GB 5009.36-2023 English PDF

GB 5009.36-2023: National food safety standard - Determination of Cyanide in Foods
Delivery: 9 seconds. Download (& Email) true-PDF + Invoice.
Get Quotation: Click GB 5009.36-2023 (Self-service in 1-minute)
Historical versions (Master-website): GB 5009.36-2023
Preview True-PDF (Reload/Scroll-down if blank)

GB 5009.36-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S 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’s 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....