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GB 5009.129-2023 English PDF (GB5009.129-2023)

GB 5009.129-2023 English PDF (GB5009.129-2023)

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GB 5009.129-2023: National food safety standard - Determination of ethoxyquin in foods
This Standard specifies the liquid chromatography and gas chromatography determination methods for ethoxyquin in food. This Standard applies to the determination of ethoxyquin in fresh fruits. Method I: Liquid chromatography
GB 5009.129-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
GB 5009.129-2023
National food safety standard - Determination of ethoxyquin
in food
ISSUED ON: SEPTEMBER 06, 2023
IMPLEMENTED ON: MARCH 06, 2024
Issued by: National Health Commission of the People’s Republic of China; State Administration for Market Regulation.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents and materials ... 4
4 Instruments and equipment ... 5
5 Analysis procedure ... 6
6 Expression of analysis results ... 7
7 Precision ... 7
8 Others ... 8
9 Principle ... 8
10 Reagents and materials ... 8
11 Instruments and equipment ... 9
12 Analysis procedure ... 9
13 Expression of analysis results ... 10
14 Precision ... 11
15 Others ... 11
Annex A Ethoxyquin chromatograms ... 12
National food safety standard - Determination of ethoxyquin
in food
1 Scope
This Standard specifies the liquid chromatography and gas chromatography determination methods for ethoxyquin in food.
This Standard applies to the determination of ethoxyquin in fresh fruits. Method I: Liquid chromatography
2 Principle
The ethoxyquin in the sample is extracted with n-hexane under alkaline conditions, blown to dryness with nitrogen, redissolved in acetonitrile solution containing ascorbic acid, determined by liquid chromatography, and quantified by external standard method. 3 Reagents and materials
Unless otherwise stated, the reagents used in this method are of analytical regent, and the water is Grade 1 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Sodium hydroxide (NaOH).
3.1.2 Ascorbic acid (C6H8O6).
3.1.3 Acetonitrile (C2H3N): chromatographically pure.
3.1.4 n-hexane (C6H14).
3.2 Preparation of reagents
3.2.1 Sodium hydroxide solution (0.1 mol/L): Weigh 4 g of sodium hydroxide, dissolve in water and dilute to 1000 mL.
3.2.2 Acetonitrile solution containing ascorbic acid: Weigh 0.1 g of ascorbic acid, dissolve in 100 mL of acetonitrile, shake thoroughly, filter, and take the filtrate. Prepare freshly each time before use.
3.3 Reference material
Ethoxyquin reference material (C14H19NO, CAS number: 91-53-2): purity ≥ 99 %, or a reference material certified by the country and awarded a reference material certificate. 3.4 Preparation of standard solutions
3.4.1 Ethoxyquin standard stock solution (1.00 mg/mL): Weigh 100 mg of ethoxyquin reference material (accurate to 0.1 mg) in a 100 mL volumetric flask, dissolve with acetonitrile solution containing ascorbic acid and dilute to the mark, and mix well. Transfer the solution to a brown glass container and store it in the dark at -18 °C. The validity period is 3 months.
3.4.2 Ethoxyquin standard intermediate solution (10.0 μg/mL): Pipette 1.00 mL of the standard stock solution (1.00 mg/mL) into a 100 mL volumetric flask, dilute to the mark with acetonitrile solution containing ascorbic acid, and mix well. Transfer the solution to a brown glass container and store it in the dark at -18 °C. The validity period is 1 month.
3.4.3 Ethoxyquin standard use solution (1.00 μg/mL): Pipette 1.00 mL of the standard intermediate solution (10.0 μg/mL) into a 10 mL volumetric flask, dilute to the mark with acetonitrile solution containing ascorbic acid, and mix well. Prepare freshly each time before use.
3.4.4 Ethoxyquin standard series working solutions: Pipette 40.0 μL, 100 μL, 200 μL, 500 μL and 1000 μL of the standard use solution (1.00 μg/mL) into 10 mL volumetric flasks respectively, dilute to the mark with acetonitrile solution containing ascorbic acid, and mix well. The concentrations of ethoxyquin standard series working solutions are 4.00 ng/mL, 10.0 ng/mL, 20.0 ng/mL, 50.0 ng/mL and 100 ng/mL respectively. Prepare freshly each time before use.
4 Instruments and equipment
4.1 Liquid chromatograph: equipped with a fluorescence detector.
4.2 Tissue masher.
4.3 Analytical balances: the minimum divisions are 0.01 g and 0.1 mg respectively. 4.4 Vortex mixer.
4.5 Oscillator.
4.6 Nitrogen concentration device.
4.7 Centrifuge.
5 Analysis procedure
5.1 Preparation of samples
Take 500 g of the edible part of the representative sample, add 10 g of ascorbic acid, crush and mix with a tissue masher and process into a slurry, put into a clean container and seal it. The prepared samples are frozen and stored at -18 °C for determination as soon as possible.
NOTE: When GB 2763 is used for judgment, the determination site shall be in accordance with the provisions of GB 2763.
