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HJ 649-2013: Soil. Determination of exchangeable acidity by potassium chloride extraction. Titration method
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Soil. Determination of exchangeable acidity by potassium chloride extraction. Titration method
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HJ 649-2013
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Standard similar to HJ 649-2013 HJ 511 HJ 945.3 HJ 943 Basic data | Standard ID | HJ 649-2013 (HJ649-2013) | | Description (Translated English) | Soil. Determination of exchangeable acidity by potassium chloride extraction. Titration method | | Sector / Industry | Environmental Protection Industry Standard | | Word Count Estimation | 9,998 | | Quoted Standard | HJ 613; HJ/T 166 | | Regulation (derived from) | Department of Environmental Protection Bulletin 2013 No. 33 | | Issuing agency(ies) | Ministry of Ecology and Environment | | Summary | This standard specifies: Determination of soil exchangeable acidity potassium chloride extraction titration. This standard applies to: Acidic soil exchangeable acidity determination. When taking 5. 00g sample extract volume to 25, When ml, method detectio | HJ 649-2013: Soil. Determination of exchangeable acidity by potassium chloride extraction. Titration method
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Soil.Determination of exchangeable acidity by potassium chloride extraction.Titration method
National Environmental Protection Standard of the People's Republic
Determination of exchangeable acidity of soil
Potassium chloride extraction-titration
Soil - Determination of exchangeable acidity by potassium chloride
Extraction -Titration method
Published on.2013-06-03
2013-09-01 implementation
Ministry of Environmental Protection released
Content
Foreword.I
1 Scope..1
2 Normative references..1
3 Terms and Definitions.1
4 method principle..1
5 Reagents and materials.1
6 instruments and equipment.2
7 samples. 2
8 Analysis steps..3
9 Calculation and representation of results..3
10 precision 4
11 Quality Assurance and Quality Control 4
12 Notes. 4
Foreword
To implement the "Environmental Protection Law of the People's Republic of China", protect the environment, protect human health, and regulate the monitoring of exchangeable acidity in soil.
Methodology, the development of this standard.
This standard specifies the potassium chloride extraction-titration method for the determination of exchangeable acidity in soil.
This standard applies to the determination of exchangeable acidity in acidic soils.
This standard is the first release.
This standard was formulated by the Science and Technology Standards Department of the Ministry of Environmental Protection.
This standard is mainly drafted by. Yingkou City Environmental Monitoring Center Station, Environmental Protection Institute of the Ministry of Environmental Protection.
This standard is verified by. Dalian Environmental Monitoring Center, Anshan Environmental Monitoring Center Station, Tieling Environmental Monitoring Center Station, Jinzhou
City Environmental Monitoring Center Station, Panjin City Environmental Protection Station.
This standard was approved by the Ministry of Environmental Protection on June 3,.2013.
This standard has been implemented since September 1,.2013.
This standard is explained by the Ministry of Environmental Protection.
Determination of exchangeable acidity of soil - Potassium chloride extraction - titration
1 Scope of application
This standard specifies the potassium chloride extraction-titration method for determining the exchangeable acidity in soil.
This standard applies to the determination of exchangeable acidity in acidic soils.
When taking 5.00g sample and distilling to 250ml, the detection limit of the method is 0.10mmol/kg. The lower limit of the method is
0.40 mmol/kg.
2 Normative references
The contents of this standard refer to the terms in the following documents. For undated references, the valid version applies to this standard.
HJ 613 Determination of dry matter and moisture in soils - Gravimetric method
HJ/T 166 Technical Specifications for Soil Environmental Monitoring
3 Terms and definitions
Exchangeable acidity exchangeable acidity
The soil is extracted with a neutral salt solution, and the hydrogen ions and aluminum ions adsorbed on the soil colloid are exchanged to make a solution, and then
Titration with a sodium hydroxide standard solution, the titration result is called exchangeable acidity.
4 Principle of the method
Extraction principle. repeatedly rinsing soil samples with appropriate potassium chloride solution, so that the exchangeable aluminum and exchangeable hydrogen on the soil colloid are separated by potassium.
The sub-exchanges form hydrogen ions and trivalent aluminum ions into the solution. The exchange process is expressed by the following formula.
