GB 5009.18-2025 PDF EnglishUS$140.00 · In stock · Download in 9 seconds
GB 5009.18-2025: National food safety standard - Determination of fluorine in foods Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB 5009.18: Historical versions
Similar standardsGB 5009.18-2025: National food safety standard - Determination of fluorine in foods---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GB5009.18-2025GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National Food Safety Standard - Determination of Fluorine in Foods Issued on. MARCH 16, 2025 Implemented on. SEPTEMBER 16, 2025 Issued by. National Health Commission of the People’s Republic of China; State Administration for Market Regulation. Table of ContentsForeword... 3 1 Scope... 4 Method I - Ion Chromatography... 4 2 Principle... 4 3 Reagents and Materials... 4 4 Instruments and Equipment... 6 5 Analytical Steps... 6 6 Expression of Analytical Results... 8 7 Precision... 9 8 Others... 9 Method II - Fluoride Ion Selective Electrode Method... 9 9 Principle... 9 10 Reagents and Materials... 9 11 Instruments and Equipment... 11 12 Analytical Steps... 11 13 Expression of Analytical Results... 12 14 Precision... 12 15 Others... 12 Appendix A Ion Chromatograms... 13ForewordThis Standard replaces GB/T 5009.18-2003 Determination of Fluorine in Foods. In comparison with GB/T 5009.18-2003, the main changes are as follows. ---The title of the Standard is modified into National Food Safety Standard - Determination of Fluorine in Foods; ---The scope of application of the Standard is modified; ---Method I - ion chromatography is added; ---The previous first method, diffusion-fluorine reagent colorimetric method, and the second method, ashing distillation-fluorine reagent colorimetric method, are deleted; ---The previous third method, fluoride ion selective electrode method is adjusted to the second method, the linear range of the method is modified, and the method quantitative limit is added. National Food Safety Standard - Determination of Fluorine in Foods1 ScopeThis Standard specifies the determination method for fluorine in foods. The first method of this Standard is applicable to the determination of fluoride content in foods other than table salt and brick tea, and the second method is applicable to the determination of fluoride content in brick tea. Method I - Ion Chromatography2 PrincipleThe fluorine in the specimen is fixed with alkali, ashed at high temperature, and converted into the form of salt. Under neutral or weakly alkaline conditions, it is separated by ion exchange chromatography column, determined by electrical conductivity detector, and quantified by the external standard method.3 Reagents and MaterialsUnless otherwise specified, all reagents used in this Method are guaranteed reagents, the water is Grade-1 water specified in GB/T 6682, and all utensils used are made of plastic (polyethylene or polypropylene). 3.1 Reagents 3.1.1 Potassium hydroxide (KOH). 3.2 Preparation of Reagents 3.2.1 Eluent (sodium carbonate 8.0 mmol/L and sodium bicarbonate 0.25 mmol/L). weigh-take 0.848 g of sodium carbonate and 0.021 g of sodium bicarbonate, dissolve them in an appropriate amount of water, and reach a constant volume of 1,000 mL. 3.4 Preparation of Standard Solutions 3.4.1 Fluorine standard stock solution (1,000 mg/L). accurately weigh-take 0.2210 g (accurate to 0.0001 g) of sodium fluoride dried to constant weight at 95 C ~ 105 C into a beaker, use water to dissolve it, transfer it to a 100 mL volumetric flask, add water to a constant volume, and mix it well. At 0 C ~ 4 C, store it sealed and away from light, and it shall remain valid for 6 months. 3.4.2 Fluorine standard intermediate solution (10.0 mg/L). accurately transfer-take 1.00 mL of fluorine standard stock solution (1,000 mg/L) into a 100 mL volumetric flask, add water to a constant volume and mix it well. At 0 C ~ 4 C, store it sealed and away from light, and it shall remain valid for 1 month. 3.5 Materials 3.5.1 Strong acid cation exchange resin. H type (2.5 mL). 3.5.2 Syringe. 2.5 mL or 5.0 mL. 3.5.3 0.45 m aqueous membrane syringe filter.4 Instruments and Equipment4.1 Ion chromatograph. equipped with electrical conductivity detector and suppressor. 4.2 Balance. the division value is respectively 0.0001 g and 0.001 g. 4.5 Muffle furnace. 4.6 High-speed pulverizer. 4.7 Homogenizer.5 Analytical StepsNOTE. all plastic utensils and nickel crucibles need to be soaked in sodium hydroxide solution (100 g/L) overnight, repeatedly rinsed with tap water, and finally rinsed with water. 5.1 Preparation of Specimens 5.1.1 Solid specimens 5.2 Specimen Pre-treatment 5.2.1 Specimen extraction Accurately weigh-take 0.5 g ~ 1.0 g (accurate to 0.001 g) of solid, semi-solid or solid-liquid mixed specimen or accurately transfer-take 1.00 mL ~ 2.00 mL of liquid specimen and place it in a nickel crucible, 5.3 Instrument Reference Conditions 5.3.1 Hydroxide elution system 5.3.1.1 Chromatographic columns. analytical column (250 mm 4 mm, particle size 5 m) and guard column (50 mm 4 mm, particle size 5 m), with quaternary ammonium polystyrene resin as the filler or others with equivalent performance. 5.3.2.3 Flow rate. 0.7 mL/min. 5.3.2.4 Detection cell temperature. 35 C. 5.3.2.5 Column oven temperature. 45 C. 5.3.2.6 Injection volume. 20 L. 5.4 Preparation of Standard Curve Respectively inject the standard series working solutions into the ion chromatograph, determine the corresponding fluoride ion peak height or peak area, and with the fluoride ion concentration of the standard working solution as the horizontal axis and the fluoride ion peak height or peak area as the vertical axis, draw a standard curve. 5.5 Determination of Specimen Solution Inject the specimen solution into the ion chromatograph to obtain the corresponding fluoride ion peak height or peak area. In accordance with the standard curve, obtain the fluoride ion concentration in the specimen solution.6 Expression of Analytical ResultsThe fluorine content in the specimen is calculated in accordance with Formula (1).7 PrecisionThe absolute difference between two independent determination results obtained under repeatability conditions must not exceed 10% of the arithmetic mean.8 OthersWhen the sampling size is 0.5 g (or 1 mL) and the constant volume is 50 mL, the detection limit of the Method is 0.2 mg/kg (or 0.1 mg/L) and the quantification limit is 0.5 mg/kg (or 0.25 mg/L).9 PrincipleThe fluoride in the specimen is extracted with water and determined with a fluoride ion selective electrode under a certain total ionic strength.10 Reagents and MaterialsUnless otherwise specified, all reagents used in this Method are analytically pure, the water is Grade-3 water specified in GB/T 6682, and all utensils used are made of plastic (polyethylene or polypropylene). 10.1 Reagents 10.2 Preparation of Reagents 10.2.1 Sodium acetate solution (3 mol/L). weigh-take 204 g of sodium acetate and dissolve it in 300 mL of water. Add acetic acid (1 mol/L) to adjust the pH to 7.0 and add water to a constant volume of 500 mL. 10.3 Standard Substance Same as 3.3. 10.4 Preparation of Standard Solutions 10.4.1 Fluoride standard stock solution (1,000 mg/L). see 3.4.1. 10.4.2 Fluorine standard intermediate solution (50.0 mg/L). accurately transfer-take 5.00 mL of fluorine standard stock solution (1,000 mg/L) into a 100 mL volumetric flask, add water to reach a constant volume and mix it well. At 0 C ~4 C, store it sealed and away from light, and it shall remain valid for 2 months. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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