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HJ 1081-2019: Soil and sediment--Determination of cobalt--Flame atomic absorption spectrometry
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Soil and sediment--Determination of cobalt--Flame atomic absorption spectrometry
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HJ 1081-2019
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Basic data | Standard ID | HJ 1081-2019 (HJ1081-2019) | | Description (Translated English) | Soil and sediment--Determination of cobalt--Flame atomic absorption spectrometry | | Sector / Industry | Environmental Protection Industry Standard | | Classification of Chinese Standard | Z18 | | Classification of International Standard | 13.080 | | Word Count Estimation | 12,127 | | Date of Issue | 2019 | | Date of Implementation | 2020-06-30 | | Issuing agency(ies) | Ministry of Ecology and Environment | HJ 1081-2019: Soil and sediment--Determination of cobalt--Flame atomic absorption spectrometry---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Soil and sediment--Determination of cobalt--Flame atomic absorption spectrometry
National Environmental Protection Standard of the People's Republic of China
Determination of cobalt in soil and sediment
Flame atomic absorption spectrophotometry
Soil and sediment-Determination of cobalt
-Flame atomic absorption spectrometry
2019-12-31 released
2020-06-30 implementation
Released by the Ministry of Ecology and Environment
Contents
Foreword ... ii
1 Scope ... 1
2 Normative references ... 1
3 Methodology ... 1
4 Interference and cancellation ... 1
5 Reagents and materials ... 1
6 Instruments and equipment ... 2
7 Sample ... 2
8 Analysis steps ... 4
9 Results calculation and representation ... 5
10 Precision and accuracy ... 5
11 Quality Assurance and Quality Control ... 6
12 Waste disposal ... 7
13 Notes ... 7
Appendix A (informative) Standard addition method ... 8
Foreword
In order to implement the "Environmental Protection Law of the People's Republic of China"
Environment, protect human health, standardize the determination method of cobalt in soil and sediment, and formulate this standard.
This standard specifies the flame atomic absorption spectrophotometry for the determination of cobalt in soil and sediment.
Appendix A of this standard is an informative appendix.
This standard is issued for the first time.
This standard is formulated by the Department of Eco-Environmental Monitoring, Laws and Standards Department of the Ministry of Ecology and Environment.
This standard was drafted. Hunan Ecological Environment Monitoring Center.
Verification units of this standard. Tianjin Ecological Environment Monitoring Center, Guangxi Zhuang Autonomous Region Ecological Environment Monitoring Center, Hunan
Changsha Ecological Environment Monitoring Center of Hunan Province, Xiangtan Ecological Environment Monitoring Center of Hunan Province, Chenzhou Ecological Environment Monitoring Center of Hunan Province and
Radio and Television Metrology and Testing (Hunan) Co., Ltd.
This standard was approved by the Ministry of Ecology and Environment on December 31,.2019.
This standard will be implemented from June 30, 2020.
This standard is explained by the Ministry of Ecology and Environment.
Determination of cobalt in soil and sediment by flame atomic absorption spectrophotometry
Warning. nitric acid, perchloric acid, hydrofluoric acid, etc. are highly oxidizing and corrosive. The reagent preparation and sample preparation process should be
It should be carried out in a fume hood, and protective equipment should be worn as required to avoid breathing into the respiratory tract or touching skin and clothing.
1 Scope
This standard specifies the flame atomic absorption spectrophotometry for the determination of cobalt in soil and sediment.
This standard applies to the determination of total cobalt in soil and sediment.
When the sample volume is 0.5 g and the constant volume is 50 ml, the detection limit of the method is 2 mg/kg, and the lower limit of determination is 8 mg/kg.
2 Normative references
This standard refers to the following documents or clauses therein. For undated references, the valid version applies to this
standard.
GB 17378.3 Marine Monitoring Code Part 3. Sample Collection, Storage and Transportation
GB 17378.5 Marine Monitoring Code Part 5. Sediment Analysis
HJ 25.2 Technical Guidelines for Soil Pollution Risk Management and Remediation Monitoring on Construction Land
HJ 494 Water Quality Sampling Technical Guide
HJ 613 Soil dry matter and moisture determination by gravimetric method
HJ 832 Digestion of total metal elements in soil and sediment by microwave digestion
HJ/T 91 Technical specifications for surface water and sewage monitoring
HJ/T 166 Technical Specifications for Soil Environmental Monitoring
3 Method principle
Cobalt formed in a high-temperature flame of a soil or sediment sample after acid digestion and sprayed into a lean air-acetylene flame
Ground state atom, which selectively absorbs the 240.7 nm characteristic spectral line emitted by a cobalt sharp-line light source or a continuous light source.
