GB 5009.17-2021 PDF English
US$380.00 · In stock · Download in 9 secondsGB 5009.17-2021: Determination of total mercury and organic-mercury in foods Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedureStatus: Valid GB 5009.17: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB 5009.17-2021 | English | 380 |
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Determination of total mercury and organic-mercury in foods
| Valid |
| GB 5009.17-2014 | English | 85 |
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National Food Safety Standard -- Determination of total mercury and organic-mercury in food
| Obsolete |
| GB/T 5009.17-2003 | English | 140 |
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Determination of total mercury and organic mercury in foods
| Obsolete |
| GB/T 5009.17-1996 | English | 279 |
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3 days
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Method for determination of total mercury in foods
| Obsolete |
| GB 5009.17-1985 | English | 199 |
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2 days
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Method for determination of total mercury in foods
| Obsolete |
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GB 5009.17-2021: Determination of total mercury and organic-mercury 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/GB5009.17-2021
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
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.
3.3 Standard Substance
Mercury chloride (HgCl2, CAS No.. 7487-94-7). purity ≥ 99%.
3.4 Preparation of Standard Solutions
4 Instruments and Equipment
4.1 Atomic fluorescence spectrometer. equipped with a mercury hollow cathode lamp.
4.2 Electronic balance. with a division value of 0.01 mg, 0.1 mg and 1 mg.
4.3 Microwave digestion system.
4.4 Pressure digester.
4.5 Constant-temperature drying oven (50 °C ~ 300 °C).
4.6 Temperature-controllable electric heating plate (50 °C ~ 200 °C).
4.7 Ultrasonic water bath.
4.8 Homogenizer.
4.9 High-speed pulverizer.
5 Analytical Procedures
5.1 Pre-treatment of Specimens
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;
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.
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.
5.2.3.5 Milk and dairy 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 and 30 mL of nitric acid; for milk, add
10 mL of sulfuric acid; for dairy products, add 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”.
5.3 Determination
6 Expression of Analytical Results
The mercury content in the specimen shall be calculated in accordance with Formula(1).
7 Precision
When the mercury content in the sample is greater than 1 mg/kg, the absolute
difference between two independent determination results obtained under repeatability
conditions shall not exceed 10% of the arithmetic mean value. When the mercury
content in the sample is less than or equal to 1 mg/kg, and greater than 0.1 mg/kg,
8 Others
When the mass of the sample is 0.5 g and the constant volume is 25 mL, the detection
limit of this Method is 0.003 mg/kg;
9 Principle
After the sample is burned at a high temperature and is subject to catalytic pyrolysis,
mercury is reduced to elemental mercury. Use gold amalgam for enrichment or directly
bring into the detector by carrier gas. At a wavelength of 253.7 nm, measure the atomic
absorption signal of mercury, or use a mercury lamp to excite the atomic fluorescence
signal of the mercury being detected, which is quantified by the external standard
method.
10 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are of top-gradepurity,
10.1 Reagents
10.2 Preparation of Reagents
10.3 Standard Substance
Mercury chloride (HgCl2, CAS No.. 7487-94-7). purity ≥ 99%.
10.4 Preparation of Standard Solutions
10.4.1 Standard stock solution of mercury (1,000 mg/L). same as 3.4.1.
10.4.2 Standard intermediate solution of mercury (100 mg/L). accurately draw 10.0 mL
of the standard stock solution of mercury (1,000 mg/L) in a 100 mL volumetric flask;
10.4.3 Standard working solution of mercury (10.0 mg/L). accurately draw 10.0 mL of
the standard intermediate solution of mercury (100 mg/L) into a 100 mL volumetric
flask; use nitric acid solution of potassium dichromate (0.5 g/L) to dilute it and reach 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 1 year.
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%).
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.
12.2 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.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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