GB 5009.267-2020 PDF English
US$205.00 · In stock · Download in 9 secondsGB 5009.267-2020: National food safety standard - Determination of iodine 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 5009.267: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB 5009.267-2020 | English | 205 |
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National food safety standard - Determination of iodine in foods
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| GB 5009.267-2016 | English | 85 |
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National Food Safety Standard -- Determination of Iodine in Foods
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GB 5009.267-2020: National food safety standard - Determination of iodine 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/GB5009.267-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard - Determination of
iodine in foods
Issued on. SEPTEMBER 11, 2020
Implemented on. MARCH 11, 2021
Issued by. National Health Commission of PRC;
State Administration for Market Regulation.
Table of Contents
Foreword... 4
1 Scope... 5
2 Principle... 5
3 Reagents and materials... 6
4 Instruments and equipment... 7
5 Analytical procedures... 7
6 Expression of analysis results... 9
7 Precision... 10
8 Others... 10
9 Principle... 10
10 Reagents and materials... 11
11 Instruments and equipment... 12
12 Analytical procedures... 13
13 Expression of analysis results... 13
14 Precision... 14
15 Others... 14
16 Principles... 14
17 Reagents and materials... 15
18 Instruments and equipment... 16
19 Analytical procedures... 17
20 Expression of analysis results... 18
21 Precision... 18
22 Others... 19
23 Principles... 19
24 Reagents and materials... 19
25 Instruments and equipment... 20
26 Analytical procedures... 20
27 Expression of analysis results... 22
28 Precision... 23
29 Others... 23
Appendix A Gas chromatogram of iodine standard derivative... 24
1 Scope
This standard specifies the determination method of iodine content in food.
The method 1 Inductively coupled plasma mass spectrometry is suitable for the
determination of iodine in food.
The method 2 Redox titration is suitable for the determination of iodine in algae
and its products.
The method 3 Arsenic-cerium catalytic spectrophotometry is suitable for the
determination of iodine in food, vegetables, fruits, beans and their products,
milk and their products, meat, fish and eggs.
The method 4 Gas chromatography is applicable to the determination of
nutritional fortifier iodine in infant formula foods and dairy products (except
infant formula foods for special medical purposes and formula foods for special
medical purposes).
Method 1 -- Inductively coupled plasma mass
spectrometry (ICP-MS)
2 Principle
The iodine in the specimen is extracted by tetramethylammonium hydroxide
solution and measured by inductively coupled plasma mass spectrometer. It is
qualitatively determined by the specific mass of iodine element 127 (mass-to-
charge ratio, m/z), the mass spectrometry signal intensity ratio between iodine
element and internal standard element which is proportional to the
concentration of the iodine element is used for quantification, to determine the
iodine content in the specimen.
3 Reagents and materials
Unless otherwise specified, the reagents used in this method are all premium-
grade pure water; the water is the grade 1 water as specified in GB/T 6682 or
the high-purity water used for instrument analysis as specified in GB/T 33087-
2016.
3.1 Reagent
3.1.1 25% Tetramethylammonium hydroxide [(CH3)4NOH] aqueous solution.
the English abbreviation name TMAH.
3.1.2 Isopropanol. Chromatographically pure.
3.1.3 Argon (Ar). Argon (≥ 99.995%) or liquid argon.
3.1.4 Helium (He). Helium (≥ 99.995%).
3.2 Preparation of reagents
3.3 Standard product
Potassium iodide (KI) or potassium iodate (KIO3). Reference reagent.
3.4 Preparation of standard solution
3.4.1 Iodine standard stock solution (1000 mg/L). Weigh 0.1685 g of potassium
iodate that has been dried at 180 °C ± 2 °C to a constant weight. Use water to
dissolve and make its volume reach to 100 mL. Or weigh 0.1307 g of potassium
iodide which had been dried in a silica gel dryer for 24 hours. Use water to
dissolve and dilute it to 100 mL. Store it in a brown bottle. It may also use the
iodine standard solution certified nationally and awarded with a certificate of
standard material.
3.4.2 Iodine standard intermediate solution (10.0 mg/L). Pipette 1.00 mL of
iodine element standard stock solution. Use diluent to make its volume reach
to 100 mL.
3.4.3 Iodine standard solution (100 μg/L). Pipette 1.00 mL of iodine element
standard intermediate solution. Use diluent to make its volume reach to 100 mL.
3.4.6 Internal standard solution. First use water to dilute the internal standard
element standard solution 10 times or 100 times. Then take an appropriate
amount of the solution and use the diluent to prepare an internal standard
solution of appropriate concentration.
