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GB 25579-2010: Zinc sulfate national food safety standards of food additives
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GB 25579-2010
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
Zinc sulfate national food safety standards of food additives
ISSUED ON: DECEMBER 21, 2010
IMPLEMENTED ON: FEBRUARY 21, 2011
Issued by: Ministry of Health of PRC
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Molecular formula and relative molecular mass ... 4
4 Technical requirements ... 4
Appendix A (Normative) Test method ... 6
Appendix B (Informative) Treatment of mercury-containing waste liquid ... 12
Zinc sulfate national food safety standards of food additives
1 Scope
This standard applies to food additive zinc sulfate made from sulfuric acid and zinc
oxide (or zinc hydroxide) as raw materials, or food additive zinc sulfate obtained by
leaching and refining sphalerite with sulfuric acid after roasting.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
3 Molecular formula and relative molecular mass
3.1 Molecular formula
Zinc sulfate monohydrate: ZnSO4·H2O
Zinc sulfate heptahydrate: ZnSO4·7H2O
3.2 Relative molecular mass
Relative molecular mass of zinc sulfate monohydrate: 179.49 (according to the 2007
international relative atomic mass)
Relative molecular mass of zinc sulfate heptahydrate: 287.58 (according to the 2007
international relative atomic mass)
4 Technical requirements
4.1 Sensory requirements: It shall meet the requirements of Table 1.
Appendix A
(Normative)
Test method
A.1 Warning
Some reagents used in the test methods of this standard are toxic or corrosive. Be careful
when operating! If splashed on the skin, rinse with water immediately. In severe cases,
seek medical treatment immediately. When using volatile acids, they must be carried
out in a fume hood.
A.2 General provisions
The reagents and water used in the test methods of this standard, unless otherwise
specified, refer to analytical pure reagents and grade 3 water specified in GB/T 6682-
2008. The standard solutions, impurity standard solutions, preparations and products
required in the test shall be prepared in accordance with the provisions of HG/T 3696.1,
HG/T 3696.2, HG/T 3696.3, unless otherwise specified.
A.3 Identification test
A.3.1 Identification of zinc ions
A.3.1.1 Reagents and materials
A.3.1.1.1 Chloroform.
A.3.1.1.2 Acetic acid solution: 1 + 10.
A.3.1.1.3 Sodium sulfate solution: 250 g/L.
A.3.1.1.4 Dithizone carbon tetrachloride solution: 1 + 100.
A.3.1.2 Analytical procedures
Weigh about 0.2 g of the specimen; dissolve it in 5 mL of water; pipette 1 mL of the
test solution; adjust the pH value of the solution to 4 ~ 5 with acetic acid solution; add
2 drops of sodium sulfate solution; add a few drops of dithizone carbon tetrachloride
solution and 1 mL of chloroform; shake it; the organic layer will appear purple-red.
A.3.2 Identification of sulfate
A.3.2.1 Reagents and materials
A.3.2.1.1 Barium chloride solution: 50 g/L.
A.3.2.1.2 Hydrochloric acid solution: 1 + 1.
A.3.2.2 Analytical procedure
Take about 1 g of the specimen; dissolve it in water; add barium chloride solution to
produce a white precipitate, which is insoluble in hydrochloric acid solution.
A.4 Determination of zinc sulfate
A.4.1 Method summary
Dissolve zinc sulfate in sulfuric acid solution; add appropriate amount of water; add
ammonium fluoride solution, thiourea, ascorbic acid as masking agents; adjust the pH
to 5 ~ 6 with acetic acid-sodium acetate solution; use xylenol orange as an indicator;
titrate with disodium ethylenediaminetetraacetic acid standard titration solution, until
the solution changes from purple-red to bright yellow, which is the end point.
A.4.2 Reagents and materials
A.4.2.1 Ascorbic acid
A.4.2.2 Thiourea solution: 200 g/L.
A.4.2.3 Ammonium fluoride solution: 200 g/L.
A.4.2.4 Sulfuric acid solution: 1 + 1.
A.4.2.5 Acetic acid-sodium acetate buffer solution: pH≈5.5.
A.4.2.6 Disodium ethylenediaminetetraacetic acid standard titration solution: c(EDTA)
= 0.05 mol/L.
A.4.2.7 Xylenol orange indicator solution: 2 g/L, use period not exceeding 1 week.
