Pretreatment method for detecting antimony isotope in high-salt sample and application

Abstract

The invention provides a pretreatment method for antimony isotope detection in a high-salt sample and application, and belongs to the technical field of antimony isotope analysis and detection. According to the pretreatment method, a sample solution and a hydride reducing agent are mixed and jointly introduced into a hydride generation unit and a gas-liquid separation unit, the antimony hydride gas is selectively generated through hydride generation reaction, and main matrix elements are retained in waste liquid of the hydride generation unit. Meanwhile, the antimony hydride is purged from the gas-liquid separator into a strong oxidizing solution through carrier gas to be subjected to oxidation trapping and recycling. The recovered sample solution can be further used for effectively separating trace interference elements by using a column chromatography separation and purification technology, so that high-precision isotope analysis of the multi-receiving-cup inductively coupled plasma mass spectrometer is ensured. The method is easy and convenient to operate, high in separation efficiency and suitable for analysis and detection of the antimony isotope in a high-salt sample and a low-antimony-content sample.

Description

Technical Field

[0001] The invention relates to the technical field of antimony isotope detection, and in particular to a pretreatment method and application of antimony isotope detection in a high-salt sample. Background Art

[0002] The study of the biogeochemical cycle of antimony (Sb) is of great significance for basic geochemical research and the assessment of pollution risks in the human living environment. Antimony has two stable isotopes: 121 Sb and 123 Sb, with an average abundance of 57.213% and 42.787%, respectively. Accurately obtaining antimony isotope composition information in environmental samples is crucial for an in-depth understanding of the biogeochemical cycle of antimony. Multi-collector cup inductively coupled plasma mass spectrometry (MC-ICP-MS) is a standard method for high-precision antimony isotope analysis, but the antimony concentration in environmental samples is extremely low. In order to meet the requirements of high-precision antimony isotope testing for on-machine concentration, a larger sample amount is usually required. In addition, high-precision antimony isotope analysis is significantly affected by isotopes, such as 123 Te + and 122 HkDJ + right 123 Sb + ,as well as 120 HkDJ + and 120 T + right 121 Sb + Therefore, effective elemental purification and separation sample pretreatment is a necessary condition for obtaining high-precision, high-quality antimony isotope data. However, excessive sample volume brings significant difficulties to the elemental separation and purification sample pretreatment of high-salinity sample antimony isotope analysis, which is not conducive to high-precision antimony isotope analysis of low antimony content and high-salinity environment samples.

[0003] In recent years, column chromatography separation and purification technology has gradually become the most popular and commonly used element separation and purification pretreatment method in isotope geochemistry research. Existing Sb purification methods are all based on column chromatography separation and purification technology, including thiol cotton fiber, cellulose powder, and Cleanert SH thiol resin. However, there are a large number of major elements such as sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) in the solution to be purified from the high-salt sample, which can easily lead to chromatographic column overloading and cause element separation and purification failure. Therefore, it is usually necessary to use Biorad AG50-X83 or Dowex AG50W-X8 cation exchange resin to pre-remove the major elements in the sample solution. However, cation exchange resins also face the risk of chromatographic column overloading, and high concentrations of Ca and Mg in the sample solution are easy to form CaF2 or MgF2 colloids with the hydrofluoric acid medium in the cation exchange resin, which is very harmful to the Sb species [SbO2 + / SbO + / Sb(OH)2 + ] produces adsorption. Faced with the above problems, conventional column chromatography separation methods have extremely limited processing capabilities for high-salt samples. Although the inventor's research group has developed a high-precision antimony isotope analysis pretreatment purification method for low-salt samples such as natural lake water (DOI: 10.1039 / d0ja00367k), this method cannot be used for high-salt seawater and sediment samples. Low-content antimony isotope analysis. Therefore, it is urgent to develop a more effective purification technology for separating the Sb element from a high-salt matrix solution to achieve high-precision Sb isotope analysis of high-salt environment samples. Summary of the invention

