Method for determining alkyl mercury in solid waste

Abstract

The invention relates to the technical field of environment detection, in particular to a method for determining alkyl mercury in solid waste. The method comprises the following steps: S1, extracting alkyl mercury in the solid waste by using a first acetic acid buffer solution to prepare a sample solution; preparing a standard solution of alkyl mercury; s2, respectively mixing the sample solution and the standard solution with a second acetic acid buffer solution and a derivatization reagent to respectively obtain a sample loading solution and a standard working solution; and S3, detecting the sample loading solution and the standard working solution by using a full-automatic alkyl mercury determinator to obtain a related chromatogram, carrying out qualitative analysis according to the retention time of target objects in the sample loading solution and the standard working solution, carrying out quantitative analysis by using an external standard method, and determining the alkyl mercury in the solid waste.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental detection, in particular to a method for determining alkylmercury in solid waste. Background Art

[0002] Mercury and its compounds are characterized by mobility, high toxicity, persistence, and bioaccumulation. Both elemental and inorganic mercury in the environment can undergo microbial-mediated reactions to form alkylmercuries. Alkylmercuries, as lipophilic toxins, can cause irreversible damage upon contact with human skin. Among the various chemical forms of elemental mercury, methylmercury has attracted considerable attention due to its extremely potent neurotoxicity and carcinogenicity. The toxicity of mercury in nature is closely related to its chemical form in the environment, leading to increasing interest in the chemical speciation of mercury. Alkylmercuries are a class of highly toxic and carcinogenic organometallic compounds, even more toxic than inorganic mercury. They are also highly likely to remain in natural media such as water and soil, accumulating in the food chain and posing serious risks to humans and animals. The most typical example of alkyl mercury poisoning caused by industrial pollution is the chronic methylmercury poisoning, also known as Minamata disease, which occurred in the Mizuho Bay area of ​​Kumamoto Prefecture, Japan, due to long-term consumption of fish and shellfish contaminated with methylmercury. The Minamata Convention on Mercury came into force on August 16, 2017. The Convention considers the management of mercury throughout its life cycle, from its release to the environment, to protect human health and the environment from the hazards of anthropogenic emissions and releases of mercury and its compounds.

[0003] Currently, methods for determining alkylmercury levels primarily rely on enrichment and analytical methods. Commonly used instruments include gas chromatography-electron capture detection, liquid chromatography-inductively coupled plasma-mass spectrometry, atomic fluorescence chromatography-high performance liquid chromatography, gas chromatography-mass spectrometry, and capillary electrophoresis. However, these methods often suffer from complex pretreatment and the toxicity of extraction solvents. According to the "Hazardous Waste Identification Standard - Leaching Toxicity Identification" (GB 5085.3-2007), my country's control standard for the leaching toxicity of alkylmercury in solid waste is "not detectable." "Not detectable" refers to methylmercury <10 ng / L and ethylmercury <20 ng / L. The recommended detection method in this standard is GB / T 14204-93, "Water Quality - Determination of Alkylmercury by Gas Chromatography." This analytical method is specific to water quality, and current national standards do not yet include a method for detecting the leaching toxicity of alkylmercury in solid waste. Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for determining alkylmercury in solid waste. The present invention achieves a short detection time, a low detection limit, and high accuracy. Furthermore, the pretreatment process for preparing an extract from the solid waste is simple, and both methylmercury and ethylmercury can be simultaneously detected.

[0005] According to one aspect of the present invention, a method for determining alkylmercury in solid waste is provided, comprising the following steps:

[0006] S1. Extracting alkylmercury from solid waste using a first acetic acid buffer solution to prepare a sample solution; and preparing a standard solution of alkylmercury;

[0007] S2, mixing the sample solution and the standard solution with a second acetate buffer solution and a derivatization reagent, respectively, to obtain a sample loading solution and a standard working solution, respectively;

[0008] S3. Use a fully automatic alkyl mercury analyzer to detect the sample solution and standard working solution to obtain relevant chromatograms. Perform qualitative analysis based on the retention time of the target substance in the sample solution and standard working solution, and perform quantitative analysis using the external standard method to determine the alkyl mercury in solid waste.