Within the range, its absorbance is directly proportional to the mass concentration of cobalt.
4 Interference and cancellation
Zn and Ni below 10 mg/L, Ba and Pb at 20 mg/L, Mn at 60 mg/L, 400 mg/L
Mg, 500 mg/L K, 900 mg/L Ti, 3000 mg/L Al, 5000 mg/L Ca, and 7000 mg/L
Na does not interfere with the determination of cobalt.
5 Reagents and materials
Unless otherwise stated, the analysis is performed using high-grade pure reagents that meet national standards. The experimental water is freshly prepared pure water or
Distilled water.
5.1 Hydrochloric acid. ρ (HCl) = 1.19 g/ml.
5.2 Nitric acid. ρ (HNO3) = 1.42 g/ml.
5.3 Hydrofluoric acid. ρ (HF) = 1.49 g/ml.
5.4 Perchloric acid. ρ (HClO4) = 1.68 g/ml.
5.5 Cobalt metal. spectrally pure.
5.6 Nitric acid solution. 1 1.
5.7 Nitric acid solution. 1 99.
5.8 Cobalt standard stock solution. ρ (Co) = 500 mg/L.
Accurately weigh 0.1 g (accurate to 0.1 mg) metal cobalt (5.5), heat and dissolve it in 6 ml nitric acid solution (5.6), cold
However, make up to.200 ml with water. Transfer to polyethylene reagent bottle, sealed and refrigerated at 0 ℃ ～ 4 ℃. Can also be straight
Then purchase a commercially available certified standard solution.
5.9 Cobalt standard solution. ρ (Co) = 50 mg/L.
Accurately pipette 10.0 ml of standard cobalt stock solution (5.8) into a 100 ml volumetric flask, and add nitric acid solution (5.7) to make up the volume
To the mark, shake well. Keep refrigerated below 4 ℃ for one year.
5.10 Gas. acetylene, purity ≥99.6%.
5.11 Assisting gas. air.
6 Instruments and equipment
6.1 Flame atomic absorption spectrophotometer.
6.2 Cobalt sharp-line light source or continuous light source with 240.7 nm spectral line.
6.3 Microwave Digestion Apparatus. Power is 600 W ～ 1500 W, temperature accuracy is ± 2.5 ℃, with microwave digestion tank.
6.4 Electric heating plate. with temperature control function, temperature accuracy is ± 5 ℃.
6.5 Teflon beaker or crucible with lid. 50 ml.
6.6 Analytical balance. The sensitivity is 0.1 mg.
6.7 Nylon screen. 0.15 mm (100 mesh).
6.8 Instruments and equipment commonly used in general laboratories.
7 samples
7.1 Sample collection and storage
Collect and preserve soil samples in accordance with the relevant requirements of HJ/T 166 and HJ 25.2; in accordance with the relevant requirements of GB 17378.3
Collect and preserve marine sediment samples; collect surface water sediment samples in accordance with the relevant requirements of HJ/T 91 and HJ 494,
Store surface water sediment samples in accordance with the relevant requirements of HJ/T 166.
7.2 Sample preparation
According to the requirements of HJ/T 166 and GB 17378.3, the foreign matter such as sticks, leaves, stones, etc. in the sample will be removed and collected.
The samples were air-dried, coarsely ground, and finely ground through a nylon sieve (6.7) in the laboratory.
7.3 Determination of moisture and dry matter
Determine the dry matter content of soil samples (7.2) according to HJ 613; determine the sediment samples (7.2) according to GB 17378.5
Moisture content.
