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GB 5009.36-2023 English PDF (GB5009.36-2023)

GB 5009.36-2023 English PDF (GB5009.36-2023)

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GB 5009.36-2023: National Food Safety Standard - Determination of Cyanide in Foods

This Standard specifies the method for the determination of cyanide in foods. The first method
GB 5009.36-2023
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
National Food Safety Standard - Determination of Cyanide
in Foods
ISSUED ON: SEPTEMBER 6, 2023
IMPLEMENTED ON: MARCH 6, 2024
Issued by: National Health Commission of the PEOPLE Republic of China; State Administration for Market Regulation.
Table of Contents
Foreword ... 4
1 Scope ... 5
Method I - Spectrophotometry ... 5
2 Principle ... 5
3 Reagents and Materials ... 5
4 Instruments and Equipment ... 7
5 Analytical Procedures ... 7
6 Expression of Analysis Results ... 10
7 Precision ... 12
8 Others ... 12
Method II - Gas Chromatography ... 12
9 Principle ... 12
10 Reagents and Materials ... 13
11 Instruments and Equipment ... 14
12 Analytical Procedures ... 14
13 Expression of Analysis Results ... 16
14 Precision ... 17
15 Others ... 17
Method III - Gas Chromatography - Mass Spectrometry ... 17
16 Principle ... 17
17 Reagents and Materials ... 18
18 Instruments and Equipment ... 18
19 Analytical Procedures ... 18
20 Expression of Analysis Results ... 20
21 Precision ... 20
22 Others ... 20
Method IV - Ion Chromatography ... 20
23 Principle ... 20
24 Reagents and Materials ... 20
25 Instruments and Equipment ... 22
26 Analytical Procedures ... 22
27 Expression of Analysis Results ... 24
28 Precision ... 24
29 Others ... 24
Method V - Flow Injection / Continuous Flow - Spectrophotometry ... 25
30 Principle ... 25
31 Reagents and Materials ... 25
32 Instruments and Equipment ... 27
33 Analytical Procedures ... 27
34 Expression of Analysis Results ... 28
35 Precision ... 28
36 Others ... 29
Appendix A Reference Conditions of Headspace Analysis ... 30
Appendix B Standard Gas Chromatogram of Cyanogen Chloride ... 31
Appendix C Setting of Ion Chromatography Conditions and Examples of Standard Chromatograms ... 33
Appendix D Cyanide Ion Determination Chart of Distilled Liquor and Its Integrated Alcoholic Beverages under Flow Injection / Continuous Flow ... 35
National Food Safety Standard - Determination of Cyanide
in Foods
1 Scope
This Standard specifies the method for the determination of cyanide in foods. The first method ?€?spectrophotometry?€? is applicable to the determination of cyanide in distilled liquor and its integrated alcoholic beverages, edible alcohol, tapioca flour, packaged drinking water and mineral water.
The second method ?€?gas chromatography?€? and the third method ?€?gas chromatography - mass spectrometry?€? are applicable to the determination of cyanide in liquor, edible alcohol, grain, packaged drinking water and mineral water.
The fourth method ?€?ion chromatography?€? is applicable to the determination of cyanide in distilled liquor and its integrated alcoholic beverages, edible alcohol, packaged drinking water, mineral water and beverages (based on almonds).
The fifth method ?€?flow injection / continuous flow - spectrophotometry?€? is applicable to the determination of cyanide in distilled liquor and its integrated alcoholic beverages, edible alcohol, packaged drinking water and mineral water.
Method I - Spectrophotometry
2 Principle
Heat the specimen under alkaline conditions to remove high-boiling-point organic matters, or heat and distill it under acidic conditions. After using sodium hydroxide solution to dissolve or absorb it, under the condition of pH = 7.0, use chloramine T to convert cyanide to cyanogen chloride, then, react it with isonicotinic acid-pyrazolone to generate a blue dye, which can be quantitatively compared with the standard series.
