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GB 5009.304-2025: National food safety standard - Determination of trivalent chromium and hexavalent chromium 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
Similar standardsGB 5009.304-2025: National food safety standard - Determination of trivalent chromium and hexavalent chromium 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/GB5009.304-2025 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National food safety standard - Determination of trivalent chromium and hexavalent chromium in food 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 Contents1 Scope... 3 Part I -- Determination of hexavalent chromium in food... 3 2 Principle... 3 3 Reagents and materials... 3 4 Instruments and equipment... 4 5 Analysis steps... 4 6 Expression of analysis results... 6 7 Precision... 6 8 Others... 6 Part II -- Determination of trivalent chromium in food... 6 9 Principle... 6 10 Reagents and materials... 7 11 Instruments and equipment... 8 12 Analysis steps... 8 13 Expression of analysis results... 9 14 Precision... 10 15 Others... 10 Annex A Reference conditions of inductively coupled plasma mass spectrometry... 11 Annex B Liquid chromatography-inductively coupled plasma mass spectrum of trivalent chromium and hexavalent chromium standard solutions... 12 National food safety standard - Determination of trivalent chromium and hexavalent chromium in food1 ScopePart I of this Standard specifies the method for the determination of hexavalent chromium in food. Part I of this Standard applies to the determination of hexavalent chromium in special medical purpose formula foods and special medical purpose infant formula foods. Part II of this Standard specifies the method for the determination of trivalent chromium in food. Part II of this Standard applies to the determination of trivalent chromium in special medical purpose formula foods and special medical purpose infant formula foods. Part I -- Determination of hexavalent chromium in food2 PrincipleThe sample is shaken with an alkaline solution to extract hexavalent chromium, then centrifuged at high speed and subjected to determination by liquid chromatography- inductively coupled plasma mass spectrometry.3 Reagents and materialsUnless otherwise specified, the reagents used in this method are analytically pure, and the water is grade 1 water specified in GB/T 6682. 3.1 Reagents 3.1.1 Nitric acid (HNO3). concentration ≥ 69 %. 3.1.2 Ammonia (NH3 • H2O). concentration ≥ 25 %. 3.1.3 Sodium hydroxide (NaOH). 3.1.4 Helium (He). helium (≥ 99.995 %). 3.1.5 Argon (Ar). argon (≥ 99.995 %) or liquid argon. 3.2 Reagent preparation 3.2.1 60 mmol/L ammonium nitrate solution. pipette 3.9 mL of nitric acid into 1 L of water, adjust the pH to 7.0 ± 0.1 with ammonia water. 3.2.2 0.05 mol/L sodium hydroxide solution. weigh 1 g of sodium hydroxide, dissolve in water and make up to 500 mL. 3.3 Standards Hexavalent chromium standard solution. 1000 μg/mL, the medium is water, and it is a reference standard certified by the state and awarded a reference standard certificate. 3.4 Preparation of standard solutions 3.4.1 Hexavalent chromium standard stock solution (10 μg/mL). pipette 1.0 mL of hexavalent chromium standard solution (1000 μg/mL), place in a 100 mL volumetric flask, make up to the mark with water, shake well, transfer to a brown reagent bottle, store at 4 ℃ in the dark, and the validity period is 1 month. 3.4.2 Hexavalent chromium standard working solution (100 μg/L). pipette 1.0 mL of hexavalent chromium standard stock solution, place in a 100 mL volumetric flask, make up to the mark with 60 mmol/L ammonium nitrate solution, shake well, transfer to a brown reagent bottle. Prepare before use.4 Instruments and equipment4.1 Liquid chromatography-inductively coupled plasma mass spectrometer (LC-ICP- MS). it consists of a liquid chromatograph and an inductively coupled plasma mass spectrometer (with a collision reaction cell). 4.2 Balance. the sensitivity is 0.001 g. 4.3 pH meter. the accuracy is 0.01. 4.4 Water bath oscillator. 4.5 Refrigerated centrifuge. the centrifugal force is not less than 13100 g. 4.6 Aqueous phase needle filter. 0.45 μm mixed cellulose filter membrane.5 Analysis steps5.1 Sample preparation 5.1.1 During sample preparation and sample storage, samples shall be protected from contamination. 5.1.2 After the powdered sample and liquid sample are mixed evenly, they are placed in a clean container, sealed and labeled, and stored at 4°C for future use. 5.2 Sample pretreatment Accurately weigh 0.25 g of sample (accurate to 0.001 g), place in a stoppered polypropylene centrifuge tube, add 5 mL of water and vortex to disperse the sample, then add 20 mL of sodium hydroxide solution (0.05 mol/L), oscillate and extract in a 25 ℃ water bath for 0.5 h, centrifuge at 10000 r/min for 10 min at 4 ℃, take the upper centrifugal clear liquid and filter through a 0.45 μm filter membrane, for determination by liquid chromatography-inductively coupled plasma mass spectrometry. Perform a blank test at the same time. 5.3 Instrument reference conditions 5.3.1 Liquid chromatography conditions Chromatographic column. Dionex AG19 guard column (4.1 mm × 50 mm, 10 μm) + AS19 analytical column (4.1 mm × 250 mm, 10 μm), or anion exchange columns with equivalent performance. Column temperature. 