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GB 5009.76-2014 (GB5009.76-2014)

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GB 5009.76-2014: PDF in English
GB 5009.76-2014
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
National food safety standard -
Determination of arsenic in food additives
ISSUED ON. SEPTEMBER 21, 2015
IMPLEMENTED ON. MARCH 21, 2016
Issued by. National Health and Family Planning Commission of the PRC
3. No action is required - Full-copy of this standard will be automatically &
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Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Principles ... 4 
3 Reagents and materials ... 4 
4 Instruments ... 6 
5 Sample treatment ... 8 
6 Determination ... 9 
7 Expression of analytical results ... 10 
8 Precision... 11 
9 Principles ... 11 
10 Reagent ... 11 
11 Instruments ... 13 
12 Analytical procedures ... 13 
13 Expression of analytical results ... 15 
14 Precision ... 15 
15 Others ... 16 
Foreword
This standard replaces GB/T 5009.76-2003 “Determination of arsenic in food
additives”.
As compared with GB/T 5009.76-2003, the main changes of this standard are
as follows.
- CHANGE the standard name into “National food safety standard –
Determination of arsenic in food additives”;
- DELETE the arsenic spot method;
- ADD the hydride atomic fluorescence determination method, as the
method 2.
National food safety standard -
Determination of arsenic in food additives
1 Scope
This standard specifies the determination of arsenic in food additives.
This standard applies to the determination of arsenic in food additives.
Method 1. Diethylamino dithiocarbamate colorimetric method
2 Principles
In the presence of potassium iodide and stannous chloride, the high valence
arsenic in the sample solution is reduced to trivalent arsenic, AND the trivalent
arsenic reacts with the newly generated hydrogen which is produced by the
zinc particles and acid, to produce arsine gas; after the interference of the
sulfuretted hydrogen is removed by the lead acetate cotton, the arsine gas is
dissolved in the triethanolamine-chloroform OR absorbed and reacted by the
diethyl diethyldithiocarbamate solution in the pyridine to produce a purple
complex, which is compared with the standard for quantification.
3 Reagents and materials
Note. Unless otherwise stated, the reagents used in this method are of
analytical pure AND the water is level 1 water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3). excellent grade pure.
3.1.2 Sulfuric acid (H2SO4). excellent grade pure.
3.1.3 Hydrochloric acid (HCl). excellent grade pure.
3.1.4 Sodium hydroxide (NaOH).
3.1.5 Magnesium oxide (MgO).
3.2.8 Absorbent solution A. WEIGH 0.25 g of diethylamino dithiocarbamate;
GRIND it; USE appropriate amount of chloroform to dissolve it; ADD 1.0 mL of
triethanolamine; USE chloroform to dilute it to 100 mL. After letting it stand,
FILTER it into a brown bottle; PRESERVE it in a refrigerator to prepare for use.
3.2.9 Absorption solution B. WEIGH 0.50 g of silver diethyldithiocarbamate;
GRIND it and USE pyridine to dissolve and dilute it to 100 mL. After letting it
stand, FILTER it into a brown bottle; PRESERVE it in a refrigerator to prepare
for use.
3.2.10 Phenolphthalein ethanol solution (10 g/L). WEIGH 1.0 g of
phenolphthalein; DISSOLVE it into 100 mL of ethanol solution.
3.2.11 Lead acetate solution (100 g/L). WEIGH 10 g of lead acetate; USE
water to dissolve it and MAKE its volume reach to 100 mL.
3.3 Standard substance
Arsenic trioxide (As2O3) standard substance. the purity is 99.99% OR the
standard substance certified and awarded the standard substance certificate
by the state.
3.4 Standard solution preparation
3.4.1 Arsenic standard stock solution (0.1 mg/mL). accurately WEIGH 0.1320
g of arsenic trioxide which had been dried to constant weight in a sulfuric acid
dryer; DISSOLVE it into 5 mL of sodium hydroxide solution. After dissolving,
ADD 25 mL of sulfuric acid solution; TRANSFER it into a 1000 mL volumetric
flask; ADD the newly boiling water to dilute it to the mark.
3.4.2 Arsenic standard use of liquid (1 μg/mL). before use, TAKE 1.0 mL of
arsenic standard stock solution; ADD 1 mL of sulfuric acid solution into a 100
mL volumetric flask; ADD the newly boiling cooling water to dilute it to the
mark.