[0009] In some embodiments of the present invention, if the pH of the solid waste is less than 5, the pH of the first acetate buffer solution is 4.5-5.5; or, if the pH of the solid waste is ≥5, the pH of the first acetate buffer solution is 2.0-3.0.

[0010] In some embodiments of the present invention, the pH of the second acetate buffer solution is 5.6-6.0.

[0011] In some embodiments of the present invention, based on dry sample, the liquid-to-solid ratio of the first acetate buffer solution to the solid waste is 8 to 12 L: 1 kg.

[0012] In some embodiments of the present invention, in step S2, the mixing includes oscillating mixing, and the oscillation frequency is 110±10 times / min, the amplitude is 40 mm, the temperature is 15-30° C., and the time is 6-10 h.

[0013] In some embodiments of the present invention, the mass concentration of the alkylmercury standard solution is 0.2-20 pg / mL.

[0014] In some embodiments of the present invention, the derivatization reagent is sodium tetrapropylborate solution.

[0015] In some embodiments of the present invention, the mass concentration of the sodium tetrapropylborate solution is 5 to 20 g / L.

[0016] In some embodiments of the present invention, the volume ratio of the sample solution to the derivatization reagent is 1 mL:1-2 μL.

[0017] In some embodiments of the present invention, the mass volume ratio of alkylmercury in the standard solution to the derivatization reagent is 0.1-10 pg:1 μL.

[0018] In some embodiments of the present invention, in step S2, the sample solution or the standard solution is mixed with a second acetate buffer solution to a pH of 4.2 to 4.8, and then a derivatization reagent is added.

[0019] In some embodiments of the present invention, the working conditions of the fully automatic alkyl mercury analyzer include:

[0020] Gas chromatography column: Filler is OV-3,

[0021] The gas chromatography column temperature is 42-54°C, for example, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 52°C.

[0022] The purge gas pressure is 40 to 50 mm, for example, 42 mm, 45 mm, or 48 mm.

[0023] The drying gas pressure is 35-45 mm, for example, 36 mm, 40 mm, 42 mm.

[0024] The carrier gas pressure is 25-35 mm, for example, 27 mm, 30 mm, 32 mm.

[0025] In some embodiments of the present invention, the working conditions of the fully automatic alkyl mercury analyzer further include:

[0026] A cold atomic fluorescence detector is used for detection, and the pressure of the cold atomic fluorescence detector is 750-800V.

[0027] In some embodiments of the present invention, the alkylmercury is selected from at least one of methylmercury and ethylmercury.

[0028] According to some embodiments of the present invention, there are at least the following beneficial effects:

[0029] The method recommended for the determination of alkyl mercury in the standard "Identification of Hazardous Wastes - Leaching Toxicity" GB 5085.3-2007 is "Determination of Alkyl Mercury in Water - Gas Chromatography" GB / T 14204-93. At the same time, a comparison was made with an industry standard method for the detection of alkyl mercury in water quality, "Determination of Methylmercury and Ethylmercury in Water - Liquid Chromatography-Atomic Fluorescence Spectrometry" HJ1268-2022, and two landmark methods, "Determination of Alkyl Mercury in Wastewater - Liquid Chromatography-Atomic Fluorescence Spectrometry" DB 22 / T2205-2014 and "Determination of Alkyl Mercury in Water - Liquid Chromatography-Atomic Fluorescence Spectrometry" DB 61 / T 562-2013. The results showed that the proposed method was superior to the standard method in terms of method validity, pretreatment, instrumentation, detection limit, and work efficiency.

[0030]

[0031]

[0032] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0034] Figure 1 is a chromatogram of the standard solution, wherein peak 1 is the zero-valent mercury chromatographic peak, peak 2 is the methylmercury chromatographic peak, peak 3 is the ethylmercury chromatographic peak, and peak 4 is the divalent mercury chromatographic peak;

[0035] Figure 2 This is the standard curve of methylmercury and ethylmercury. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0037] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.

[0038] Unless otherwise specified, “about” in the present invention means that the allowable error is within ±10%, further, within ±5%, and further, within ±2%.

