GB 31604.49-2023 National food safety standard - Food contact materials and articles - Determination of multiple elements and their migration
1 Scope
This standard specifies the determination of arsenic, cadmium, chromium and lead in food contact materials and articles and the determination of migration of aluminum, arsenic, barium, cadmium, cobalt, chromium, copper, iron, lithium, manganese, molybdenum, nickel, lead, antimony, tin and zinc.
Part I is applicable to the determination of arsenic, cadmium, chromium and lead in food contact paper and paperboard materials and articles, cork and bamboo and wood articles.
Part II is applicable to the determination of migration of aluminum, arsenic, barium, cadmium, cobalt, chromium, copper, iron, lithium, manganese, molybdenum, nickel, lead, antimony, tin and zinc in food contact plastic materials and articles, food contact painting and coating, food contact rubber materials and articles, ink for food contact materials and articles, adhesive for food contact materials and articles, food contact paper and paperboard materials and articles, pacifiers, enamel articles, ceramic articles, glass articles, food contact plastic resins and food contact metal materials and articles.
Part I Determination of arsenic, cadmium, chromium and lead
Method I Inductively coupled plasma/mass spectrometry
2 Principle
After the specimen is crushed and digested with nitric acid, the solution obtained is diluted with water to the scale and determined by inductively coupled plasma mass spectrometer, then analyzed qualitatively based on the specific mass number (mass-to-charge ratio, m/z) of the element and analyzed quantitatively by external standard method.
3 Reagents and materials
Unless otherwise specified, guaranteed reagents and Class-I water (defined in GB/T 6682) are adopted for the purpose of this method.
3.1 Reagents
3.1.1 Nitric acid (HNO3): guaranteed reagent or higher level.
3.1.2 Argon (Ar): argon (≥99.995%) or liquid argon.
3.1.3 Helium (He): helium (≥99.995%).
3.2 Preparation of reagents
3.2.1 Nitric acid solution (5+95): measure 50mL nitric acid, and pour it slowly into 950mL water and mix well.
3.2.2 Nitric acid solution (1+4): measure 1L nitric acid, and pour it slowly into 4L water and mix well.
3.3 Standards
3.3.1 Standard solutions of elements (1,000mg/L or 100mg/L): for arsenic, cadmium, chromium and lead, their standard solutions shall be single-element or multi-element standard stock solutions certified by the national authority and accompanied by a reference material certificate, with a validity period of 1 year.
3.3.2 Internal standard solutions of elements (1,000mg/L or 100mg/L): for scandium, germanium, rhodium, indium, rhenium and bismuth, their internal standard solutions shall be single-element or multi-element standard stock solutions certified by the national authority and accompanied by a reference material certificate, with a validity period of 2 years.
3.4 Preparation of standard solutions
3.4.1 Mixed standard working solution: accurately pipette a proper amount of single-element or multi-element standard stock solution, and then dilute it step by step with nitric acid solution (5+95) and prepare it into mixed standard solution series. See Table A.1 in Annex A for the concentration of each element. Transfer the mixed standard solution series to brown glass containers and store at room temperature away from light; use them within the storage period of one month.
Note: The concentration and range of the element in the standard solution series may be adjusted based on the instrument sensitivity, linearity range, and the actual content of the element in the specimen solution.
3.4.2 Internal standard working solution: take a proper amount of single-element or multi-element internal standard stock solution, and prepare it into multi-element internal standard working solutions with a proper concentration with nitric acid solution (5+95). See A.5 in Annex A for the reference concentration of internal standard elements after mixing specimen solutions. Transfer the prepared internal standard working solution to a brown glass container and store at room temperature away from light; use it within the storage period of one month.
Note: The internal standard solution may be added quantitatively by hand during preparation of mixed standard solution series and specimen solution to be determined, or added online by instrument. The internal standard concentration may be adjusted according to the ratio of internal standard injection amount to sample injection amount.
4 Instruments and equipment
Note: All glassware and plastic ware shall be soaked overnight in nitric acid solution (1+4) and rinsed with water for later use.
4.1 Inductively coupled plasma mass spectrometer (ICP-MS)
4.2 Analytical balance, with a sensitivity of 0.1mg.
4.3 Microwave digester: equipped with a polytetrafluoroethylene digestion vessel.
Foreword i
1 Scope
2 Principle
3 Reagents and materials
4 Instruments and equipment
5 Analysis steps
6 Expression of analysis results
7 Precision
8 Others
9 Principle
10 Reagents and materials
11 Instruments and equipment
12 Analysis steps
13 Expression of analysis results
14 Precision
15 Others
16 Principle
17 Reagents and materials
18 Instruments and equipment
19 Analysis steps
20 Expression of analysis results
21 Precision
22 Others
23 Principle
24 Reagents and materials
25 Instruments and equipment
26 Analysis steps
27 Expression of analysis results
28 Precision
29 Others
Annex A Mass concentration of standard solution series
Annex B Instrument reference conditions
