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GB/T 5686.4-2022 English PDF (GBT5686.4-2022)
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GB/T 5686.4-2022: Ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal -- Determination of phosphorus content -- Molybdenum blue spectrophotometric method and bismuth phosphomolybdate blue spectrophotometric method
GB/T 5686.4-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.100
CCS H 11
Replacing GB/T 5686.4-2008
Ferromanganese, Ferromanganese-silicon, Nitrogen-bearing
Ferromanganese and Manganese Metal - Determination of
Phosphorus Content - Molybdenum Blue Spectrophotometric
Method and Bismuth Phosphomolybdate Blue Spectrophotometric
Method
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: FEBRUARY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 7
2 Normative References ... 7
3 Terms and Definitions ... 8
4 Method 1: Molybdenum Blue Spectrophotometric Method ... 8
5 Method 2: Bismuth Phosphomolybdate Blue Spectrophotometric Method ... 13
6 Test Report ... 20
Appendix A (normative) Flow Chart of Specimen Analysis Result Acceptance
Procedure ... 21
Ferromanganese, Ferromanganese-silicon, Nitrogen-bearing
Ferromanganese and Manganese Metal - Determination of
Phosphorus Content - Molybdenum Blue
Spectrophotometric Method and Bismuth
Phosphomolybdate Blue Spectrophotometric Method
WARNING---the personnel using this document shall have practical experience in formal
laboratory work. This document does not point out all possible safety issues. Users are
responsible for taking appropriate safety and health measures and ensuring compliance
with the conditions stipulated in relevant national regulations.
1 Scope
This document describes the determination of phosphorus content in ferromanganese,
ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal, using
molybdenum blue spectrophotometric method and bismuth phosphomolybdate blue
spectrophotometric method.
This document is applicable to the determination of phosphorus content in ferromanganese,
ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal. The
determination range (mass fraction) is 0.0030% ~ 0.650%. Method 1: molybdenum blue
spectrophotometric method, which is applicable to the determination of phosphorus content in
ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese
metal, with a determination range (mass fraction) of 0.0030% ~ 0.450%; Method 2: bismuth
phosphomolybdate blue spectrophotometric method, which is applicable to the determination
of phosphorus content in ferromanganese, ferromanganese-silicon, nitrogen-bearing
ferromanganese and manganese metal, with a determination range (mass fraction) of 0.0030%
~ 0.650%.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 4010 Ferroalloys Sampling and Preparation of Samples for Chemical Analysis
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
GB/T 12806 Laboratory Glassware - One-mark Volumetric Flasks
GB/T 12807 Laboratory Glassware - Graduated Pipettes
GB/T 12808 Laboratory Glassware - One Mark Pipettes
3 Terms and Definitions
This document does not have terms or definitions that need to be defined.
4 Method 1: Molybdenum Blue Spectrophotometric Method
4.1 Principle
The test portion is decomposed by nitric acid and hydrofluoric acid. Add perchloric acid to
evaporate it, until emitting smoke, thereby oxidizing phosphorus into orthophosphoric acid.
Add sodium bisulfite to reduce iron, etc., add ammonium molybdate and hydrazine sulfate to
generate phosphomolybdenum blue. At a wavelength of 825 nm, use a spectrophotometer to
measure its absorbance, and calculate the mass fraction of phosphorus.
4.2 Reagents and Materials
Unless otherwise specified, only reagents that are confirmed to be analytically pure are used in
the analysis. The test water is distilled water, deionized water or water with an equivalent purity
of Grade-3 or above that complies with the provisions of GB/T 6682.
4.2.1 Nitric acid, = 1.42 g/mL.
4.2.2 Hydrochloric acid, = 1.19 g/mL.
4.2.3 Hydrofluoric acid, = 1.15 g/mL.
4.2.4 Hydrobromic acid, = 1.38 g/mL.
4.2.5 Perchloric acid, = 1.67 g/mL.
4.2.6 Sodium bisulfite solution, 100 g/L.
4.2.7 Ammonium molybdate solution, 20 g/L.
Weigh-take 20 g of ammonium molybdate [(NH4)6Mo7O24 4H2O] and dissolve it in 100 mL
of warm water. Add 700 mL of sulfuric acid (1 + 1), cool, use water to dilute to 1,000 mL and
mix it well.
