GB 5009.36-2016_English: PDF (GB5009.36-2016)
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Method for analysis of hygienic standard of grains
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GB 5009.36-2016
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| GB 5009.36-2023 | English | 410 |
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National Food Safety Standard - Determination of Cyanide in Foods
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GB 5009.36-2023
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Newer version: GB 5009.36-2023 Standards related to: GB 5009.36-2023
| Standard ID | GB 5009.36-2016 (GB5009.36-2016) | | Description (Translated English) | Method for analysis of hygienic standard of grains | | Sector / Industry | National Standard | | Classification of Chinese Standard | X09 | | Word Count Estimation | 13,142 | | Date of Issue | 2016-12-23 | | Date of Implementation | 2017-06-23 | | Older Standard (superseded by this standard) | GB/T 5009.36-2003 Partial; GB/T 5009.48-2003 Partial; GB/T 8538-2008 Partial | | Regulation (derived from) | National Health and Family Planning Commission Notice No.17 of 2016 | GB 5009.36-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard -
Determination of Cyanide in Foods
ISSUED ON. DECEMBER 23, 2016
IMPLEMENTED ON. JUNE 23, 2017
Issued by. National Health and Family Planning Commission of the
People’s Republic of China;
State Food and Drug Administration of the People’s Republic
of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
Method I Spectrophotometry ... 4
2 Principle ... 4
3 Reagents and Materials ... 4
4 Instruments and Equipment ... 6
5 Analytical Procedures ... 6
6 Expression of Analysis Results ... 7
7 Precision ... 9
8 Others ... 9
Method II Gas Chromatography ... 9
9 Principle ... 9
10 Reagents and Materials... 10
11 Instruments and Equipment ... 11
12 Analytical Procedures ... 11
13 Precision ... 14
14 Others ... 14
Method III Qualitative Method ... 14
15 Principle ... 14
16 Reagents and Materials... 14
17 Instruments ... 15
18 Analytical Procedures ... 15
19 Others ... 15
Appendix A Gas Chromatogram of Cyanide ... 17
Appendix B Headspace Inlet Conditions ... 18
National Food Safety Standard -
Determination of Cyanide in Foods
1 Scope
This Standard specifies the method of determining cyanide in foods.
Method I in this Standard is applicable to the detection of cyanide in distilled liquor and
its compounds, as well as cassava, packaged drinking water and mineral water.
Method II and Method III in this Standard are applicable to the detection of cyanide in
distilled liquor and its compounds, as well as grains, cassava, packaged drinking
water and mineral water.
Method I -- Spectrophotometry
2 Principle
Adopt sodium hydroxide solution to absorb hydrocyanic acid that’s distilled from
cyanide in cassava, packaged drinking water and mineral water under acidic
conditions. Under the condition of pH=7.0, distill liquid chloramine-T, which converts
cyanide into hydrogen chloride. Generate blue dye under the effect of isonicotinic
acid-pyrazolone; quantitatively compare with the standard series.
Heat up distilled liquor and its compounds under alkaline conditions, remove organics
with a high boiling point. Under the condition of pH=7.0, adopt chloramine-T to convert
cyanide into hydrogen chloride. Generate blue dye under the effect of isonicotinic
acid-pyrazolone; quantitatively compare with the standard series.
3 Reagents and Materials
Unless otherwise indicated, the reagents adopted under this method are of analytical
purity. The water is third-grade water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Methyl orange (C14H14O3N3SNa). indicator.
3.1.2 Phenolphthalein (C20H14O4). indicator.
3.1.3 Tartaric acid (C4H6O6).
② that contains 10 mL of 20 g/L sodium hydroxide solution. Repeat distillation till the
gathered distillate reaches approximately 80 mL. Stop the heating, continue to gather
approximately 100 mL of distillate; remove the conical flask②. Remove the distilling
flask and thoroughly stir the contents. Insert the lower end of the condensing tube into
the liquid level of 100 mL conical flask③ that contains 10 mL of 20 g/L sodium
hydroxide solution. Start steam distillation, till the conical flask ③ gathers
approximately 50 mL of distillate; remove the conical flask③. Completely transfer
distillate gathered in conical flask①, conical flask② and conical flask③ to 250 mL
volumetric flask; add water to the constant volume. Measure-take 10 mL of solution
(V2) and place it in 25 mL colorimetric tube as sample solution.
