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GB 25576-2020 PDF in English


GB 25576-2020 (GB25576-2020) PDF English
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GB 25576-2020: PDF in English

GB 25576-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard - Food additive - Silicon
dioxide
ISSUED ON: SEPTEMBER 11, 2020
IMPLEMENTED ON: MARCH 11, 2021
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 Molecular formula and relative molecular mass ... 4 
3 Technical requirements ... 4 
Appendix A Inspection method ... 6 
Foreword
This Standard replaces GB 25576-2010, “Food Additives - Silicon dioxide”.
Compared with GB 25576-2010, the major changes of this Standard are as
follows:
-- Modify the indicator of loss on drying for Type-III products to not more than
7.0%;
-- Modify the drying time for the inspection method of loss on drying;
-- Modify the ignition time for the inspection method of loss on ignition;
-- Modify the reference method of lead content determination;
-- Modify the reference method of arsenic content determination.
National food safety standard - Food additive - Silicon
dioxide
1 Scope
This Standard applies to fumed silica that is produced by the gas phase method
(chlorosilane is hydrolyzed in the oxygen-hydrogen flame), silica gel and
hydrated silica gel that are produced by the gel method (reaction of sodium
silicate solution and acid), and precipitated silicon dioxide that is produced by
the precipitation method (reaction of sodium silicate solution and acid).
2 Molecular formula and relative molecular mass
2.1 Molecular formula
SiO2
2.2 Relative molecular mass
60.08 (according to the international relative atomic mass in 2016)
3 Technical requirements
3.1 Sensory requirements
Sensory requirements shall be in accordance with Table 1.
Table 1 -- Sensory requirements
3.2 Physical and chemical indicators
Physical and chemical indicators shall be in accordance with Table 2.
Appendix A 
Inspection method
A.1 Warning
Some reagents that are used in the test method of this Standard are toxic or
corrosive. The operator must be cautious! If splashed on the skin, use water to
rinse immediately. In severe cases, treat immediately.
A.2 General provisions
The reagents and water that are used in this Standard, when no other
requirements are specified, refer to analytical reagents and grade-III water
which is specified in GB/T 6682. The impurity standard solutions, preparations
and products, which are used in the test, shall be prepared according to the
provisions of GB/T 602 and GB/T 603 when no other requirements are specified.
The used solution, if not indicated which solvent is used, refers to aqueous
solution.
A.3 Identification test
A.3.1 Reagents and materials
A.3.1.1 Anhydrous potassium carbonate.
A.3.1.2 Ammonia.
A.3.1.3 Nitric acid.
A.3.1.4 Disodium hydrogen phosphate solution: Dissolve 12 g of disodium
hydrogen phosphate (Na2HPO4.7H2O); add water to 100 mL.
A.3.1.5 Ammonium molybdate solution: Dissolve 6.5 g of molybdic acid powder
in a mixture of 14 mL of water and 14.5 mL of ammonia; cool it; slowly add it to
the pre-cooled mixture of 32 mL of nitric acid and 40 mL of water under stirring;
leave it for 48 h. Perform suction filtration; store the filtrate in a dark place. This
solution will deteriorate and become invalid when it is left for a long time. When
2 mL of disodium hydrogen phosphate solution is added to 5 mL of the above
solution, and the solution does not immediately produce a large amount of
yellow precipitate, the solution becomes invalid.
A.3.1.6 O-tolidine glacial acetic acid saturated solution.
A.3.2 Identification method
A.3.2.1 Weigh about 5 mg of the sample in a platinum crucible; add 200 mg of
anhydrous potassium carbonate to mix; burn for about 10 minutes at 500 °C ~
Where:
m1 -- mass of the sample and the platinum crucible, in grams (g);
m2 -- mass of the hydrofluoric acid residue after treatment and the platinum
crucible, in grams (g);
m0 -- mass of the platinum crucible, in grams (g);
The test result is based on the arithmetic mean of the parallel determination
results. The absolute difference between two independent determination results
that are obtained under repeatability conditions is not more than 0.3%.
A.5 Determination of loss on drying
A.5.1 Instruments and apparatuses
A.5.1.1 Electrothermal constant-temperature drying oven: Control the
temperature at 105 °C ± 2 °C.
A.5.1.2 Weighing bottle: ϕ60 mm × 30 mm.
A.5.2 Analysis steps
Use a weighing bottle that is dried at 105 °C ± 2 °C to weigh 2 g ~ 3 g of the
sample (for Type-II, weigh 8 g ~ 10 g), accurate to 0.000 2 g. Transfer it into the
electrothermal constant-temperature drying oven; dry at 105 °C ± 2 °C for 120
min ± 5 min; cool in a desiccator; weigh. Keep this dried sample as sample A,
for use in the determination of loss on ignition in A.6.
A.5.3 Result calculation
Calculate the mass fraction w2 of loss on drying according to Formula (A.2):
Where:
m4 -- mass of the sample and weighing bottle before drying, in grams (g);
m5 -- mass of the sample and weighing bottle after drying, in grams (g);
m3 -- mass of the weighing bottle, in grams (g).
The test result is based on the arithmetic mean of the parallel determination
results. The absolute difference between two independent determination results
that are obtained under repeatability conditions is not more than 0.2%.
Weigh 5.00 g ± 0.01 g of the sample that has been dried at 105 °C ± 2 °C for 2
h; put it in a 250 mL flask that is equipped with a cooling reflux device; add 50
mL of hydrochloric acid solution; slowly heat it to boiling on the electric furnace;
boil slightly for 15 min; then, cool it. Let the insoluble matter precipitate; use a
glass sand funnel to perform suction filtration; transfer the filtrate into a 100 mL
volumetric flask; use hot water to wash the insoluble matter 3 times; use 10 mL
of water each time. Transfer the filtrate to a volumetric flask; finally, use 15 mL
of hot water to wash the funnel and the suction flask; cool the filtrate to room
temperature; use water to dilute to the mark; shake well. This solution is sample
solution A, which is used for the determination of lead, heavy metals, and
arsenic.
Do a blank test at the same time.
A.7.2.2 Determination
Use sample solution A (see A.7.2.1) and the corresponding blank solution, as
the sample solution after digestion; perform the determination in accordance
with the method that is specified in GB 5009.12. The water that is used in the
test is grade-II water that meets the requirements of GB/T 6682.
The test result is based on the arithmetic mean of the parallel determination
results. The absolute difference between two independent determination results
that are obtained under repeatability conditions is not more than 1 mg/kg.
A.8 Determination of heavy metals (in Pb)
Accurately pipette 20 mL of sample solution A (see A.7.2.1) and 3 mL of lead
standard use solution (10 μg/mL); perform the determination according to
Chapter 6 in GB 5009.74-2014. The water that is used in the test is grade-II
water that meets the requirements of GB/T 6682.
A.9 Determination of arsenic (As)
Use sample solution A (see A.7.2.1) and the corresponding blank solution, as
the sample solution after digestion; perform the determination in accordance
with the method that is specified in GB 5009.76. The water that is used in the
test is grade-II water that meets the requirements of GB/T 6682.
The test result is based on the arithmetic mean of the parallel determination
results. The absolute difference between two independent determination results
that are obtained under repeatability conditions is not more than 0.6 mg/kg.
A.10 Determination of soluble dissociated salt (in Na2SO4)
A.10.1 Reagents and materials
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.