3 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are all analytically pure, and the water is Grade-3 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Absolute ethanol (C2H6O).
distillation device (for water cooling, a condenser is required to adjust the temperature to 10 ???C ~ 15 ???C for distillation), insert the lower end of the condenser tube under the liquid level of a 100 mL volumetric flask containing 10 mL of sodium hydroxide solution (20 g/L) (if the room temperature is higher than 25 ???C, use an ice pack to cool it down, so that the temperature of the distillate is between 20 ???C ~ 25 ???C), and perform distillation. When the distillate collected is nearly 100 mL, use water to reach a constant volume to the scale. Accurately draw 1.00 mL of the solution into a 10 mL colorimetric tube, add 2 g/L of sodium hydroxide solution to 5 mL, shake it well, and use it as a specimen solution.
5.1.1.2 Add 2 drops of phenolphthalein indicator solution to the specimen solution, add acetic acid solution to adjust it, until the red color fades, then, use 20 g/L sodium hydroxide solution to adjust it to nearly red color. Add 2 mL of phosphate buffer solution, then add 0.2 mL of chloramine T solution, shake it well and let it stand for 3 min. Add 2 mL of isonicotinic acid- pyrazolone solution, add water to reach a constant volume to the scale. Add a stopper and shake to evenly mix it. Place it in a constant-temperature water bath at 37 ???C for 40 min and reserve it for testing.
5.1.2 Distilled liquor and its integrated alcoholic beverages, edible alcohol 5.1.2.1 Accurately draw 1.00 mL of specimen (for sesame-flavor liquor, Maotai-flavor liquor and special-flavor liquor specimens, draw 0.10 mL) into a 25 mL beaker, add 5 mL of sodium hydroxide solution (2 g/L), and leave it for 10 min. Then, place it on an electric heating plate at 160 ???C ~ 180 ???C and heat it at low temperature, until about 1 mL of the solution remains. Remove it and place it at room temperature. Use 2 g/L sodium hydroxide solution to transfer it to a 10 mL colorimetric tube with a stopper. Finally, add 2 g/L sodium hydroxide solution to 5 mL.
5.1.2.2 If the liquor specimen is turbid or colored, take 25.0 mL of specimen into a 250 mL distillation flask, add 100 mL of water, add a few glass beads, and dropwise add a few drops of methyl orange indicator. Insert the lower end of the condenser tube under the liquid level of the colorimetric tube containing 10 mL of sodium hydroxide solution (20 g/L), add 1 g ~ 2 g of tartaric acid, the solution changes from orange to orange-red. Quickly connect the distillation device to perform distillation, and collect nearly 50 mL of the distillate, then, use water to reach a constant water of 50 mL, and evenly mix it. Take 2.00 mL of the distillate and operate in accordance with 5.1.2.1.
5.1.2.3 Same as 5.1.1.2.
5.1.3 Packaged drinking water and mineral water
5.1.3.1 Measure-take 250 mL of water specimen (when the cyanide content exceeds 20 ???g, take an appropriate amount of water specimen and add water to 250 mL) and place it into a 500 mL distillation device. Add 1 ~ 2 drops of methyl orange indicator, then, add 5 mL of zinc acetate solution, and add 1 g ~ 2 g of tartaric acid, the solution changes from orange to orange-red. Quickly connect the distillation device, insert the lower end of the condenser tube under the liquid level of a 50 mL colorimetric tube with a stopper containing 5.0 mL of sodium hydroxide solution (20 g/L). By adjusting the temperature, control the distillation speed at 2 mL/min ~ 3 mL/min, collect nearly 50 mL of the distillate, then, use water to reach a constant water of 50 mL, and evenly mix it. Take 10.0 mL of the distillate and place it in a 25 mL colorimetric tube with a stopper.
5.1.3.2 Add 5.0 mL of phosphate buffer solution to the colorimetric tube containing the specimen, place it in a constant-temperature water bath at 37 ???C, then, add 0.25 mL of chloramine T solution, add a stopper to mix it, leave it for 5 min. Then, add 5.0 mL of isonicotinic acid-pyrazolone solution, add water to 25 mL and mix it well. Place it in a constant- temperature water bath at 37 ???C for 40 min and reserve it for testing.
