GB/T 8574-2024 PDF English
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| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB/T 8574-2024 | English | 195 |
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Determination of potassium content for compound fertilizers
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| GB/T 8574-2010 | English | 90 |
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Determination of potassium content for compound fertilizers -- Potassium tetraphenylborate gravimetric method
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| GB/T 8574-2002 | English | 239 |
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Determination of potassium content for compound fertilizers potassium tetraphenylborate gravimetric method
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| GB/T 8574-1988 | English | 199 |
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Determination of potassium content for compound fertilizers potassium tetraphenylborate gravimetric method
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GB/T 8574-2024: Determination of potassium content for compound fertilizers---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/GBT8574-2024
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.080
CCS G 20
Replacing GB/T 8574-2010
Determination of Potassium Content for Compound
Fertilizers
Issued on: SEPTEMBER 29, 2024
Implemented on: APRIL 1, 2025
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 Terms and Definitions... 4
4 Samples... 5
5 Preparation of Specimen Solutions... 5
6 Determination of Potassium in the Specimen Solution... 6
Appendix A (normative) Potassium Tetraphenylborate Gravimetric Method... 7
Appendix B (normative) Inductively Coupled Plasma Atomic Emission Spectrometry
... 11
Appendix C (informative) Statistical Data and Other Data Obtained from
Interlaboratory Test Results... 14
Determination of Potassium Content for Compound
Fertilizers
1 Scope
This document describes the determination of potassium in compound fertilizers using the
potassium tetraphenylborate gravimetric method, inductively coupled plasma atomic emission
spectrometry, or flow analyzer method, through either heating and boiling extraction or
ultrasonic extraction. For the heating and boiling extraction, the potassium tetraphenylborate
gravimetric method is the arbitration method.
This document applies to the determination of potassium content in compound fertilizers. The
determination of potassium content in other potassium-containing inorganic fertilizers may take
this document as a reference.
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 6274 Fertilizers and Soil Conditioners - Vocabulary
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
GB/T 8571 Preparation of Laboratory Samples for Compound Fertilizers
GB/T 15063 Compound Fertilizer
GB/T 22923-2008 Determination of Nitrogen, Phosphorus and Potassium for Fertilizers by
Auto Analyzer
HG/T 2843 Chemical Fertilizer Products - Standard Volumetric, Standard Reagent and
Indicator Solutions for Chemical Analysis
3 Terms and Definitions
The terms and definitions defined in GB/T 6274 and GB/T 15063 are applicable to this
document.
4 Samples
Sample preparation shall be carried out in accordance with GB/T 8571.
5 Preparation of Specimen Solutions
5.1 Reagents or Materials
Water shall comply with Grade 3 water specifications in GB/T 6682.
5.2 Instruments and Equipment
5.2.1 Common laboratory instruments and equipment.
5.2.2 Ultrasonic cleaner.
5.3 Preparation Procedures
5.3.1 Specimen weighing
Perform two tests in parallel.
For samples to be determined for potassium content using the potassium tetraphenylborate
gravimetric method (6.1), weigh-take approximately 400 mg of specimen containing potassium
oxide, accurate to 0.0002 g.
For samples to be determined for potassium content using the inductively coupled plasma
atomic emission spectrometry (6.2), weigh-take 100 mg ~ 250 mg of specimen containing
potassium oxide, accurate to 0.0002 g.
5.3.2 Extraction method 1 (heating and boiling)
In accordance with the requirements of 5.3.1, weigh-take the specimen and place it in a 250 mL
conical flask. Add approximately 150 mL of water, and heat and boil it for 30 minutes. Cool,
quantitatively transfer it to a 250 mL volumetric flask, use water to dilute to the scale, mix it
well, dry filter it, and discard the first 50 mL of the filtrate.
5.3.3 Extraction method 2 (ultrasonic extraction)
In accordance with the requirements of 5.3.1, weigh-take the specimen and place it in a 250 mL
volumetric flask. Add 150 mL of water, place the volumetric flask in an ultrasonic cleaner and
ultrasonically extract it for 8 minutes (the ultrasonic cleaner liquid level is not lower than the
liquid level in the volumetric flask). Cool to room temperature, use water to dilute to the scale,
mix it well, dry filter it, and discard the first 50 mL of the filtrate.
6 Determination of Potassium in the Specimen Solution
6.1 Potassium Tetraphenylborate Gravimetric Method
Proceed in accordance with Appendix A.
