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This standard replaces GB/T 23296.12-2009 Food Contact Materials - Polymers - Determination of 11-aminoundecanoic Acid in Food Simulants - High Performance Liquid Chromatography.
The following changes have been made with respect to GB/T 23296.12-2009 (the previous edition):
——This standard is renamed as "National Standard of Food Safety - Food Contact Materials and Articles - Determination of Migration of 11-aminoundecanoic Acid";
——The preparation of food simulant test solutions is modified;
——The expression of analysis result is modified.
National Standard for Food Safety
Food Contact Materials and Articles
Determination of Migration of
11-aminoundecanoic Acid
1 Scope
This standard specifies the test method of high performance liquid chromatography for migration of 11-aminoundecanoic acid in food contact materials and articles.
This standard is applicable to determination of migration of 11-aminoundecanoic acid in food contact materials and articles.
2 Principle
The 11-aminoundecanoic acid in food simulants reacts with fluorescamine and produce derivatives. Separate the derivatives and test their content with a fluorescence detector, convert to work out the content of 11-aminoundecanoic acid and carry out quantative 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. As for the containers and transferring tools in the test, those made of plastic material shall not be used.
3.1 Reagents
3.1.1 Sodium tetraborate decahydrate (Na2B4O7·10H2O).
3.1.2 Phosphoric acid (H3PO4).
3.1.3 Boric acid (H3BO3).
3.1.4 Fluorescamine (C17H10O4).
3.1.5 Sodium hydroxide (NaOH).
3.1.6 Sodium phosphate monobasic monohydrate (NaH2PO4·H2O).
3.1.7 Glacial acetic acid (CH3COOH).
3.1.8 Absolute ethyl alcohol (CH3CH2OH).
3.1.9 Acetone (CH3COCH3): chromatographically pure.
3.1.10 Isooctane [(CH3)2CHCH2C(CH3)3].
3.1.11 Methanol (CH3OH): chromatographically pure.
3.1.12 Nitrogen (N2): with purity ≥99.9%.
3.2 Reagent preparation
3.2.1 Water-based, acidic, alcoholic and oil-based food simulants: operate according to GB 5009.156.
3.2.2 Acetic acid solution (96 %): measure 9.6 mL of glacial acetic acid and dilute it to 100 mL with water.
3.2.3 Phosphoric acid solution (10%): measure 10mL of phosphoric acid and dilute it to 100 mL with water.
3.2.4 Boric acid solution (5 %): weigh 5.0 g of boric acid, add in 100mL of water and dissolve it fully.
3.2.5 Sodium hydroxide solution (20%): weigh 20.0 g of sodium hydroxide, add in 100mL of water and dissolve it fully.
3.2.6 Phosphate buffer solution (0.005mol/L): accurately weigh 690 mg of sodium phosphate monobasic monohydrate, dissolve it in about 900 mL of water, add in a small amount of phosphoric acid solution slowly to adjust its pH to (3±0.2), and scale the volume to 1L with water.
3.2.7 Boric acid buffer solution (0.04mol/L): accurately weigh 1.53 g of sodium tetraborate decahydrate, dissolve it in about 90 mL of water, add in a small amount of boric acid solution (5 %) slowly to adjust its pH to (9±0.2), and scale the volume to 100mL with water.
3.2.8 Fluorescamine solution: accurately weigh 20 mg of fluorescamine, add in 100mL of acetone and dissolve it fully, then preserve it away from light.
3.3 Standard products
11-aminoundecanoic acid (C11H23O2N, CAS No.:2432-99-7) with purity ≥99%, or standard substance approved and awarded with reference material certificate by the state.
3.4 Preparation of standard solutions
3.4.1 Stock solution of 11-aminoundecanoic acid water solution (1.25 mg/mL): accurately weigh 125 mg (accurate to 0.1 mg) of 11-aminoundecanoic acid standard product, dissolve it with 2 mL of acetic acid (96 %) and transfer it to a volumetric flask (100mL), then scale the volume to the scale with water and put it into the refrigerator (4℃) for preservation.
3.4.2 Stock solution of 11-aminoundecanoic acid isooctane solution (0.50mg/mL): accurately weigh 25 mg (accurate to 0.1 mg) of 11-aminoundecanoic acid standard product, dissolve it with 5 mL of glacial acetic acid and transfer it to a volumetric flask (50mL), then scale the volume to the scale with isooctane and put it into the refrigerator (4℃) for preservation.
