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GB 5009.17-2021 English PDF (GB 5009.17-2014, GB/T 5009.17-2003)

GB 5009.17-2021_English: PDF (GB5009.17-2021)
Standard IDContents [version]USDSTEP2[PDF] delivered inStandard Title (Description)StatusPDF
GB 5009.17-2021English380 Add to Cart 0--9 seconds. Auto-delivery Determination of total mercury and organic-mercury in foods Valid GB 5009.17-2021
GB 5009.17-2014English85 Add to Cart 0--9 seconds. Auto-delivery National Food Safety Standard -- Determination of total mercury and organic-mercury in food Obsolete GB 5009.17-2014
GB/T 5009.17-2003English140 Add to Cart 0--9 seconds. Auto-delivery Determination of total mercury and organic mercury in foods Obsolete GB/T 5009.17-2003
GB/T 5009.17-1996English279 Add to Cart 3 days [Need to translate] Method for determination of total mercury in foods Obsolete GB/T 5009.17-1996
GB 5009.17-1985English199 Add to Cart 2 days [Need to translate] Method for determination of total mercury in foods Obsolete GB 5009.17-1985


BASIC DATA
Standard ID GB 5009.17-2021 (GB5009.17-2021)
Description (Translated English) Determination of total mercury and organic-mercury in foods
Sector / Industry National Standard
Word Count Estimation 26,263
Date of Issue 2021-09-07
Date of Implementation 2022-03-07
Issuing agency(ies) National Health Commission of the People's Republic of China, State Administration of Market Supervision and Administration

BASIC DATA
Standard ID GB 5009.17-2014 (GB5009.17-2014)
Description (Translated English) National Food Safety Standard - Determination of total mercury and organic-mercury in food
Sector / Industry National Standard
Classification of Chinese Standard C53;X09
Classification of International Standard 67.040
Word Count Estimation 15,159
Date of Issue 2015/9/21
Date of Implementation 2016/3/21
Older Standard (superseded by this standard) GB/T 5009.17-2003
Administrative Organization National Health and Family Planning
Regulation (derived from) National Food Safety Standard Announcement 2015 No.7
Issuing agency(ies) National Health and Family Planning Commission of the People's Republic of China

BASIC DATA
Standard ID GB/T 5009.17-2003 (GB/T5009.17-2003)
Description (Translated English) Determination of total mercury and organic-mercury in foods
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard C53;X09
Classification of International Standard 67.040
Word Count Estimation 15,169
Date of Issue 2003-08-11
Date of Implementation 2004-01-01
Older Standard (superseded by this standard) GB/T 5009.17-1996; GB/T 5009.45-1996
Drafting Organization Ministry of Health Food Hygiene Supervision and Inspection
Administrative Organization People's Republic of China Ministry of Health
Proposing organization Ministry of Health of the People Republic of China
Issuing agency(ies) People Republic of China Ministry of Health China National Standardization Management Committee
Summary This standard specifies: all kinds of food in the total mercury determination. This standard applies to: all kinds of food in the total mercury determination. Atomic Fluorescence Spectrometry


GB 5009.17-2021 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National Food Safety Standard - Determination of Total Mercury and Organic-mercury in Food ISSUED ON: SEPTEMBER 7, 2021 IMPLEMENTED ON: MARCH 7, 2022 Issued by: National Health Commission of the People’s Republic of China; State Administration for Market Regulation. Table of Contents Foreword ... 4  1 Scope ... 5  Part 1 - Determination of Total Mercury in Food ... 5  Method 1 - Atomic Fluorescence Spectrometry ... 5  2 Principle ... 5  3 Reagents and Materials ... 5  4 Instruments and Equipment ... 7  5 Analytical Procedures ... 7  6 Expression of Analytical Results ... 10  7 Precision ... 11  8 Others ... 11  Method 2 - Direct Injection Method for Mercury Determination ... 11  9 Principle ... 11  10 Reagents and Materials ... 12  11 Instruments and Equipment ... 13  12 Analytical Procedures ... 13  13 Expression of Analytical Results ... 14  14 Precision ... 15  15 Others ... 15  Method 3 - Inductively Coupled Plasma Mass Spectrometry ... 15  Method 4 - Cold Atomic Absorption Spectrometry ... 15  16 Principle ... 15  17 Reagents and Materials ... 16  18 Instruments and Equipment ... 17  19 Analytical Procedures ... 