Translated English of Chinese Standard: GB31604.49-2016 www.chinesestandard.net Sales@ChineseStandard.net NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA GB GB 31604.49-2016 National food safety standard Food contact materials and articles Determination of arsenic, cadmium, chromium and lead; migration of arsenic, cadmium, chromium, nickel, lead, antimony and zinc 食品安全国家标准食品接触材料及制品砷 镉 铬 铅的测定和砷 镉 铬 镍 铅 锑 锌迁移量的测定 Issued on: October 19, 2016 Implemented on: April 19, 2017 Issued by National Health and Family Planning Commission of the PRC www.chinesestandard.net Page 1 of 19
Table of contents Foreword... 3 1 Scope... 4 Part I: Determination of arsenic, cadmium, chromium and lead Inductively coupled plasma mass spectrometry... 4 2 Principle... 4 3 Reagents and materials... 4 4 Instruments and equipment... 6 5 Analytical procedures... 6 6 Expression of analytical results... 8 7 Precision... 9 8 Others... 9 Part II: Determination of migration quantity of arsenic, cadmium, chromium, nickel, lead, antimony, and zinc... 9 Method I: Inductively coupled plasma mass spectrometry... 9 9 Principle... 9 10 Reagents and materials... 9 11 Instruments and equipment... 11 12 Analytical procedures... 11 13 Expression of analytical results... 12 14 Precision... 13 15 Others... 13 Method II: Inductively coupled plasma - atomic emission spectrometry... 13 16 Principle... 13 17 Reagents and materials... 13 18 Instruments and equipment... 14 19 Analytical procedures... 15 20 Expression of analytical results... 15 21 Precision... 15 22 Others... 15 Appendix A Instrument reference working conditions and the recommended mass-to-charge ratio or analysis wavelength of each element... 17 www.chinesestandard.net Page 2 of 19
Foreword This standard replaces the determination of migration quantity of arsenic, cadmium, chromium, nickel, lead, antimony and zinc as well as the content of arsenic, cadmium, chromium, and lead in paper products and cork stoppers as specified in 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, 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 2594-2010 Food contact materials - Determination of lead, cadmium, chromium, and arsenic in cork stoppers by inductively coupled plasma mass spectrometry. As compared with SN/T 2829-2011, SN/T 2597-2010 and SN/T 2594-2010, the main changes of this standard are as follows: - CHANGE the standard name into National food safety standard - Food contact materials and articles - Determination of arsenic, cadmium, chromium and lead; migration of arsenic, cadmium, chromium, nickel, lead, antimony and zinc. www.chinesestandard.net Page 3 of 19
National food safety standard Food contact materials and articles Determination of arsenic, cadmium, chromium and lead; migration of arsenic, cadmium, chromium, nickel, lead, antimony and zinc 1 Scope This standard specifies the inductively coupled plasma mass spectrometry and inductively coupled plasma emission spectrometry for the determination of arsenic, cadmium, chromium, nickel, lead, antimony and zinc in the food contact materials and articles after being immersed in food simulants, AND specifies the inductively coupled plasma mass spectrometry for the determination of arsenic, cadmium, chromium and lead in paper products and cork stoppers. This standard applies to the determination of the migration quantity of arsenic, cadmium, chromium, nickel, lead, antimony and zinc in various food contact materials and articles, as well as the determination of arsenic, cadmium, chromium and lead in paper products and cork stoppers. 2 Principle Part I: Determination of arsenic, cadmium, chromium and lead Inductively coupled plasma mass spectrometry Paper products and cork stoppers are crushed AND digested by nitric acid; AND the solution obtained is diluted by water to make its volume reach to the mark, determined by the inductively coupled plasma mass spectrometry, AND compared with the standard series for quantitative purposes. 3 Reagents and materials Unless otherwise stated, the reagents used in this method are of guarantee reagent AND the water is level I water as specified in GB/T 6682. 3.1 Reagents 3.1.1 Nitric acid (HNO3). www.chinesestandard.net Page 4 of 19
WEIGH 0.5 g of the crushed sample (accurate to 0.1 mg); PLACE it in the polytetrafluoroethylene digestion inner tank; ADD 5 ml ~ 8 ml of nitric acid; COVER it and LET it stand for 1 h; SEAL the digestion tank and PLACE it in the microwave digestion system; CONDUCT digestion in accordance with the standard operation procedures of the microwave digestion instrument; AND it may make reference to the digestion conditions in A.6 for digestion purposes. After finishing the digestion, TAKE the digestion tank out of the digestion instrument; when the digestion tank is completely cooled down, slowly OPEN the inner cover; USE a small amount of water to rinse the inner cover for two times; COMBINE the rinsing water into the digestion tank. PLACE the digestion tank onto the temperature control heating plate at 140 C to heat it for 30 min, or otherwise PLACE it into the ultrasonic water bath ultrasonic for degassing for 5 min; TRANSFER all the digestion solution into a 50 ml volumetric flask; USE water to make the volume reach to the mark; MIX it uniformly; PREPARE for determination. And meanwhile MAKE the sample blank. 