5.2 Drawing of Standard Working Curve
5.2.1 Standard curve of tapioca flour
Respectively and accurately draw 0 mL, 0.40 mL, 0.80 mL, 1.20 mL, 1.60 mL and 2.00 mL of cyanide ion standard solution (1.0 ???g/mL) into a 10 mL colorimetric tube [equivalent to the mass of cyanide (CN?€?): 0 ???g, 0.40 ???g, 0.80 ???g, 1.20 ???g, 1.60 ???g and 2.00 ???g], add 2 g/L sodium hydroxide solution to 5 mL. In accordance with 5.1.1.2, conduct synchronous operation with the sample below. Take the prepared standard curve solution to be tested, use a 1 cm cuvette, and take 2 g/L sodium hydroxide solution as the blank solution to adjust the zero point. At a wavelength of 638 nm, determine the absorbance; take the mass of cyanide ions as the x- coordinate and the absorbance of cyanide ions as the y-coordinate, and draw a standard curve. 5.2.2 Standard curve of distilled liquor and its integrated alcoholic beverages, edible alcohol
Respectively and accurately draw 0 mL, 0.40 mL, 0.80 mL, 1.20 mL, 1.60 mL and 2.00 mL of cyanide ion standard solution (1.0 ???g/mL) into a 50 mL beaker [equivalent to the mass of cyanide (CN?€?): 0 ???g, 0.40 ???g, 0.80 ???g, 1.20 ???g, 1.60 ???g and 2.00 ???g], add 5 mL of sodium hydroxide solution (2 g/L) and leave it for 10 min. In accordance with 5.1.2.1 and 5.1.2.3, conduct synchronous operation with the sample below. Take the prepared standard curve solution to be tested, use a 1 cm cuvette, and take 2 g/L sodium hydroxide solution as the blank solution to adjust the zero point. At a wavelength of 638 nm, determine the absorbance; take the mass of cyanide ions as the x-coordinate and the absorbance of cyanide ions as the y- coordinate, and draw a standard curve.
5.2.3 Standard curve of packaged drinking water and mineral water
Respectively and accurately draw 0 mL, 0.10 mL, 0.20 mL, 0.40 mL, 0.80 mL and 1.00 mL of cyanide ion standard solution (1.0 ???g/mL) into a 25 mL colorimetric tube [equivalent to the mass of cyanide (CN?€?): 0 ???g, 0.10 ???g, 0.20 ???g, 0.40 ???g, 0.80 ???g and 1.00 ???g], add 2 g/L sodium hydroxide solution to 10.0 mL. In accordance with 5.1.3.2, conduct synchronous operation with the sample below. Take the prepared standard curve solution to be tested, use a 3 cm cuvette, and take 2 g/L sodium hydroxide solution as the blank solution to adjust the zero point. At a wavelength of 638 nm, determine the absorbance; take the mass of cyanide ions as the x- coordinate and the absorbance of cyanide ions as the y-coordinate, and draw a standard curve. cyanide in the specimen, under acidic conditions, use chloramine T to derive it into cyanogen chloride. Cyanogen chloride reaches equilibrium in the gas phase and liquid phase, and the gas phase part is introduced into the gas chromatograph for separation. Use an electron capture detector for detection and the external standard method for quantitative determination. 10 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are all analytically pure, and the water is Grade-2 water specified in GB/T 6682.
10.1 Reagents
10.1.1 Chloramine T (C7H7ClNNaO2S ??? 3 H2O).
10.1.2 Phosphoric acid (H3PO4): ??? 85%.
10.1.3 Sodium hydroxide (NaOH).
10.2 Reagent Preparation
10.2.1 Chloramine T solution (10 g/L): weigh-take 0.1 g of chloramine T, use water to dissolve it and reach a constant volume of 10 mL. Prepare it right before use.
10.2.2 Phosphoric acid solution (1 + 5): measure-take 10 mL of concentrated phosphoric acid, add it to 50 mL of water, and evenly mix it.
10.2.3 0.1% sodium hydroxide solution: weigh-take 1.0 g of sodium hydroxide, use water to dissolve it and reach a constant volume of 1 L.
10.2.4 0.01 mol/L sodium hydroxide solution: weigh-take 0.4 g of sodium hydroxide, use water to dissolve it and reach a constant volume of 1 L.
NOTE: when the prepared chloramine T solution is turbid, it needs to be replaced with newly prepared chloramine T.