17  20 Expression of Analytical Results ... 18  21 Precision ... 19  22 Others ... 19  Part 2 - Determination of Methyl Mercury in Food ... 19  Method 1 - Liquid Chromatography - Atomic Fluorescence Spectrometry ... 19  23 Principle ... 19  24 Reagents and Materials ... 19  25 Instruments and Equipment ... 22  26 Analytical Procedures ... 23  27 Expression of Analytical Results ... 25  28 Precision ... 25  29 Others ... 25  Method 2 - Liquid Chromatography - Inductively Coupled Plasma Mass Spectrometry... 26  30 Principle ... 26  31 Reagents and Materials ... 26  32 Instruments and Equipment ... 28  33 Analytical Procedures ... 29  34 Expression of Analytical Results ... 30  35 Precision ... 31  36 Others ... 31  Appendix A Reference Conditions of Microwave Digestion ... 32  Appendix B Reference Conditions of Instruments ... 33  Appendix C Chromatograms of LC-AFS Method ... 35  Appendix D Chromatograms of LC-ICP-MS Method ... 38  National Food Safety Standard - Determination of Total Mercury and Organic-mercury in Food 1 Scope Part 1 of this Standard specifies the methods for the determination of total mercury in food. Part 1 of this Standard is applicable to the determination of total mercury in food. Part 2 of this Standard specifies the methods for the determination of methyl mercury in food. Part 2 of this Standard is applicable to the determination of methyl mercury in aquatic animals and their products, as well as rice and edible fungi. Part 1 - Determination of Total Mercury in Food Method 1 - Atomic Fluorescence Spectrometry 2 Principle After the specimen is heated and digested by acid, in the acidic medium, the mercury in the specimen is reduced to atomic-state mercury by potassium borohydride or sodium borohydride, which is brought into the atomizer by the carrier gas (argon). Under the irradiation of mercury hollow cathode lamp, the ground-state mercury atoms are excited to a high-energy state. When they return from the high-energy state to the ground-state, they emit fluorescence with a characteristic wavelength. The fluorescence intensity is directly proportional to the mercury content, which is quantified by the external standard method. 3 Reagents and Materials Unless it is otherwise specified, the reagents used in this Method are of top-grade purity, and the water is Grade-1 water specified in GB/T 6682. 3.1 Reagents 3.1.1 Nitric acid (HNO3). 3.1.2 Hydrogen peroxide (H2O2). 3.1.3 Sulfuric acid (H2SO4). 3.1.4 Potassium hydroxide (KOH). 3.1.5 Potassium borohydride (KBH4): analytically pure. 3.1.6 Potassium dichromate (K2Cr2O7). 3.2 Preparation of Reagents 3.2.1 Nitric acid solution (1 + 9): measure-take 50 mL of nitric acid; slowly add it to 450 mL of water; mix it up. 3.2.2 Nitric acid solution (5 + 95): measure-take 50 mL of nitric acid; slowly add it to 950 mL of water; mix it up. 3.2.3 Potassium hydroxide solution (5 g/L): weigh-take 5.0 g of potassium hydroxide; use water to dissolve it and dilute to 1,000 mL; mix it up. 3.2.4 Potassium borohydride solution (5 g/L): weigh-take 5.0 g of potassium borohydride; use potassium hydroxide solution (5 g/L) to dissolve it and dilute to 1,000 mL; mix it up. Prepare it right before use. 3.2.5 Nitric acid solution of potassium dichromate (0.5 g/L): weigh-take 0.5 g of potassium dichromate; use nitric acid solution (5 + 95) to dissolve it and dilute to 1,000 mL; mix it up. NOTE: this method may also use sodium borohydride as a reducing agent: weigh-take 3.5 g of sodium borohydride; use sodium hydroxide solution (3.5 g/L) to dissolve it and reach a constant volume of 1,000 mL; mix it up. Prepare it right before use. 3.3 Standard Substance Mercury chloride (HgCl2, CAS No.: 7487-94-7): purity ≥ 99%. 3.4 Preparation of Standard Solutions 3.4.1 Standard stock solution of mercury (1,000 mg/L): accurately weigh-take 0.1354 g of mercury chloride; use nitric acid solution of potassium dichromate (0.5 g/L) to dissolve it and transfer to a 100 mL volumetric flask; dilute it to a constant volume to the scale; mix it up. Store it at 2 °C ~ 8 °C in the refrigerator; keep away from light; it shall remain valid for 2 years. Or a mercury standard solution certified by the country and awarded with a standard substance certificate. 