H -|soil colloid|-Al3 3KCl|soil colloid|-3K Al3 3Cl- H
Determination of exchangeable acidity. After extracting the sample, take a part of the soil eluent and titrate directly with sodium hydroxide standard solution.
The result is exchangeable acidity.
Determination of exchangeable aluminum. After extracting the sample, take another part of the soil extract and add an appropriate amount of sodium fluoride solution to make the fluoride ion
The aluminum ion forms a complex, Al3 is fully complexed, and is titrated with a sodium hydroxide standard solution, and the result is exchangeable hydrogen. Exchangeable
The difference between acidity and exchangeable hydrogen is exchangeable aluminum.
5 reagents and materials
Unless otherwise stated, analytically pure reagents in accordance with national standards were used for the analysis, and the experimental water was freshly boiled distilled water.
5.1 Freshly boiled distilled water
The distilled water is boiled and evaporated in a beaker (evaporation amount 10%), sealed and sealed, and sealed for use. It should be used now.
5.2 hydrochloric acid solution. c (HCl) = 1.0mol/L
83 ml of concentrated hydrochloric acid (ρ = 1.19 g/ml) was diluted with water to 1 L.
5.3 Potassium chloride solution. c (KCl) = 1.0mol/L
Weigh 74.55g of potassium chloride, dissolve it in water, transfer it to a 1L volumetric flask, dilute to the mark with water, and mix.
5.4 Potassium hydrogen phthalate standard solution. c (C8H5KO4) = 0.01mol/L
Weigh 0.5106g of potassium hydrogen phthalate, which has been dried by 105°C～110°C, dissolved in appropriate amount of water and transferred to 250ml.
In the volumetric flask, add water (5.1) to the mark and mix.
5.5 sodium hydroxide standard solution. c (NaOH) = 0.01 mol/L
Weigh 0.4g of sodium hydroxide in an appropriate amount of water, and after the solution is cooled, transfer it to a 1L volumetric flask, dilute to the mark, mix and store.
In polyethylene plastic containers. Calibration was carried out using potassium hydrogen phthalate standard solution (5.4).
Calibration method. Pipette 25.00ml of hydrogen phthalate standard solution (5.4) into a beaker, put a stirrer in the beaker, insert
When entering the electrode, titrate with sodium hydroxide solution (5.5). Until the pH reaches 7.80 ± 0.08, it is stable for 30 seconds. At the same time, do a blank test.
The measurement was performed three times in succession, and the average value of the calibration results was taken three times.
The sodium hydroxide standard solution concentration is calculated according to formula (1).
1 VV
Vcc −
×= (1)
Where. c1 - sodium hydroxide standard solution concentration, mol/L;
C2 -- concentration of potassium hydrogen phthalate solution, mol/L;
V0-- blank test consumes the volume of sodium hydroxide solution, ml;
V1-- the volume of the sodium hydroxide solution consumed by the calibration, ml;
V2-- volume of potassium hydrogen phthalate solution, ml.
5.6 sodium fluoride solution. c (NaF) = 1.0mol/L
Weigh 42.0g of sodium fluoride dissolved in water and dilute to about 900ml, adjust to pH 7.0 with hydrochloric acid solution (5.2), and dissolve the solution.
Transfer to a 1000ml volumetric flask, dilute to the mark with water, and mix.
5.7 Quartz sand. 30-60 mesh, heated at 300 ° C for 2 h before use.
6 Instruments and equipment
6.1 Soil sieve. The pore size is 2.0 mm.
6.2 pH meter. Accuracy is 0.01 pH units.
6.3 Magnetic stirrer.
6.4 Microburette. The minimum scale is 0.02 ml.
6.5 Common instruments and equipment used in general laboratories.
7 samples
7.1 Sample collection and preservation
Soil samples were collected and stored in accordance with the relevant regulations of HJ/T 166.
7.2 Air drying and preparation of samples
Air dried samples were prepared as required by HJ/T 166. Air dry the sample through a 2 mm pore size sieve, mix well and mix well.
Take two parts of the method, one for the stock and one for the other.
7.3 Preparation of samples
Weigh 5.00g of air-dried soil sample, place it in the funnel with the filter paper, and rinse it with a small amount of potassium chloride solution (5.3).
The addition of the potassium chloride solution must be carried out after the filtrate in the funnel is filtered. The filtrate is taken up in a 250mL volumetric flask.