A.4.3 Analytical procedure
Weigh about 0.2 g of zinc sulfate monohydrate or 0.3 g of zinc sulfate heptahydrate
sample, accurate to 0.0002 g; place in a 250 mL conical flask; add a small amount of
water to moisten; add 2 drops of sulfuric acid solution to dissolve the specimen; add 50
mL of water, 10 mL of ammonium fluoride solution, 2.5 mL of thiourea solution, 0.2 g
of ascorbic acid; shake well to dissolve; add 15 mL of acetic acid-sodium acetate buffer
solution and 3 drops of xylenol orange indicator solution; titrate with disodium
ethylenediaminetetraacetic acid standard titration solution, until the solution changes
from red to bright yellow, which is the end point. Perform a blank test at the same time.
In the blank test, except that no specimen is added, other operations and the types and
amounts of reagents added (except standard titration solution) are the same as those for
the test specimen.
absorption value displayed by the instrument. Subtract the absorption value of the
reagent blank solution from the absorption value of each working curve solution; draw
the working curve with the mass of mercury (mg) in each solution as the abscissa and
the corresponding absorption value as the ordinate.
A.9.3.3 Determination of specimen solution
The test solution is operated according to the provisions in A.9.3.2 from "Add 1 mL of
stannous chloride..." until the absorption value of the solution is determined. Mercury-
containing waste liquid is treated as shown in Appendix B.
A.9.4 Result calculation
The mercury content is expressed as the mass fraction w3 of mercury (Hg); the value is
expressed in mg/kg and calculated according to formula (A.3):
Where:
m1 - The value of the mass of mercury in the specimen solution obtained from the
working curve, in milligrams (mg);
m - The value of the mass of the sample, in grams (g).
The arithmetic mean of the parallel determination results is taken as the determination
result; the absolute difference of the parallel determination results is not greater than
0.5 mg/kg.
A.10 Determination of selenium
Weigh 5.00 g ± 0.01 g of the specimen; place it in a 150 mL beaker; add 20 mL of water
to dissolve it; add 1 mL of nitric acid solution (1 + 1); evaporate it to dryness on a water
bath. The following is determined according to the hydride atomic fluorescence
spectrometry of GB/T 5009.93-2010.
A.11 Determination of arsenic
Weigh 1.00 g ± 0.01 g of specimen; place in a conical flask; moisten with water;
neutralize with hydrochloric acid to neutrality (check with pH test paper); then add 5
mL in excess and shake well. Transfer 2.00 mL of arsenic standard solution (1 mL
solution contains 1.0µ of gAs) as a standard. Place in another conical flask. Add 5 mL
of hydrochloric acid solution (1 + 3) to each. Then determine according to 6.2 or
Chapter 11 of GB/T 5009.76-2003.
The silver diethylaminodithiocarbamate colorimetric method is the arbitration method.
GB 25579-2010
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
Zinc sulfate national food safety standards of food additives
ISSUED ON: DECEMBER 21, 2010
IMPLEMENTED ON: FEBRUARY 21, 2011
Issued by: Ministry of Health of PRC
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Molecular formula and relative molecular mass ... 4
4 Technical requirements ... 4
Appendix A (Normative) Test method ... 6
Appendix B (Informative) Treatment of mercury-containing waste liquid ... 12
Zinc sulfate national food safety standards of food additives
1 Scope
This standard applies to food additive zinc sulfate made from sulfuric acid and zinc
oxide (or zinc hydroxide) as raw materials, or food additive zinc sulfate obtained by
leaching and refining sphalerite with sulfuric acid after roasting.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
3 Molecular formula and relative molecular mass
3.1 Molecular formula
Zinc sulfate monohydrate: ZnSO4·H2O
Zinc sulfate heptahydrate: ZnSO4·7H2O
3.2 Relative molecular mass
Relative molecular mass of zinc sulfate monohydrate: 179.49 (according to the 2007
international relative atomic mass)
Relative molecular mass of zinc sulfate heptahydrate: 287.58 (according to the 2007
international relative atomic mass)
4 Technical requirements
4.1 Sensory requirements: It shall meet the requirements of Table 1.
Appendix A
(Normative)
Test method
A.1 Warning
Some reagents used in the test methods of this standard are toxic or corrosive. Be careful
when operating! If splashed on the skin, rinse with water immediately. In severe cases,
seek medical treatment immediately. When using volatile acids, they must be carried
out in a fume hood.
A.2 General provisions
The reagents and water used in the test methods of this standard, unless otherwise
specified, refer to analytical pure reagents and grade 3 water specified in GB/T 6682-
2008. The standard solutions, impurity standard solutions, preparations and products
required in the test shall be prepared in accordance with the provisions of HG/T 3696.1,
HG/T 3696.2, HG/T 3696.3, unless otherwise specified.