3.4.2 Standard intermediate solution of mercury (10.0 mg/L): accurately draw 1.00 mL a clean polyethylene bottle; seal and store it for later use. 5.1.2 In terms of fresh samples, such as: vegetables, fruits, fish, meat and eggs, wash and dry them; take the edible part and homogenize it; put it into a clean polyethylene bottle; seal it; store it at 2 °C ~ 8 °C in the refrigerator for later use. 5.1.3 In terms of milk and dairy products, after homogenizing it, put it into a clean polyethylene bottle; seal it; store it at 2 °C ~ 8 °C in the refrigerator for later use. 5.2 Digestion of Specimens 5.2.1 Method of microwave digestion Weigh-take 0.2 g ~ 0.5 g of solid specimen (accurate to 0.001 g; for samples with relatively more water content, the sampling amount may be properly increased to 0.8 g), or accurately weigh-take 1.0 g ~ 3.0 g of liquid specimen (accurate to 0.001 g). For samples that are difficult to digest, for example, vegetable oils, weigh-take 0.2 g ~ 0.5 g (accurate to 0.001 g). Place it in a digestion tank; add 5 mL ~ 8 mL of nitric acid; put on the lid and let it stand for 1 h. For samples that are difficult to digest, add 0.5 mL ~ 1 mL of hydrogen peroxide; tightly screw the lid; in accordance with the standard operating procedures of the microwave digestion apparatus (please refer to Table A.1 in Appendix A for the reference conditions of microwave digestion), conduct the digestion. After cooling it down, take it out; slowly open the lid of the tank to exhaust air; use a small amount of water to rinse the inner lid. Place the digestion tank on a temperature-controllable electric heating plate or in the ultrasonic water bath; at 80 °C, heat it up or ultrasonically degas for 3 min ~ 6 min to drive off the brown gas. Take out the digestion inner tank; transfer the digestion solution to a 25 mL volumetric flask. Use a small amount of water to rinse the inner tank in 3 times; combine the washing liquid in a volumetric flask and reach a constant volume to the scale; mix it up for later use. Meanwhile, conduct a blank test. 5.2.2 Method of pressure tank digestion Weigh-take 0.2 g ~ 1.0 g of solid specimen (accurate to 0.001 g; for samples with relatively more water content, the sampling amount may be properly increased to 2 g), or accurately weigh-take 1.0 g ~ 5.0 g of liquid specimen (accurate to 0.001 g). For samples that are difficult to digest, for example, vegetable oils, weigh-take 0.2 g ~ 0.5 g (accurate to 0.001 g). Place it in a digestion tank; add 5 mL of nitric acid; let it stand for 1 h or overnight. Put on the inner lid; tightly screw the stainless steel enclosure; put it in a constant-temperature drying oven; at 140 °C ~ 160 °C, maintain for 4 h ~ 5 h. Let it naturally cool down to room temperature; slowly loosen the stainless steel enclosure. Take out the digestion inner tank; use a small amount of water to rinse the inner lid. Put the digestion tank on a temperature-controllable electric heating plate or in the ultrasonic water bath; at 80 °C, heat it up or conduct ultrasonic degassing for 3 min ~ 6 min to drive off the brown gas. Take out the digestion inner tank; transfer the digestion solution to a 25 mL volumetric flask; use a small amount of water to rinse the inner tank in 3 times; combine the washing liquid in a volumetric flask and reach a constant volume to the scale; mix it up for later use. Meanwhile, conduct a blank test. 5.2.3 Method of reflux digestion 5.2.3.1 Grains Weigh-take 1.0 g ~ 4.0 g (accurate to 0.001 g) of specimen; place it in a conical flask of the digestion device. Add several glass beads; add 45 mL of nitric acid and 10 mL and sulfuric acid; rotate the conical flask to prevent local carbonization. After installing the condenser pipe, heat it up at a low temperature. When it starts foaming, stop heating. After foaming stops, heat to reflux for 2 h. If the solution turns brown during the heating process, add 5 mL of nitric acid and continue to reflux for 2 h. Conduct digestion, until the sample is completely dissolved, which is generally pale yellow or colorless. After cooling, carefully add 20 mL of water from the upper end of the condenser pipe; continue to heat and reflux for 10 min. After leaving it to cool down, use an appropriate amount of water to rinse the condenser pipe; incorporate the rinsing liquid into the digestive fluid. Filter the digestive fluid