7.4 Preparation of test specimens
7.4.1 Hot plate digestion
Weigh a 0.5 g (accurate to 0.1 mg) sample (7.2), place it in a Teflon beaker or crucible (6.5), add 2 to
After 3 drops of water wetting, add 2 ml of hydrochloric acid (5.1), 10 ml of nitric acid (5.2), 2 ml of hydrofluoric acid (5.3), and 1 ml
Perchloric acid (5.4), cover with 180 ° C and digest for about 1 hour, cover the fly silicon and catch the acid, control the temperature within 210 ° C, and steam to near dryness.
If there are black carbides on the beaker or crucible wall, continue to add 1 ml perchloric acid (5.4) until the contents are white or light
Yellow non-flowing semi-solidified. Remove the Teflon beaker or crucible, cool slightly, add 0.5 ml nitric acid (5.2), warm
Dissolve the soluble residue, transfer to the 50 ml volumetric flask after cooling, make up to the mark with water, shake well, let it stand, and take it
Serum to be tested.
7.4.2 Microwave Digestion
Weigh 0.5 g (accurate to 0.1 mg) sample, put it in a microwave digestion tank, add 2 to 3 drops of water to wet it, and add 1 ml
Hydrochloric acid (5.1), 5 ml of nitric acid (5.2) and 2 ml of hydrofluoric acid (5.3) were digested according to certain digestion conditions (see Table 1).
Dissolve, cool to room temperature after digestion, transfer all digestion solution to Teflon beaker or crucible (6.5), add 1 ml
Perchloric acid (5.4), heated by electric hot plate, temperature controlled at 180 ° C and heated for 30 min, then cover the acid (temperature
Controlled at 180 ° C. In order to achieve good flying silicon effect, shake the beaker or crucible frequently) until the solution is almost dry. If beaker or
If there are black carbides on the crucible wall, continue to add 1 ml of perchloric acid (5.4) until the contents are white or pale yellow.
Moving semi-solidified. Remove the Teflon beaker or crucible, cool slightly, add 0.5 ml nitric acid (5.2), and dissolve in warm
Residual residue, transferred to a 50 ml volumetric flask after cooling, make up to the mark with water, shake well, let it stand, and take the supernatant for testing.
Or follow the digestion method of cobalt in HJ 832 for digestion.
Table 1 Reference table for microwave digestion heating program
Step temperature (° C) Heating time (min) Holding time (min)
1 room temperature to 150 7 3
2 150 ～ 210 5 20
7.5 Preparation of blank sample
Without weighing the sample, follow the same steps as for sample preparation (7.4) to prepare a blank sample.
8 Analysis steps
8.1 Instrument Reference Working Conditions
Adjust the instrument to the best working condition according to the instrument instruction manual. See Table 2 for reference test conditions.
Table 2 Instrument working parameters
Name parameter
Measurement wavelength (nm) 240.7
Passband width (nm) 0.2
Lamp current (mA) 7.0
Acetylene flow (L/min) 2.5
Air flow (L/min) 13.5
Flame type lean burn
8.2 Establishment of standard curve
Accurately remove 0 ml, 0.20 ml, 1.00 ml, 2.00 ml, 4.00 ml, 6.00 ml, and 10.00 ml cobalt standards
Use the liquid (5.9) in a 100 ml volumetric flask, make up to the mark with a nitric acid solution (5.7), shake well, and make the mass concentration of cobalt
They are 0 mg/L, 0.10 mg/L, 0.50 mg/L, 1.00 mg/L, 2.00 mg/L, 3.00 mg/L, and 5.00 mg/L. Press instrument
The measuring conditions of the device are used to determine the absorbance of the standard solution in order from low to high concentration. With Cobalt Standard Series Mass Concentration
The corresponding absorbance is the ordinate, and a standard curve is established.
Note 1. When using the standard addition method for determination, see Appendix A;
Note 2. Standard series of other concentration levels can be prepared according to the sensitivity of the instrument or the concentration range of the sample. At least 6 concentration points (including
Zero concentration point).
8.3 Sample determination
The measurement of the sample (7.4) shall be carried out in accordance with the same instrument conditions as the standard curve establishment (8.2). If the sample concentration range
Beyond the standard curve range, determine after diluting with nitric acid solution (5.7).
8.4 Determination of blank sample
Follow the same procedure as for the sample measurement (8.3) to measure the blank sample (7.5).