Potassium chloride solution (5.3) is made up to volume.
7.4 Preparation of blank samples
The quartz sample was used instead of the soil sample, and a blank sample extract was prepared in the same manner as the sample preparation.
7.5 Determination of moisture content
The moisture content was measured in accordance with HJ 613.
8 Analysis steps
8.1 Determination of exchangeable acidity
8.1.1 Determination
Pipette 100ml sample extract into the beaker and boil for 5min to volatilize the carbon dioxide that may be present in the solution and cool to
At room temperature, using a pH meter as an indicator, titrate with a sodium hydroxide solution to a pH of 7.80 ± 0.08, record the volume of sodium hydroxide solution consumed.
The number of milliliters of V1.
8.1.2 Blank test
The 100 ml blank sample extract (7.4) was simultaneously titrated by the method of 8.1.1, and the amount of the consumption of the sodium hydroxide solution volume V was recorded.
8.2 Determination of exchangeable hydrogen
8.2.1 Determination
Pipette 100ml sample extract into the beaker, add 2.5ml sodium fluoride solution (5.6), boil for 5min, and drive out carbon dioxide.
Cool to room temperature, use pH as an indicator, titrate with sodium hydroxide solution to pH 7.80 ± 0.08, record consumption of sodium hydroxide solution
The number of milliliters of volume V2.
8.2.2 Blank test
The 100 ml blank sample extract (7.4) was simultaneously titrated by the method of 8.2.1, and the number of milliliters of the volume of the spent sodium hydroxide solution V0 was recorded.
9 Calculation and representation of results
9.1 Calculation of results
The exchangeable acidity in the soil sample is calculated according to formula (2).
1001000) ( 1 w
mV
VcVV
NaOH
××
×××−= empty (2)
Where. EA-dryable soil exchangeable acidity, mmol/kg;
V1 - direct titration of soil sample consumption sodium hydroxide volume, ml;
V empty - blank sample consumed sodium hydroxide volume, ml;
CNaOH-sodium hydroxide solution concentration, mol/L;
V-extraction final volume, ml;
VS-drop timing removed extract volume, ml;
M-air dry soil quality, g;
W-air dry soil moisture content, mass fraction.
Exchangeable hydrogen and exchangeable aluminum in soil samples are calculated according to equations (3) and (4).
1001000) ( 02 w
mV
VcVV
NaOH
××
×××−= (3)
−= HAAl EEE (4)
Where. EH - exchangeable acid hydrogen of soil samples, mmol/kg;
EAl--exchangeable aluminum of soil samples, mmol/kg;
V2--the volume of sodium hydroxide consumed by the soil sample after adding sodium fluoride, ml;
V0--the blank sample consumes sodium hydroxide volume after adding sodium fluoride, ml;
The meaning of other parameters is shown in equation (2).
9.2 Results representation
When the measurement result is less than 1.0 mmol/kg, it is retained to two decimal places; when it is greater than or equal to 1.0 mmol/kg, three places are retained.
effective number.
10 precision
Six laboratories tested uniform samples with exchangeable acidities of 4.52 mmol/kg and 72.6 mmol/kg. in the laboratory
The relative standard deviations were. 2.0% to 4.2%, 0.5% to 1.3%; the relative standard deviations between laboratories were. 1.9% to 4.1%,
0.4%~1.0%; the repeatability limits were. 0.13 mmol/kg, 0.70 mmol/kg; the reproducibility limits were. 0.19 mmol/kg, 1.20
Mmmol/kg.
11 Quality Assurance and Quality Control
11.1 Make at least 2 blank tests for each batch of samples.
11.2 Make at least 10% parallel samples for each batch of samples. When the measured value is ≤10.0mmol/kg, the maximum allowable relative deviation is ±20%; the measured value
At 10.0~100mmol/kg, the maximum allowable relative deviation is ±10%; the measured value is ≥100mmol/kg, and the maximum allowable relative deviation is ±5%.
11.3 The pH meter must be calibrated with a pH standard buffer before use.
12 Precautions
12.1 Soil samples should be titrated as soon as possible after leaching to avoid prolonged exposure to air, causing errors.
12.2 The preservation and air drying of soil samples should be carried out in a ventilated and non-polluting environment.
12.3 Control the titration rate and stabilize it as soon as possible until the pH is around 7.80.
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