through glass wool into a 100 mL volumetric flask; use a small amount of water to wash the conical flask and filter. Incorporate the washing liquid into the volumetric flask; add water to the scale; mix it up for later use. Meanwhile, conduct a blank test. 5.2.3.2 Vegetable oils and animal fats Weigh-take 1.0 g ~ 3.0 g (accurate to 0.001 g) of specimen; place it in a conical flask of the digestion device. Add several glass beads; add 7 mL of sulfuric acid; carefully mix it up, until the solution turns brown, then, add 40 mL of nitric acid. The subsequent steps are the same as 5.2.3.1 “After installing the condenser pipe, heat it up with a small fire…. Meanwhile, conduct a blank test”. 5.2.3.3 Potatoes and soy products Weigh-take 1.0 g ~ 4.0 g (accurate to 0.001 g) of specimen; place it in a conical flask of the digestion device. Add several glass beads, 30 mL of nitric acid and 5 mL of sulfuric acid; rotate the conical flask to prevent local carbonization. The subsequent steps are the same as 5.2.3.1 “After installing the condenser pipe, heat it up with a small fire…. Meanwhile, conduct a blank test”. 5.2.3.4 Meat and eggs Weigh-take 0.5 g ~ 2.0 g (accurate to 0.001 g) of specimen; place it in a conical flask of the digestion device. Add several glass beads, 30 mL of nitric acid and 5 mL of sulfuric acid. Rotate the conical flask to prevent local carbonization. The subsequent steps are the same as 5.2.3.1 “After installing the condenser pipe, heat it up with a small fire…. Meanwhile, conduct a blank test”. 5.2.3.5 Milk and dairy products mg/L, 2.0 mg/L, 3.0 mg/L, 4.0 mg/L and 6.0 mg/L. NOTE: in accordance with the type and measuring range of the detector configured in the instrument, or the actual content of mercury in the sample, the range of mass concentration of mercury in the standard series solutions may be determined. 11 Instruments and Equipment 11.1 Direct mercury meter. 11.2 Electronic balance: with a division value of 0.01 mg, 0.1 mg and 1 mg. 11.3 Homogenizer. 11.4 High-speed pulverizer. 11.5 Sample boat: nickel boat or quartz boat. 11.6 Carrier gas: oxygen (99.9%) or air; argon-hydrogen mixture (9 : 1, volume ratio) (99.9%). 11.7 Sieve: particle size ≤ 425 μm (or sieve opening ≥ 40 mesh). NOTE: the glassware needs to be soaked in nitric acid solution (1 + 4) for 24 h; use tap water to repeatedly rinse it, and finally, use water to thoroughly rinse it. 12 Analytical Procedures 12.1 Pre-treatment of Specimens 12.1.1 In terms of grains and beans, take the edible part and evenly crush it, with a particle size of 425 μm or less (equivalent to 40 mesh or more). Put it into a clean polyethylene bottle; seal and store it for later use. 12.1.2 In terms of samples with relatively more water content, for example, vegetables, if necessary, wash and drain them; take the edible part and homogenize it. For samples like aquatic products, meat and eggs, take the edible part and homogenize it. Put it in a clean polyethylene bottle; seal it; store it at 2 °C ~ 8 °C in the refrigerator for later use. 12.1.3 In terms of quick-frozen and canned food, thawed quick-frozen food and canned food samples, take the edible part and homogenize it. Put it in a clean polyethylene bottle; seal it; store it at 2 °C ~ 8 °C in the refrigerator for later use. 12.1.4 For milk and dairy products, shake them well. 12.2 Determination 12.2.1 Reference conditions of instrument In accordance with the performance of the used direct mercury meter, adjust to the optimum state. The reference conditions of catalytic pyrolysis gold amalgam cold atomic absorption mercury meter are shown in Table B.1 in Appendix B; the reference conditions of catalytic pyrolysis gold amalgam atomic fluorescence mercury meter are shown in Table B.2; the reference conditions of pyrolysis cold atomic absorption mercury meter are shown in Table B.3. 12.2.2 Sample boat purification After the sample ash remaining in the sample boat is cleaned up, adopt the built-in heating program of the instrument or muffle furnace to conduct high-temperature burning (600 °C ~ 800 °C) for more than 20 min to remove the mercury residue. 