[0004] The purpose of the present invention is to address the above-mentioned deficiencies of the prior art and provide a pretreatment method and application for the detection of antimony isotopes in high-salt samples, by selectively converting antimony in high-salt environment samples into gaseous antimony hydrogen through hydride generation technology (HG), thereby separating it from major matrix elements such as Na, K, Ca, Mg, Fe, and Mn that cannot produce hydrogenation reactions. On this basis, column chromatography separation and purification technology is further used to separate trace elements such as Cd and Sn, thereby realizing low-concentration Sb isotope analysis of high-salt environment samples.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The first object of the present invention is to provide a pretreatment method for detecting antimony isotopes in a high-salt sample, wherein the antimony content in the high-salt sample is in the range of 0.01 μg kg -1 ~10 μg kg -1 , the salinity range is 1% to 35%, and the pre-treatment method specifically comprises the following steps:

[0007] S1. Pretreatment of high-salt samples

[0008] The high-salinity samples include seawater samples and mudstone sediment samples;

[0009] Acidifying and pre-reducing the seawater sample so that antimony in the seawater sample exists in a trivalent form, thereby obtaining a first solution;

[0010] Alternatively, the mudstone sediment sample is digested and pre-reduced so that the antimony in the digested solution exists in a trivalent form, thereby obtaining a second solution;

[0011] S2. Separation and purification of antimony elements

[0012] The trivalent antimony element in the first solution or the second solution is converted into gaseous antimony hydrogen by hydride generation technology, the gaseous antimony hydrogen is separated out by gas-liquid separation, and is captured by a capture liquid to obtain a third solution;

[0013] S3, evaporate the third solution obtained in step S2 at 90°C to 95°C and then redissolve it, repeat the operation several times, and dissolve the dry sample in a solution with a concentration of 0.5 to 0.55 mol L -1 A 10-12% potassium iodide solution is added to the hydrochloric acid solution to fully pre-reduce the antimony for 5-6 hours to obtain a fourth solution;

[0014] S4. The fourth solution obtained in step S4 is eluted, enriched and purified by column chromatography separation and purification technology, and the eluate is collected and dried to obtain a sample after pretreatment.

[0015] Furthermore, in step S1, the pretreatment process of the seawater sample is to add concentrated hydrochloric acid solution to the seawater sample so that the volume proportion of hydrochloric acid in the sample is 5-5.5%, and add 1g-10g of potassium iodide solid powder to acidify and pre-reduce the seawater sample solution for 5-6 hours to obtain a first solution.

[0016] Furthermore, in step S1, the digestion process of the mudstone sediment sample is to add the ground mudstone sediment sample into a high-pressure digestion tank, add concentrated nitric acid and hydrofluoric acid, and maintain it at 180-190° C. for at least 48 hours until the sediment is completely digested and the solution is clear, and then evaporate and redissolve, and repeat the operation multiple times to obtain a dry product.

[0017] Furthermore, in step S1, the pre-reduction process of the mudstone sediment sample is to dissolve the dried material in a 5-6% hydrochloric acid solution, and add a 10-12% potassium iodide solution by volume for pre-reduction for 5-6 hours to obtain a second solution.

[0018] Furthermore, in step S2, a separation and purification device is used to separate and purify the antimony element. The separation and purification device includes a hydride generating unit, a gas-liquid separation unit and a gas collector which are connected in sequence through pipelines. The hydride generating unit includes a hydride reducing agent reagent bottle, a sample bottle and a peristaltic pump. The hydride reducing agent reagent bottle and the sample bottle are respectively connected to the inlet of the peristaltic pump. The gas-liquid separation unit is a U-shaped gas-liquid separator. The inlet of the U-shaped gas-liquid separator is connected to the outlet of the peristaltic pump, the gas outlet of the U-shaped gas-liquid separator is connected to the gas collector, and the liquid outlet of the U-shaped gas-liquid separator is connected to a waste liquid bottle.

[0019] Furthermore, a carrier gas pipeline is connected to the inlet of the U-shaped gas-liquid separator, and the carrier gas pipeline contains an inert gas, which is high-purity argon.

[0020] Furthermore, the gas collector is filled with a collecting liquid, and the collecting liquid is a strong oxidizing solution.

[0021] Furthermore, the hydride reducing agent reagent bottle is filled with potassium borohydride solution.

[0022] Furthermore, in step S4, the chromatographic column used in the column chromatography separation and purification technology includes a thiol cotton fiber column, a cellulose powder column or a Cleanert SH thiol resin column.

