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HJ 923-2017Soil and sediment--Determination of total mercury--Catalytic pyrolysis-cold atomic absorption spectrophotometry (English PDF)

土壤和沉积物总汞的测定催化热解-冷原子吸收分光光度法

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Issued by

Ministry of Ecology and Environment

Level / Type

National · Mandatory

Issue date

December 28, 2017

Implementation date

April 1, 2018

Scope

HJ 923-2017 is the English-translated version of 土壤和沉积物总汞的测定催化热解-冷原子吸收分光光度法.

HJ 923-2017 — This standard specifies the catalytic pyrolysis - cold atomic absorption spectrophotometry for the determination of total mercury in soils and sediments.

This standard applies to the determination of total mercury in soils and sediments. When the sample volume is 0.1 g, the detection limit of this standard method is 0.2 µg/kg and the determination range is 0.8 to 6.0 × 103 µg/kg.

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Document preview — HJ 923-2017

National Standard of the People's Republic of China

Classification: Z 18

Issued by: Ministry of Ecology and Environment

Foreword .ii
1 Scope of application .1
2 Normative references .1
3 Method principle .1
4 Reagents and materials .1
5 Instruments and equipment .2
6 Samples .2
7 Analysis steps .3
8 Results Calculation and Presentation .4
9 Precision and accuracy
10 Quality Assurance and Quality Control .5
11 Waste treatment
12 Matters needing attention
Appendix A (Informative) Methods of precision and accuracy .7

Foreword

In order to carry out "Environmental Protection Law of the People's Republic of China", protect the environment, protect human health, regulate soil and sediment Determination of total mercury, the development of this standard.

This standard specifies the catalytic pyrolysis - cold atomic absorption spectrophotometry for the determination of total mercury in soils and sediments.

Appendix A of this standard is an informative annex.

This standard is released for the first time.

This standard by the Environmental Protection Department of Environmental Monitoring Division and Science and Technology Standards Division to develop.

This standard was drafted. Jiangsu Provincial Environmental Monitoring Center.

This standard verification unit. Zhenjiang City Environmental Monitoring Center Station, Lianyungang City Environmental Monitoring Center Station, Jiangsu Province, disease prevention Control Center, China Geological Survey Nanjing Geological Survey Center, Ministry of Land Resources Nanjing Mineral Resources Supervision and Testing Center and River Suzhou Provincial Environmental Monitoring Center.

This standard MEP approved on December 28, this standard since April 1, 2018 come into operation.

This standard is interpreted by the MEP.

Determination of total mercury in soils and sediments - Catalytic pyrolysis - Cold atoms Absorption spectrophotometry Warning. The nitric acid used in the experiment is highly volatile and corrosive. The standard solution preparation process should be done in a fume hood ; Operation should be required to wear protective equipment to avoid inhalation of the respiratory tract and direct contact with the skin, clothing.

1 Scope of application

This standard specifies the catalytic pyrolysis - cold atomic absorption spectrophotometry for the determination of total mercury in soils and sediments.

This standard applies to the determination of total mercury in soils and sediments.

When the sample volume is 0.1 g, the detection limit of this standard method is 0.2 µg/kg and the determination range is 0.8 to 6.0 × 103 µg/kg.

2 Normative references

This standard references the following documents or the terms. For undated references, the effective version applies to this standard.

GB 17378.3 Marine monitoring code - Part 3. Sample collection, storage and transport GB 17378.5 Marine monitoring code - Part 5. Sediment analysis HJ 494 water sampling technical guidance HJ 613 Determination of soil dry matter and moisture Gravimetric method HJ/T 91 Technical Specifications for Surface Water and Sewerage Monitoring HJ/T 166 Soil Environmental Monitoring Technical Specifications

3 Method principle

After the sample is introduced into the combustion catalytic converter, the various forms of mercury are reduced to elemental mercury through the processes of drying, thermal decomposition and catalytic reaction, Mercury into the kerosene generated gold amalgam, rapid chemical vaporization of mercury in the amalgam mercury released as a vapor form, mercury vapor was the carrier gas was taken into a cold atomic absorption spectrophotometer, and mercury vapor absorbed the 253.7 nm characteristic line. At a certain concentration range, Absorption intensity is proportional to the concentration of mercury.