12.2.3 Drawing of standard curve Respectively draw 0.1 mL of the low-concentration and high-concentration standard series solutions of mercury and place them in the sample boat. The mercury mass of the low-concentration standard series is respectively 0.0 ng, 1.0 ng, 5.0 ng, 10.0 ng, 20.0 ng, 30.0 ng and 40.0 ng; the mercury mass of the high-concentration standard series is respectively 40.0 ng, 80.0 ng, 100 ng, 200 ng, 300 ng, 400 ng and 600 ng. In accordance with the reference conditions of the instrument (Appendix B), adjust the instrument to the optimum state. In accordance with the mercury mass from low to high, successively determine the standard series solutions; record the signal response value. Take the mercury mass (ng) in each series standard solution as the x-coordinate; take the corresponding signal response value as the y-coordinate; respectively draw the standard curve of low-concentration or high-concentration mercury. 12.2.4 Determination of specimen In accordance with the sample type, accurately weigh-take 0.05 g ~ 0.5 g (accurate to 0.0001 g or 0.001 g) of sample in the sample boat. In accordance with the reference conditions set by the instrument (Appendix B), conduct the determination; obtain the corresponding atomic absorption or atomic fluorescence spectral signal value. Read the corresponding mercury mass from the standard curve; calculate the mercury content in the sample. Conduct parallel sample determination on each sample; take the average value. 13 Expression of Analytical Results The mercury content in the specimen shall be calculated in accordance with Formula (2). 17 Reagents and Materials Unless it is otherwise specified, the reagents used in this Method are of top-grade purity, and the water is Grade-1 water specified in GB/T 6682. 17.1 Reagents 17.1.1 Nitric acid (HNO3). 17.1.2 Hydrochloric acid (HCl). 17.1.3 Hydrogen peroxide (H2O2) (30%). 17.1.4 Anhydrous calcium chloride (CaCl2): analytically pure. 17.1.5 Potassium permanganate (KMnO4): analytically pure. 17.1.6 Potassium dichromate (K2Cr2O7): analytically pure. 17.1.7 Stannous chloride (SnCl2  2H2O): analytically pure. 17.2 Preparation of Reagents 17.2.1 Potassium permanganate solution (50 g/L): weigh-take 5.0 g of potassium permanganate; place it in a 100 mL brown bottle; use water to dissolve it and dilute to 100 mL; mix it up. 17.2.2 Nitric acid solution (5 + 95): measure-take 50 mL of nitric acid; slowly pour it into 950 mL of water; mix it up. 17.2.3 Nitric acid solution of potassium dichromate (0.5 g/L): weigh-take 0.5 g of potassium dichromate; use nitric acid solution (5 + 95) to dissolve it and dilute to 1,000 mL; mix it up. 17.2.4 Stannous chloride solution (100 g/L): weigh-take 10 g of stannous chloride; dissolve it in 20 mL of hydrochloric acid. Heat it up in a water bath at 90 °C; slightly shake it. After the stannous chloride is dissolved into a transparent shape, cool it down; use water to dilute to 100 mL; add several pieces of metal tin. Store it in a cool and dark place. Once turbidity is found, it shall be re-prepared. 17.2.5 Nitric acid solution (1 + 9): measure-take 50 mL of nitric acid; slowly add it to 450 mL of water; mix it up. 17.3 Standard Substance Mercury chloride (HgCl2, CAS No.: 7487-94-7): purity ≥ 99%. 17.4 Preparation of Standard Solutions 17.4.1 Standard stock solution of mercury (1,000 mg/L): same as 3.4.1. 17.4.2 Standard intermediate solution of mercury (10.0 mg/L): same as 3.4.2. 17.4.3 Standard working solution of mercury (50.0 μg/L): same as 3.4.3. 17.4.4 Standard series solutions of mercury: same as 3.4.4. 18 Instruments and Equipment 18.1 Mercury meter: equipped with gas circulation pump, gas drying device, mercury vapor generating device and mercury vapor absorption bottle, or full-automatic mercury measuring instrument. 18.2 Balance: with a division value of 0.01 mg, 0.1 mg and 1 mg. 18.3 Microwave digestion system. 18.4 Pressure digester. 18.5 Constant-temperature drying oven (200 °C ~ 300 °C). 18.6 Temperature-controllable electric heating plate (50 °C ~ 200 °C). 18.7 Ultrasonic water bath. 18.8 Homogenizer. 18.9 High-speed pulverizer. NOTE: the glassware and PTFE digestion inner tank need to be soaked in nitric acid solution (1 + 4) for 24 h; use tap water to repeatedly rinse it, and finally, use water to thoroughly rinse it. 19 Analytical Procedures 19.1 Pre-treatment of Specimens Same as 5.1. 19.2 Digestion of Specimens Same as 5.2. 19.3 Determination 19.3.1 Reference conditions of instrument ......


