Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard replaces GB/T 23296.21-2009 Food Contact Materials - Polymer - Determination of Maleic Acid and Maleic Anhydride in Food Simulants - High Performance Liquid Chromatography.
The following main changes have been made with respect to GB/T 23296.21-2009 (the previous edition):
——this standard is renamed as National Food Safety Standard - Food Contact Materials and Articles - Determination of Migration of Maleic Acid and Its Acid Anhydride;
——high performance liquid chromatography condition is modified;
——detection limit is modified.
National Food Safety Standard
Food Contact Materials and Articles
Determination of Migration of Maleic Acid and Its Acid Anhydride
1 Scope
This standard specifies the determination of migration of maleic acid and its acid anhydride in food contact materials and articles.
This standard is applicable to the determination of total maleic acid in food simulants.
2 Principle
Maleic anhydride is transformed to maleic acid when reacting with water and indirectly obtain the migration of maleic acid and its acid anhydride by determining the content of the maleic acid. After soaking the specimen, directly inject the sample for water-based food simulant, extract with sodium bicarbonate solution and purify with C18 solid-phase extraction column for oil-based food simulant, determine by high performance liquid chromatography. Separate with reversed-phase chromatographic column, detect with ultraviolet detector and carry out the quantitative determination by external standard method.
3 Reagents and Materials
Unless otherwise specified, analytically-pure reagents and Class-I water (defined in GB/T 6682) are adopted for the purpose of this method. Containers and transfer appliances in test shall not be made of plastic materials.
3.1 Reagents
3.1.1 Methanol (CH4O): chromatographic pure.
3.1.2 Phosphoric acid (H3PO4).
3.1.3 Sodium bicarbonate (NaHCO3).
3.1.4 Reagents required for preparation of water-based, acidic, alcoholic and oil-based food simulants: the reagents adopted shall be in accordance with the requirements of GB 31604.1.
3.2 Preparation of reagents
3.2.1 Water-based, acidic, alcoholic and oil-based food simulants: prepared according to the requirements of GB 5009.156.
3.2.2 1% sodium bicarbonate solution: weigh 1.0 g (accurate to 0.1 g) sodium bicarbonate and dissolve in 100 mL water.
3.3 Standard product
Maleic acid (C4H4O4, CAS No.: 110-16-7): with purity>99.0%
3.4 Preparation of standard solutions
3.4.1 Maleic acid stock solution (5,000 mg/L): accurately weigh 500 mg (accurate to 0.1 mg) maleic acid standard product, dissolve with absolute ethanol and transfer to a 100mL volumetric flask, scale the volume with absolute ethanol, shake well. Preserve at 0℃~4℃; this solution is valid for 2 months.
3.4.2 Maleic acid standard solution: pipet 0 mL, 0.500 mL, 1.00 mL, 2.00 mL, 5.00 mL and 10.0 mL maleic acid stock solutions into six 50 mL volumetric flasks, scale the volume with absolute ethanol to the scale, and shake well; the concentrations of maleic acid are 0.00 mg/L, 50.0 mg/L, 100 mg/L, 200 mg/L, 500 mg/L and 1,000 mg/L respectively.
3.4.3 Preparation of standard working solutions
3.4.3.1 Standard working solutions of water-based, acidic and alcoholic food simulants
Pipet 1.00 mL maleic acid standard solutions with different concentrations into 25mL volumetric flasks, add food simulant solutions to the scale and mix uniformly so that the concentrations of the maleic acid in the food simulant solutions are 0.00 mg/L, 2.00 mg/L, 4.00 mg/L, 8.00 mg/L, 20.0 mg/L and 40.0 mg/L respectively. In the same way, prepare maleic acid standard working solution with the same concentration with corresponding water-based, acidic and alcoholic food simulants respectively.
3.4.3.2 Standard working solution of oil-based food simulant
Weigh 25 g (accurate to 0.1 g) oil-based food simulant into six separating funnels, add 1.00 mL maleic acid standard solutions with different concentrations, mix uniformly to make the concentrations of maleic acid in oil-based food simulants be 0.00 mg/kg, 2.00 mg/kg, 4.00 mg/kg, 8.00 mg/kg, 20.0 mg/kg and 40.0 mg/kg respectively, add 25mL sodium bicarbonate solution (1%), oscillate for 5 min, keep them still until layering, transfer the solution at the lower layer, filter with C18 solid-phase extraction column, take 1.0 mL filtrate, filter through 0.45 μm filter membrane into a sample-injecting bottle, and place it on the machine for determination.
4 Instruments and Apparatus
4.1 High-performance liquid chromatograph: equipped with diode array detector or ultraviolet detector.
4.2 Electro-thermal constant-temperature dry oven.
4.3 Analytical balance: with sensibility of 1.0 mg and 0.1 mg.
4.4 Vortex oscillator.
4.5 C18 solid-phase extraction column: with fillers of 500mg.
5 Analysis Steps
5.1 Preparation of food simulant test solutions
5.1.1 Migration test
According to the requirements of GB 5009.156 and GB 31604.1, carry out migration test on the sample to obtain the food simulant test solution.
5.1.2 Treatment of soak solution
5.1.2.1 Preparation of water-based food simulant test solution (including distilled water, 4% acetic acid and alcohol simulant)
Take about 1.5 mL water-based food simulant obtained from the migration test, filter with 0.45 μm filter membrane for determination, and prepare 2 parallel samples.
5.1.2.2 Oil-based food simulant
Accurately weigh 25 g (accurate to 0.1 g) oil-based food simulant soak solution, put into a separating funnel, add 25 mL sodium bicarbonate solution (1%), oscillate for 5 min, keep it still until layering; transfer the solution at the lower layer, and filter it with C18 solid-phase extraction column; take 1.0 mL filtrate, filter through 0.45 μm filter membrane into a sample-injecting bottle, and place on the machine for determination. Sample solution may be diluted according to specific circumstances so that its determination value is within the linear range of standard curve.
5.1.3 Preparation of blank test solution
Treat the food simulants which have not been in contact with food contact materials and articles as described in 5.1.2.
5.2 Determination
5.2.1 Reference conditions of liquid chromatography
a) Chromatographic column: C18 with length of 250 mm, inside diameter of 4.6 mm and particle size of 5 μm, or chromatographic column with equivalent performance;
b) Mobile phase: methanol and -0.1% phosphoric acid solution (20: 80, volume ratio);
c) Flow rate: 0.8 mL/min;
d) Detection wavelength: 214 nm;
e) Column temperature: 30℃;
f) Injection volume: 5 μL.
5.2.2 Plotting of standard curve
According to the reference conditions listed in 5.2.1, inspect the standard working solution (3.4.3.1 and 3.4.3.2). Plot the standard work curve with the concentration of the maleic acid (in the standard work curve of food simulants) as horizontal ordinates and the peak area of the maleic acid as vertical coordinates, obtain the linear equation, and carry out the quantitative determination according to the standard curve of peak area of maleic acid in the specimen. See Annex A for standard solution chromatogram.
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Instruments and Apparatus
5 Analysis Steps
6 Expression of Analysis Results
7 Accuracy
8 Other
Annex A High Performance Liquid Chromatogram of Maleic Acid