[0023] The second object of the present invention is to provide the above-mentioned pretreatment method to pre-treat the high-salt sample, and then use a multi-receiving cup inductively coupled plasma mass spectrometer to detect antimony isotopes.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The pretreatment method provided by the present invention can efficiently separate and purify the antimony element in the high-salt matrix and realize high-precision antimony isotope analysis. The method mixes the sample solution with a hydride reducing agent, and introduces them into a hydride generating gas-liquid separator, and utilizes the hydride generating reaction to selectively generate antimony hydrogen gas, while the main matrix elements are retained in the waste liquid of the hydride generating module. At the same time, the antimony hydrogen is purged from the gas-liquid separator into a strong oxidizing solution by a carrier gas for oxidation capture and recovery. The recovered sample solution can further use a commercial thiol column to effectively separate trace interfering elements, ensuring that a multi-receiving cup inductively coupled plasma mass spectrometer can realize high-precision isotope analysis. The method is simple to operate and has high separation efficiency. It is suitable for effectively separating and purifying antimony elements in high-salt samples and samples with low antimony content.

[0026] (2) Combining the separation of major elements by hydride generation and the separation of trace elements by column purification can effectively purify the antimony element in complex matrix sample solutions and achieve high-precision antimony isotope analysis of samples in high-salt environments with low antimony concentrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the separation and purification device provided by the present invention.

[0028] In the figure: 1. hydride generating unit; 11. hydride reducing agent reagent bottle; 12. sample bottle; 13. peristaltic pump; 2. gas-liquid separation unit; 21. carrier gas pipeline; 3. gas trap; 4. waste liquid bottle. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention clearer, embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0030] The method for expressing antimony isotopes in the present invention is

[0031] δ 123 Sb=[( 123 Sb / 121 Sb) sample / ( 123 Sb / 121 Sb) standard -1]×1000. In the formula, “sample” is the

[0032] The standard solution used in the embodiment of the present invention is the Spex-Sb standard solution produced by Spex Certiprep Company in the United States.

[0033] The pretreatment method for detecting antimony isotopes in high-salt samples provided by the present invention is suitable for high-salt samples with an antimony content in the range of 0.01 μg kg -1 ~10 μg kg -1, the salinity range is 10% to 35%. This method mixes the sample solution with a hydride reducing agent, and jointly introduces them into a hydride generating unit and a gas-liquid separation unit, and utilizes the hydride generating reaction to selectively generate antimony hydrogen gas, while the main matrix elements are retained in the waste liquid of the hydride generating module. At the same time, antimony hydrogen is purged from the gas-liquid separator into a strong oxidizing solution by a carrier gas for oxidation capture and recovery. The recovered sample solution can be further separated by column chromatography separation and purification technology to effectively separate trace interfering elements, ensuring that the multi-receiving cup inductively coupled plasma mass spectrometer can achieve high-precision isotope analysis. Specifically, the following steps are included:

[0034] S1. Pretreatment of high-salt samples

[0035] The high-salinity samples include seawater samples and mudstone sediment samples;

[0036] Acidifying and pre-reducing the seawater sample so that antimony in the seawater sample exists in a trivalent form, thereby obtaining a first solution;

[0037] Alternatively, the mudstone sediment sample is digested and pre-reduced so that the antimony in the digested solution exists in a trivalent form, thereby obtaining a second solution;

[0038] S2. Separation and purification of antimony elements

[0039] The trivalent antimony element in the first solution or the second solution is converted into gaseous antimony hydrogen by using hydride generation technology, the gaseous antimony hydrogen is separated out by gas-liquid separation, and is captured by using a capture liquid to obtain a third solution;

[0040] S3, evaporate the third solution obtained in step S2 at 90°C to 95°C and then redissolve it. Repeat the operation for several times and dissolve the dry sample in a solution with a concentration of 0.5 mol L -1 A 10% potassium iodide solution is added to the hydrochloric acid solution to fully pre-reduce the antimony for 5 to 6 hours to obtain a fourth solution;

[0041] S4. The fourth solution obtained in step S4 is eluted, enriched and purified by column chromatography separation and purification technology, and the eluate is collected and dried to obtain a sample after pretreatment.