4 Reagents and materials

Unless otherwise specified, the analysis of the use of analytical reagents in line with national standards, experimental water for the newly prepared deionized Water or distilled water.

4.1 Nitric acid (HNO3). rho = 1.42 g/ml, excellent grade pure.

4.2 potassium dichromate (K2Cr2O7). excellent grade pure.

4.3 Mercury chloride (HgCl2). excellent grade pure.

Pro use the dryer when fully dry.

4.4 Fixative.

Dissolve 0.5 g potassium dichromate (4.2) in 950 ml distilled water, add 50 ml nitric acid (4.1) and mix well.

4.5 Mercury standard stock solution. rho (Hg) = 100 mg/L.

Weigh 0.1354 g mercury chloride (4.3), with a fixed solution (4.4) dissolved, transferred to 1000 ml volumetric flask, and then solid Set the liquid (4.4) to the marking line, and shake it well. Can also be purchased directly from the market certified standard solution.

4.6 Mercury standard solution. rho (Hg) = 10.0 mg/L.

Pipette mercury standard stock solution (4.5) 10.0 ml, placed in 100 ml volumetric flask, with a fixed solution (4.4) to the mark, Mix well. Pro use now with.

4.7 carrier gas. high purity oxygen (O2), purity >= 99.999%.

4.8 quartz sand. 75 µm ~ 150 µm (200 mesh ~ 100 mesh).

Placed in a muffle furnace 850 °C 2h, cooled and filled into the stopper sealed glass jar sealed.

5 Instruments and equipment

5.1 Mercury analyzer. Equipped with a sample boat (nickel boat or magnetic boat), a catalytic combustion furnace, a homogeneous pipe, a desorption furnace and a cold atomic absorption spectrophotometer.

Refer to the working flow chart, see Figure 1.

1 - sample boat 2 - combustion catalyst 3 - homogeneous tube 4 - desorption furnace 5 - cold atomic absorption spectrophotometer 6 - low concentration detection cell;

7-high concentration detection cell; C-carrier gas; W-exhaust gas.

Figure 1 reference workflow

5.2 Analytical Balance. Feel 0.0001 g.

5.3 General Laboratory common equipment and equipment.

6 Samples

6.1 Sample Collection and Storage

Soil samples were collected and stored according to the relevant requirements of HJ/T 166, and samples of marine sediments were collected according to the phase of GB 17378.3 Off Requirements Collection and storage, surface water sediment samples collected according to HJ/T 91 and HJ 494 requirements. After sample collection, Store in a glass bottle below 4 °C for storage for 28 days.

6.2 Sample Preparation

According to HJ/T 166 and GB 17378.3, the collected samples were air-dried in the laboratory, crushed, sieved and stored for future use.

6.3 Determination of moisture

The dry matter content of the soil sample (6.2) was determined according to HJ 613 and the sediment sample (6.2) was determined according to GB 17378.5 Moisture content.

7 Analysis steps

7.1 Instrument reference conditions

According to the instruction manual of the instrument, connect the gas path of the instrument, and check the gas path before use. Reference instrument Instructions, select the best analysis conditions. Instrument reference conditions shown in Table 1.

Table 1 instrument reference conditions

Parameter reference value Drying temperature (°C).200 Drying time (s) 10 Decomposition temperature (°C) 700 Decomposition time (s) 140 Catalytic temperature (°C) 600 Amalgamation heating temperature (°C) 900 Amalgamation mixing heating time (s) 12 Carrier gas flow (ml/min) 100 Detection wavelength (nm) 253.7

7.2 Calibration curve established

7.2.1 Preparation of standard series of solutions

7.2.1.1 Low concentration standard series solution. Pipette 0 µl, 50.0 µl, 100 µl,.200 µl, 300 µl, 400 µl and 500 µl of Mercury standard solution (4.6), fixed solution (4.4) to 10 ml to prepare mercury at an injection volume of 100 µl the standard solutions were 0 ng, 5.0 ng, 10.0 ng, 20.0 ng, 30.0 ng, 40.0 ng and 50.0 ng respectively.

