GB 31604.21-2025National food safety standard - Food contact materials and products - Determination of migration of benzoic acid (English PDF)

3.1 Reagents

3.1.1 Glacial acetic acid (C2H4O2). to the mark with water, and mix well. The mass concentrations of trimesic acid in the obtained standard series working solutions are

0.031 mg/L,

0.10 mg/L,

0.25 mg/L,

0.50 mg/L,

0.75 mg/L, and

1.0 mg/L, respectively. The mass concentrations of the other 6 types of target analytes are

0.375 mg/L,

9.0 mg/L, and 12 mg/L, respectively. Prepare fresh before use. When the mass concentrations of benzoic acid and phthalic acid in the sample solution exceed the above linear range, accurately transfer

6.0 mL of the mixed standard intermediate solution C into six 10 mL volumetric flasks, respectively, dilute to the mark with water, and mix well. The mass concentrations of the 7 types of target analytes in the obtained standard series working solutions are 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L, 50 mg/L, and 60 mg/L, respectively. Prepare fresh before use.

3.4.5.2 Mixed standard working solution series E (applicable to quantitative analysis of target analytes in other food simulants and chemical substitute solvents) Accurately transfer

0.10 mL,

0.125 mL,

0.40 mL,

4.4 Balance. Sensitivities of

0.01 g and

0.1 mg, respectively.

4.5 Centrifuge. Speed >= 3000 r/min.

4.6 Pipettes. Capacities of 100 µL, 1 mL, and 5 mL, respectively.

4.7 Rotary evaporator or nitrogen evaporator.

5.2.1 Treatment of olive oil soaking solution

5.2.1.1 Benzenedicarboxylic acid and benzenetricarboxylic acid test solution. Accurately weigh

5.0 g (to the nearest

0.01

g) of the olive oil soaking solution obtained from the migration test into a 25 mL stoppered glass centrifuge tube, add

5.00 mL of n- heptane and

4.00 mL of 50 % (volume fraction) ethanol solution sequentially, vortex at 1500 r/min for 15 min, centrifuge at 3000 r/min for 10 min, and collect the ethanol solution on the lower layer and filter through a filter membrane, for later test.

5.2.1.2 Benzoic acid test solution. Accurately weigh

10.0 g (to the nearest

0.01

g) of the olive oil soaking solution obtained from the migration test into a 25 mL stoppered glass centrifuge tube, add

4.00 mL of acetonitrile solution (5+1), vortex at 1500 r/min for 15 min, centrifuge at 3000 r/min for 10 min, take approximately 2 mL of the supernatant and filter through a filter membrane, accurately transfer

1.00 mL of the filtrate and add

1.00 mL of water, and mix well, for later test.

5.2.2 Treatment of isooctane soaking solution

5.2.2.1 Benzenedicarboxylic acid and benzenetricarboxylic acid test solution. Accurately transfer

5.00 mL of the isooctane soaking solution obtained from the migration test into a 25 mL stoppered glass centrifuge tube, add

4.00 mL of 50 % (volume fraction) ethanol solution, vortex at 1500 r/min for 15 min, centrifuge at 3000 r/min for 10 min, and collect the ethanol solution on the lower layer and filter through a filter membrane, for later test.

5.2.2.2 Benzoic acid test solution. Accurately transfer

10.0 mL of the isooctane soaking solution obtained from the migration test to a 25 mL stoppered glass centrifuge tube, add

4.00 mL of acetonitrile solution (5+1), vortex at 1500 r/min for 15 min, centrifuge at 3000 r/min for 10 min, take approximately 2 mL of the lower layer solution and filter

5.4.6 UV detector or diode detector. For trimesic acid, trimellitic acid, hemimellitic acid, phthalic acid, and isophthalic acid, the detection wavelength is 214 nm; for benzoic acid and terephthalic acid, the detection wavelength is 230 nm. The acquisition time for each detection wavelength is determined based on the retention time of each target analyte.

5.5 Plotting of standard curve Determine the mixed standard working solution according to the instrument reference conditions listed in 5.4, to obtain the chromatograms of the target analytes in the corresponding standard working solution. A standard curve is plotted with the mass concentration of the target analyte in the standard working solution as the abscissa and the corresponding chromatographic peak area as the ordinate to obtain the linear equation. See Figure B.1 in Annex B for the chromatogram of the standard working solution.

5.6 Determination of test solutions

5.6.1 Qualitative determination Determine the sample test solution (5.2) and the mixed standard working solution (3.4.5) according to the instrument reference conditions listed in 5.4.If the retention time of the chromatographic peak of the analyte in the test solution deviates from the chromatographic peak of the same target analyte in the standard working solution within ±

0.1 min, it is determined that the sample contains the corresponding analyte.

5.6.2 Quantitative determination Determine the sample test solution (5.2) and the blank solution (5.3) according to the instrument reference conditions listed in 5.4, to obtain the peak area of each target analyte. Read the content rho and rho0 of each analyte in the sample test solution and the blank solution from the corresponding standard curve, the content rho0 of each target analyte in the blank solution shall not be higher than the method detection limit concentration.