GB 31604.42-2016 PDF in English
GB 31604.42-2016 (GB31604.42-2016) PDF English
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Method for analysis of hygienic standard of rubber sheet (ring) for food use
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Standards related to (historical): GB 31604.42-2016
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GB 31604.42-2016: PDF in English GB 31604.42-2016
GB
NATIONAL STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
National standard for food safety -
Determination of zinc migration quantity in
food contact materials and products
ISSUED ON. OCTOBER 19, 2016
IMPLEMENTED ON. APRIL 19, 2017
Issued by. National Health and Family Planning Commission of the
People’s Republic of China
3. No action is required - Full-copy of this standard will be automatically &
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Table of Contents
Foreword ... 3
1 Scope ... 4
Method I Flame atomic absorption spectrometry ... 4
2 Principle... 4
3 Reagents and materials ... 4
4 Instruments and equipment ... 5
5 Analytical procedures ... 6
6 Expression of analysis results ... 6
7 Precision... 7
8 Others ... 7
Method II Inductively coupled plasma atomic emission spectrometry ... 7
Method III Inductively coupled plasma mass spectrometry ... 7
Method IV Dithizone colorimetry ... 7
9 Principle... 7
10 Reagents and materials... 7
11 Instruments and equipment ... 10
12 Analytical procedures ... 10
13 Expression of analysis results ... 11
14 Precision ... 12
15 Others ... 12
Annex A Reference conditions for flame atomic absorption spectrometry ... 13
Foreword
The determination of zinc migration quantity in GB/T 5009.72-2003 Method for
analysis of hygienic standard of aluminum-wares for food use, GB/T 5009.64-
2003 Method for analysis of hygienic standard of rubber sheet (ring) for food
use, GB/T 5009.65-2003 Method for analysis of hygienic standard of rubber
sealing ring for pressure cooker for food use, GB/T 5009.66-2003 Method for
analysis of hygienic standard of nipple of a feeding bottle, GB/T 5009.79-2003
Hygienic analytical method of rubber hose for food use and SN/T 2829-2011
Food contact materials for export - Metal materials - Determination of migrant
heavy metals in food simulant - Inductively coupled plasma atomic emission
spectrometric method is substituted by this Standard.
Compared with GB/T 5009.72-2003, the major changes in this Standard are as
follows.
— MODIFY the standard name as “National standard for food safety -
Determination of zinc migration quantity in food contact materials and
products”;
— ADD the flame atomic absorption spectrometry;
— ADD the inductively coupled plasma atomic emission spectrometry; and
— ADD the inductively coupled plasma mass spectrometry.
National standard for food safety -
Determination of zinc migration quantity in food
contact materials and products
1 Scope
This Standard specifies the flame atomic absorption spectrometry, inductively
coupled plasma atomic emission spectrometry, inductively coupled plasma
mass spectrometry, and dithizone colorimetry for the determination of zinc
migration quantity in food contact materials and their products after immersed
in food simulant.
This Standard is applicable to the determination of zinc migration quantity in
food contact materials and their products.
Method I Flame atomic absorption spectrometry
2 Principle
USE food simulant to immerse the sections expected to be in contact with the
food in the food contact materials and products. USE a flame atomic absorption
spectrometer to determine the soaking solution. DETERMINE the content of
zinc in samples by using the quantitative relationship between absorption
intensity and its mass concentration at 213.9nm.
3 Reagents and materials
Unless otherwise indicated, the reagents and water used in this method are
guaranteed reagents and Type II reagent grade water specified in GB/T 6682,
respectively.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3.1.2 Reagents needed for the preparation of food simulant. in accordance
with the provisions of GB 31604.1.
7 Precision
The absolute difference between two independent determination results under
repetitive conditions shall not exceed 10% of the arithmetic mean.
8 Others
The method detection limit is 0.02mg/L. The limit of quantitation is 0.06mg/L.
Method II Inductively coupled plasma atomic emission
spectrometry
SEE GB 31604.49.
Method III Inductively coupled plasma mass spectrometry
SEE GB 31604.49.
Method IV Dithizone colorimetry
9 Principle
After the sample is soaked, zinc ion and dithizone form a magenta complex at
the pH of 4.0 to 5.5. DISSOLVE in carbon tetrachloride. ADD sodium thiosulfate
to prevent copper, mercury, lead, silver and cadmium ion interference.
COMPARE with the standard series for quantitation.
10 Reagents and materials
Unless otherwise indicated, the reagents and water used in this method are
analytical reagents and Type III reagent grade water specified in GB/T 6682,
respectively.
10.1 Reagents
10.1.1 Glacial acetic acid (CH3COOH). guaranteed reagent.
10.1.2 Nitric acid (HNO3). guaranteed reagent.
10.2.10 Methyl orange indicator (2g/L). WEIGH 0.2g of methyl orange. USE
ethanol to dissolve to the volume of 100mL.
10.2.11 Acetic acid - acetate buffer solution. WEIGH same amount of acetic
acid solution (2mol/L) and sodium acetate solution (2mol/L) for mixture. The pH
of this solution is about 4.7. USE dithizone - carbon tetrachloride solution
(0.1g/L) for several extractions. 10mL each time. REMOVE the zinc until the
green color on the carbon tetrachloride layer remains the same. DISCARD the
carbon tetrachloride layer. USE carbon tetrachloride to extract the excessive
dithizone in acetic acid - acetate buffer solution, until carbon tetrachloride
becomes colorless. DISCARD the carbon tetrachloride layer.
10.2.12 Sodium thiosulfate solution (250g/L). WEIGH 25g of sodium
thiosulfate. ADD 60mL of water. USE acetic acid solution (2mol/L) to adjust the
pH to 4.0 to 5.5. ADD water to 100mL. USE dithizone - carbon tetrachloride
solution (0.1g/L) to extract several times. 10mL each time. REMOVE the zinc
until the green color on the carbon tetrachloride layer remains the same.
DISCARD the carbon tetrachloride layer. USE carbon tetrachloride to extract
the excessive dithizone in acetic acid - acetate buffer solution, until carbon
tetrachloride becomes colorless. DISCARD the carbon tetrachloride layer.
10.2.13 Dithizone - carbon tetrachloride working solution. DRAW 1mL of
dithizone - carbon tetrachloride solution (0.1g/L). ADD carbon tetrachloride to
10mL. MIX evenly. USE a 1cm cuvette. USE carbon tetrachloride to adjust the
zero point. DETERMINE the absorbance (A) at a wavelength of 520nm.
CALCULATE the number of milliliters (V) of dithizone - carbon tetrachloride
solution (0.1g/L) required for the preparation of 100mL of dithizone - carbon
tetrachloride working solution (57% transmittance) according to the Formula (1).
DRAW VmL of dithizone - carbon tetrachloride solution (0.1g/L). USE carbon
tetrachloride to dilute to 100mL.
10.3 Standard substance
Zinc oxide (ZnO, CAS number. 1314-13-2). Zinc standard solution with the
purity of greater than 99.99%, or a certain concentration of zinc standard
solution certified by China and granted the Reference Material Certificate.
10.4 Standard solution preparation
10.4.1 Zinc standard stock solution (1 000mg/L). Accurately WEIGH 1.244 7g
of zinc oxide. ADD small amount of nitric acid solution (1 + 1). HEAT for
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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