9 Calculation and representation of results
9.1 Calculation of results
9.1.1 Calculation of soil samples
The cobalt content w1 (mg/kg) in the soil sample is calculated according to formula (1).
dmwm
VD
w
) (01
(1)
In the formula. w1--Cobalt content in soil sample, mg/kg;
-mass concentration of cobalt in the sample calculated from the standard curve, mg/L;
o-mass concentration of cobalt in blank sample, mg/L;
V-constant volume of sample, ml;
D--the dilution factor of the sample;
m-the weight of the soil sample, g;
wdm-dry matter content of soil sample,%.
9.1.2 Calculation of sediment samples
The cobalt content w2 (mg/kg) in the sediment sample is calculated according to formula (2).
)1(
) (
OHwm
VDw
(2)
In the formula. w2--Cobalt content in sediment sample, mg/kg;
-mass concentration of cobalt in the sample calculated from the standard curve, mg/L;
o-mass concentration of cobalt in blank sample, mg/L;
V-constant volume of sample, ml;
D--the dilution factor of the sample;
m-the weighing amount of the sediment sample, g;
OHw 2-moisture content of sediment sample,%.
9.2 Representation of results
The number of decimal places in the measurement result is consistent with the detection limit of the method, and a maximum of 3 significant digits are retained.
10 Precision and accuracy
10.1 Precision
Six laboratories carried out three actual soil samples with cobalt contents of 8.1 mg/kg, 11.6 mg/kg, and 22.8 mg/kg.
After 6 repeated determinations, the relative standard deviation ranges in the hot-plate laboratory were 3.2% to 9.1%, 1.9% to 4.1%,
1.7% ～ 4.5%, the relative standard deviations among the laboratories are 19%, 9.3%, 7.1%, and the repeatability limits are 2 mg/kg,
2 mg/kg, 3 mg/kg, the reproducibility limits are 5 mg/kg, 4 mg/kg, and 5 mg/kg respectively; relative standards in the microwave method laboratory
The deviation ranges are 3.2% to 5.0%, 2.3% to 4.7%, 1.5% to 5.4%, and the relative standard deviations between laboratories are
16.9%, 8.2%, 9.4%, repeatability limits are 1 mg/kg, 2 mg/kg, 3 mg/kg, and reproducibility limits are 4 mg/kg,
3 mg/kg, 7 mg/kg.
Six laboratories tested actual samples of three sediments with cobalt contents of 12.0 mg/kg, 17.4 mg/kg, and 24.0 mg/kg, respectively.
The product was subjected to 6 repeated determinations. The relative standard deviation ranges in the hot-plate laboratory were 1.2% to 5.7% and 1.7% to
5.5%, 1.2% ～ 4.0%, the relative standard deviations among laboratories are 12%, 9.6%, 5.8%, and the repeatability limits are
2 mg/kg, 2 mg/kg, 2 mg/kg, with reproducibility limits of 5 mg/kg, 5 mg/kg, and 5 mg/kg respectively; in the microwave method laboratory
The relative standard deviation ranges from 2.6% to 5.5%, 1.3% to 6.4%, and 1.6% to 4.9%, respectively.
Reproducibility limits are 11%, 10.7%, and 7.3% respectively, and the repeatability limits are 2 mg/kg, 2 mg/kg, and 2 mg/kg, respectively.
4 mg/kg, 6 mg/kg, 6 mg/kg.
10.2 Accuracy
Six laboratories performed six repeated determinations of two soil certified reference materials, GSS-9 and GSS-5.
The relative error range of the method is -9.3% to 8.6%, -11% to 4.2%, and the final relative error values are -1.8% ± 14.8%,
-0.1% ± 12.2%; the relative error ranges of the microwave method are -7.1% to 6.4% and -7.9% to 6.7%, respectively.
The difference is -0.2% ± 9.2%, -1.6% ± 10.4%.
Six laboratories performed six repeated determinations of GSD-7a and GSD-11 certified reference materials.
The relative error ranges of the hot plate method are -2.6% to 0.7%, -4.7% to 4.8%, and the final relative errors are
-1.1% ± 2.6%, -1.6% ± 9.0%; the relative error ranges of microwave method are -2.6% ～ 2.7%, -4.7% ～ 5.9%, relative
The final error values were 0.03% ± 3.6% and -1.8% ± 9.0%.