4.2.8 Hydrazine sulfate solution, 1.5 g/L.
4.2.9 Color development solution. When in use, transfer-take 25 mL of ammonium molybdate
solution (see 4.2.7) and 10 mL of hydrazine sulfate solution (see 4.2.8), add 65 mL of water and
mix it well.
4.2.10 Phosphorus standard solution, 100 g/mL.
Weigh-take 0.4394 g of potassium dihydrogen phosphate (standard reagent) that has been dried
at 110 C 5 C for 2 hours and cooled in a desiccator to a constant mass in a 250 mL beaker.
After using water to dissolve it, transfer it into a 1,000 mL volumetric flask. Use water to dilute
to the scale and mix it well. 1 mL of this solution contains 100 g of phosphorus.
4.2.11 Phosphorus standard solution, 20 g/mL.
Transfer-take 50.00 mL of phosphorus standard solution (see 4.2.10) in a 250 mL volumetric
flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 20 g of
phosphorus.
4.3 Instruments
In the analysis, only common laboratory instruments are used. The one-mark volumetric flasks,
graduated pipettes and one-mark pipettes used shall comply with the requirements of GB/T
12806, GB/T 12807 and GB/T 12808, respectively.
4.4 Sampling and Sample Preparation
In accordance with the provisions of GB/T 4010, conduct sampling and sample preparation.
The specimens shall all pass the 0.125 mm sieve mesh.
4.5 Analytical Steps
4.5.1 Number of determinations
For the same specimen, conduct at least 2 independent determinations.
4.5.2 Amount of test portion
In accordance with Table 1, weigh-take the specimens, accurate to 0.0001 g.
remove silicon; if the silicon content is above 50 mg, 5 mL of hydrofluoric acid (see 4.2.3) and
5 mL of perchloric acid (see 4.2.5) can be added to decompose and remove silicon again (there
will be interference if the silicon content is greater than 70 mg).
4.5.4.1.2.2 Add 10 mL of perchloric acid (see 4.2.5), heat and evaporate it, until emitting smoke.
After about 5 minutes, remove it and eliminate the hydrofluoric acid. After cooling, use warm
water to wash it into a 150 mL beaker, and use a watch glass to cover it.
4.5.4.1.2.3 Continue to heat and evaporate it, until emitting perchloric acid smoke, and reflux
for about 10 minutes, then, remove it and eliminate all nitric acid, and cool it. When the arsenic
content in the test solution is less than or equal to 0.5 mg, directly operate in accordance with
4.5.4.2. When the arsenic content in the test solution is above 0.5 mg, add 5 mL of hydrochloric
acid (see 4.2.2), heat to decompose the manganese dioxide, continue to heat and evaporate it,
until perchloric acid smoke just emerges. Remove and cool it and add 5 mL of hydrobromic
acid (see 4.2.4). Remove the watch glass, heat and evaporate it at a low temperature. When
perchloric acid smoke emerges, use a watch glass to cover it, continue to heat and evaporate it,
until emitting perchloric acid smoke, and reflux for about 10 minutes, then, remove it, so as to
allow arsenic and hydrogen bromide to completely escape (there will be interference if it is
greater than 0.5 mg). Follow 4.5.4.2 for the subsequent operations.
4.5.4.2 Color development and determination
4.5.4.2.1 Slightly cool, remove the watch glass, add about 30 mL of warm water, heat and boil
to dissolve the soluble salts. Remove it, dropwise add sodium bisulfite solution (see 4.2.6) to
decompose manganese dioxide, etc. Use a medium-speed filter paper to filter it into a 250 mL
volumetric flask. Use warm water to wash it, until there is no acidity, cool to room temperature,
use water to dilute to the scale and mix it well.
