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GB 31604.42-2016National standard for food safety - Determination of zinc migration quantity in food contact materials and products (English PDF)

食品安全国家标准食品接触材料及制品锌迁移量的测定

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Issued by

National Health and Family Planning Commission of the People’s Republic of China 3. No action is required - Fu

Level / Type

National · Mandatory

Issue date

October 19, 2016

Implementation date

April 19, 2017

Scope

GB 31604.42-2016 is the English-translated version of 食品安全国家标准食品接触材料及制品锌迁移量的测定.

GB 31604.42-2016 — 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

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Document preview — GB 31604.42-2016

National Standard of the People's Republic of China

Issued by: National Health and Family Planning Commission of the People’s Republic of China 3. No action is required - Fu

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

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