[0039] The fully automatic alkyl mercury analyzer used in the examples of the present invention is a MERX fully automatic alkyl mercury analyzer from Brooks Rand Labs, USA; the horizontal oscillator is a JRY-S08 model purchased from Hunan Jinrongyuan Instrument Equipment Co., Ltd.; the inverted oscillator is an HF-08S model purchased from Shanghai Hetian Scientific Instrument Co., Ltd.; methylmercury and ethylmercury standards are purchased from Shanghai Anpu Laboratory Technology Co., Ltd. and prepared as a 10 mg / L stock solution; sodium tetrapropylborate is purchased from Shanghai Yizhen Analytical Instrument Co., Ltd.; potassium hydroxide, sulfuric acid, nitric acid, and acetic acid are high-grade reagents purchased from Sinopharm Chemical Reagent Co., Ltd.; and the solid waste sample is from a chemical company with the serial number SW25377.

[0040] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0041] Example 1

[0042] This embodiment provides a method for detecting methylmercury and ethylmercury in solid waste, comprising the following steps:

[0043] 1. Solvent preparation

[0044] 1.1 Acetate buffer: Weigh 32.8 g sodium acetate and 2 mL anhydrous acetic acid and dissolve them in experimental water to make up to 100 mL.

[0045] 1.2. Propylation Derivatization Reagent: Weigh 97 g of ultrapure water into a glass bottle (can also be replaced with a Teflon bottle), weigh 2.0 g of KOH and add it to the water. Place the 2% KOH solution in a 0°C refrigerator until ice crystals appear in the solution, add 1.0 g of sodium tetrapropylborate reagent and shake well. Quickly divide the solution into 2.0 mL injection bottles and place them in the freezer until use. Observe the divided vials for 2 hours after placement. If they are not frozen into ice, discard them and do not use them.

[0046] 1.3. Sulfuric acid-nitric acid extract: prepare the sulphuric acid-nitric acid extract according to the sulphuric acid-nitric acid method for leaching toxicity of solid waste (HJ / T 299-2007). Add a mixture of concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 2:1 to distilled water to adjust the pH to 3.20±0.05.

[0047] 1.4. Acetic acid extract: prepare acetic acid extract according to the acetic acid buffer solution method for leaching toxicity of solid waste (HJ / T 300-2007) and measure the pH of the solid waste. If the pH is less than 5, use the following preparation steps for the acetic acid extract: add 5.7 mL of glacial acetic acid to 500 mL of reagent water, add 64.3 mL of 1 mol sodium hydroxide, and dilute to 1 L. The pH value of the prepared solution should be 4.93±0.05. If the pH is ≥5, use the following preparation steps for the acetic acid extract: add 17.25 mL of glacial acetic acid to ultrapure water, dilute to 1 L, and adjust the pH to 2.64±0.05.

[0048] 1.5. Copper sulfate-nitric acid-dichloromethane extraction: Weigh 15 mL of copper sulfate (2 M) and 75 mL of nitric acid (25%, v / v) in 50 mL of dichloromethane.

[0049] 1.6 Potassium hydroxide-methanol extract: Weigh 25 g potassium hydroxide into 100 mL methanol, cover tightly, and sonicate for 20 min until the solution turns milky white.

[0050] 1.7. Water extract: Watsons distilled water.

[0051] 2. Automatic alkyl mercury analyzer to determine the leaching toxicity of methylmercury and ethylmercury in solid waste

[0052] 2.1. Preparation of sample solution

[0053] Method 1: Horizontal Oscillation Method (HJ 557-2010): Determine the moisture content of the sample. Weigh 100 g of the sample on a dry basis into a 2 L polytetrafluoroethylene bottle. Add the required amount of water extract, acetic acid extract, sulfuric acid-nitric acid extract, copper sulfate-nitric acid-dichloromethane extract, or potassium hydroxide-methanol extract according to the moisture content of the sample and the liquid-solid ratio of the dry basis sample to the extract of 10:1 (L / kg). Install the horizontal oscillation device and adjust the oscillation frequency to 110 ± 10 times / min and the amplitude to 40 mm, shaken at room temperature for 8 hours, then allowed to stand for 16 hours. Except for the copper sulfate-nitric acid-dichloromethane extraction, the organic phase was collected, deionized water was added, and the sample solution was obtained by heating to approximately 60°C until the visible organic phase disappeared, then heating for approximately 1 hour to completely evaporate the dichloromethane. The sample solution was then diluted to volume with deionized water. The sample solutions treated with water, acetic acid, sulfuric acid-nitric acid, and potassium hydroxide-methanol were directly filtered, and the leachate was collected as the sample solution and refrigerated for analysis. A blank test was also performed to obtain a blank solution.