4 Instruments and equipment
4.1 Inductively coupled plasma mass spectrometer (ICP-MS).
4.2 Analytical balance. Sensitivity is 0.1 mg and 1 mg.
4.3 Constant temperature drying oven or constant temperature water bath shaker.
4.6 Vortex mixer.
5 Analytical procedures
5.1 Preparation of specimen
5.1.1 Solid samples
5.1.1.1 Dry sample
For samples of beans, grains, fungi, tea, dried fruits, baked foods, etc., take the
edible part; use a high-speed grinder to crush it; stir until uniform. For solid dairy
products, protein powders, flour and other homogeneous powder samples,
shake it uniformly.
5.1.1.2 Fresh sample
Wash and drain samples of vegetables, fruits, aquatic products, etc., if
necessary; homogenize the edible part. For samples of meat and eggs,
homogenize the edible part.
5.1.1.3 Quick frozen and canned food
Homogenize the edible part of the thawed quick-frozen food and canned food
samples to homogeneity.
5.1.2 Liquid sample
Shake the samples of soft drinks, condiments, etc., uniformly.
5.2 Specimen processing
Weigh 0.2 g ~ 1 g (accurate to 0.001 g) of the specimen in a 50 mL plastic
centrifuge tube which is resistant to 110 °C temperature. Add 5 mL of extraction
solution. Vortex for 1 min, to make the sample fully dispersed.
5.3 Instrument reference conditions
5.3.1 Reference working conditions for instrument operation
Radio frequency power 1550 W; plasma gas flow rate 15 L/min; carrier gas flow
rate 0.80 L/min ~ 0.90 L/min; auxiliary gas flow rate 0.30 L/min ~ 0.40 L/min;
pump speed during analysis.
5.3.2 Measurement reference conditions
After the tuning instrument meets the measurement requirements, edit the
measurement method and select the iodine isotope (127I) and the internal
standard tellurium isotope (125Te, 130Te) or 103Rh or 115In or 185Re.
5.4 Preparation of standard curve
Inject iodine standard solution into ICP-MS. Measure the signal response value
of iodine element and internal standard element. Take the mass concentration
of iodine element as the abscissa, the ratio of the response signal value of
iodine element and the selected internal standard element as the ordinate, to
draw standard curve.
5.5 Measurement of sample solution
Inject the blank and sample solution into the inductively coupled plasma mass
spectrometer, respectively. Measure the signal response values of the iodine
element and the selected internal standard element. Calculate the ratio of the
response signal value of the iodine element and the selected internal standard
element.
6 Expression of analysis results
The iodine content in the specimen is calculated according to formula (1).
7 Precision
When the iodine content in the sample is greater than 1 mg/kg, the absolute
difference between the two independent determination 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, the absolute
difference between two independent determination results obtained under
repeatability conditions shall not exceed 15% of the arithmetic mean.
8 Others
Calculated with a sampling volume of 0.5 g and a constant volume to 50 mL,
the detection limit of the method is 0.01 mg/kg; the limit of quantification is 0.03 mg/kg.
9 Principle
After the sample is carbonized and ashed, in an acidic medium, liquid bromine
is used to oxidize iodide ions into iodate ions. The iodate oxidizes potassium
iodide in the acidic solution to precipitate iodine.
10 Reagents and materials
Unless otherwise specified, the reagents used in this method are all analytically
pure; the water is grade-3 water as specified in GB/T 6682.
10.1 Reagents
10.1.1 Anhydrous sodium carbonate (Na2CO3).
10.1.2 Liquid bromine (Br2).
10.1.3 Sulfuric acid (H2SO4).
10.1.4 Sodium formate (CHNaO2).
10.1.5 Sodium thiosulfate (Na2S2O3 • 5H2O).
10.1.6 Potassium iodide (KI). Reference substance.
10.1.7 Methyl orange.
10.1.8 Soluble starch.
10.2 Reagent preparation
10.2.1 Sodium carbonate solution (50 g/L). Weigh 5 g of anhydrous sodium
carbonate. Use water to dissolve it and make its volume reach to 100 mL.
10.2.2 Saturated bromine water.
10.2.6 Sodium formate solution (200 g/L). Weigh 20.0 g of sodium formate. Use
water to dissolve and dilute it to 100 mL.
10.3 Preparation of standard solution
10.3.1 Standard stock solution of sodium thiosulfate (0.1 mol/L). Weigh 26 g of
sodium thiosulfate (Na2S2O3 • 5H2O). Add 0.2 g of anhydrous sodium carbonate.
Dissolve it in 1000 mL water. Slowly boil it for 10 min. Cool it down. Filter and
calibrate after being placed for two weeks.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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