10.3 Reference Material
Cyanide standard solution (50.0 ???g/mL, calculated as CN?€?): a standard substance certified by the state and awarded a reference material certificate. Please refer to the reference material certificate for shelf life and storage conditions.
10.4 Preparation of Standard Solutions
10.4.1 Cyanide ion (calculated as CN?€?) standard intermediate solution: accurately transfer-take 2.00 mL of cyanide standard solution (50.0 ???g/mL) into a 10.0 mL volumetric flask; use 0.1% sodium hydroxide solution to reach a constant volume. The mass concentration of this solution is 10.0 mg/L. Prepare it right before use.
10.4.2 Cyanide ion (calculated as CN?€?) standard working solutions: transfer-take an appropriate amount of cyanide ion (calculated as CN?€?) standard intermediate solution (10.0 mg/L), and use 0.01 mol/L sodium hydroxide solution to dilute it and prepare working solutions respectively with a mass concentration of 0.001 mg/L, 0.005 mg/L, 0.050 mg/L, 0.100 mg/L and 0.200 mg/L. Prepare it right before use.
NOTE: since cyanide is a highly toxic substance, please operate in a fume hood. 11 Instruments and Equipment
11.1 Gas chromatograph: equipped with an electron capture detector (ECD). 11.2 Headspace sampler.
11.3 Headspace bottle: 20 mL.
11.4 Vortex mixer.
11.5 Analytical balance: with a division value of 0.0001 g.
11.6 Ultrasonic cleaner.
11.7 Centrifuge: with a rotational speed ??? 4,000 r/min.
12 Analytical Procedures
12.1 Pre-treatment of Sample
12.1.1 Specimen preparation
Take about 500 g of solid specimen, use a sample crushing device to make it into powder, put it into a clean container, seal it, and store it at 0 ???C ~ 4 ???C. Take about 500 mL of liquid specimen, thoroughly mix it, put it into a clean container, seal it, and store it at 0 ???C ~ 4 ???C. NOTE: during the operation of specimen preparation, samples must be prevented from being contaminated.
12.1.2 Determination of specimen solution
12.1.2.1 Liquor and edible alcohol
Accurately transfer-take 0.20 mL of specimen into a headspace bottle, add 9.80 mL of 0.01 mol/L sodium hydroxide solution, let it stand for 5 min, add 0.2 mL of phosphoric acid solution. Then, add 0.2 mL of chloramine T solution, immediately cap seal it, and reserve it for testing. 12.1.2.2 Grain
24.1.4 Methanol (CH3OH).
24.1.5 Acetonitrile (C2H3N).
24.2 Reagent Preparation
24.2.1 Eluent: 100 mmol/L sodium hydroxide + 500 mmol/L sodium acetate + 0.5% ethylenediamine (volume ratio): weigh-take 41.02 g of sodium acetate and dissolve it in 1 L of water; pass it through a 0.22 ???m nylon microporous filter membrane, add 5.00 mL of ethylenediamine and 5.24 mL of 50% sodium hydroxide.
24.2.2 500 mmol/L sodium hydroxide solution: draw 2.62 mL of 50% sodium hydroxide, add it to 100 mL of water, and evenly mix it.
24.3 Reference Material
Cyanide standard solution (50.0 ???g/mL, calculated as CN?€?): a standard substance certified by the state and awarded a reference material certificate. Please refer to the reference material certificate for shelf life and storage conditions.
24.4 Preparation of Standard Solution
24.4.1 Preparation of distilled liquor and its integrated alcoholic beverages, edible alcohol standard series solutions
24.4.1.1 Cyanide (calculated as CN?€?) standard intermediate solution (1.00 mg/L): draw 0.20 mL of cyanide standard solution (50.0 ???g/mL) into a 10 mL volumetric flask, add water to reach a constant volume to the scale, and evenly mix it. Prepare it right before use. 24.4.1.2 Cyanide (calculated as CN?€?) standard series working solutions: respectively draw 0.050 mL, 0.10 mL, 0.20 mL, 0.50 mL and 1.00 mL of cyanide (calculated as CN?€?) standard intermediate solution (1.00 mg/L) into a 10 mL volumetric flask, add water to reach a constant volume to the scale, and evenly mix it. The mass concentration of the cyanide (calculated as CN?€?) standard series working solutions is respectively 0.0050 mg/L, 0.010 mg/L, 0.020 mg/L, 0.050 mg/L and 0.100 mg/L. Prepare it right before use.