[0054] Method 2: Tumbling oscillation method (GB 5086.1-1997): Determine the moisture content of the sample. Weigh a certain amount of dry sample into a 2L polytetrafluoroethylene bottle. Add the required amount of water extract, acetic acid extract, sulfuric acid-nitric acid extract, copper sulfate-nitric acid-dichloromethane extract, or potassium hydroxide-methanol extract according to the moisture content of the sample and the liquid-solid ratio of dry sample to extract of 10:1 (L / kg). Cover the bottle tightly and fix it on a tumbling mixer. Adjust the speed to 30±2r / min and tumble at room temperature. After 18 hours of stirring, remove the extraction vessel and allow to stand for 30 minutes. After the copper sulfate-nitric acid-dichloromethane extraction, the organic phase is collected, deionized water is added, and the sample solution is obtained by heating to approximately 60-65°C until the visible organic phase disappears. The sample solution is then diluted to volume with deionized water to obtain the sample solution. Sample solutions obtained from the water, acetic acid, sulfuric acid-nitric acid, and potassium hydroxide-methanol extractions are filtered through a filter apparatus pre-installed with a filter membrane (or filter paper). The entire filtrate is collected as the sample solution, shaken well, and then used for analysis. A blank test is also performed to obtain a blank solution.

[0055] 2.2 Derivatization reaction and on-machine analysis

[0056] Take 40 mL of filtered sample solution, wherein the sample solutions after leaching with acetic acid extract and sulfuric acid-nitric acid extract are adjusted with 200 g / L KOH aqueous solution, and the sample solutions after leaching with water, potassium hydroxide-methanol extract, and copper sulfate-nitric acid-dichloromethane extract are adjusted with acetate buffer solution to a pH of 4.5±0.2, then add 50 μL of sodium tetrapropylborate solution respectively, add experimental distilled water to fill the bottle, cover the lid tightly, shake well, and let it stand for 2 hours before measuring on the machine.

[0057] 2.3. Preparation of standard working solution

[0058] Pre-fill a 40mL brown injection vial with approximately 30mL of water after high-temperature purification. Then, add varying amounts of methylmercury and ethylmercury standard stock solutions. Adjust the pH to 4.5 ± 0.2 with sodium acetate buffer. Add 50μL of sodium tetrapropylborate aqueous solution, and finally, add the volume to 40mL. Invert and mix thoroughly before testing. At this point, the brown injection vial contains 10pg, 50pg, 100pg, 150pg, and 200pg of methylmercury and 10pg, 50pg, 100pg, 150pg, and 200pg of ethylmercury, respectively.

[0059] 2.4 Instrumental analysis conditions

[0060] The fully automatic alkyl mercury analyzer uses a gas-liquid separator, multi-channel purge, and Tenax trapping technology to purge alkyl mercury (methylmercury, ethylmercury) from the liquid and enrich it through a trap. The trap is then rapidly heated, and the alkyl mercury is desorbed and carried into the gas chromatography along with the carrier gas for separation and high-temperature cracking and reduction. Finally, the alkyl mercury content is detected by a cold atomic fluorescence detector. The instrument setting conditions are:

[0061] Chromatographic column: The packing liquid of the column is OV-3, the column length is 340 mm, and the inner diameter is 1.59 mm (Brooks Rand MERX, USA); the capillary column: the stationary phase is 100% dimethylpolysiloxane, the column length is 15 m, the inner diameter is 0.53 mm, and the film thickness is 0.5 μm;

[0062] Column temperature: 48°C;

[0063] Purge conditions: purge gas is nitrogen, purge gas pressure: 45 mm, drying gas pressure: 40 mm, carrier gas is argon, carrier gas pressure: 30 mm;

[0064] Cold atomic fluorescence detector pressure: 770V;

[0065] Injection volume: 40 mL;

[0066] Injection conditions: heating time: 9.9 s; trap tube cooling time: 3.0 min; nitrogen purge time: 9.0 min; drying time: 5.0 min;

[0067] Running time: 10.0min.

