GB 5009.12-2023 PDF EnglishUS$230.00 · In stock · Download in 9 seconds
GB 5009.12-2023: National food safety standard - Determination of lead 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 5009.12: Historical versions
Similar standardsGB 5009.12-2023: National food safety standard - Determination of lead 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/GB5009.12-2023GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National food safety standard - Determination of lead in foods Issued on. SEPTEMBER 06, 2023 Implemented on. MARCH 06, 2024 Issued by. National Health Commission of the People’s Republic of China; State Administration for Market Regulation. Table of ContentsForeword... 3 1 Scope... 4 2 Principle... 4 3 Reagents and materials... 4 4 Instruments and apparatuses... 6 5 Analysis steps... 6 6 Expression of analysis results... 8 7 Precision... 9 8 Others... 9 9 Principle... 10 10 Reagents and materials... 10 11 Instruments and apparatuses... 11 12 Analysis steps... 12 13 Expression of analysis results... 13 14 Precision... 13 15 Others... 13 Appendix A Microwave digestion heating program... 14 Appendix B Desalted sample operation steps... 15 Appendix C Apparatus reference conditions for graphite furnace atomic absorption spectrometry... 17 Appendix D Apparatus reference conditions for flame atomic absorption spectrometry ... 18ForewordThis Standard replaces GB 5009.12-2017 Food safety national standard - Determination of lead in food. Compared with GB 5009.12-2017, the major changes of this Standard are as follows. -- Add the pretreatment method for samples that need to be desalted in Method 1 – Graphite furnace atomic absorption spectrometry; -- Remove Method 4 – Dithizone colorimetry; -- Modify the detection limit and quantitation limit of Method 1 – Graphite furnace atomic absorption spectrometry. National food safety standard - Determination of lead in foods1 ScopeThis Standard specifies the methods for the determination of lead in foods by graphite furnace atomic absorption spectrometry, inductively coupled plasma mass spectrometry and flame atomic absorption spectrometry. This Standard applies to the determination of lead in foods. Method 1 – Graphite furnace atomic absorption spectrometry2 PrincipleAfter digestion treatment, the sample is atomized in a graphite furnace and the absorbance is measured at 283.3 nm. Within a certain concentration range, the absorbance value of lead is proportional to the lead content and can be compared quantitatively with the standard series.3 Reagents and materialsUnless otherwise stated, the reagents used in this method are guaranteed reagents, and the water is grade-II water as specified in GB/T 6682. 3.1 Reagents 3.1.1 Nitric acid (HNO3). 3.1.2 Perchloric acid (HClO4). 3.1.3 Ammonium dihydrogen phosphate (NH4H2PO4). 3.1.4 Palladium nitrate [Pd(NO3)2]. 3.1.5 Ammonium acetate (CH3COONH4). 3.1.6 Sodium acetate (CH3COONa). 3.2 Preparation of reagents 3.2.1 Nitric acid solution (5+95). Measure 50 mL of nitric acid; slowly add it to 950 mL of water; mix well. 3.2.2 Nitric acid solution (1+9). Measure 50 mL of nitric acid; slowly add it to 450 mL of water; mix well. 3.2.3 Nitric acid solution (1+99). Measure 10 mL of nitric acid; slowly add it to 990 mL of water; mix well. 3.2.4 Sodium acetate solution (2 mol/L). Weigh 164.0 g of sodium acetate; add water to dissolve; adjust the volume to 1 000 mL. 3.2.5 Ammonium acetate solution (1 mol/L). Weigh 77.1 g of ammonium acetate; add water to dissolve; adjust the volume to 1 000 mL. 3.2.6 Ammonium dihydrogen phosphate-palladium nitrate solution. Weigh 0.02 g of palladium nitrate; add a small amount of nitric acid solution (1+9) to dissolve it; then, add 2 g of ammonium dihydrogen phosphate; after dissolution, use nitric acid solution (5+95) to adjust the volume to 100 mL; mix well. 3.3 Standard Lead nitrate [Pb(NO3)2, CAS number. 10099-74-8]. purity >99.99%, or lead standard solution certified by the state and granted with a reference material certificate. 3.4 Preparation of standard solution4 Instruments and apparatusesNote. All glassware and polytetrafluoroethylene digestion inner tanks need to be soaked in nitric acid solution (1+5) or nitric acid solution (1+4) overnight, rinsed repeatedly with tap water, and finally rinsed with water and dried. 4.1 Atomic absorption spectrometer. equipped with graphite furnace atomizer and accompanied by lead hollow cathode lamp. 4.2 Analytical balance. The sensitivity is 0.1 mg and 1 mg, respectively. 4.5 Constant-temperature drying oven. 4.6 Pressure digestion tank. equipped with polytetrafluoroethylene digestion inner tank. 4.7 Solid-phase extraction column.5 Analysis steps5.1 Sample preparation 5.1.1 Solid samples 5.1.2 Liquid samples For samples of soft drinks, alcoholic beverages, condiments, etc., shake well. 5.1.3 Semi-solid samples Mix well. 5.2 Sample pretreatment 5.3 Determination 5.3.1 Apparatus reference conditions See Appendix C for apparatus reference conditions. 