A.3 Identification test
A.3.1 Identification of zinc ions
A.3.1.1 Reagents and materials
A.3.1.1.1 Chloroform.
A.3.1.1.2 Acetic acid solution: 1 + 10.
A.3.1.1.3 Sodium sulfate solution: 250 g/L.
A.3.1.1.4 Dithizone carbon tetrachloride solution: 1 + 100.
A.3.1.2 Analytical procedures
Weigh about 0.2 g of the specimen; dissolve it in 5 mL of water; pipette 1 mL of the
test solution; adjust the pH value of the solution to 4 ~ 5 with acetic acid solution; add
2 drops of sodium sulfate solution; add a few drops of dithizone carbon tetrachloride
solution and 1 mL of chloroform; shake it; the organic layer will appear purple-red.
A.3.2 Identification of sulfate
A.3.2.1 Reagents and materials
A.3.2.1.1 Barium chloride solution: 50 g/L.
A.3.2.1.2 Hydrochloric acid solution: 1 + 1.
A.3.2.2 Analytical procedure
Take about 1 g of the specimen; dissolve it in water; add barium chloride solution to
produce a white precipitate, which is insoluble in hydrochloric acid solution.
A.4 Determination of zinc sulfate
A.4.1 Method summary
Dissolve zinc sulfate in sulfuric acid solution; add appropriate amount of water; add
ammonium fluoride solution, thiourea, ascorbic acid as masking agents; adjust the pH
to 5 ~ 6 with acetic acid-sodium acetate solution; use xylenol orange as an indicator;
titrate with disodium ethylenediaminetetraacetic acid standard titration solution, until
the solution changes from purple-red to bright yellow, which is the end point.
A.4.2 Reagents and materials
A.4.2.1 Ascorbic acid
A.4.2.2 Thiourea solution: 200 g/L.
A.4.2.3 Ammonium fluoride solution: 200 g/L.
A.4.2.4 Sulfuric acid solution: 1 + 1.
A.4.2.5 Acetic acid-sodium acetate buffer solution: pH≈5.5.
A.4.2.6 Disodium ethylenediaminetetraacetic acid standard titration solution: c(EDTA)
= 0.05 mol/L.
A.4.2.7 Xylenol orange indicator solution: 2 g/L, use period not exceeding 1 week.
A.4.3 Analytical procedure
Weigh about 0.2 g of zinc sulfate monohydrate or 0.3 g of zinc sulfate heptahydrate
sample, accurate to 0.0002 g; place in a 250 mL conical flask; add a small amount of
water to moisten; add 2 drops of sulfuric acid solution to dissolve the specimen; add 50
mL of water, 10 mL of ammonium fluoride solution, 2.5 mL of thiourea solution, 0.2 g
of ascorbic acid; shake well to dissolve; add 15 mL of acetic acid-sodium acetate buffer
solution and 3 drops of xylenol orange indicator solution; titrate with disodium
ethylenediaminetetraacetic acid standard titration solution, until the solution changes
from red to bright yellow, which is the end point. Perform a blank test at the same time.
In the blank test, except that no specimen is added, other operations and the types and
amounts of reagents added (except standard titration solution) are the same as those for
the test specimen.
absorption value displayed by the instrument. Subtract the absorption value of the
reagent blank solution from the absorption value of each working curve solution; draw
the working curve with the mass of mercury (mg) in each solution as the abscissa and
the corresponding absorption value as the ordinate.
A.9.3.3 Determination of specimen solution
The test solution is operated according to the provisions in A.9.3.2 from "Add 1 mL of
stannous chloride..." until the absorption value of the solution is determined. Mercury-
containing waste liquid is treated as shown in Appendix B.
A.9.4 Result calculation
The mercury content is expressed as the mass fraction w3 of mercury (Hg); the value is
expressed in mg/kg and calculated according to formula (A.3):
Where:
m1 - The value of the mass of mercury in the specimen solution obtained from the
working curve, in milligrams (mg);
m - The value of the mass of the sample, in grams (g).
The arithmetic mean of the parallel determination results is taken as the determination
result; the absolute difference of the parallel determination results is not greater than
0.5 mg/kg.
A.10 Determination of selenium
Weigh 5.00 g ± 0.01 g of the specimen; place it in a 150 mL beaker; add 20 mL of water
to dissolve it; add 1 mL of nitric acid solution (1 + 1); evaporate it to dryness on a water
bath. The following is determined according to the hydrid...