7.2.1.2 High concentration standard series solution. Pipette 0 ml, 0.50 ml, 1.00 ml, 2.00 ml, 3.00 ml, 4.00 ml, 6.00 ml Mercury standard use solution (4.6), fixed solution (4.4) to 10 ml, prepared when the injection volume of 100 µl Mercury the standard solutions were 0 ng, 50 ng, 100 ng,.200 ng, 300 ng, 400 ng and 600 ng respectively.

7.2.2 The establishment of the standard curve Pipette 100 µl standard series of solutions (7.2.1.1) or (7.2.1.2) into the sample boat, according to the instrument reference Pieces (7.1) followed by the standard series of determination of the solution, recording absorbance values. The mercury content of each standard series solution is horizontal Coordinates, with its corresponding absorbance value for the vertical axis, respectively, to establish a low concentration or high concentration standard curve.

Note. According to the actual sample concentration can choose to establish different concentrations of the standard curve.

7.3 Determination of the sample

Weigh 0.1 g (accurate to 0.0001 g) of sample (6.2) in the sample boat and establish the same instrument as the standard curve Condition (7.1) The sample was measured. Sampling volume can be adjusted according to the sample concentration, the recommended sampling volume of 0.1 g ~ 0.5g.

7.4 Blank test

Replacing the sample with quartz sand (4.8) Perform the blank test according to the same procedure as for the determination of the sample (7.3).

8 Results calculated and said

8.1 Calculation Results

8.1.1 Calculation of soil sample results

The total mercury content omega1 (Hg, µg/kg) in soil samples is calculated according to equation (1).

Where. omega1 - total mercury content in the sample, µg/kg;

m1 - total mercury content in the sample obtained from the standard curve, ng;

m - Weigh the quality of the sample, g;

wdm - sample dry matter content,%.

8.1.2 Calculation of Sediment Sample Results

The total mercury content in the sediment samples, omega2 (Hg, µg/kg), is calculated according to equation (2).

8.2 Results indicated

When the test result is less than 10.0 µg/kg, the result is retained after the decimal point. When the test result is greater than or equal to 10.0 µg/kg when the result holds three significant figures.

9 Precision and accuracy

9.1 Precision

In six laboratories, soil samples with mercury contents of 95 µg/kg ± 4 µg/kg were certified as standard samples with mercury contents of 22 Six replicate determinations were performed on standard samples of sediment evidence of µg/kg ± 2 µg/kg and 83 µg/kg ± 9 µg/kg. laboratory phase the standard deviations were 0.65% ~ 6.8%, 2.7% ~ 8.8%, 2.1% ~ 12% respectively. The relative standard deviations 1.3%, 6.2% and 2.3%, respectively. The reproducibility was 8.2 µg/kg, 3.9 µg/kg and 15 µg/kg respectively. The reproducibility limits were 8.2 µg/kg, 5.4 µg/kg, 16 µg/kg.

In the six laboratories, three soil samples with mercury contents of 0.3 µg/kg, 21.0 µg/kg and 116 µg/kg, respectively, and mercury One sediment actual sample with a content of 45.0 µg/kg was subjected to 6 replicate determinations. the relative standard deviations in the laboratory were Were 0.63% ~ 13%, 6.0% ~ 20%, 2.6% ~ 12%, 3.7% ~ 8.6% .The relative standard deviations in laboratory were 2.7% the repeatability was 0.089 µg/kg, 7.2 µg/kg, 23 µg/kg and 7.3 µg/kg respectively. The reproducibility the limits were 0.091 µg/kg, 7.8 µg/kg, 27 µg/kg and 11 µg/kg, respectively.