5.2.2 Pressure sealed digestion WEIGH 0.5 g of the pulverized sample (accurate to 0.1 mg); PLACE it in polytetrafluoroethylene digestion inner tank; ADD 5 ml ~ 8 ml of nitric acid; COVER and LET it stand for 1 h; SEAL the digestion inner tank into the stainless steel outer tank; PLACE it into the constant temperature oven for digestion; AND it may make reference to the digestion conditions of A.6 for digestion. After finishing the digestion, when the digestion tank is completely cooled down, slowly OPEN the inner cover; USE a small amount of water to rinse the inner cover for two times; COMBINE the rinsing water into the digestion tank. PLACE the digestion tank onto the temperature control heating plate at 140 C to heat it for 30 min, or otherwise PLACE it into the ultrasonic water bath ultrasonic for degassing for 5 min; TRANSFER all the digestion solution into a 50 ml volumetric flask; USE water to make the volume reach to the mark; MIX it uniformly; PREPARE for determination. And meanwhile MAKE the sample blank. 5.3 Instrument reference conditions 5.3.1 USE the instrument tuning use solution to optimize the working conditions of the instrument, with the instrument reference conditions as shown in A.1 AND the element reference analysis mode as shown in A.2. Note: For instruments that do not have the appropriate interference elimination mode, it is required to use the interference correction equation to correct the determination results of arsenic, cadmium and lead. AND the interference correction equation is as shown in A.3. 5.3.2 In the selected instrument working conditions, EDIT the determination; SELECT the mass-to-charge ratio of the element to be determined and the internal standard substance, with the reference conditions as shown in A.1 and A.2. www.chinesestandard.net Page 7 of 19
10.1.1 Argon (Ar): purity 99.99%, or liquid argon. 10.1.2 Nitric acid (HNO3). 10.1.3 Helium (He): purity 99.995%. 10.1.4 Reagents required for preparing food simulant: in accordance with the provisions of GB 31604.1. 10.2 Reagent preparation 10.2.1 Food simulant: PREPARE it in accordance with the provisions of GB 5009.156. 10.2.2 Nitric acid solution (5 + 95): MEASURE 50 ml of nitric acid; ADD it into 950 ml of water; MIX it uniformly. 10.3 Standard substance 10.3.1 Element standard stock solution (1000 mg/l or 100 mg/l): arsenic, cadmium, chromium, nickel, lead, antimony and zinc adopt the single element or multi-element standard stock solution as certified by the state AND awarded with standard substance certificate. 10.3.2 Internal standard element stock solution (1000 mg/l or 100 mg/l): scandium, germanium, indium, rhodium, rhenium, bismuth and so on adopt the single element or multi-element standard stock solution as certified by the state AND awarded with standard substance certificate. 10.4 Preparation of standard solution 10.4.1 Mixed standard series solution: accurately ABSORB appropriate amount of single element standard stock solution or multi-element mixed standard stock solution; USE the corresponding food simulant to dilute it step by step AND prepare it into the mixed standard series of solutions, AND the concentration of each element is as shown in Table 4. The mixed standard series solution is, after preparation, transferred into clean polyethylene bottles for preservation. Note: It may determine the concentration and range of the element in the standard series solution in accordance with the instrument sensitivity, linear range, and the actual content of each element in the sample solution. If the selected food simulant is neutral or alkaline, it is required to add appropriate amount of nitric acid to make the nitric acid concentration in this solution of about 5% (volume fraction). www.chinesestandard.net Page 10 of 19
In accordance with the expected use and conditions of use of the sample to be tested, MAKE the migration test using the migration test method and test conditions as specified in GB 5009.156 and GB 31604.1. After soaking solution fully and uniformly mixed, TAKE part of the soaking test solution for analysis purposes. If the soaking test solution is neutral or alkaline, ADD appropriate amount of nitric acid so that the concentration of nitric acid in the test solution is about 5% (volume fraction). At the same time, MAKE the sample blank test. 12.2 Instrument reference conditions 12.2.1 USE the instrument tuning use solution to optimize the working conditions of the instrument, with the instrument reference conditions as shown in A.1 AND the element reference analysis mode as shown in A.2. Note: For instruments that do not have the appropriate interference elimination mode, it is required to use the interference correction equation to correct the determination results of arsenic, cadmium and lead. AND the interference correction equation is as shown in A.3. 