[0068] Calculation of measurement results: The prepared sample solution is measured to obtain the peak height response value of the target compound in the sample solution. The content of the target compound in the sample solution is obtained based on the corresponding relationship between the peak height response value of the target compound and the concentration of the target compound. That is, the content of methylmercury and ethylmercury in the sample is calculated according to the following formulas:

[0069]

[0070] Where X represents the methylmercury or ethylmercury content in the sample, in μg / kg; C represents the concentration of the target compound in the sample loading solution, in pg; C0 represents the concentration of the target compound in the blank loading solution, in pg; V represents the volume of the sample solution, in mL; m represents the mass of the sample weighed, in g; and v represents the volume of the sample loading solution transferred to the injection vial, in mL. When calculating according to the formula, the average of three replicates is used as the final result.

[0071] 2.5 Quality Control and Assurance

[0072] Standard working curves for methylmercury and ethylmercury exhibited linear relationships within the range of 0 to 200 pg (40 mM), with linear fit coefficients greater than 0.999. Each batch of 20 samples consisted of at least one blank sample and one spiked recovery sample. The blank sample contained methylmercury and ethylmercury levels below the MDL, and the spiked sample recovery range exceeded 60%.

[0073] 3. Optimization of parameters during the detection process

[0074] 3.1 Optimization of sample extraction method

[0075] Alkylmercury determination results in solid waste using different shaking methods and extraction solutions were investigated. Experimental accuracy was determined by spike recovery. The specific operating procedures were as described in "2. Determination of the Leaching Toxicity of Alkylmercury in Solid Waste Using a Fully Automatic Alkylmercury Analyzer." The spike recoveries for methylmercury and ethylmercury in solid waste samples are shown in Tables 1 and 2.

[0076] Table 1 Spiked recovery of different extracts under horizontal oscillation (HJ557-2010)

[0077]

[0078] Table 2 Spiked recovery of different extracts under tumbling and shaking conditions (GB 5086.1-1997)

[0079]

[0080]

[0081] From Tables 1 and 2, it can be seen that the difference in the spike recovery of the two different shaking methods, horizontal shaking method and flip shaking method, in the same extract is not much, but the difference in the spike recovery rate in the water extraction, sulfuric acid-nitric acid extraction, acetic acid extraction, copper sulfate-nitric acid-dichloromethane extraction, potassium hydroxide-methanol extraction treatment group is significant. From the results, it can be seen that the water extraction recovery rate using the shaking method is between 53.2.8% and 75.5%, the sulfuric acid-nitric acid extraction recovery rate is between 22.3% and 48.9%, the copper sulfate-nitric acid-dichloromethane extraction recovery rate is between 63.6% and 72.6%, the potassium hydroxide-methanol extraction recovery rate is between 31.4% and 52.2%, and the acetic acid extraction recovery rate is between 66.7% and 84.6%. Comparing the five extracts, the sulfuric acid-nitric acid extract has the lowest extraction recovery rate, which is because sulfate (SO4 2- ) to alkylmercury (such as methylmercury CH3Hg + ) content has a dual effect, which can promote or inhibit its formation, depending on the environmental conditions (such as microbial activity, sulfide concentration, redox state, etc.). -Or under acidic conditions, NO3 - May oxidize CH3Hg by generating reactive nitrogen species (such as HNO2) + , generating Hg 2+ and CH4. Therefore, sulfuric acid-nitric acid extraction of alkylmercury may result in unstable results. Comparing the five extraction agents, the acetic acid solution extraction recovery rate reached over 66%, making it suitable for use as the extraction solution of the present invention. Therefore, acetic acid solution extraction was subsequently used to optimize the test conditions of the present invention.

[0082] 3.2 Optimization of derivatization reagents

[0083] Refer to "2. Determination of leaching toxicity of methylmercury and ethylmercury in solid waste by fully automatic alkylmercury analyzer" for the following analysis. The difference is that in "2.1. Preparation of sample solution", acetic acid extraction solution is used for extraction; in "2.3. Derivatization reaction and on-machine analysis", sodium tetrapropylborate is replaced by sodium tetraethylborate. The recoveries of methylmercury and ethylmercury in solid waste samples are shown in Table 3.