GB 5009.17-2014 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National Food Safety Standard-Determination of total mercury and organic-mercury in foods ISSUED ON. SEPTEMBER 21, 2015 IMPLEMENTED ON. MARCH 21, 2016 Issued by. National Health and Family Planning Commission Table of Contents Foreword ... 4  1 Scope ... 5  Chapter I Determination of total mercury in foods ... 5  The first method Atomic fluorescence spectrometry ... 5  2 Principle... 5  3 Reagents and materials ... 5  4 Apparatus ... 7  5 Analysis procedures ... 7  6 Representation of analysis result ... 10  7 Precision... 10  8 Other ... 10  The second Method Cold Atomic Absorption Spectrometric Method ... 11  9 Principle... 11  10 Reagents and materials... 11  11 Apparatus ... 12  12 Analysis procedures ... 13  13 Representation of analysis result ... 14  14 Precision ... 14  15 Other ... 15  Chapter II Determination of methylmercury in foods ... 15  Liquid chromatography - atomic fluorescence spectrometry method ... 15  16 Principle... 15  17 Reagents and materials... 15  18 Apparatus ... 17  19 Analysis procedures ... 17  13 Representation of analysis result ... 19  21 Precision ... 20  22 Other ... 20  Annex A ... 21  Annex B ... 22  Foreword This Standard replaces GB/T 5009.17-2003 Determination of Total Mercury and Organic-mercury in Foods. Compared with GB/T 5009.17-2003, the main changes are as follows. - modified the standard name to “National Food Safety Standard- Determination of total mercury and organic-mercury in foods”; - deleted double sulphur hydrazone colorimetry method for determination of total mercury, gas chromatography for determination of organic mercury and atomic absorption spectrometry; - added liquid chromatography - atomic fluorescence spectrometry (LC- AFS) for determination of methylmercury. National Food Safety Standard - Determination of total mercury and organic-mercury in foods 1 Scope The first chapter of this Standard specified the determination method for total mercury in foods. The first chapter of this Standard is applicable to the determination of total mercury in foods. The second chapter of this Standard specifies the liquid chromatography - atomic fluorescence spectrometry for determination of methylmercury in foods. The second chapter of this Standard is applicable to the determination of methylmercury in foods. Chapter I Determination of total mercury in foods The first method Atomic fluorescence spectrometry 2 Principle After the sample is heated and digested by acid, in acidic medium, mercury in sample is reduced to atomic mercury by potassium borohydride or sodium borohydride. It is brought by carrier gas (argon) into the atomizer. Under irradiation of mercury hollow cathode lamp, ground state mercury atom is stimulated to high energy state. When it is back from high energy state to ground state, it shall emit the characteristic wavelength fluorescence. Its fluorescence intensity is proportional to the mercury content, in quantitative comparison with the standard series solution. 3 Reagents and materials NOTE. Unless otherwise indicated, reagents used in this method are guaranteed reagents; water is the grade one water specified in GB/T 6682. 3.1 Reagents 3.1.1 Nitric acid (HNO3). 3.1.2 Hydrogen peroxide (H2O2). 3.1.3 Sulfuric acid (H2SO4). 3.1.4 Potassium hydroxide (KOH). 3.1.5 Potassium borohydride (KBH4). analytically pure. 3.2 Reagent preparation 3.2.1 Nitric acid solution (1+9). measure 50 mL of nitric acid; slowly add it into 450 mL of water. 3.2.2 Nitric acid solution (95+5). measure 5 mL of nitric acid; slowly add it into 95 mL of water. 3.2.3 Potassium hydroxide solution (5g/L). weigh 5.0 g of potassium hydroxide; dissolve it in pure water; set volume to 1000 mL; well mix it. 3.2.4 Solution of potassium borohydride (5g/L). weigh 5.0 g of potassium borohydride; use 5g/L potassium hydroxide solution to dissolve and set volume to 1000 mL; well mix it; prepare it when required. 3.2.5 Potassium dichromate nitric acid solution (0.5 g/L). weigh 0.05 g of potassium dichromate to dissolve in 100 mL of nitric acid solution (5+95). 3.2.6 Nitric acid-perchloric acid mixed solution (5+1). measure 500 mL of nitrate and 100 mL of perchloric acid; well mix. 3.3 Standard product Mercuric chloride (HgCl2). purity ≥ 99%. 3.4 Preparation of standard solution 3.4.1 Mercury standard stock solution (1.00 mg/mL). accurately weigh 0.1354 g of dried mercuric chloride; use potassium dichromate nitric acid solution (0.5 g/L) to dissolve and transfer to 100 mL measuring flask; dilute it to scale; well mix; the concentration of this solution is 1.00 mg/mL; store it in 4°C refrigerator in dark conditions; it can be stored for 2 years; or purchase the standard solution substance awarded by national certification standard certificate. 