25 ℃. Mobile phase. 60 mmol/L ammonium nitrate, pH = 7.0. Flow rate. 1.0 mL/min. Sample injection volume. 50 μL. 5.3.2 Mass spectrometry conditions See Annex A. 5.4 Plotting of standard curve Respectively pipette 0 μL, 5 μL, 10 μL, 20 μL, 50 μL, 100 μL, and 200 μL of hexavalent chromium standard working solution, make up to 1 mL with water, and prepare the series standard solutions with hexavalent chromium mass concentrations of 0 ng/mL, 0.5 ng/mL, 1.0 ng/mL, 2.0 ng/mL, 5.0 ng/mL, 10.0 ng/mL, and 20.0 ng/mL respectively, for determination by liquid chromatography-inductively coupled plasma mass spectrometry. Plot a standard working curve using the peak area of hexavalent chromium as the ordinate and the concentration of hexavalent chromium as the abscissa. 5.5 Determination of sample solution Under the same conditions, inject the blank test solution and the sample solution into the instrument for determination, and calculate the concentration of hexavalent chromium in the test solution using the standard working curve. centrifugation, the sample is subjected to liquid chromatography-inductively coupled plasma mass spectrometry for determination of trivalent chromium. Under this determination condition, trivalent chromium and hexavalent chromium are converted in equal amounts, the amount of trivalent chromium measured minus the amount of hexavalent chromium determined in part I is the trivalent chromium content in the sample.10 Reagents and materialsUnless otherwise specified, all reagents used in this method are analytically pure, and the water is grade 1 water specified in GB/T 6682. 10.1 Reagents 10.1.1 Sodium thiosulfate (Na2S2O3 • 5H2O). 10.1.2 Disodium ethylenediaminetetraacetic acid (EDTA-2Na). 10.1.3 Nitric acid (HNO3). ultra-high purity, concentration ≥ 69 %. 10.1.4 Ammonia (NH3 • H2O). chromatographic purity, concentration ≥ 25 %. 10.1.5 Helium (He). helium (≥ 99.995 %). 10.1.6 Argon (Ar). argon (≥ 99.995 %) or liquid argon. 10.2 Reagent preparation 10.2.1 0.1 mol/L sodium thiosulfate solution. weigh 26 g of sodium thiosulfate, dissolve in 1000 mL of boiled and cooled water for later use. 10.2.2 60 mmol/L ammonium nitrate solution. pipette 3.9 mL of nitric acid into 1 L of water, adjust pH to 7.0 ± 0.1 with ammonia water. 10.2.3 20 mmol/L disodium ethylenediaminetetraacetic acid solution. weigh 3.38 g of disodium ethylenediaminetetraacetic acid, dissolve with ammonium nitrate solution (60 mmol/L) and add water to nearly 500 mL, adjust pH to 9.0 ± 0.1 with ammonia water, transfer to a 500 mL volumetric flask, and make up to the mark with water. 10.2.4 5 % nitric acid solution. weigh a certain amount of nitric acid that is converted to 5 g and place in a 100 mL volumetric flask, add water to dilute to the mark. 10.3 Standards Trivalent chromium standard solution. 1000 μg/mL, the medium is hydrochloric acid, it is a reference standard certified by the state and awarded a reference standard certificate. 10.4 Preparation of standard solutions 10.4.1 Trivalent chromium standard stock solution (10 μg/mL). pipette 1.0 mL of trivalent chromium standard solution (1000 μg/mL), place in a 100 mL volumetric flask, make up to the mark with hydrochloric acid, shake well, transfer to a brown reagent bottle, store at 4 ℃ in the dark, and the validity period is 1 month. 10.4.2 Trivalent chromium standard working solution (1000 μg/L). pipette 10.0 mL of trivalent chromium standard stock solution, place in a 100 mL volumetric flask, make up to the mark with 60 mmol/L ammonium nitrate solution, shake well, and transfer to a brown reagent bottle. Prepare before use.11 Instruments and equipmentSame as Clause 4.12 Analysis steps12.1 Sample preparation Same as 5.1. 12.2 Sample pretreatment Accurately weigh 0.5 g of sample (accurate to 0.001 g), place in a stoppered polypropylene centrifuge tube, add 5 mL of 5 % nitric acid solution, oscillate in a 80 ℃ water bath for 1 h, add 5 mL sodium thiosulfate solution (0.1 mol/L) after cooling, adjust pH to 9.0 ± 0.1 with ammonia water, add 15 mL disodium ethylenediaminetetraacetic acid solution (20 mmol/L), oscillate in a 80 ℃ water bath for 1 h, cool to room temperature, add water to make up to 25 mL, centrifuge at 4 ℃ 10000 r/min for 10 min, filter through a 0.45 μm filter membrane, and put on the machine. Perform a blank test at the same time. 12.3 Instrument reference conditions 12.3.1 Liquid chromatography conditions Same as 5.3.1. 12.3.2 Mass spectrometry conditions See Annex A. 12.4 Plotting of standard curve Respectively pipette 0 μL, 12.5 μL, 25 μL, 50 μL, 125 μL, 250 μL, and 500 μL of trivalent chromium standard working solution, add 5 mL of sodium thiosulfate solution ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of English version of GB 5009.304-2025 be delivered?Answer: The full copy PDF of English version of GB 5009.304-2025 can be downloaded in 9 seconds, and it will also be emailed to you in 9 seconds (double mechanisms to ensure the delivery reliably), with PDF-invoice.Question 2: Can I share the purchased PDF of GB 5009.304-2025_English with my colleagues?Answer: Yes. 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