4.5.4.2.2 Transfer-take 25.00 mL of test solution (see 4.5.4.2.1) into a 100 mL volumetric flask,
add 10 mL of sodium bisulfite solution (see 4.2.6), heat in boiling water bath, until the solution
becomes colorless. Remove it and immediately add 25 mL of the color development solution
(see 4.2.9), then, heat again in boiling water bath for 15 minutes. Remove it, use running water
to cool it to room temperature, use water to dilute to the scale and mix it well.
4.5.4.2.3 Transfer the test solution (see 4.5.4.2.2) into a suitable cuvette, at a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure its absorbance.
Subtract the absorbance of the accompanying blank solution to obtain the net absorbance of the
test portion solution. From the calibration curve, find the corresponding phosphorus content.
4.5.5 Drawing of calibration curve
4.5.5.1 Drawing of calibration curve of manganese metal with low phosphorus content
(mass fraction 0.0030% ~ 0.020%)
4.5.5.1.1 Transfer-take 0 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, 10.00 mL and 12.00 mL
of phosphorus standard solution (see 4.2.11) and place them into a set of 100 mL beakers.
Respectively add 5 mL of perchloric acid (see 4.2.5), heat and evaporate them, until emitting
perchloric acid smoke. Remove them and follow 4.5.4.2 for the subsequent operations.
4.5.5.1.2 Transfer the test solutions (see 4.5.5.1.1) into 3 cm cuvettes. At a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure their absorbance.
4.5.5.1.3 The absorbance of each solution in the calibration curve series minus the absorbance
of the zero-concentration solution is the net absorbance of the phosphorus standard series
solution. Take the phosphorus content as the x-coordinate and the net absorbance as the y-
coordinate to draw the calibration curve.
4.5.5.2 Drawing of calibration curve of manganese metal with high phosphorus content
(mass fraction 0.020% ~ 0.050%)
4.5.5.2.1 Transfer-take 0 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL, 5.00 mL and 6.00 mL of
phosphorus standard solution (see 4.2.10) and place them into a set of 100 mL beakers.
Respectively add 5 mL of perchloric acid (see 4.2.5), heat and evaporate them, until emitting
perchloric acid smoke. Remove them and follow 4.5.4.2 for the subsequent operations.
4.5.5.2.2 Transfer the test solutions (see 4.5.5.2.1) into 1 cm cuvettes. At a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure their absorbance.
4.5.5.2.3 The absorbance of each solution in the calibration curve series minus the absorbance
of the zero-concentration solution is the net absorbance of the phosphorus standard series
solution. Take the phosphorus content as the x-coordinate and the net absorbance as the y-
coordinate to draw the calibration curve.
4.5.5.3 Drawing of calibration curve of ferromanganese, ferromanganese-silicon,
nitrogen-bearing ferromanganese
4.5.5.3.1 Transfer-take 0 mL, 1.00 mL, 3.00 mL, 5.00 mL, 7.00 mL and 9.00 mL of phosphorus
standard solution (see 4.2.10) and place them into a set of 100 mL beakers. Respectively add 5
mL of perchloric acid (see 4.2.5), heat and evaporate them, until emitting perchloric acid smoke.
Remove them and follow 4.5.4.2 for the subsequent operations.
4.5.5.3.2 Transfer the test solutions (see 4.5.5.3.1) into 1 cm cuvettes. At a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure their absorbance.
4.5.5.3.3 The absorbance of each solution in the calibration curve series minus the absorbance
of the zero-concentration solution is the net absorbance of the phosphorus standard series
solution. Take the phosphorus content as the x-coordinate and the net absorbance as the y-
coordinate to draw the calibration curve.
4.6 Calculation of Analysis Results
In accordance with Formula (1), calculate the phosphorus content wP in the specimen, expressed
in mass fraction (%):
700 nm, measure its absorbance and calculate the mass fraction of phosphorus.
5.2 Reagents and Materials
Unless otherwise specified, only reagents that are confirmed to be analytically pure are used in
the analysis. The test water is distilled water or water with an equivalent purity of Grade-3 or
above that complies with the provisions of GB/T 6682.