5.1.2 Adopt pipette to respectively measure-take 0.0 mL, 0.3 mL, 0.6 mL, 0.9 mL, 1.2
mL and 1.5 mL of standard intermediate fluid of cyanide ion; place it in 25 mL
colorimetric tube; add water to 10 mL.
5.1.3 Add 1 mL of 10 g/L sodium hydroxide solution and 1 drop of phenolphthalein
indicator fluid respectively to the sample solution and standard series of solution;
adopt acetic acid solution to slowly adjust the solution, till the color of red fades. Add 5
mL of phosphate buffer solution; start thermal insulation for 10 min in
constant-temperature water bath kettle at 37 °C. Respectively add 0.25 mL of
chloramine-T solution; plug it and shake it well; place it evenly for 5 min. Respectively
add 5 mL of isonicotinic acid-pyrazolone solution; add water to 25 mL; mix it up. Place
it for 40 min in constant-temperature water bath kettle at 37 °C. Adopt 2 cm
colorimetric cup; adjust the zero point through the zero tube; measure absorbance at
the wavelength of 638 nm. Draw a calibration curve; acquire the mass of cyanide in
the sample tube through the curve.
6 Expression of Analysis Results
6.1 Calculation of Cassava Powder
The content of cyanide (calculated by CN-) in the sample shall be calculated in
accordance with Formula (1).
chloride in foods into hydrogen chloride under acidic conditions. Hydrogen chloride
reaches a balance in gas and liquid phase. Import the gas phase into gas
chromatography for separation, adopt electronic capture detector for detection. Adopt
the external standard method to quantify the content.
10 Reagents and Materials
Unless otherwise indicated, the reagents adopted under this method are of analytical
purity. The water is second-grade water as specified in GB/T 6682.
10.1 Reagents
10.1.1 Chloramine-T (C7H7ClNNaO2S.3H2O). stored in dryer.
10.1.2 Phosphoric acid (H3PO4). ≥85%.
10.1.3 Sodium hydroxide (NaOH).
10.2 Preparation of Reagents
10.2.1 Chloramine-T solution (10 g/L). weigh-take 0.1 g of chloramine-T; add water to
dilute to the constant volume of 10 mL (use immediately after preparation).
10.2.2 Phosphoric acid solution (1+5). measure-take 10 mL of concentrated
phosphoric acid; add it to 50 mL of water, mix it up.
10.2.3 1% sodium hydroxide solution. weigh-take 1.0 g of sodium hydroxide; add
water to dilute to the constant volume of 1 L.
10.3 Preparation of Standard Solutions
10.3.1 Standard substance of cyanide analysis in water (50 μg/mL). No. of standard
substance. GBW(E)080115.
10.3.2 Standard intermediate fluid of cyanide ion (calculated by CN-). accurately
remove-take 2.00 mL of standard substance of cyanide analysis in water (10.3.1);
place it in 10 mL volumetric flask. Adopt 0.1% sodium hydroxide solution to the
constant volume (concentration of solution. 10 mg/L). Store in the refrigerator at
0 °C~4 °C. It can remain valid for 3 months.
10.3.3 Standard working fluid of cyanide ion (calculated by CN-). Remove-take an
appropriate amount of standard intermediate fluid of cyanide ion (calculated by CN-);
add water to dilute to working fluid under the concentration of 0 mg/L, 0.001 mg/L,
0.002 mg/L, 0.010 mg/L, 0.050 mg/L and 0.100 mg/L.
Note. when the prepared chloramine-T solution is turbid, it is necessary to replace
new chloramine-T.
f) Split ratio. 5.1;
g) Column flow rate. 2.0 mL/min.
12.3 Draw a Standard Curve Line
Respectively and accurately remove-take 10.0 mL of standard working fluid of
cyanide ion (10.3.3); place it in 6 headspace bottles; add 0.2 mL of phosphoric acid
solution. Start vortex mixing. Add 0.2 mL of chloramine-T solution; immediately seal it.
Start vortex mixing; reserve for determination.
