GB 1886.325-2021 English PDF

GB 1886.325-2021: National food safety standard - Food additives - Potassium polymetaphosphate
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GB 1886.325-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard - Food additives -
Potassium polymetaphosphate
ISSUED ON: FEBRUARY 22, 2021
IMPLEMENTED ON: AUGUST 22, 2021
Issued by: National Health Commission of the People's Republic of
China;
State Administration for Market Regulation.
Table of Contents
1 Scope ... 3 
2 Molecular formula and relative molecular mass ... 3 
3 Technical requirements ... 3 
Appendix A Inspection method ... 5 
National food safety standard - Food additives -
Potassium polymetaphosphate
1 Scope
This Standard applies to the food additive potassium polymetaphosphate which
is made by high-temperature dehydration polymerization, with monopotassium
phosphate as the raw material.
2 Molecular formula and relative molecular mass
2.1 Molecular formula
(KPO3)n
2.2 Relative molecular mass
118.069n (according to the international relative atomic mass in 2018)
3 Technical requirements
3.1 Sensory requirements
Sensory requirements shall be in accordance with Table 1.
3.2 Physical and chemical indicators
Physical and chemical indicators shall be in accordance with Table 2.
Table 2 – Physical and chemical indicators
Appendix A 
Inspection method
WARNING: Some reagents used in this test method are toxic or corrosive;
the operator shall be careful. If it is splashed on the skin, use water to
rinse it immediately. If it is serious, seek medical attention immediately.
A.1 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 standard solution, the standard solutions,
preparations and products for impurity determination, which are used in the test,
are all prepared in accordance with the provisions of GB/T 601, GB/T 602, and
GB/T 603, when no other requirements are specified. The solution used in the
test, if not indicated which solvent is used, refers to aqueous solution.
A.2 Identification test
A.2.1 Reagents and materials
A.2.1.1 Hydrochloric acid.
A.2.1.2 Silver nitrate solution: 17 g/L.
A.2.1.3 Ammonia solution: 2+3.
A.2.1.4 Nitric acid solution: 1+9.
A.2.1.5 Sodium acetate solution: 40 g/L.
A.2.2 Identification method
A.2.2.1 Identification of potassium ions
Weigh 0.1 g of the sample and dissolve it in 10 mL of water. Dip the platinum
wire in hydrochloric acid; burn it on the flame until it is colorless; then, dip the
sample solution and burn it on the flame; observe that the flame is purple under
the cobalt glass.
A.2.2.2 Identification of phosphate
Weigh 1 g of the sample; dissolve it in 20 mL of water; add silver nitrate solution,
to produce a yellow precipitate. This precipitate is soluble in ammonia solution
or nitric acid solution.
again; continue to boil until the precipitate stratifies; cool to room temperature.
Use a crucible that has been dried to constant weight at 180 °C ± 2 °C for
filtration; filter the supernatant first; use water to rinse the precipitate and filter
6 times (about 30 mL of water each time); move the precipitate into the crucible;
then, use water to rinse the precipitate 4 times; put the precipitate together with
the crucible in a drying box; take it out after drying at 180 °C for 45 minutes;
cool it to room temperature in a desiccator; weigh it. Use 10 mL of water instead
of the sample solution, to do a blank test at the same time.
A.3.5 Result calculation
Calculate the mass fraction w1 of phosphorus pentoxide (P2O5) (on a dry basis)
according to Formula (A.1).
Where:
m1 – the mass of quinoline phosphomolybdate precipitate that is formed by the
test solution, in grams (g);
m2 – the mass of quinoline phosphomolybdate precipitate that is formed by the
blank solution, in grams (g);
0.032 07 – the coefficient of conversion of quinoline phosphomolybdate to
phosphorus pentoxide (P2O5);
500 – the initial volume of the sample solution, in milliliters (mL);
m – the mass of the dried sample, in grams (g);
10 – the measured volume of the sample solution, in milliliters (mL).
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.4 Determination of loss on ignition (on a dry basis)
A.4.1 Instruments and apparatuses
A.4.1.1 Crucible.
A.4.1.2 Electrothermal constant-temperature dry box.
