NY/T 1121.10-2006 Soil testing Part 10: Determination of total mercury in soil
Some standard content:
ICS13.080.05
Agricultural Industry Standard of the People's Republic of China
NY/T1121.10—2006
Soil Testing
Part 1o: Method for determination of soil total mercury hydrargyrumPublished on July 10, 2006
Implemented on October 1, 2006
Published by the Ministry of Agriculture of the People's Republic of China
NY1121 "Soil Testing" is a series of standards, including the following parts:Part 1: Collection, processing and storage of soil samplesPart 2: Determination of soil pHPart 3: Determination of soil mechanical compositionPart 4: Determination of soil bulk densityPart 5: Determination of cation exchange capacity of calcareous soilsPart 6: Determination of soil organic matterPart 7: Determination of available phosphorus in acidic soilsPart 8: Part: Determination of available boron in soil fill
Part 9: Determination of available molybdenum in soil
Part 10: Determination of total mercury in soil
Part 11: Determination of total arsenic in soil
Part 12: Determination of total chromium in soil
Part 13: Determination of exchangeable calcium and magnesium in soil Part 14: Determination of available sulfur in soil
Part 15: Determination of available silicon in soil
Part 16: Determination of total water-soluble salt content in soil Part 17: Determination of oxygen ion content in soil Part 18: Determination of sulfate ion content in soil This part is Part 10 of NYT1121.
This part is proposed and managed by the Ministry of Agriculture of the People's Republic of China. NY/T1121.10-2006
The drafting units of this part: National Agricultural Technology Extension Service Center, Institute of Agricultural Resources and Agricultural Zoning of Chinese Academy of Agricultural Sciences, Shanghai Agricultural Technology Extension Service Center, Shanxi Soil and Fertilizer Workstation. The main drafters of this part: Tian Youguo, Xin Jingshu, Ren Yi, Long Huaiyu, Zhu En, Wang Jinmin, Zheng Lei. I
1 Scope of application
Soil testing
Part 10: Determination of total mercury in soil
This part is applicable to the determination of trace mercury in general soil. NY/T1121.10—2006
The minimum detection amount of this part is 0.04ng mercury. If 0.5g of sample is weighed for determination, the minimum detection limit is 0.002mg/kg, and the upper limit of determination can reach 0.4mg/kg
2 Method Summary
Ground state mercury atoms produce resonance fluorescence when excited by ultraviolet light with a wavelength of 235.7nm. Under certain measurement conditions and in a lower concentration range, the fluorescence concentration is proportional to the mercury concentration. The sample is heated and digested in a boiling water bath with a mixed reagent of nitric acid and hydrochloric acid, so that all the mercury contained enters the solution in the form of divalent mercury. Then, potassium hydride is used to reduce the divalent mercury to elemental mercury to form mercury vapor, which is introduced into the fluorescence cell of the instrument driven by the carrier gas, and the fluorescence peak is measured to obtain the mercury content in the sample.
3 Instruments and equipment
3.1 Atomic fluorescence spectrometerWww.bzxZ.net
3.2 Argon or high-purity ammonia cylinder
4 Reagents and solutions
The reagents and water used in this test method, unless otherwise specified, are analytical reagents and first-grade water specified in GB/T6682. If the solvent is not specified, the solution is an aqueous solution. 4.1 (1+1) Aqueous Regia Solution
Mix 3 parts of concentrated hydrochloric acid (superior grade, p=1.19g/cm2) with 1 part of concentrated nitric acid (superior grade, p=1.40g/cm2), and then dilute it 1 time with second-grade water.
4.2 Potassium borohydride (KBH)-potassium hydroxide (KOH) solution (reducing agent) Weigh 0.2 potassium hydroxide (KOH) into a beaker and dissolve it with a small amount of water. Weigh 0.01g potassium borohydride (KBH499%) and put it into potassium hydroxide solution, dilute it to 100mL with water. 4.3 Preservative solution
Weigh 0.5g potassium dichromate (KCr2Of, high-grade pure), dissolve it in a small amount of water, add 50mL concentrated nitric acid (high-grade pure, p=1.40g/cml), dilute it to 1L with water, and shake it.
4.4 Dilution solution
Weigh 0.2g potassium dichromate (K, CrO7, high-grade pure) and dissolve it in 900mL water, add 28mL concentrated sulfuric acid (high-grade pure, p=1.84g/cm), dilute it to 1L with water, and shake it well. 4.5 Mercury standard stock solution [p(Hg)=0.1g/L] Weigh 0.1354g of mercuric chloride (HgCl, high-grade pure) placed in a silica gel desiccator overnight, dissolve it with preservation solution (4.3) and transfer it to a 1L volumetric flask without damage with preservation solution (4.3), and make up to volume with preservation solution (4.3), which is a standard stock solution containing 100mg/L of mercury (Hg). Accurately pipette 10.00mL of the above mercury standard stock solution, transfer it to a 1L volumetric flask, and make up to volume with preservation solution (4.3), which is a standard solution containing 1
NY/T1121.10—2006
1.00mg/L of mercury (Hg).