3.4.3 Standard intermediate solution of 11-aminoundecanoic acid water solution (25μg/mL): respectively transfer 2mL of stock solution of its water solution to three different volumetric flasks (100mL) and then scale the volume with water-based, acidic or alcoholic food simulant respectively.
3.4.4 Standard working solutions of water-based, acidic and alcoholic food simulants: Respectively transfer 0mL, 1.0 mL, 2.0 mL,4.0 mL,10.0 mL and 20.0 mL of standard intermediate solution of 11-aminoundecanoic acid water solution into volumetric flasks (50mL), then scale the volume with water. The concentrations of the standard working solutions are: 0μg/mL, 0.5μg/mL, 1.0μg/mL, 2.0μg/mL, 5.0μg/mL and 10.0μg/mL. Prepare standard working solution of 11-aminoundecanoic acid with the same concentration series in the same way with corresponding acidic and alcoholic food simulants respectively. Prepare prior to use.
3.4.5 Standard working solution of oil-based food simulant: respectively weigh 5 g (accurate to 0.01 g) olive oil and put them into six different conical flasks (25mL). Respectively add in 0μL, 5μL, 10μL,20μL, 50μL and 100μL of the stock solution of 11-aminoundecanoic acid isooctane solution, and then mix uniformly and sufficiently. The concentrations of the standard working solutions are: 0μg/g, 0.5μg/g, 1.0 μg/g, 2.0μg/g, 5.0μg/g and 10.0μg/g. Then proceed in accordance with 5.2.2.
4 Instruments and Apparatus
4.1 High-performance liquid chromatograph: equipped with fluorescence detector.
4.2 Oscillator: to-and-fro type.
4.3 Vortex oscillator.
4.4 Nitrogen concentrator: equipped with heating unit.
4.5 Analytical balance: with sensibility of 1mg and 0.1mg.
4.6 pH meter: with precision of 0.01.
4.7 Microfiltration membrane: 0.22 μm.
5 Analysis Steps
5.1 Preparation of food simulant test solutions
According to the requirements of GB 5009.156 and GB 31604.1, carry out migration test on the samples and obtain the food simulant test solutions.
5.2 Treatment of soak solutions
5.2.1 Water-based, acidic or alcoholic food simulant
Accurately transfer 1.0 mL of water-based, acidic or alcoholic food simulant obtained from the migration test to the reaction tube (10mL). In case the simulant is 4% acetic acid, 150 μL of sodium hydroxide solution shall be added in at the same time to adjust the pH value. Carry out derivation according to 5.4 for the rest steps, with two parallel samples prepared.
5.2.2 Oil-based food simulant
Weigh 5 g (accurate to 0.01 g) olive oil medium food simulant obtained from the migration test to a conical flask (25mL), add in 5mL of isooctane and mix uniformly. Accurately transfer 5.0 mL of acetic acid (96 %) into the conical flask, then place it on the oscillator for oscillation which lasts for 30 min. After the two phases separate, accurately transfer 1.0 mL of acetic acid extraction solution in the sublayer to a reaction tube (10mL), and blow dry the acetic acid extraction solution at 40℃ with the nitrogen concentrator. Accurately transfer 1.0 mL of water into the blow-dried reaction tube, and place it on the vortex oscillator for treatment of 10 s and then mix uniformly and sufficiently. Carry out derivation according to 5.4 for the rest steps, with two parallel samples prepared.
5.3 Preparation of blank test solution
Treat the food simulants which have not contacted food contact materials and articles as described in 5.2, and carry out derivation according to 5.4 for the rest steps.
5.4 Derivative of 11-aminoundecanoic acid
Accurately transfer 1.0 mL of boric acid buffer solution into the prepared water-based, acidic, alcoholic or oil-based food simulant test solution and the blank solutions, then put it on the vortex oscillator for treatment which lasts for 10 s, and then mix uniformly and sufficiently. During mixing, add in 1.0 mL of fluorescamine solution. Filter the derivative solution obtained through the microfiltration membrane, leaving the remaining filtrate to be tested.
5.5 Reference conditions of apparatus
a) Chromatographic column: C18 column (length: 250mm; inner diameter: 4.6 mm; particle size: 5 μm); or chromatographic column of equivalent performance.
b) Mobile phase: buffer solution of methanol - phosphate (75+30, volume ratio).
c) Flow rate: 1.0 mL/min;
d) Injection volume: 10μL.
e) Column temperature: ambient temperature.
f) Fluorescence detector: with excitation wavelength of 390 nm and emission wavelength of 480nm.
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 Others
Annex A Chromatogram of 11-aminoundecanoic Acid Standard Substance Derivative