3.4.2 Mercury standard intermediate solution (10 μg/mL). pipette 1.00 mL of mercury standard solution (1.00 mg/mL) in 100 mL measuring flask; use potassium dichromate nitric acid solution (0.5 g/L) to dilute to scale; well mix; sample OR pipette 1 mL ~ 5 mL of liquid sample (accurate to 0.001 g) into digestion inner tank. Add 5 mL of nitrate to soak overnight. Cover the inner lid. Tighten the stainless steel jacket. Place into thermostatic oven for 4h ~ 5h at 140°C ~ 160°C. Naturally cool it to room temperature in the oven. Then slowly loosen the stainless steel jacket. Take it from the digestion inner tank. Use few amount of water to clean the inner lid. Place on temperature control heating plate or ultrasonic water bath. Drive away brown gas at 80°C or by 2 min ~ 5 min of ultrasonic degassing. Take the digestion inner tank out. Transfer the digestive fluid to 25 mL flask. Use few amount of water to clean the inner tank for 3 times. Combine the detergent in the flask and set volume to scale. Well mix for use. Conduct the blank test at the same time. 5.2.2 Microwave digestion method Weigh 0.2 g ~ 0.5 g (accurate to 0.001 g) of solid sample, 0.2 g ~ 0.8 g of fresh sample OR pipette 1 mL ~ 3 mL of liquid sample into digestion inner tank. Add 5 mL ~ 8 mL of nitrate. Cover and place for overnight. Tighten the lid. Digest according to the standard operation procedures of microwave digestion system (see Table A.1 of Annex A for digestion reference conditions). Take it out after cooling. Slowly open the tank to exhaust. Use few amount of water to clean the inner lid. Place on temperature control heating plate or ultrasonic water bath. Drive away brown gas at 80°C or by 2 min ~ 5 min of ultrasonic degassing. Take the digestion inner tank out. Transfer the digestive fluid to 25 mL plastic flask. Use few amount of water to clean the inner tank for 3 times. Combine the detergent in the flask and set volume to scale. Well mix for use. Conduct the blank test at the same time. 5.2.3 Reflux digestion method 5.2.3.1 Grain Weigh 1.0 g ~ 4.0 g (accurate to 0.001 g) of sample. Place it in digestion Erlenmeyer flask. Add few glass beads. Add 45 mL of nitric acid, 10 mL of sulfuric acid. Rotate the Erlenmeyer flask to prevent partial carbonization. After mounting condenser tube, low heat it when it starts bubbling. After bubbling stops, heat it for 2h. If during heating, the solution turns brown, it shall add 5 mL of nitrate. Add 5 mL of nitrate, and continue refluxing for 2h till the sample is dissolved by digestion. Generally, it appears light yellow or colorless. After ... ......


GB/T 5009.17-2003 GB/T5009.17-2003 GB ICS 67.040 C 53 NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA Replacing GB/T 5009.17-1996, partially replacing GB/T 5009.45-1996 Determination of total mercury and organic-mercury in foods ISSUED ON. AUGUST 11, 2003 IMPLEMENTED ON. JANUARY 01, 2004 Issued by. Ministry of Health of the People’s Republic of China; Standardization Administration of the People’s Republic of China Table of Contents Foreword ... 4  1  Scope ... 5  2  Principle ... 5  3  Reagents ... 5  4  Instruments ... 6  5  Analysis Procedures ... 6  6  Result calculation ... 9  7  Precision ... 9  8  Principle ... 9  9  Reagents ... 10  10  Instruments ... 10  11  Analysis procedures ... 10  12  Result calculation ... 12  13  Precision ... 12  14  Reagents ... 12  15  Instruments ... 13  16  Analysis procedures ... 13  17  Result calculation ... 15  18  Precision ... 16  19  Principle ... 16  20  Reagents ... 16  21  Instruments ... 17  22  Analysis procedures ... 17  23  Result calculation ... 19  24  Precision ... 19  25  Scope ... 19  26  Principle ... 20  27  Reagents ... 20  28  Instruments ... 21  29  Analysis procedures ... 21  30  Result calculation ... 22  31  Precision ... 23  32  Principle ... 23  33  Reagents ... 23  34  Instruments ... 24  35  Analysis procedures ... 24  36  Result calculation ... 24  37  Precision ... 