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This standard replaces the determination methods of antimony in GB/T 5009.101-2003 Determination of Antimony in Polyester Resin and Products for Food Containers and Packaging Materials, GB/T 5009.63-2003 Method for Analysis of Hygienic Standard of Enamel for Food Containers, SN/T 2597-2010 Determination of Lead, Cadmium, Chromium, Arsenic, Antimony, Germanium Migration Quantity in Polymer for Food Contact Materials - Inductively Coupled Plasma Atomic Emission Spectrometry Method 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.
The following main changes have been made with respect to GB/T 5009.101-2003 (the previous edition):
——this standard is renamed as National Food Safety Standard - Food Contact Materials and Articles - Determination of Migration of Antimony;
——atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry are added.
National Food Safety Standard
Food Contact Materials and Articles
Determination of Migration of Antimony
1 Scope
This standard specifies the graphite furnace atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission spectrometry and malachite green spectrophotometery for determination of migration of antimony after soaking the food contact materials and articles in food simulants.
This standard is applicable to the determination of migration of antimony in food contact materials and articles.
Method I Graphite Furnace Atomic Absorption Spectrometry
2 Principle
Soak the parts of the food contact materials and articles which are expected to contact with food in the food simulants, atomize the soak solution by the graphite furnace; within certain concentration range, the absorption value determined at 231.2 nm is in direct proportion to the antimony content and is compared with standard series for quantification.
3 Reagents and Materials
Unless otherwise specified, guaranteed reagents and Class-II water (defined in GB/T 6682) are adopted for the purpose of this method.
3.1 Reagents
3.1.1 Ammonium dihydrogen phosphate (NH4H2PO4).
3.1.2 Hydrochloric acid (HCl).
3.1.3 Sulfuric acid(H2SO4).
3.1.4 Nitric acid(HNO3).
3.1.5 Reagents required for preparation of food simulants: in accordance with the requirements of GB 31604.1.
3.2 Preparation of reagents
3.2.1 Food simulants: prepared according to the requirements of GB 5009.156.
3.2.2 Ammonium dihydrogen phosphate solution (20 g/L): weigh 2.0 g ammonium dihydrogen phosphate, dissolve in water and scale the volume to 100 mL.
3.2.3 Hydrochloric acid solution (1+9): measure 10 mL hydrochloric acid, add 90 mL water and mix uniformly.
3.3 Standard product
Metallic antimony (Sb, CAS No.: 7440-36-0): with purity >99.99%, or reference material approved and awarded with reference material certificate by the State.
3.4 Preparation of standard solutions
3.4.1 Antimony standard stock solution (500 mg/L): accurately weigh 0.25 g (accurate to 0.0001g) metallic antimony, add 25 mL concentrated sulfuric acid and heat slowly to dissolve it; transfer such solution quantitatively into a 500 mL volumetric flask with about 100 mL water, and dilute with water to the scale, or with the reference material approved and awarded with reference material certificate by the State.
3.4.2 Antimony standard intermediate solution (5.00 mg/L): pipet 1.00 mL stock solution, dilute with hydrochloric acid solution (1+9) to 100 mL and mix uniformly.
3.4.3 Antimony standard working solution (0.500 mg/L): pipet 10.0 mL intermediate solution, dilute with hydrochloric acid solution (1+9) to 100 mL and mix uniformly.
3.4.4 Antimony standard series solutions: pipet 0 mL, 0.500 mL, 1.00 mL, 2.00 mL, 3.00 mL and 4.00 mL antimony standard working solution (0.500 mg/L) into 50mL volumetric flasks, add corresponding food simulants to the scale and mix uniformly. The concentration of corresponding standard series are 0 μg/L, 5.00 μg/L, 10.0 μg/L, 20.0 μg/L, 30.0 μg/L and 40.0 μg/L respectively.
Note: specific concentration of antimony in standard solution series may be determined according to the sensitivity and linear range of instruments and actual concentration of antimony in the soak solution. If the selected food simulant is neutral or alkaline, then appropriate amount of nitric acid shall be added to make the concentration of nitric acid in such solution be about 5% (volume fraction).
4 Instruments and Apparatus
Note: all glassware shall be soaked in nitric acid (1+5) overnight and washed clean with water for standby.
4.1 Atomic absorption spectrometer: equipped with graphite furnace atomizer and antimony hollow cathode lamp.
4.2 Analytical balance: with sensibility of 0.1 mg.
5 Analysis Steps
5.1 Pre-treatment of specimen
Carry out migration test according to the intended use and service conditions of to-be-tested sample and the migration test methods and conditions specified in GB 5009.156 and GB 31604.1. After fully mixing the soak solution, take some soak test solution for analysis. If the soak test solution is neutral or alkaline, then add appropriate amount of nitric acid to make the concentration of nitric acid in such test solution be about 5% (volume fraction). Meanwhile, carry out the specimen blank test.
5.2 Determination
5.2.1 Test conditions of instruments
See Table A.1 for reference conditions of instruments.
5.2.2 Plotting of standard curve
Respectively pipet 10 μL antimony standard series solution and 5 μL ammonium dihydrogen phosphate solution (20 g/L) (optimum injection volume may be determined according to the adopted instrument) and simultaneously inject them into a graphite furnace from low concentration to high concentration, determine the absorbance after atomization, and plot the standard curve with the concentration of standard series as x-axis and the corresponding absorbance as y-axis.
Note: the concentration and range of antimony in standard series solution may be determined according to the sensitivity and linear range of instruments and the actual content of antimony in the sample solution.
5.2.3 Determination of specimen
Under the same test conditions as those for determination of standard solution, respectively pipet 10 μL sample solution and 5 μL ammonium dihydrogen phosphate solution (20 g/L) (optimum injection volume may be determined according to the adopted instrument) and simultaneously inject them into a graphite furnace, determine the absorbance after atomization and compare with standard series for quantification. Meanwhile, test the specimen blank solution.
6 Expression of Analysis Results
Obtain the concentration of antimony in specimen solution from the standard curve, carry out migration calculation in accordance with GB 5009.156 after deduction of the blank value, and obtain the migration of antimony in food contact materials and articles; the calculation result is accurate to three significant figures..
7 Accuracy
The absolute difference of the results from two independent determinations under repeatability condition shall not exceed 20% of their arithmetic average.
8 Other
For the purpose of this method, the detection limit and the quantitation limit are 0.4 μg/L and 1.2 μg/L respectively.
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Instruments and Apparatus
5 Analysis Steps
6 Expression of Analysis Results
7 Accuracy
8 Other
9 Principle
10 Reagents and Materials
11 Instruments and Apparatus
12 Analysis Steps
13 Expression of Analysis Results
14 Accuracy
15 Other
16 Principle
17 Reagents and Materials
18 Instruments and Apparatus
19 Analysis Steps
20 Expression of Analysis Results
21 Accuracy
22 Other
Annex A Reference Temperature Rise Procedures of Graphite Furnace Atomic absorption Spectrometer
Annex B Reference Operating Conditions of Atomic Fluorescence Spectrometer
