GB/T 35069-2018 PDF English
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| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB/T 35069-2018 | English | 130 |
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Coke - Determination of Phosphorus Content - Reduced Molybdophosphate Spectrophotometric Method
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GB/T 35069-2018: Coke - Determination of Phosphorus Content - Reduced Molybdophosphate Spectrophotometric Method
---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT35069-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 75.160.10
H 32
Coke - Determination of Phosphorus Content - Reduced
Molybdophosphate Spectrophotometric Method
Issued on: MAY 14, 2018
Implemented on: DECEMBER 1, 2018
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Principle ... 5
4 Reagents and Materials ... 5
5 Instruments and Equipment ... 6
6 Sampling and Sample Preparation ... 6
7 Analytical Procedure ... 6
8 Analysis Result Calculation and Expression ... 7
9 Precision ... 8
10 Test Report ... 9
Appendix A (Normative) Sample Analysis Result Acceptance Procedure ... 10
Appendix B (Informative) Precision Test Primary Data ... 12
Coke - Determination of Phosphorus Content - Reduced
Molybdophosphate Spectrophotometric Method
Warning -- personnel who use this Standard shall have practical experience of
working at a regular laboratory. This Standard does not point out all the possible
safety questions. Users shall undertake the responsibility of adopting proper
safety and health measures and guaranteeing the compliance with the
conditions of relevant national laws and regulations.
1 Scope
This Standard specifies the determination of phosphorus content through reduced
Molybdophosphate spectrophotometric method.
This Standard is applicable to the determination of phosphorus content in coke
(metallurgical coke, foundry coke, ferroalloy coke, gasification coke and semi-coke,
etc.). Coal for coking can take this as a reference. The range of determination (mass
fraction). 0.0050% ~ 0.10%.
2 Normative References
The following documents are indispensable to the application of this Standard. In terms
of references with a specified date, only versions with a specified date are applicable
to this Standard. The latest version (including all the modifications) of references
without a specified date is also applicable to this Standard.
GB/T 1997 Coke - Sampling and Preparation of Samples
GB/T 2001 Coke - Determination of Proximate Analysis
GB/T 6379.2 Accuracy (trueness and precision) of Measurement Methods and Results
- Part 2. Basic Method for the Determination of Repeatability and Reproducibility of a
Standard Measurement Method
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
GB/T 7729 Chemical Analysis of Metallurgical Products, General Rule for
Spectrophotometric Methods
GB/T 8170 Rules of Rounding off for Numerical Values & Expression and Judgement
of Limiting Values
3 Principle
After ashing sample, use acid to dissolve the sample, which will emit perchloric acid
smoke; completely oxidize phosphorus into orthophosphoric acid. Under the existence
of bismuth salt, add ammonium molybdate to generate phosphorus molybdenum
bismuth ternary heteropoly acid. Take ethanol as the stabilizer; use ascorbic acid to
reduce into phosphorus bismuth molybdenum blue; measure its absorbance.
4 Reagents and Materials
Unless it is otherwise stated, analytical purity reagents that are acknowledged, and
above Level-3 distilled water that complies with the stipulation in GB/T 6682 or water
of equivalent purity shall be merely adopted in analysis.
4.1 Nitric acid, 1.42 g/mL.
4.2 Hydrofluoric acid, 1.15 g/mL.
4.3 Perchloric acid, 1.67 g/mL.
4.4 Sodium nitrite solution, 100 g/L.
4.5 Boric acid-anhydrous sodium carbonate flux, 1+2.
4.6 Sulfuric acid solution, 1+1.
4.7 Nitric acid-bismuth nitrate solution, 10 g/L. Use nitric acid (1+3) to prepare it.
4.8 Sodium thiosulfate-anhydrous sodium sulfite solution; 100 mL of solution contains
0.2 g of sodium thiosulfate and 1 g of anhydrous sodium sulfite solution.
4.9 Ascorbic acid ethanol solution, 20 g/L. Weigh -take 20 g of ascorbic acid; dissolve
it in 1 L of ethanol solution (1+1).
4.10 Ammonium molybdate-potassium sodium tartrate solution; 100 mL of solution
contains 3.5 g of ammonium molybdate and 6.5 g of potassium sodium tartrate.
4.11 Phosphorus standard solution. weigh-take 0.4394 g of potassium dihydrogen
phosphate that is previously dried at 105 °C to a constant weight. Use a proper amount
of water to dissolve it; add 10 mL of nitric acid, then, transfer it into a 1,000 mL
volumetric flask. Use water to dilute to the constant volume, then, mix it up. Transfer
25.00 mL into a 500 mL volumetric flask; use water to dilute to the constant volume,
then, mix it up. 1 mL of this solution contains 5.0 μg of phosphorus.
7.3.2 Alkali melting decomposition method
Add the sample (please refer to 7.1) to a platinum crucible, which already has 3 g ~ 4
g of boric acid-anhydrous sodium carbonate flux (please refer to 4.5); mix it up. Then,
cover it with 2 g ~ 3 g of boric acid-anhydrous sodium carbonate flux (please refer to
4.5). Place it into a 950 °C ~ 1,000 °C Muffle furnace; start high-temperature melting
for 10 min ~ 15 min. Take it down to cool it down, then, use water to rinse the external
wall of the platinum crucible. Place the platinum crucible into a 250 mL beaker which
holds 50 mL of water. Take 10 mL of sulfuric acid solution (please refer to 4.6), then,
heat it up, start leaching; clean the crucible. Continue the heating, till it boils, then, cool
it down to room temperature. Transfer it into a 100 mL volumetric flask; use water to
dilute to the constant volume, then, mix it up.
7.4 Color Development and Determination
Divide-take 10.00 mL of solution (please refer to 7.3), then, place it into a 50 mL
volumetric flask. Add 15 mL of nitric acid-bismuth nitrate solution (please refer to 4.7),
5 mL of sodium thiosulfate-anhydrous sodium sulfite solution (please refer to 4.8), 10
mL of ascorbic acid ethanol solution (please refer to 4.9) and 5 mL of ammonium
molybdate-potassium sodium tartrate solution (please refer to 4.10). After placing it for
1 min ~ 2 min, use water to dilute to the constant volume, then, mix it up. Place it at
room temperature for over 15 min. On a spectrophotometer, use a 1 cm ~ 3 cm
colorimetric cuvette; at the wavelength of 700 nm, take blank test solution as a
reference. Measure the absorbance of the color developing solution; obtain
corresponding phosphorus content through the calibration curve.
NOTE. after adding various reagents in turn, thoroughly mix it up.
7.5 Draw a Calibration Curve
Respectively transfer-take 0 mL, 0.50 mL, 1.00 mL, 2.00 mL, 4.00 mL, 6.00 mL and
8.00 mL of phosphorus standard solution (please refer to 4.11); place it in a group of
50 mL volumetric flasks; comply with the operation (in 7.4). Take phosphorus-free
standard solution as a reference; take the measured absorbance as the y-coordinate;
take the mass of phosphorus in the standard series solution as the x-coordinate to
draw a calibration curve.
8 Analysis Result Calculation and Expression
8.1 Calculation of Analysis Result
In accordance with Formula (1), calculate the content of phosphorus in coke; calculate
by mass fraction; the numerical value shall be expressed in %.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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