GB 31604.46-2023National food safety standard - Food contact materials and products - Determination of free phenol and migration (English PDF)

3.1 Reagents

3.1.1 Hydrochloric acid (HCl). mass fraction 36% ~ 38%.

3.1.2 Trichloromethane (CHCl3).

3.1.3 Ethanol (C2H6O).

3.2 Preparation of Reagents

3.3 Reference Materials

3.3.1 Sodium thiosulfate pentahydrate (Na2S2O3  5H2O, CAS No.. 10102-17-7). working

reference reagent, or a standard substance certified by the state and awarded a reference material

certificate.

3.3.2 Potassium bromate (KBrO3, CAS No.. 7758-01-2). working reference reagent, or a

standard substance certified by the state and awarded a reference material certificate.

3.4 Preparation of Standard Solutions

4.1 Balance. with a division value of 0.01 g and 0.1 mg, respectively.

5.1 Distillation of Specimens

Weigh-take 1.0 g (accurate to 0.01 g) of epoxy phenolic resin coating specimen for food contact,

put it into a distillation bottle, add 20 mL of ethanol to dissolve it (for water-based modified

epoxy resin coatings, add 20 mL of water). Add 50 mL of water, then, use steam to distill off

free phenol. Collect the distilled solution in a 500 mL conical flash. Within 40 min ~ 50 min,

distill 300 mL ~ 400 mL of distilled liquid.

5.2 Titration

Transfer-take 100 mL of distilled liquid, place it in a 500 mL stoppered conical flask, add 25

mL of bromine standard solution and 5 mL of hydrochloric acid. At room temperature, use a

stopper to cover it to avoid light, and react for 15 min.

5.3 Blank Test

Take 20 mL of ethanol and use water to dilute it to 500 mL, then, transfer-take 100 mL of the

diluted solution (for water-based modified epoxy resin coatings, transfer-take 100 mL of water).

In accordance with the method of 5.2, conduct the determination.

10.1 Reagents

10.1.1 Absolute ethanol (C2H6O).

10.1.2 Glacial acetic acid (C2H4O2).

10.1.3 Isooctane (C8H18).

10.2 Preparation of Reagents

10.2.1 Water-based food simulants. in accordance with the stipulations of GB 5009.156,

conduct the preparation.

10.3 Reference Material

Phenol (C6H6O, CAS No.. 108-95-2). with a purity > 99%, or a standard substance certified by

the state and awarded a reference material certificate.

10.4 Preparation of Standard Solutions

10.4.7 Standard series of working solutions in isooctane

Respectively and accurately transfer-take 0 mL, 0.25 mL, 0.50 mL, 1.00 mL, 1.50 mL and 3.00

mL of the standard intermediate solution (100 mg/L) into six 50 mL volumetric flasks; use

isooctane to reach a constant volume to the scale and evenly mix them. The concentration of

phenol in the standard series of working solutions is respectively 0.00 mg/L, 0.50 mg/L, 1.00

mg/L, 2.00 mg/L, 3.00 mg/L and 6.00 mg/L.

10.5 Material

Nylon filter membrane. with a pore size of 0.45 m.

11.1 Visible spectrophotometer.

11.3 Distillation apparatus.

12.1 Migration Test

Food contact materials and products shall be subject to migration test in accordance with the

requirements of GB 31604.1 and GB 5009.156.

12.2 Pre-treatment of Soaking Solutions

12.3 Blank Test

In accordance with 12.1 and 12.2, conduct the treatment on food simulants and chemical

alternative solvents that are not in contact with the food contact materials and products.

12.4 Drawing of Standard Curve

After the standard series of working solutions in the various food simulants and chemical

alternative solvents are treated in the same way as the corresponding soaking solution, in

accordance with the conditions specified in Table 1, determine the absorbance of the standard

series of working solutions in each food simulant. Take the absorbance of the standard working

solution as the y-coordinate and the mass concentration of phenol in the corresponding standard

working solution as the x-coordinate to draw the standard curve.

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