24.4.2 Preparation of packaged drinking water and mineral water standard series solutions
24.4.2.1 Cyanide (calculated as CN?€?) standard intermediate solution (1.00 mg/L): draw 0.20 mL of cyanide standard solution (50.0 ???g/mL) into a 10 mL volumetric flask, add water to reach a constant volume to the scale, and evenly mix it. Prepare it right before use. 24.4.2.2 Cyanide (calculated as CN?€?) standard series working solutions: respectively draw 0.050 mL, 0.10 mL, 0.20 mL, 0.50 mL and 1.00 mL of cyanide standard solution (1.00 mg/L) into a 10 mL volumetric flask, add water to reach a constant volume to the scale. Then, add 0.10 mL of sodium hydroxide solution (500 mmol/L), and evenly mix it. The mass concentration of the cyanide (calculated as CN?€?) standard series working solutions is Take about 500 mL of sample, thoroughly mix it, put it into a clean container, seal it, and store it at 0 ???C ~ 4 ???C.
26.1.2 Specimen dilution, purification and pH adjustment
26.1.2.1 Packaged drinking water and mineral water
Accurately transfer-take 10.0 mL of specimen into a colorimetric tube, add 0.1 mL of sodium hydroxide solution (500 mmol/L), evenly mix it, and reserve it for testing. 26.1.2.2 Distilled liquor and its integrated alcoholic beverages, edible alcohol Accurately transfer-take 1.00 mL of specimen into a 10.0 mL colorimetric tube, use water to dilute to reach a constant volume to the scale, and evenly mix it. Then, filter it through 0.22 ???m nylon microporous filter membrane and reserve it for testing. When the sample color is relatively dark or the sugar content is relatively high, firstly, pass the test solution through the IC-RP solid-phase extraction column, control the entire flow rate at 4 mL/min, discard the initial 3 mL or 6 mL (selected in accordance with the column specifications), then, filter it through the 0.22 ???m nylon microporous filter membrane, and reserve it for testing.
26.1.2.3 Beverages (based on almonds)
Accurately transfer-take 4.00 mL of specimen into a 10.0 mL colorimetric tube, use acetonitrile to reach a constant volume to the scale, perform vortex mix for 2 min. Transfer it to a centrifuge tube, let it stand, then, centrifuge for 10 min. Accurately transfer-take 2.5 mL of the supernatant and use water to reach a constant volume to 10.0 mL. Take an appropriate amount of the above- mentioned solution, firstly, pass it through the IC-RP solid phase extraction column, control the entire flow rate at 4 mL/min, discard the initial 3 mL or 6 mL (selected in accordance with the column specifications), then, filter it through the 0.22 ???m nylon microporous filter membrane, and reserve it for testing.
26.2 Reference Conditions of Instruments
Chromatographic column: the filler is an anion protection column and separation column of polystyrene divinylbenzene copolymer with alkyl quaternary ammonium groups, or those with equivalent performance.
Eluent: 100 mmol/L sodium hydroxide + 500 mmol/L sodium acetate + 0.5% ethylenediamine (volume ratio), perform isocratic elution.
Flow rate: 1 mL/min.
Column temperature: 30 ???C.
Detector: ampere detector.
Injection volume: 250 ???L for beverages (based on almonds); 50 ???L for others. 31.2 Reagent Preparation
31.2.1 Flow injection method
31.2.1.1 Sodium hydroxide solution (1.0 g/L): weigh-take 1.0 g of sodium hydroxide, dissolve in water, and reach a constant volume of 1,000 mL. Prepare it right before use. Before use, it needs to be degassed. This solution is also used for the standard curve and the alkaline hydrolysis dilution of liquor samples.
31.2.1.2 Distillation reagent (pH = 3.8): weigh-take 13.2 g of tartaric acid into a 1,000 mL beaker, add 800 mL of water, then, weigh 3.5 g of sodium h...

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