6.2 Inductively Coupled Plasma Atomic Emission Spectrometry
Proceed in accordance with Appendix B.
6.3 Flow Analyzer Method
Proceed in accordance with 3.4 of GB/T 22923-2008.
Appendix A
(normative)
Potassium Tetraphenylborate Gravimetric Method
A.1 Principle
In a weakly alkaline solution, sodium tetraphenylborate solution reacts with potassium ions in
the specimen solution to generate potassium tetraphenylborate precipitate. Filter, dry and weigh
the precipitate. If the specimen contains cyanamides or organic matter, it can be treated by
adding bromine water and activated carbon first. To prevent cationic interference, an
appropriate amount of ethylenediaminetetraacetic acid disodium salt (EDTA) can be added in
advance to allow the cations to complex with the EDTA.
A.2 Reagents or Materials
Unless otherwise specified, only analytically pure reagents shall be used. The standard titration
solutions, standard solutions, reagent solutions, and indicator solutions used in this Method,
unless the preparation method is specified, shall be prepared in accordance with HG/T 2843.
A.2.1 Water, GB/T 6682, Grade 3.
A.2.2 Sodium tetraphenylborate solution. 15 g/L.
A.2.3 Ethylenediaminetetraacetic acid disodium salt (EDTA) solution. 40 g/L.
A.2.4 Sodium hydroxide solution. 400 g/L.
A.2.5 Aqueous bromine solution. approximately 5% (mass fraction).
A.2.6 Sodium tetraphenylborate washing solution. 1.5 g/L.
A.2.7 Phenolphthalein. 5 g/L ethanol solution, dissolve 0.5 g of phenolphthalein in 100 mL of
95% (mass fraction) ethanol.
A.2.8 Activated carbon. shall not adsorb or release potassium ions.
A.3 Instruments and Equipment
A.3.1 Common laboratory instruments and equipment.
A.3.2 Glass crucible filter. No. 4, 30 mL.
A.3.3 Electrically heated constant-temperature drying oven. temperature controllable within the
range of 120 °C 5 °C.
A.4 Test Procedures
A.4.1 Test solution preparation
The specimen does not contain cyanamides or organic matter. pipette 25.0 mL of the specimen
solution (5.3.2 or 5.3.3) into a 200 mL beaker. Add 20 mL of EDTA solution (40 mL if there
are a large number of cations), 2 ~ 3 drops of phenolphthalein solution, and dropwise add
sodium hydroxide solution, until a red color appears. Add an excess of 1 mL. In a well-
ventilated fume hood, slowly heat and boil for 15 minutes. Then, let it cool or cool to room
temperature under running water. If the red color disappears, use sodium hydroxide solution to
adjust the color to red again.
If the specimen contains cyanamides or organic matter. pipette 25.0 mL of the specimen
solution (5.3.2 or 5.3.3) into a 200 mL ~ 250 mL beaker. Add 5 mL of aqueous bromine solution.
Boil the solution, until all the bromine water is removed (no bromine color). If it contains other
colors, after the solution cools, add 0.5 g of activated carbon, and thoroughly stir to adsorb it.
Then, filter and wash it 3 ~ 5 times, using approximately 5 mL of water each time. Collect all
the filtrate and add 20 mL of EDTA solution (40 mL if there are a large number of cations). The
following steps are the same as for specimens without cyanamides or organic matter.
A.4.2 Precipitation and filtration
While continuously stirring, dropwise add sodium tetraphenylborate solution to the specimen
solution (A.4.1) at a rate of 0.5 mL per 1 mg of potassium oxide, with an excess of
approximately 7 mL. Continue stirring for 1 minute and let it stand for at least 15 minutes. Use
the decantation method to filter the precipitate into a No. 4 glass crucible filter that has been
pre-weighed to a constant mass at 120 °C. Use sodium tetraphenylborate washing solution to
wash the precipitate 5 ~ 7 times, using approximately 5 mL each time. Finally, use water to
wash it twice, using 5 mL each time.
A.4.3 Drying
Place the crucible containing the precipitate in an electrically heated constant-temperature
drying oven at 120 °C 5 °C for 1.5 hours. Then, remove the crucible and place it in a desiccator
to cool to room temperature; weigh it.
NOTE. when washing the crucible, using acetone can remove difficult-to-clean precipitates.
A.4.4 Blank test
Except for not adding the specimen, the analytical procedures and reagent dosages are identical
to those described above.
A.5 Test Data Processing
Calculate the potassium content w1 in accordance with Formula (A.1).
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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