5.2.1 Nitric acid, = 1.42 g/mL.
5.2.2 Hydrofluoric acid, = 1.15 g/mL.
5.2.3 Perchloric acid, = 1.67 g/mL.
5.2.4 Sulfuric acid, 1 + 4.
5.2.5 Sulfuric acid, 1 + 19.
5.2.6 Sodium sulfite solution, 100 g/L.
Weigh-take 100 g of anhydrous sodium sulfite, dissolve it in water, then, use water to dilute to
1,000 mL and mix it well.
5.2.7 Sodium hydroxide solution, 250 g/L. Stored in plastic bottles.
5.2.8 Sodium thiosulfate solution, 10 g/L.
Weigh-take 1.0 g of sodium thiosulfate and 2.0 g of anhydrous sodium sulfite, dissolve it in 100
mL of water, and mix it well. Prepare it right before use.
5.2.9 Bismuth nitrate solution, 30 g/L.
Weigh-take 30 g of bismuth nitrate [Bi(NO3)3 5H2O] and dissolve it in 100 mL of nitric acid
(see 5.2.1). After it is completely dissolved, add 900 mL of water and 4 g of urea, and mix it
well.
5.2.10 Ammonium molybdate solution, 30 g/L.
Weigh-take 30 g of ammonium molybdate [(NH4)6Mo7O24 4H2O], place it in a 400 mL beaker,
add 300 mL of water, and warm to dissolve it. After filtration, add 700 mL of water and mix it
well.
5.2.11 Ascorbic acid solution, 10 g/L. Prepare with ethanol solution (1 + 1) and prepare it right
before use.
5.2.12 Ferric nitrate solution, 40 g/L.
Weigh-take 20 g of ferric nitrate [Fe(NO3)3 9H2O] into a 250 mL beaker, use water to dissolve
it, then, transfer it to a 500 mL volumetric flask. Use water to dilute to the scale and mix it well.
1 mL of thi...
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GB/T 5686.4-2022: Ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal -- Determination of phosphorus content -- Molybdenum blue spectrophotometric method and bismuth phosphomolybdate blue spectrophotometric method
GB/T 5686.4-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.100
CCS H 11
Replacing GB/T 5686.4-2008
Ferromanganese, Ferromanganese-silicon, Nitrogen-bearing
Ferromanganese and Manganese Metal - Determination of
Phosphorus Content - Molybdenum Blue Spectrophotometric
Method and Bismuth Phosphomolybdate Blue Spectrophotometric
Method
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: FEBRUARY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 7
2 Normative References ... 7
3 Terms and Definitions ... 8
4 Method 1: Molybdenum Blue Spectrophotometric Method ... 8
5 Method 2: Bismuth Phosphomolybdate Blue Spectrophotometric Method ... 13
6 Test Report ... 20
Appendix A (normative) Flow Chart of Specimen Analysis Result Acceptance
Procedure ... 21
Ferromanganese, Ferromanganese-silicon, Nitrogen-bearing
Ferromanganese and Manganese Metal - Determination of
Phosphorus Content - Molybdenum Blue
Spectrophotometric Method and Bismuth
Phosphomolybdate Blue Spectrophotometric Method
WARNING---the personnel using this document shall have practical experience in formal
laboratory work. This document does not point out all possible safety issues. Users are
responsible for taking appropriate safety and health measures and ensuring compliance
with the conditions stipulated in relevant national regulations.
1 Scope
This document describes the determination of phosphorus content in ferromanganese,
ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal, using
molybdenum blue spectrophotometric method and bismuth phosphomolybdate blue
spectrophotometric method.