5.3.2 Preparation of standard curve In order of mass concentration from low to high, add 10 μL of lead standard series solution and 5 μL of ammonium dihydrogen phosphate-palladium nitrate solution (the optimal injection volume and optimal matrix modifier can be determined according to the instrument used, and samples passing through the solid-phase extraction column do not need to be added with matrix modifier) into the graphite furnace at the same time, and measure their absorbance values after atomization.6 Expression of analysis resultsThe content of lead in the sample is calculated according to Formula (1).7 PrecisionWhen the lead content in the sample is greater than 1 mg/kg, the absolute difference between the two independent measurement results obtained under repeatability conditions shall not exceed 10% of the arithmetic mean; when it is less than or equal to 1 mg/kg and greater than 0.1 mg/kg,8 OthersWhen the sample volume is 0.5 g (or 0.5 mL) and the constant volume is 10 mL, the detection limit of the method is 0.02 mg/kg (or 0.02 mg/L), and the quantitation limit is 0.04 mg/kg (or 0.04 mg/ L). For samples such as raw milk, pasteurized milk, sterilized milk, fruit and vegetable juices and their beverages [excluding fruit and vegetable juices containing berries and small fruits, as well as their beverages, and concentrated fruit and vegetable juices (pulp)], liquid infant and young child formula foods, etc., when the sample volume is 2 g (or 2 mL) and the constant volume is 10 mL, the detection limit of the method is 0.005 mg/kg (or 0.005 mg/L), and the quantitation limit is 0.01 mg/kg (or 0.01 mg/L).9 PrincipleAfter the sample is processed, lead ions form a complex with sodium diethyldithiocarbamate (DDTC) under certain pH conditions, which is extracted and separated by 4-methyl-2-pentanone (MIBK) and introduced into the atomic absorption spectrometer. After flame atomization, measure the absorbance at 283.3 nm. Within a certain concentration range, the absorbance value of lead is proportional to the lead content and can be compared quantitatively with the standard series.10 Reagents and materialsUnless otherwise specified, all the reagents used in this method are analytical reagents, and the water used is grade-II water as specified by GB/T 6682. 10.1 Reagents 10.1.1 Nitric acid (HNO3). guaranteed reagent. 10.1.2 Perchloric acid (HClO4). guaranteed reagent. 10.1.3 Ammonium sulfate [(NH4)2SO4]. 10.1.4 Ammonium citrate [C6H5O7(NH4)3]. 10.1.5 Bromothymol blue (C27H28O5SBr2). 10.1.6 Sodium diethyldithiocarbamate [DDTC, (C2H5)2NCSSNa·3H2O]. 10.1.7 Ammonia (NH3·H2O). guaranteed reagent. 10.1.8 4-Methyl-2-pentanone (MIBK, C6H12O). 10.1.9 Hydrochloric acid (HCl). guaranteed reagent. 10.2 Preparation of reagents 10.3 Standard Lead nitrate [Pb(NO3)2, CAS number. 10099-74-8]. purity >99.99%, or lead standard solution certified by the state and granted with a reference material certificate. 10.4 Preparation of standard solution 10.4.1 Lead standard stock solution (1 000 mg/L). Accurately weigh 1.598 5 g (accurate to 0.000 1 g) of lead nitrate; use a small amount of nitric acid solution (1+9) to dissolve it; transfer it to a 1 000 mL volumetric flask; add water to the mark; mix well. 10.4.2 Lead standard working solution (10.0 mg/L). Accurately draw 1.00 mL of lead standard stock solution (1 000 mg/L) into a 100 mL volumetric flask; add nitric acid solution (5+95) to the mark; mix well.11 Instruments and apparatusesNote. All glassware needs to be soaked in nitric acid solution (1+5) or nitric acid solution (1+4) overnight, rinsed repeatedly with tap water, and finally rinsed with water and dried. 11.1 Atomic absorption spectrometer. equipped with flame atomizer and accompanied by lead hollow cathode lamp. 11.2 Analytical balance. The sensitivity is 0.1 mg and 1 mg, respectively. 11.3 Adjustable electric furnace and adjustable electric hot plate.12 Analysis steps12.1 Sample preparation Same as 5.1. 12.2 Sample pretreatment Same as 5.2.1. 12.3 Determination 12.3.1 Apparatus reference conditions See Appendix D for apparatus reference conditions. 12.3.2 Preparation of standard curve Respectively draw 0 mL, 0.25 mL, 0.50 mL, 1.00 mL, 1.50 mL and 2.00 mL of lead standard working solution (equivalent to 0 μg, 2.50 μg, 5.00 μg, 10.0 μg, 15.0 μg and 20.0 μg of lead) into 125 mL separatory funnels; add additional water to 60 mL. Add 2 mL of ammonium citrate solution (250 g/L), 3 ~ 5 drops of bromothymol blue aqueous solution (1 g/L); use ammonia solution (1+1) to adjust the pH until the solution changes from yellow to blue; add 10 mL of ammonium sulfate solution (300 g/L) and 10 mL of DDTC solution (50 g/L); shake well. Leave it for about 5 minutes; add 10 mL of MIBK; shake vigorously for extraction for 1 min; let it stand for layering; discard the water layer; put the MIBK layer into a 10 mL graduated tube with a stopper to obtain a standard series of solutions.13 Expression of analysis resultsThe content of lead in the sample is calculated according to Formula (2).14 PrecisionThe absolute difference of two independent test results obtained under repeatability cannot exceed 10% of the arithmetic mean value.15 OthersWhen the sample volume is 0.5 g (or 0.5 mL), the detection limit of the method is 0.4 mg/kg (or 0.4 mg/L), and the quantification limit is 1.2 mg/kg (or 1.2 mg/L). ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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