Six laboratories carried out standard analysis on soil samples with a cobalt content of 8.1 mg/kg and 22.8 mg/kg.
The recovery ranges of the standard addition of the hot plate method are 92.5% ～ 102% and 85.0% ～ 111%, respectively. The final values of the standard recovery rates are
97.1% ± 7.6%, 97.4% ± 16.6%; the recovery range of microwave method spiked standard is 91.0% ～ 105%, 86.7% ～ 109%,
The final recoveries were 97.3% ± 9.0% and 98.1% ± 15.0%.
Six laboratories carried out standard addition analysis on sediment samples with cobalt content of 12.0 mg/kg and 24.0 mg/kg.
The ranges of the recovery rates for the hot plate method are 91.0% ～ 102% and 86.5% ～ 108%, respectively. The final values of the standard recovery rates are
95.3% ± 8.2%, 98.9% ± 16.4%; the recovery range of the standard addition of microwave method is 83.0% ～ 111%, 93.5% ～ 101%,
The final recoveries were 96.8% ± 19.0% and 95.6% ± 7.4%.
11 Quality Assurance and Quality Control
11.1 Make at least 2 blank samples for each batch of samples. The blank value should be lower than the lower limit of the method.
11.2 A standard curve should be drawn for each determination, and its linear correlation coefficient should be ≥0.999. Every 20 samples or batches (less than
(20 samples/batch) After the analysis is completed, the standard series of zero concentration points and intermediate concentration points need to be checked. Zero concentration point measurement
It should be lower than the detection limit of the method, and the relative deviation between the measured value of the intermediate concentration and the concentration at that point should be ≤10%, otherwise the standard should be re-established
curve.
11.3 Every 20 samples or each batch (less than 20 samples/batch) should be tested once in parallel with double samples, single in parallel
The relative deviation of the measurement results should be ≤15%.
11.4 Every 20 samples or each batch of samples is measured simultaneously with a certified standard sample, and the relative error between the measurement result and the guaranteed value
The difference should be within ± 20%. Or each batch (less than 20 samples/batch) should be spiked with 1 actual sample.
The yield should be between 80% and 120%.
12 Waste treatment
The waste generated during the experiment should be collected in a centralized manner, be labeled accordingly, and be entrusted to a qualified unit for processing.
13 Notes
13.1 If the quality control and quality assurance requirements of this standard are met through verification, the sampling volume and
The amount of acid is adjusted appropriately.
13.2 During the experiment, metal utensils should be avoided.
Appendix A
(Informative appendix)
Standard addition method
A.1 Method of drawing calibration curve
Measure four equal volumes of the test sample (concentration Cx), and prepare four solutions with the same total volume. First unmarked
Quasi-solution, the second, third, and fourth parts are respectively added to the standard solution of different concentrations in proportion, the concentrations of the four solutions are. Cx, Cx Co
, Cx 2Co, Cx 3Co. Zero with a blank reagent, and sequentially measure the absorbance of the four solutions under the same conditions. To absorb light
The degree is the ordinate, the concentration of the standard solution added is the abscissa, and the standard addition curve is drawn. The intersection of the curve extension and the abscissa
That is the concentration of the sample to be tested. The relationship between the concentration of the test sample and the corresponding absorbance is shown in Figure A.1.
Figure A.1 Relationship between the concentration of the sample to be measured and the corresponding absorbance
A.2 Precautions
A.2.2 This method is only applicable to the area where the concentration of the sample to be measured is linear with the absorbance.
A.2.3 The volume change caused by adding the standard solution should not exceed 0.5%.
A.2.4 This method can only compensate for the effects caused by the matrix effect, and cannot eliminate the effects of background absorption.
A.3 Applicability judgment of standard addition method
Determine the absorbance of the sample to be tested as A, and check the concentration as x from the calibration curve. Add the standard solvent to the test sample
Liquid, the spiked concentration is s, the absorbance is determined as B, and the concentration is y from the calibration curve. Calculated according to formula (A.1)
Concentration C of the sample to be tested.
() sC x
yx
(A.1)
When matrix effect exists, s/(yx) is between 0.5 and 1.5, and standard addition method can be used; when s/(yx) exceeds this range
During the period, the standard addition method does not apply.
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