This document is applicable to the determination of phosphorus content in ferromanganese,
ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese metal. The
determination range (mass fraction) is 0.0030% ~ 0.650%. Method 1: molybdenum blue
spectrophotometric method, which is applicable to the determination of phosphorus content in
ferromanganese, ferromanganese-silicon, nitrogen-bearing ferromanganese and manganese
metal, with a determination range (mass fraction) of 0.0030% ~ 0.450%; Method 2: bismuth
phosphomolybdate blue spectrophotometric method, which is applicable to the determination
of phosphorus content in ferromanganese, ferromanganese-silicon, nitrogen-bearing
ferromanganese and manganese metal, with a determination range (mass fraction) of 0.0030%
~ 0.650%.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 4010 Ferroalloys Sampling and Preparation of Samples for Chemical Analysis
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
GB/T 12806 Laboratory Glassware - One-mark Volumetric Flasks
GB/T 12807 Laboratory Glassware - Graduated Pipettes
GB/T 12808 Laboratory Glassware - One Mark Pipettes
3 Terms and Definitions
This document does not have terms or definitions that need to be defined.
4 Method 1: Molybdenum Blue Spectrophotometric Method
4.1 Principle
The test portion is decomposed by nitric acid and hydrofluoric acid. Add perchloric acid to
evaporate it, until emitting smoke, thereby oxidizing phosphorus into orthophosphoric acid.
Add sodium bisulfite to reduce iron, etc., add ammonium molybdate and hydrazine sulfate to
generate phosphomolybdenum blue. At a wavelength of 825 nm, use a spectrophotometer to
measure its absorbance, and calculate the mass fraction of phosphorus.
4.2 Reagents and Materials
Unless otherwise specified, only reagents that are confirmed to be analytically pure are used in
the analysis. The test water is distilled water, deionized water or water with an equivalent purity
of Grade-3 or above that complies with the provisions of GB/T 6682.
4.2.1 Nitric acid, = 1.42 g/mL.
4.2.2 Hydrochloric acid, = 1.19 g/mL.
4.2.3 Hydrofluoric acid, = 1.15 g/mL.
4.2.4 Hydrobromic acid, = 1.38 g/mL.
4.2.5 Perchloric acid, = 1.67 g/mL.
4.2.6 Sodium bisulfite solution, 100 g/L.
4.2.7 Ammonium molybdate solution, 20 g/L.
Weigh-take 20 g of ammonium molybdate [(NH4)6Mo7O24 4H2O] and dissolve it in 100 mL
of warm water. Add 700 mL of sulfuric acid (1 + 1), cool, use water to dilute to 1,000 mL and
mix it well.
4.2.8 Hydrazine sulfate solution, 1.5 g/L.
4.2.9 Color development solution. When in use, transfer-take 25 mL of ammonium molybdate
solution (see 4.2.7) and 10 mL of hydrazine sulfate solution (see 4.2.8), add 65 mL of water and
mix it well.
4.2.10 Phosphorus standard solution, 100 g/mL.
Weigh-take 0.4394 g of potassium dihydrogen phosphate (standard reagent) that has been dried
at 110 C 5 C for 2 hours and cooled in a desiccator to a constant mass in a 250 mL beaker.
After using water to dissolve it, transfer it into a 1,000 mL volumetric flask. Use water to dilute
to the scale and mix it well. 1 mL of this solution contains 100 g of phosphorus.
4.2.11 Phosphorus standard solution, 20 g/mL.
Transfer-take 50.00 mL of phosphorus standard solution (see 4.2.10) in a 250 mL volumetric
flask, use water to dilute to the scale and mix it well. 1 mL of this solution contains 20 g of
phosphorus.
4.3 Instruments
In the analysis, only common laboratory instruments are used. The one-mark volumetric flasks,
graduated pipettes and one-mark pipettes used shall comply with the requirements of GB/T
12806, GB/T 12807 and GB/T 12808, respectively.
4.4 Sampling and Sample Preparation
In accordance with the provisions of GB/T 4010, conduct sampling and sample preparation.
The specimens shall all pass the 0.125 mm sieve mesh.
4.5 Analytical Steps
4.5.1 Number of determinations
For the same specimen, conduct at least 2 independent determinations.
4.5.2 Amount of test portion
In accordance with Table 1, weigh-take the specimens, accurate to 0.0001 g.
remove silicon; if the silicon content is above 50 mg, 5 mL of hydrofluoric acid (see 4.2.3) and
5 mL of perchloric acid (see 4.2.5) can be added to decompose and remove silicon again (there
will be interference if the silicon content is greater than 70 mg).