A.4.1.3 High temperature furnace.
GB 1886.325-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard - Food additives -
Potassium polymetaphosphate
ISSUED ON: FEBRUARY 22, 2021
IMPLEMENTED ON: AUGUST 22, 2021
Issued by: National Health Commission of the People's Republic of
China;
State Administration for Market Regulation.
Table of Contents
1 Scope ... 3 
2 Molecular formula and relative molecular mass ... 3 
3 Technical requirements ... 3 
Appendix A Inspection method ... 5 
National food safety standard - Food additives -
Potassium polymetaphosphate
1 Scope
This Standard applies to the food additive potassium polymetaphosphate which
is made by high-temperature dehydration polymerization, with monopotassium
phosphate as the raw material.
2 Molecular formula and relative molecular mass
2.1 Molecular formula
(KPO3)n
2.2 Relative molecular mass
118.069n (according to the international relative atomic mass in 2018)
3 Technical requirements
3.1 Sensory requirements
Sensory requirements shall be in accordance with Table 1.
3.2 Physical and chemical indicators
Physical and chemical indicators shall be in accordance with Table 2.
Table 2 – Physical and chemical indicators
Appendix A 
Inspection method
WARNING: Some reagents used in this test method are toxic or corrosive;
the operator shall be careful. If it is splashed on the skin, use water to
rinse it immediately. If it is serious, seek medical attention immediately.
A.1 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 standard solution, the standard solutions,
preparations and products for impurity determination, which are used in the test,
are all prepared in accordance with the provisions of GB/T 601, GB/T 602, and
GB/T 603, when no other requirements are specified. The solution used in the
test, if not indicated which solvent is used, refers to aqueous solution.
A.2 Identification test
A.2.1 Reagents and materials
A.2.1.1 Hydrochloric acid.
A.2.1.2 Silver nitrate solution: 17 g/L.
A.2.1.3 Ammonia solution: 2+3.
A.2.1.4 Nitric acid solution: 1+9.
A.2.1.5 Sodium acetate solution: 40 g/L.
A.2.2 Identification method
A.2.2.1 Identification of potassium ions
Weigh 0.1 g of the sample and dissolve it in 10 mL of water. Dip the platinum
wire in hydrochloric acid; burn it on the flame until it is colorless; then, dip the
sample solution and burn it on the flame; observe that the flame is purple under
the cobalt glass.
A.2.2.2 Identification of phosphate
Weigh 1 g of the sample; dissolve it in 20 mL of water; add silver nitrate solution,
to produce a yellow precipitate. This precipitate is soluble in ammonia solution
or nitric acid solution.
again; continue to boil until the precipitate stratifies; cool to room temperature.
Use a crucible that has been dried to constant weight at 180 °C ± 2 °C for
filtration; filter the supernatant first; use water to rinse the precipitate and filter
6 times (about 30 mL of water each time); move the precipitate into the crucible;
then, use water to rinse the precipitate 4 times; put the precipitate together with
the crucible in a drying box; take it out after drying at 180 °C for 45 minutes;
cool it to room temperature in a desiccator; weigh it. Use 10 mL of water instead
of the sample solution, to do a blank test at the same time.
A.3.5 Result calculation
Calculate the mass fraction w1 of phosphorus pentoxide (P2O5) (on a dry basis)
according to Formula (A.1).
Where:
m1 – the mass of quinoline phosphomolybdate precipitate that is formed by the
test solution, in grams (g);
m2 – the mass of quinoline phosphomolybdate precipitate that is formed by the
blank solution, in grams (g);
0.032 07 – the coefficient of conversion of quinoline phosphomolybdate to
phosphorus pentoxide (P2O5);
500 – the initial volume of the sample solution, in milliliters (mL);
m – the mass of the dried sample, in grams (g);
10 – the measured volume of the sample solution, in milliliters (mL).
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.4 Determination of loss on ignition (on a dry basis)
A.4.1 Instruments and apparatuses
A.4.1.1 Crucible.
A.4.1.2 Electrothermal constant-temperature dry box.
A.4.1.3 High temperature furnace.