12.4 Determination of Sample Solutions
12.4.1 Distilled liquor and its compounds
Accurately remove-take 0.2 mL of sample and place it in headspace bottle; add 9.8
mL of distilled water; add 0.2 mL of phosphoric acid solution. Start vortex mixing. Add
0.2 mL of chloramine-T solution; immediately seal it. Start vortex mixing; reserve for
determination.
12.4.2 Grains
Accurately weigh-take 1 g (accurate to 0.0001 g) of sample; add distilled water to the
constant volume of 100 mL. Start ultrasonic extraction for 20 min and centrifugation at
4,000 r/min for 5 min. Accurately remove-take 10 mL of extract, then, place it in
headspace bottle. Add 0.2 mL of phosphoric acid solution. Start vortex mixing. Add 0.2
mL of chloramine-T solution; immediately seal it. Start vortex mixing; reserve for
determination.
12.4.3 Packaged drinking water and mineral water
Accurately weigh-take 10 mL of sample and place it in headspace bottle. Add 0.2 mL
of phosphoric acid solution; start vortex mixing. Add 0.2 mL of chloramine-T solution;
immediately seal it. Start vortex mixing; reserve for determination.
12.5 Sample Blank Determination
Follow the steps in 12.4 till 0.2 mL of phosphoric acid solution is added and vortex
mixing is completed; inlet nitrogen gas and blow for 15 min in 50 °C water bath. Add
0.2 mL of chloramine-T solution; immediately seal it. Start vortex mixing; reserve for
determination. The result of determination is sample blank.
12.6 Gas Chromatographic Detection
Determine the standard solution and sample solution in accordance with the
conditions stipulated in 12.2. Determine the nature in accordance with the retention
time of chloride; measure the response value of peak area (or peak height) of the
sample solution; adopt the external standard method to quantify the content. The
response value of cyanide derivatives in the sample solution shall be within the
standard linear range. If it exceeds this range, before adding phosphoric acid solution,
add water to dilute it, till it reaches the range. Under the above-mentioned
chromatographic conditions, the retention time of cyanide is approximately 1.77 min.
16.2.1 Sodium carbonate solution (100 g/L). weigh-take 10.0 g of sodium carbonate;
add water to dilute to the constant volume of 100 mL.
16.2.2 Saturated picric acid ethanol solution.
16.3 Materials
Picrate test paper. take qualitative filter paper, then, cut it into a paper slip (length. 7
cm, width. 0.3 cm~0.5 cm); soak it in saturated picric acid ethanol solution; take it out
after several minutes; dry it in the shade; reserve for later usage.
17 Instruments
17.1 Take 100 mL conical flask, prepare a suitable rubber stopper for the bullet hole;
insert a glass tube (diameter. 0.4 cm~0.5 cm, length. 5 cm) into the hole; hang a
picrate test paper inside the tube. Use sodium carbonate solution to humidify the test
paper for temporary usage.
17.2 Constant-temperature water bath kettle. control the temperature between
40 °C~50 °C.
18 Analytical Procedures
18.1 Grains
Weigh-take 5 g of sample, place it in 100 mL conical flask; add 20 mL of water and 0.5
g of tartaric acid. Promptly insert the rubber stopper with a hanging picrate test paper
that’s humidified with sodium carbonate. Slightly shake it to dissolve tartaric acid;
place it in 40 °C~50 °C water bath, heat it up for 30 min. Observe color changes on
the test paper. If there’s no color change, it signifies that cyanide generates negative
reaction or doesn’t exceed the stipulations; if the color changes, it is necessary to
conduct a quantitative test.
18.2 Liquor
Promptly weigh-take 20 mL of sample, place it in 100 mL conical flask; add 0.5 g of
tartaric acid. Promptly insert the rubber stopper with a hanging picrate test paper
that’s humidified with sodium carbonate. Slightly shake it to dissolve tartaric acid;
place it in 40 °C~50 °C water bath, heat it up for 30 min. Observe color changes on
the test paper. If there’s no color change, it signifies that cyanide generates negative
reaction or doesn’t exceed the stipulations; if the color changes, it is necessary to
conduct a quantitative test.
19 Others
In this Method, the detection limit of liquor is 1.0 mg/L; the detection limit of grains is
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