4.5.4.1.2.2 Add 10 mL of perchloric acid (see 4.2.5), heat and evaporate it, until emitting smoke.
After about 5 minutes, remove it and eliminate the hydrofluoric acid. After cooling, use warm
water to wash it into a 150 mL beaker, and use a watch glass to cover it.
4.5.4.1.2.3 Continue to heat and evaporate it, until emitting perchloric acid smoke, and reflux
for about 10 minutes, then, remove it and eliminate all nitric acid, and cool it. When the arsenic
content in the test solution is less than or equal to 0.5 mg, directly operate in accordance with
4.5.4.2. When the arsenic content in the test solution is above 0.5 mg, add 5 mL of hydrochloric
acid (see 4.2.2), heat to decompose the manganese dioxide, continue to heat and evaporate it,
until perchloric acid smoke just emerges. Remove and cool it and add 5 mL of hydrobromic
acid (see 4.2.4). Remove the watch glass, heat and evaporate it at a low temperature. When
perchloric acid smoke emerges, use a watch glass to cover it, continue to heat and evaporate it,
until emitting perchloric acid smoke, and reflux for about 10 minutes, then, remove it, so as to
allow arsenic and hydrogen bromide to completely escape (there will be interference if it is
greater than 0.5 mg). Follow 4.5.4.2 for the subsequent operations.
4.5.4.2 Color development and determination
4.5.4.2.1 Slightly cool, remove the watch glass, add about 30 mL of warm water, heat and boil
to dissolve the soluble salts. Remove it, dropwise add sodium bisulfite solution (see 4.2.6) to
decompose manganese dioxide, etc. Use a medium-speed filter paper to filter it into a 250 mL
volumetric flask. Use warm water to wash it, until there is no acidity, cool to room temperature,
use water to dilute to the scale and mix it well.
4.5.4.2.2 Transfer-take 25.00 mL of test solution (see 4.5.4.2.1) into a 100 mL volumetric flask,
add 10 mL of sodium bisulfite solution (see 4.2.6), heat in boiling water bath, until the solution
becomes colorless. Remove it and immediately add 25 mL of the color development solution
(see 4.2.9), then, heat again in boiling water bath for 15 minutes. Remove it, use running water
to cool it to room temperature, use water to dilute to the scale and mix it well.
4.5.4.2.3 Transfer the test solution (see 4.5.4.2.2) into a suitable cuvette, at a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure its absorbance.
Subtract the absorbance of the accompanying blank solution to obtain the net absorbance of the
test portion solution. From the calibration curve, find the corresponding phosphorus content.
4.5.5 Drawing of calibration curve
4.5.5.1 Drawing of calibration curve of manganese metal with low phosphorus content
(mass fraction 0.0030% ~ 0.020%)
4.5.5.1.1 Transfer-take 0 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, 10.00 mL and 12.00 mL
of phosphorus standard solution (see 4.2.11) and place them into a set of 100 mL beakers.
Respectively add 5 mL of perchloric acid (see 4.2.5), heat and evaporate them, until emitting
perchloric acid smoke. Remove them and follow 4.5.4.2 for the subsequent operations.
4.5.5.1.2 Transfer the test solutions (see 4.5.5.1.1) into 3 cm cuvettes. At a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure their absorbance.
4.5.5.1.3 The absorbance of each solution in the calibration curve series minus the absorbance
of the zero-concentration solution is the net absorbance of the phosphorus standard series
solution. Take the phosphorus content as the x-coordinate and the net absorbance as the y-
coordinate to draw the calibration curve.
4.5.5.2 Drawing of calibration curve of manganese metal with high phosphorus content
(mass fraction 0.020% ~ 0.050%)
4.5.5.2.1 Transfer-take 0 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL, 5.00 mL and 6.00 mL of
phosphorus standard solution (see 4.2.10) and place them into a set of 100 mL beakers.