25  Foreword  This standard replaces GB/T 5009.17-1996 “Method for determination of total mercury in foods”, and Section 4.6 Methylmercury of GB/T 5009.45-1996 “Method for analysis of hygienic standard of fish and other aquatic products”. Compared with GB/T 5009.17-1996 and Section 4.6 Methylmercury of GB/T 5009.45-1996 “Method for analysis of hygienic standard of fish and other aquatic products”, the main changes of this standard are as follows. — Change the Chinese title of the standard to be “Determination of total mercury and organic-mercury in foods”; — Revise the structure of previous standard according to GB/T 20001.4-2001 “Rules for drafting standards - Part 4. Methods of chemical analysis”. This standard was proposed by and shall be under the jurisdiction of Ministry of Health of the People’s Republic of China. The participating drafting organizations of “First Method. Determination of total mercury” in this standard. Food Hygiene Supervision and Inspection Institute of MOH, Beijing Food Hygiene Supervision and Inspection Institute, Sichuan Food Hygiene Supervision and Inspection Institute, and Beijing Hygiene Supervision and Inspection of Import Food. The responsible drafting organizations of “Second Method (1). Determination of total mercury” in this standard. Shanghai Food Hygiene Supervision and Inspection Institute, Institute of Nutrition and Food Hygiene, and Chinese Academy of Preventive Medicine and Food Hygiene Supervision and Inspection Institute of MOH. The responsible drafting organizations of “Second Method (2). Determination of total mercury” in this standard. Food Hygiene Supervision and Inspection Institute of MOH. The responsible drafting organization of “Third Method. Determination of total mercury” in this standard. Jiangsu Sanitation and Anti-epidemic Station. The responsible drafting organizations of “Third Method. Determination of methylmercury” in this standard. Shanghai Food Hygiene Supervision and Inspection Institute, Jiangsu Sanitation and Anti-epidemic Station, Hangzhou Sanitation and Anti-epidemic Station, Food Hygiene Supervision and Inspection Institute of MOH, and Qinghai Sanitation and Anti-epidemic Station and Fujian Hygiene School. The chief drafting staffs of First Method of this standard. Yang Huifen, Huang Liusheng, Mao Hong, Qiang Weiguo, and Yan Jun. Previous standard was issued in 1985 for the first time, first revised in 1996. And this is the second revision. Determination of total mercury and organic-mercury in foods Determination of total mercury 1  Scope  This standard specifies the method of determining the total mercury in all kinds of foods. This standard is applicable to the determination of total mercury in all kinds of foods. Atomic fluorescence spectrometry. detection limit is 0.15µ/kg; the best linear range of standard curve is 0µg/L~60µg/L. Detection limit of cold atomic absorption spectrometry. for pressure digestion method, it is 0.4µg/kg; for other digestion methods, it is 10µg/kg; for colorimetric method, it is 25µg/kg. First Method Atomic Fluorescence Spectrometry 2  Principle  After being digested by acid under high temperature, and in acid media, the mercury in samples is reduced to atomic state by potassium borohydride (KBH4) or sodium borohydride. It is introduced to atomizer by carrier gas (argon). Under special mercury hollow cathode lamp, the ground state mercury atom will be excited to high energy state. During the process of being deactivated to ground state, it can emit fluorescence with characteristic wavelength. The fluorescence intensity is proportional to the content of mercury. Determine the content by comparing with standard series. 3  Reagents  3.1 Nitric acid (GR). 3.2 30% hydrogen peroxide. 3.3 Sulfuric acid (GR). 3.4 Sulfuric acid + nitric acid + water (1+1+8). Measure 10mL of nitric acid and 10mL of sulfuric acid. Pour them into 80mL of water slowly. Mix carefully after cooling. 16.1.1 Reflux digestion method 16.1.1.1 Grains or foods with low water content. place 10.00g of sample into conical flask of digestion device. Add several glass beads, 45mL of nitric acid and 10mL of sulfuric acid. Keep rotating the conical flask to avoid partial carbonization. Install condenser pipe and heat with low flame. Stop heating when it starts foaming. When the foaming stops, keep heating reflux for 2h. During process of heating, if solution turns brown, add 5mL of nitric acid, and keep heating reflux for 2h. After cooling, pour 20mL of water from the top of condenser pipe carefully. Keep heating reflux for 10min continuously. After cooling, wash the condenser pipe. And the washing liquor is merged into the digestion solution. Filter digestion solution into a 100mL volumetric flask through glass wool. Wash conical flask and filter with small amount of water. Washing liquor is merged into volumetric flask. Dilute with water to volume and mix well. Make reagent blank test in accordance with the same method. 16.1.1.2 Vegetable oil and animal fats. place 5.00g of sample into conica... ......

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