5.2 Extraction of samples
Weigh 5 g (accurate to 0.01 g) of the sample in a 50 mL centrifuge tube, add 5 mL of sodium hydroxide solution (0.1 mol/L), vortex and mix for 30 s, add 10 mL of n-hexane, vortex and mix for 30 s, oscillate for 15 min for extraction, then centrifuge at 4000 r/min for 5 min, transfer the n-hexane layer to a 25 mL volumetric flask, add 10 mL n- hexane to the residue, repeat the extraction once, centrifuge at 4000 r/min for 5 min, combine the n-hexane layer in the same volumetric flask, add n-hexane to dilute to the mark, and mix well. Pipette 5.0 mL of n-hexane extract, concentrate to dryness with nitrogen at 30 °C, quickly add 5.0 mL of acetonitrile solution containing ascorbic acid, vortex and mix for 30 s, filter through a 0.45 μm organic microporous membrane to prepare the sample solution to be tested.
5.3 Reference conditions for liquid chromatography
a) Chromatographic column: C18 chromatographic column (4.6 mm × 250 mm, 5 μm) or one with equivalent performance.
b) Mobile phase: acetonitrile-water (65 : 35, volume ratio).
c) Flow rate: 1 mL/min.
d) Column temperature: 30 ℃.
e) Excitation wavelength: 365 nm; emission wavelength: 435 nm.
f) Sample injection volume: 10 μL.
5.4 Plotting of standard curve
Inject the standard series working solutions into the liquid chromatograph respectively, measure the corresponding peak areas, and plot a standard curve with the concentration of ethoxyquin in the standard series working solutions as the abscissa and the peak area as the ordinate. For the liquid chromatogram of ethoxyquin standard solutions, see Figure A.1 in Annex A.
8 Others
The detection limit of this method is 0.01 mg/kg, and the quantitation limit is 0.02 mg/kg.
Method II: Gas chromatography
9 Principle
The ethoxyquin in the sample is extracted with n-hexane under alkaline conditions, blown to dryness with nitrogen, redissolved in n-hexane, determined with a gas chromatograph equipped with a nitrogen and phosphorus detector, and quantified by external standard method.
10 Reagents and materials
Unless otherwise stated, the reagents used in this method are of analytical regent, and the water is Grade 1 water specified in GB/T 6682.
10.1 Reagents
10.1.1 Sodium hydroxide (NaOH).
10.1.2 Ascorbic acid (C6H8O6).
10.1.3 n-hexane (C6H14).
10.2 Preparation of reagents
Sodium hydroxide solution (0.1 mol/L): Weigh 4 g of sodium hydroxide, dissolve in water and dilute to 1000 mL.
10.3 Reference material
Same as 3.3.
10.4 Preparation of standard solutions
10.4.1 Ethoxyquin standard stock solution (1.00 mg/mL): Weigh 100 mg of ethoxyquin reference material (accurate to 0.1 mg) in a 100 mL volumetric flask, dissolve with n- hexane and dilute to the mark, and mix well. Transfer the solution to a brown glass container and store it in the dark at -18 °C. The validity period is 1 month. 10.4.2 Ethoxyquin standard intermediate solution (10.0 μg/mL): Pipette 1.00 mL of the standard stock solution (1.00 mg/mL) into a 100 mL volumetric flask, dilute to the mark with n-hexane, and mix well. Transfer the solution to a brown glass container and store it in the dark at -18 °C. The validity period is 1 month.
10.4.3 Ethoxyquin standard series working solutions: Pipette 20.0 μL, 50.0 μL, 100 μL, 200 μL and 400 μL of the standard intermediate solution (10.0 μg/mL) into 10 mL volumetric flasks respectively, dilute to the mark with n-hexane, and mix well. The concentrations of ethoxyquin standard series working solutions are 20.0 ng/mL, 50.0 ng/mL, 100 ng/mL, 200 ng/mL and 400n g/mL respectively. Prepare freshly each time before use.
11 Instruments and equipment
11.1 Gas chromatograph: equipped with a nitrogen and phosphorus detector. 11.2 Tissue masher.
11.3 Analytical balances: the minimum divisions are 0.01 g and 0.1 mg respectively. 11.4 Vortex mixer.
11.5 Oscillator.
11.6 Nitrogen concentration device.
11.7 Centrifuge.
12 Analysis procedure
12.1 Preparation of samples
Same as 5.1.
12.2 Extraction of samples
Weigh 5 g (accurate to 0.01 g) of the sample in a 50 mL centrifuge tube, add 5 mL of sodium hydroxide solution (0.1 mol/L), vortex and mix for 30 s, add 10 mL of n-hexane, vortex and mix for 30 s, oscillate for 15 min for extraction, then centrifuge at 4000 r/min for 5 min, transfer the n-hexane layer to a 25 mL volumetric flask, add 10 mL n- hexane to the residue, repeat the extraction once, centrifuge at 4000 r/min for 5 min, combine the n-hexane layer in the same volumetric flask, add n-hexane to dilute to the mark, and mix well. Pipette 5.0 mL of n-hexane extract, concentrate to dryness with nitrogen at 30 °C, quickly add 1.0 mL of n-hexane, vortex and mix for 30 s, and filter through a 0.45 μm organic microporous membrane to prepare the sample solution to be tested.
12.3 Reference conditions for gas chromatography
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