Respectively add 5 mL of perchloric acid (see 4.2.5), heat and evaporate them, until emitting
perchloric acid smoke. Remove them and follow 4.5.4.2 for the subsequent operations.
4.5.5.2.2 Transfer the test solutions (see 4.5.5.2.1) into 1 cm cuvettes. At a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure their absorbance.
4.5.5.2.3 The absorbance of each solution in the calibration curve series minus the absorbance
of the zero-concentration solution is the net absorbance of the phosphorus standard series
solution. Take the phosphorus content as the x-coordinate and the net absorbance as the y-
coordinate to draw the calibration curve.
4.5.5.3 Drawing of calibration curve of ferromanganese, ferromanganese-silicon,
nitrogen-bearing ferromanganese
4.5.5.3.1 Transfer-take 0 mL, 1.00 mL, 3.00 mL, 5.00 mL, 7.00 mL and 9.00 mL of phosphorus
standard solution (see 4.2.10) and place them into a set of 100 mL beakers. Respectively add 5
mL of perchloric acid (see 4.2.5), heat and evaporate them, until emitting perchloric acid smoke.
Remove them and follow 4.5.4.2 for the subsequent operations.
4.5.5.3.2 Transfer the test solutions (see 4.5.5.3.1) into 1 cm cuvettes. At a wavelength of 825
nm, use water as a reference to zero the spectrophotometer, and measure their absorbance.
4.5.5.3.3 The absorbance of each solution in the calibration curve series minus the absorbance
of the zero-concentration solution is the net absorbance of the phosphorus standard series
solution. Take the phosphorus content as the x-coordinate and the net absorbance as the y-
coordinate to draw the calibration curve.
4.6 Calculation of Analysis Results
In accordance with Formula (1), calculate the phosphorus content wP in the specimen, expressed
in mass fraction (%):
700 nm, measure its absorbance and calculate the mass fraction of phosphorus.
5.2 Reagents and Materials
Unless otherwise specified, only reagents that are confirmed to be analytically pure are used in
the analysis. The test water is distilled water or water with an equivalent purity of Grade-3 or
above that complies with the provisions of GB/T 6682.
5.2.1 Nitric acid, = 1.42 g/mL.
5.2.2 Hydrofluoric acid, = 1.15 g/mL.
5.2.3 Perchloric acid, = 1.67 g/mL.
5.2.4 Sulfuric acid, 1 + 4.
5.2.5 Sulfuric acid, 1 + 19.
5.2.6 Sodium sulfite solution, 100 g/L.
Weigh-take 100 g of anhydrous sodium sulfite, dissolve it in water, then, use water to dilute to
1,000 mL and mix it well.
5.2.7 Sodium hydroxide solution, 250 g/L. Stored in plastic bottles.
5.2.8 Sodium thiosulfate solution, 10 g/L.
Weigh-take 1.0 g of sodium thiosulfate and 2.0 g of anhydrous sodium sulfite, dissolve it in 100
mL of water, and mix it well. Prepare it right before use.
5.2.9 Bismuth nitrate solution, 30 g/L.
Weigh-take 30 g of bismuth nitrate [Bi(NO3)3 5H2O] and dissolve it in 100 mL of nitric acid
(see 5.2.1). After it is completely dissolved, add 900 mL of water and 4 g of urea, and mix it
well.
5.2.10 Ammonium molybdate solution, 30 g/L.
Weigh-take 30 g of ammonium molybdate [(NH4)6Mo7O24 4H2O], place it in a 400 mL beaker,
add 300 mL of water, and warm to dissolve it. After filtration, add 700 mL of water and mix it
well.
5.2.11 Ascorbic acid solution, 10 g/L. Prepare with ethanol solution (1 + 1) and prepare it right
before use.
5.2.12 Ferric nitrate solution, 40 g/L.
Weigh-take 20 g of ferric nitrate [Fe(NO3)3 9H2O] into a 250 mL beaker, use water to dissolve
it, then, transfer it to a 500 mL volumetric flask. Use water to dilute to the scale and mix it well.
1 mL of thi...
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