GB 5009.307-2025 National food safety standard - Determination of formaldehyde in foods English, Anglais, Englisch, Inglés, えいご
1 Scope
This standard specifies the method for determination of formaldehyde in foods.
For the purpose of this standard, Method I is applicable to the determination of formaldehyde in beer; Method II is applicable to the determination of formaldehyde in foods.
Method I Spectrophotometry
2 Principle
The sample is subjected to steam distillation. The formaldehyde in the distillate reacts with acetylacetone and forms a yellow compound, which has a maximum absorbance at 415 nm. Within a certain range, the absorbance is in direct proportion to the formaldehyde content.
3 Reagents and materials
Unless otherwise specified, only analytically pure reagents and Grade 3 water specified in GB/T 6682 are used for the purpose of this method.
3.1 Reagents
3.1.1 Glacial acetic acid (C2H4O2).
3.1.2 Acetylacetone (C5H8O2).
3.1.3 Ammonium acetate (C2H7O2N).
3.1.4 Phosphoric acid (H3PO4).
3.1.5 Dimethyl silicone oil.
3.2 Preparation of reagents
3.2.1 Acetylacetone solution: Weigh 25.0 g of ammonium acetate and dissolve it in 90 mL of water; add 0.4 mL of acetylacetone and 3.0 mL of glacial acetic acid into the solution, dilute it to 100 mL with water, and mix well; then transfer it to a brown reagent bottle. Prepare it immediately before use.
3.2.2 Phosphoric acid solution (200 g/L): Weigh 20 g of phosphoric acid, dilute it with water to 100 mL, then mix well, and store it at room temperature.
3.3 Standards
Formaldehyde (CH?O, CAS No.: 50-00-0) standard solution: 1,000 mg/L, or a standard certified by the state and granted a standard substance certificate.
Note: Formaldehyde standard solution may also be prepared from 36ﾨC38% formaldehyde solution and calibrated before use. See Annex A for the specific operation.
3.4 Preparation of standard solutions
3.4.1 Formaldehyde standard intermediate solution (100 mg/L): Accurately pipette 1.00 mL of the 1,000 mg/L formaldehyde standard solution, dilute it with water to 10 mL to prepare it into a formaldehyde standard intermediate solution with mass concentration of 100 mg/L. Store it away from light at 2ﾨC8ﾡ￦, with a shelf life of 3 months.
3.4.2 Formaldehyde standard working solution (1.0 mg/L): Accurately pipette 1.0 mL of the 100 mg/L formaldehyde standard intermediate solution, dilute it with water to 100 mL to prepare it into the formaldehyde standard working solution with mass concentration of 1.0 mg/L. Prepare it immediately before use.
3.4.3 Formaldehyde standard working solution series: Accurately pipette 0 mL, 0.50 mL, 1.0 mL, 2.0 mL, 4.0 mL, 8.0 mL, and 10.0 mL of the 1.0 mg/L formaldehyde standard working solution, and place them into 25-mL colorimetric tubes with plug; dilute them to 10 mL with water to obtain formaldehyde standard working solution series with mass concentrations of 0 mg/L, 0.050 mg/L, 0.10 mg/L, 0.20 mg/L, 0.40 mg/L, 0.80 mg/L, and 1.0 mg/L, respectively. Prepare it immediately before use.
4 Instruments and apparatus
4.1 Spectrophotometer.
4.2 Steam distillation apparatus.
4.3 Water bath: Temperature controllable at 100ﾡ1ﾡ￦, with an accuracy of 0.1ﾡ￦.
Contents
Foreword I
1 Scope
2 Principle
3 Reagents and materials
4 Instruments and apparatus
5 Analytical procedures
6 Expression of analysis results
7 Precision
8 Others
9 Principle
10 Reagents and materials
11 Instruments and apparatus
12 Analytical procedures
13 Expression of analysis results
14 Precision
15 Others
Annex A Preparation and calibration of formaldehyde standard solution
Annex B Liquid chromatogram for derivative of formaldehyde standard substance
