methanol and then dichloromethane, and bake at 600°C for at least 12 h after the solvent is evaporated. Freshly prepare before use.
3.2.2 Acidified silica gel (mass fraction: 44%): Weigh 112.0 g of activated silica gel in a 250 mL rotary flask with stopper and grinding mouth, add 88.0 g of concentrated sulfuric acid, seal it and place it on a shaking table to oscillate until the silica gel is in an even flow state. Freshly prepare before use.
3.2.3 Alkalized silica gel (mass fraction: 33%): Weigh 100.0 g of activated silica gel in a 250 mL rotary flask with stopper and grinding mouth, add 49.0 g of 1 mol/L sodium hydroxide solution, seal it and place it on a shaking table to oscillate until the silica gel is in an even flow state. Freshly prepare before use.
3.2.4 Silver nitrate silica gel: Weigh 10.0 g of silver nitrate in a 250 mL rotary flask with stopper and grinding mouth, add 40 mL of water to dissolve it, then slowly add 90.0 g of activated silica gel, seal it and place it on a shaking table to oscillate until the silica gel is in an even flow state. Freshly prepare before use.
3.2.5 Alkaline aluminium oxide: Activate alkaline aluminium oxide at 600°C for 24 h. Freshly prepare before use.
3.2.6 Aqueous florisil (mass fraction: 1%): Take a quantity of florisil into Soxhlet extractor, extract it with n-hexane and dichloromethane (by volume ratio of 1:1) for 24 h; weigh 99.0 g after the solvent dries, add 1.0 mL of water, and mix it evenly in a closed container (such as a glass flask with stopper or a glass triangular flask with stopper). Freshly prepare before use.
3.2.7 Mixed activated carbon: Weigh 9.0 g of activated carbon and 41.0 g of diatomite for purification, mix them evenly in a closed container (such as glass flask with stopper or glass triangle flask with stopper), and then activate them at 130°C for 6 h. Freshly prepare before use.
3.2.8 Anhydrous sodium sulfate: Take anhydrous sodium sulfate and burn it at 660°C for 6 h. Freshly prepare before use.
3.3 Standard solution
3.3.1 Standard solution for resolution test: solution containing natural PCDD/Fs. See Table B.1 of Annex B for the specific compounds and concentrations.
3.3.2 Standard solution for PCDD/Fs isotope labeled quantitative internal standard: solution containing 15 types of 13C12-PCDD/Fs. See Table B.2 for the specific compounds and concentrations.
Foreword i
1 Scope
2 Principle
3 Reagents and materials
4 Instruments and apparatus
5 Analytical procedures
6 Expression of analysis results
7 Precision
8 Detection limit
9 Others
10 Principle
11 Reagents and materials
12 Instruments and apparatus
13 Analytical steps
14 Expression of analysis results
15 Precision
16 Quantitative limit of the method
17 Others
Annex A 17 types of 2,3,7,8-substituted PCDD/Fs and 12 types of DL-PCBs with names, CAS numbers, IUPAC numbers, and WHO specified toxic equivalent factors (TEF)
Annex B Standard solution
Annex C Technical requirements for determination methods
Annex D Separation and purification process of automatic sample purification system
Annex E Chromatogram of standard solution