[0084] Table 3 Table 3 Spiked recovery of different derivatization reagents under tumbling and shaking (GB 5086.1-1997)

[0085]

[0086]

[0087] 3.3 Optimization of pH value

[0088] Refer to “2. Determination of leaching toxicity of alkyl mercury in solid waste by fully automatic alkyl mercury analyzer”, except that in “2.1. Preparation of sample solution”, acetic acid extraction solution was used for extraction; in “2.3. Derivatization reaction and on-machine analysis”, pH 4.5±0.2 was replaced by pH 2.0±0.2, 6.0±0.2, and 10.0±0.2. The recoveries of methylmercury and ethylmercury in solid waste samples were determined and shown in Table 4.

[0089] Table 4 Spiked recovery at different pH values ​​under tumbling and shaking conditions (GB 5086.1-1997)

[0090]

[0091] 3.4. Optimization of chromatographic column temperature

[0092] Refer to "2. Determination of leaching toxicity of alkyl mercury in solid waste by fully automatic alkyl mercury analyzer" for the test. The difference is that in "2.4. Instrumental analysis conditions", the column temperature of 48°C is replaced with 40°C and 60°C. The test results show that the OV-3 alkyl mercury column is used for the on-board determination. The chromatogram of the alkyl mercury standard solution is shown in Figure 1 The peaks of methylmercury (2.091 min) and ethylmercury (4.812 min) are sharp and symmetrical, indicating good separation. However, when the column temperature is 40°C or 60°C, the separation of methylmercury and ethylmercury deteriorates, reducing the accuracy of the detection method.

[0093] 4. Methodological Validation

[0094] 4.1 Standard Curve

[0095] Prepare 0.1μg / L, 1μg / L, and 10μg / L standard working solutions, respectively, and prepare a series of standard solutions with absolute methylmercury and ethylmercury contents of 0, 1, 5, 10, 50, 100, 500, and 1000pg. After preparation, perform the test on the machine according to the solution concentration from low to high, referring to "2. Determination of leaching toxicity of alkylmercury in solid waste by fully automatic alkylmercury analyzer". After the test, fit the absolute mercury content-peak height / area, and use the linear fit R as the linear fit. 2 The linearity is consistent. The instrument has been tested to find that the standard curve has a good fit in the range of 0-1000pg for the absolute methylmercury / ethylmercury content. The fitting degree of methylmercury is R 2 =0.9999, the fitting degree of ethyl mercury is R 2 =0.9999 (results see Figure 2 ), which can meet the testing requirements.

[0096] 4.2. Linear range and detection limit of the method

[0097] In accordance with the relevant provisions of the "Technical Guidelines for the Revision of Environmental Testing and Analysis Methods" (HJ 168-2020), and following the full sample analysis steps, the detection limit test for methylmercury and ethylmercury was repeated 11 times using solid waste leachate spiked with 1 pg, and the average value, standard deviation, relative standard deviation, detection limit and other parameters were calculated. The detection limit is calculated according to the formula (1) MDL = t (n-1,0.99) × S calculation; in formula (1), MDL refers to the method detection limit; n refers to the number of replicates of the sample. The detection limit is 2.764 times the standard deviation, and the lower limit of determination is 3 times the detection limit.

[0098] The test results showed that the detection limit of the method for methylmercury was 0.020 ng / L and the quantification limit was 0.060 ng / L; the detection limit of ethylmercury was 0.050 ng / L and the quantification limit was 0.150 ng / L. The specific results are shown in Table 5.

[0099] Table 5 Detection limit and quantification limit determination results

[0100]

[0101] 4.3 Precision and Accuracy

[0102] Since there are no relevant standard substances available for purchase on the market for solid waste, the spike recovery method was used to determine the precision and accuracy. A spike recovery test was conducted on the solid waste sample numbered SW2537. The solid waste sample of SW2537 was prepared into four levels of spiked sample solutions with spiked masses of 25, 100, 500, and 1000 mg / kg, respectively. Six samples were prepared in parallel for each spiked level and the solution was determined under "2. Determination of the leaching toxicity of alkyl mercury in solid waste by fully automatic alkyl mercury analyzer". The results are shown in Table 6. As can be seen from Table 6, the average recovery rate of the sample spike was 60.4% to 90.7%, and the relative standard deviation of the determination results was 2.7% to 8.4%, indicating that the accuracy and precision of this method were good.