12.2.2 In the selected instrument working conditions, EDIT the determination; SELECT the mass-to-charge ratio of the element to be determined and the internal standard substance, with the reference conditions as shown in A.1 and A.2. 12.3 Production of standard curve After determining the intensity of the mass spectrum of the blank solution, respectively DETERMINE the mass spectral intensity of each element in the mixed standard solution series in descending order; DRAW the standard curve in accordance with the mass spectrum signal ratio between the element to be determined and its internal standard element as well as the corresponding element concentration. 12.4 Determination of sample solution DETERMINE the mass spectrum signal intensity ratio of the element to be determined and its internal standard element of the sample blank solution and the sample solution, respectively. From the standard curve, CALCULATE the content of each element under determination. If the determination results exceed the linear range of the standard curve, USE the corresponding matrix acid solution to dilute it before making determination. 13 Expression of analytical results From the standard curve, OBTAIN the concentration of a certain element to be determined in the sample solution; DEDUCT the blank value or MAKE migration quantity calculation in accordance with GB 5009.156, to get the migration quantity of a certain element in the food contact materials and articles. The calculation result is retained with three significant digits. www.chinesestandard.net Page 12 of 19
14 Precision The absolute difference between the two independent determinations obtained under repeatability shall not exceed 10% of the arithmetic mean. 15 Others The detection limits for each element are shown in Table 5. Table 5 -- Detection limits for each element of this method Element As Cd Cr Ni Pb Sb Zn Detection limit / (μg/l) 0.2 0.1 1 0.3 0.3 0.03 0.2 The quantitative limits for each element are shown in Table 6. Table 6 -- Quantitative limits for each element of this method Element As Cd Cr Ni Pb Sb Zn Quantitative limit / (μg/l) 0.6 0.3 3 0.8 0.9 0.1 0.6 Method II: Inductively coupled plasma - atomic emission spectrometry 16 Principle The food simulant is used to soak the portion of food contact materials and articles which is expected to contact with food; the soaking solution is atomized and delivered into the plasma by the carrier gas, evaporated, atomized, excited, and ionized in high temperature and inert argon. The atomic or ion of the element to be determined is excited to produce characteristic radiation. In the inductively coupled plasma spectrometer, the spectral line signal intensity of the element to be determined is proportional to the concentration of the element to be determined in the test solution, AND it is compared with the standard series for quantification. 17 Reagents and materials Unless otherwise stated, the reagents used in this method are of guarantee reagent AND the water is level I water as specified in GB/T 6682. 17.1 Reagent 17.1.1 Nitric acid (HNO3). 17.1.2 Argon (Ar): purity 99.99%, or liquid argon. www.chinesestandard.net Page 13 of 19
18.1 Inductively coupled plasma atomic emission spectrometer (ICP-OES). 18.2 Analytical balance: sensitivity of 0.1 mg. 19 Analytical procedures 19.1 Sample preparation Same as 12.1. 19.2 Determination 19.2.1 Instrument reference conditions Same as A.4 and A.5. 19.2.2 Production of standard curve After determining the intensity of the emission spectrum of the blank solution, respectively DETERMINE the emission spectrum intensity of each element in the mixed standard solution series in descending order; DRAW the standard curve in accordance with the emission spectrum intensity and the corresponding element concentration. 19.2.3 Determination of sample solution DETERMINE the emission spectrum intensity of the element to be determined in the sample blank solution and the sample solution, respectively. From the standard curve, CALCULATE the content of each element under determination. If the determination results exceed the linear range of the standard curve, USE the corresponding matrix acid solution to dilute it before making determination. 20 Expression of analytical results From the standard curve, OBTAIN the concentration of a certain element to be determined in the sample solution; DEDUCT the blank value; MAKE migration quantity calculation in accordance with GB 5009.156, to get the migration quantity of a certain element in the food contact materials and articles. The calculation result is retained with three significant digits. 21 Precision The absolute difference between the two independent determinations obtained under repeatability shall not exceed 10% of the arithmetic mean. 22 Others The detection limits for each element are as shown in Table 8. www.chinesestandard.net Page 15 of 19