3.5 Materials
Lead acetate cotton. DIP the absorbent cotton into the lead acetate solution
(10%) for 2 h; TAKE it out and DRY it naturally.
4 Instruments
Note. The glass instruments used shall be soaked in the nitric acid solution (1
+ 4) for more than 24 h; USE water to rinse it for several times; USE deionized
water to rinse it clean.
5 Sample treatment
5.1 Preparation of inorganic samples
The “sample treatment” of the inorganic sample may be carried out in
accordance with the method as specified in the relevant standards.
5.2 Preparation of organic samples
The “sample treatment” of organic sample shall, in addition to the requirements
of relevant standards, generally follow the methods below.
a) Wet digestion. WEIGH 5 g of sample (accurate to 0.001 g); PLACE it into
a 250 mL conical flask; ADD 10 mL of nitric acid; LET it standard for a
moment (or overnight), PLACE it on the electric heating plate to heat it;
when the reaction becomes moderate, TAKE it down and PLACE to cool
it; ADD 5 mL of sulfuric acid along the conical wall; CONTINUE heating
until the solution in the flask starts becoming brown; CONTINUE adding
nitric acid (OR some perchloric acid if necessary), until the organic matter
is completely decomposed; CONTINUE heating until a large amount of
sulfur dioxide white smoke is produced, AND finally the solution shall be
colorless or in light yellow. After cooling it down, ADD 20 mL of water and
BOIL it to remove the residual nitric acid, until white smoke is produced.
REPEAT this operation for two times; COOL it naturally; TRANSFER the
solution into a 50 mL volumetric flask; USE a small amount of water to
rinse the conical flask for 2 times ~ 3 times; COLLECT the rinsing
solution into the volumetric flask; USE water to make it reach to the mark.
TAKE the same amount of nitric acid and sulfuric acid; and meanwhile
MAKE the reagent blank test.
b) Dry ashing method. WEIGH 5 g of sample (accurate to 0.001 g) in the
porcelain crucible; ADD 10 mL of magnesium nitrate solution; MIX it
uniformly; SOAK it for 4 h; EVAPORATE it dry on the adjustable electric
furnace at low temperature or water bath; ADD 1.00 g of magnesium
oxide powder carefully to cover the dry residue; USE the adjustable
electric furnace to heat it at small fire until the carbonization is completely
finished; TRANSFER the crucible into the muffle furnace; BURN it at
550 °C until the ashing is complete; COOL it down and TAKE it out; ADD
appropriate amount of water to wet the ash; ADD several drops of
phenolphthalein ethanol solution; then ADD several drops of (1 + 1)
hydrochloric acid solution, until the red color of phenolphthalein
disappears; TRANSFER the solution into a 50 mL volumetric flask
(FILTER it if necessary); USE a small amount of water to rinse the
crucible for 3 times; COLLECT the rinsing solution into the volumetric
10.2 Reagent preparation
10.2.1 Sodium hydroxide solution (2 g/L). WEIGH 2.0 g of sodium hydroxide;
DISSOLVE it into 1000 mL of water; MIX it uniformly.
10.2.2 Sodium borohydride solution (10 g/L). WEIGH 10.0 g of sodium
borohydride; DISSOLVE it into 1000 mL of sodium hydroxide solution; MIX it
uniformly. PREPARE it before use (it may also weigh 14 g of potassium
borohydride to substitute sodium borohydride).
10.2.3 Thiourea solution (50 g/L). WEIGH 50 g of thiourea; DISSOLVE it into
1000 mL of water; MIX it uniformly.
10.2.4 Sulfuric acid solution (1 + 9). MEASURE 100 mL of sulfuric acid;
carefully POUR it into 900 mL of water; MIX it uniformly.
10.2.5 Sodium hydroxide solution (100 g/L). WEIGH 1.0 g of sodium hydroxide;
DISSOLVE it into 10 mL of water.
10.2.6 Hydrochloric acid solution (1 + 1). MEASURE 100 mL of hydrochloric
acid; slowly POUR it into 100 mL of water; MIX it uniformly; COOL it down
before use.
10.2.7 Magnesium nitrate solution (150 g/L). WEIGH 150 g of magnesium
nitrate; DISSOLVE it into 1000 mL of water; MIX it uniformly.
10.3 Standard substance
Arsenic trioxide (As2O3) standard substance. the purity is 99.99% OR the
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(Above excerpt was released on 2017-10-22, modified on 2021-06-07, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GB5009.76-2014