[0103] Table 6 Precision and accuracy test results of SW25377 solid waste sample

[0104]

[0105] In summary, the present invention establishes a method for determining the toxicity of alkylmercury leaching in solid waste using acetate buffer extraction, propyl derivatization, and a fully automatic alkylmercury analyzer. The specific steps are as follows:

[0106] Based on the sample's moisture content, the required amount of acetic acid extract was added at a liquid-to-solid ratio of 10:1 (L / kg). After horizontal / inverted shaking, 40 mL of the leached sample was collected, and 50 μL of sodium tetrapropylborate aqueous solution was added. Laboratory distilled water was added to the top of the sample. The sample was tightly capped, shaken, and allowed to stand for 2 hours. Alkylmercury was then determined using an automated alkylmercury analyzer using an external standard method. Alkylmercury mass showed a good linear relationship with chromatographic peak area over the range of 5 to 1000 pg, with a correlation coefficient of 0.9999. When the injection volume was 40.0 mL, the method had a detection limit of 0.020 ng / L and a quantification limit of 0.060 ng / L for methylmercury, and a detection limit of 0.050 ng / L and a quantification limit of 0.150 ng / L for ethylmercury. Average recoveries for spiked samples ranged from 60.4% to 90.7% at different concentration levels, with relative standard deviations ranging from 2.7% to 8.4% (n=6).

[0107] The experimental results show that the acetic acid buffer extraction-propyl derivatization-automatic alkylmercury analyzer is a fast, accurate and convenient experimental method for determining the leaching toxicity of alkylmercury in solid waste.

[0108] The above content describes the embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. In addition, the embodiments of the present invention and the features thereof can be combined with each other unless there is a conflict.

Claims

1. A method for determining alkylmercury in solid waste, characterized in that: The steps include: S1. Extracting alkylmercury from solid waste using a first acetic acid buffer solution to prepare a sample solution; and preparing a standard solution of alkylmercury; S2, mixing the sample solution and the standard solution with a second acetate buffer solution and a derivatization reagent, respectively, to obtain a sample loading solution and a standard working solution, respectively; S3. Use a fully automatic alkyl mercury analyzer to detect the sample solution and the standard working solution to obtain relevant chromatograms, perform qualitative analysis based on the retention time of the target substance in the sample solution and the standard working solution, and perform quantitative analysis using an external standard method to determine the alkyl mercury in the solid waste.

2. The method according to claim 1, characterized in that If the pH of the solid waste is less than 5, the pH of the first acetic acid buffer solution is 4.5 to 5.5; or, if the pH of the solid waste is greater than or equal to 5, the pH of the first acetic acid buffer solution is 2.0 to 3.

0.

3. The method according to claim 1, characterized in that The pH of the second acetate buffer solution is 5.6-6.

0.

4. The method according to claim 1, wherein Calculated on a dry basis, the liquid-to-solid ratio of the first acetic acid buffer solution to the solid waste is 8 to 12 L: 1 kg.

5. The method according to claim 1, wherein The mass concentration of the alkylmercury standard solution is 0.2-20 pg / mL.

6. The method according to claim 1, characterized in that The derivatization reagent is a sodium tetrapropylborate solution, and the mass concentration of the sodium tetrapropylborate solution is 5-20 g / L.

7. The method according to claim 6, characterized in that The volume ratio of the sample solution to the derivatization reagent is 1 mL: 1-2 μL; or the mass volume ratio of the alkylmercury in the standard solution to the derivatization reagent is 0.1-10 pg: 1 μL.

8. The method according to claim 1, characterized in that The working conditions of the fully automatic alkyl mercury analyzer include: the gas chromatography column temperature is 42-54°C.

9. The method according to claim 1, characterized in that The working conditions of the fully automatic alkyl mercury analyzer also include: using a cold atomic fluorescence detector for detection, and the pressure of the cold atomic fluorescence detector is 750-800V.

10. The method according to claim 1, characterized in that The alkylmercury is selected from at least one of methylmercury and ethylmercury.

Images