9.2 Accuracy

In six laboratories, soil samples with mercury contents of 95 µg/kg ± 4 µg/kg were certified as standard samples with mercury contents of 22 Six replicate determinations were made on standard samples of sediment evidence of µg/kg ± 2 µg/kg and 83 µg/kg ± 9 µg/kg.

The average values were 95.8 µg/kg, 23.7 µg/kg and 86.2 µg/kg, respectively. The relative errors were -0.72% -2.5%, 1.6% 17%, 0.26% ~ 6.8%. The final relative error was 0.88% ± 2.6%, 7.6% ± 13%, 3.8% ± 4.8%.

10 Quality Assurance and Quality Control

10.1 Blank Analysis

10.1.1 Sample boat blank

Before each experiment to be used on all samples of the boat blank test, the sample boat blank value should be below the detection limit.

Otherwise, the sample boat was placed in a muffle furnace and after burning at 850 ° C for 2 h, the blank value was measured again until the sample boat became empty the method detection limit.

10.1.2 Blank test

Every 20 samples or batches (less than 20 samples/batch) to be a blank experiment to determine the total mercury content the amount should not exceed the method detection limit.

10.2 Calibration

The standard curve should contain at least 5 non-zero concentration points with a correlation coefficient r >= 0.955.

After each boot, in accordance with the standard curve to establish the same instrument conditions, the determination of the standard curve concentration range of a the mercury content of the standard sample, the measurement value should be within the standard value of the certificate. Otherwise, the standard curve should be re-established.

10.3 Parallel determination

A parallel sample should be analyzed for every 20 samples or batches (less than 20 samples/batch), and the result of the parallel sample determination Relative deviation should be <= 25%.

11 Waste treatment

The waste generated during the experiment should be collected centrally and properly identified, commissioned by a qualified unit for processing.

12 Precautions

12.1 Operation in a mercury-contaminated environment should be avoided.

12.2 After analysis of high concentration samples (>=400 ng), mercury will remain in the system and must use 5% nitric acid as sample Analysis, when the analysis results below the detection limit, and then the next sample analysis.

12.3 The mercury-containing exhaust gas emitted by the instrument during the experiment may be treated with iodine solution, sulfuric acid, manganese dioxide solution or 5% permanganate Absorption of potassium solution, absorption of liquid to be replaced promptly.

Appendix A.

(Informative)

The precision and accuracy of the method Six laboratories conducted a series of six replicate measurements on different soils and sediment samples. The precision data are shown in Table A.1.

Table A.1 Method precision (n = 6)

Sample type

average value

(Mg/kg)

Laboratory relative

standard deviation(%) Relative between laboratories standard deviation(%) Repeatability r (Mg/kg) Reproducibility limit R (Mg/kg) Soil 0.3 0.63 ~ 13 2.7 0.089 0.091 Soil 21.0 6.0 ~ 20 7.3 7.2 7.8 Soil 116 2.6 ~ 12 5.4 23 27 Sediment 45.0 3.7 ~ 8.6 7.1 7.3 11 Soil (GSS-15) 95.8 0.65 ~ 6.8 1.3 8.2 8.2 Sediment (GB W 07333) 23.7 2.7 ~ 8.8 6.2 3.9 5.4 Sediment (GSD-9) 86.2 2.1 ~ 12 2.3 15 16 Six laboratories on different soil, sediment certified standard samples were 6 repeated measurements, the accuracy of the data in Table A.2.

Table A.2 Method Accuracy (n = 6)

Sample type Standard value (µg/kg) Determination of the average (Mg/kg) Relative error(%) the relative error of the final value (%) Soil (GSS-15) 95 ± 4 95.8 -0.72 ~ 2.5 0.88 ± 2.6 Sediment (GB W 07333) 22 ± 2 23.7 1.6 ~ 17 7.6 ± 13 Sediment (GSD-9) 83 ± 9 86.2 0.26 ~ 6.8 3.8 ± 4.8

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 7 pages — is available in the English PDF.

Referenced standards

Normative references

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