Accurately pipette 20.00mL of the standard solution containing 1.00mg/L of mercury (Hg), transfer it to a 1L volumetric flask, and dilute it with the preservation solution (4.3), which is the standard solution containing 20.00n/mL of mercury (Hg) (prepared immediately before use) 4.6 Nitric acid solution [Φ(HNO,)=5%]
5 Analysis steps
5.1 Sample preparation
Weigh 0.2g~2.0g (accurate to 0.0001g) of the air-dried sample that has passed through a 0.149mm sieve and place it in a 50mL stoppered colorimetric tube, add 10mL (1+1) main water (4.1), carefully shake the hook after adding the stopper, heat and digest in a boiling water bath for 2h, take it out and cool it, immediately add 10mL of the preservation solution (4.3), dilute it with the diluent (4.4), and directly put it on the instrument for testing after clarification. At the same time, do a blank test. 5.2 Determination
Adjust the measurement conditions of the atomic fluorescence spectrometer according to the requirements of the instrument manual, use nitric acid solution (4.6) as the carrier and potassium hydride-potassium hydroxide solution (4.2) as the reducing agent to measure the fluorescence intensity of the test solution. 5.3 Draw a calibration curve:
Accurately pipette 0.00mL, 0.50mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL, and 5.00mL of the standard solution containing 20.00ng/mL of mercury (Hg) into 7 50mL stoppered colorimetric tubes, add 10mL of the preservation solution (4.3), dilute to the mark with the diluent (4.4), and spread the solution. This is the standard series solution containing 0.00ng/mL, 0.20ng/mL, 0.40ng/mL, 0.80ng/mL, 1.20ng/mL, 1.60ng/mL, and 2.00ng/mL of mercury (Hg). On the atomic fluorescence spectrometer, the standard series solutions of different concentrations are sucked into the atomizer for atomization under the same conditions as the sample, and the fluorescence intensity is measured and recorded respectively, and the calibration curve is drawn or the linear regression equation is obtained. 6 Result calculation
(Hg) = 1000-m
Where:
w (Hg)
Mass fraction of soil mercury, in milligrams per kilogram (mg/kg): The concentration of mercury (Hg) is obtained from the calibration curve, in nanograms per milliliter (ng/mL); The volume of the sample after digestion is in milliliters (mL). This test is 50mL; The weight of the air-dried sample is in grams (g): Convert g to the coefficient;
The results of repeated tests are expressed as the arithmetic mean, retaining two decimal places. 7 Precision
Table 1 Relative standard deviation of repeated test results Sample content range, mg/kg
8 Notes
Allowed difference (within the laboratory), %
Allowed difference (between laboratories), %
1) During operation, pay attention to checking the reagent blank of the whole procedure. If the reagent or blood station is contaminated, it should be reprocessed, strictly screened, and properly stored to prevent cross contamination.
NY/T1121.102006
This digestion system not only decomposes a large amount of organic matter in the sample due to its own oxidizing ability, but also can extract various inorganic forms of mercury. Under the condition of hydrochloric acid, a large amount of CI- reacts with Hg+ to form a stable [HgCI]?- complex ion, which can inhibit the adsorption and volatilization of mercury. However, it is necessary to avoid using boiling aqua regia to treat samples to prevent the loss of mercury in the form of oxides. When the sample contains more organic matter, the concentration and dosage of nitric acid-hydrochloric acid mixed reagent can be appropriately increased. Due to the influence of environmental factors and the limitation of instrument stability, a calibration curve must be drawn at the same time when each batch of samples is measured. If the mercury content in the sample is too high and cannot be measured directly, the sample weight should be appropriately reduced to keep the mercury content in the sample within the linear range of the calibration curve. After the sample is digested, it is usually diluted with preservation solution and diluent to prevent the loss of mercury. However, it is better to measure the sample as soon as possible. Generally, it is only allowed to be stored for 2d to 3d.
Excited mercury atoms collide with certain atoms or compounds (such as oxygen, ammonia and carbon dioxide, etc.) to transfer energy and produce "fluorescence quenching", so inert gas argon or high-purity nitrogen is used as a carrier gas to pass into the fluorescence cell to help improve the sensitivity and stability of the test. During operation, care should be taken to prevent air and water vapor from entering the fluorescence cell.
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