[0042] It should be noted that the solution fluid driving method in the above technical scheme can be either a peristaltic pump or a syringe pump, with no restrictions on specifications and brands, assisted by a peristaltic pump tube of corresponding diameter. The material of the peristaltic pump tube is usually acid- and alkali-resistant silicone tube or fluororubber tube, with no restrictions on brand, diameter and wall thickness.

[0043] In some embodiments, a separation and purification device can be used to separate and purify the antimony element, such as Figure 1As shown, the separation and purification device includes a hydride generating unit 1, a gas-liquid separation unit 2 and a gas trap 3 which are sequentially connected through pipelines. The hydride generating unit 1 includes a hydride reducing agent reagent bottle 11, a sample bottle 12 and a peristaltic pump 13. The hydride reducing agent reagent bottle 11 and the sample bottle 12 are respectively connected to the inlet of the peristaltic pump 13. The gas-liquid separation unit 2 is a U-shaped gas-liquid separator. The inlet of the U-shaped gas-liquid separator is connected to the outlet of the peristaltic pump 12. The gas outlet of the U-shaped gas-liquid separator is connected to the gas trap 3. The liquid outlet of the U-shaped gas-liquid separator is connected to a waste liquid bottle 4. The inlet of the U-shaped gas-liquid separator is connected to a carrier gas pipeline 21, and the carrier gas pipeline carries a high-purity inert gas.

[0044] In some embodiments, the gas collector 3 is a corrosion-resistant container that is resistant to acid and alkali corrosion and can hold a strong oxidizing solution. The material is usually a closed container made of quartz glass or polytetrafluoroethylene. There are two connecting ports. The gas enters from the inlet and flows out from the outlet after passing through the capturing liquid.

[0045] In some embodiments, the type of hydride reducing agent filled in the hydride reducing agent reagent bottle 11 is not limited, and it only needs to have the ability to provide solution hydrogen free radicals, such as potassium borohydride or sodium borohydride.

[0046] In some embodiments, enrichment and purification can be achieved by various means, including but not limited to thiol cotton fiber column, cellulose powder column, Cleanert SH thiol resin column.

[0047] The following describes it in detail with reference to specific embodiments.

[0048] The separation and purification device structure used in the following examples is as follows: Figure 1 As shown, the inner diameters of the peristaltic pump tubes for introducing the sample solution and the reducing agent are 1.0 mm and 2.0 mm, respectively, and the wall thickness is 0.5 mm. The gas-liquid separation device of the hydride generation module is a classic U-shaped gas-liquid separator with a frosted cone inside. The frosted cone bottom diameter is 1 cm and the height is 8 cm. The inner diameter of the U-shaped tube is 1.5 cm, the total height is 10 cm, the width is 5 cm, and the total volume of the gas-liquid separator is 50 mL. The carrier gas type is high-purity argon (>99.999%), and the flow rate is 300 mL min -1 The capture module is a gas capture bottle with an inlet pipe and an outlet pipe, the volume specification is 15mL, and the capture liquid is 10mL of reverse aqua regia.

[0049] The column chromatography separation technique for the trace element separation part used a commercial thiol chemically bonded silica gel packed column (Cleaner SH, Tianjin Bona Aijiela Technology Co., Ltd., China, pore size: 60°A, particle size: 40 mm, specification: 0.25 g / 6 mL, length: 60 mm, inner diameter: 10 mm, surface area: 490 m 2 g-1 .

[0050] The antimony isotope composition was determined using a Nu Plasma-II multi-collector inductively coupled plasma mass spectrometer produced by the British Nu Company, with an ICP power of 1300 W and a plasma gas argon flow rate of 13.0 L min -1 , auxiliary gas argon flow rate 0.85Lmin -1 The sampling cone and the intercepting cone are made of nickel. The injection system is an ApexΩ membrane desolvation injection device from ESI, and the sample introduction flow rate is 100 μL min -1 , spray chamber temperature 100℃, membrane desolvation temperature 140℃, argon purge flow rate 2.9L min -1 . The data acquisition parameter settings of MC-ICP-MS are: automatic peak search mode, magnetic field stabilization time 10 seconds, signal integration time 10 seconds, acquisition times 40 times, and single analysis time 10+10×40=410 seconds. The Nu Plasma-II multi-collector inductively coupled plasma mass spectrometer has a total of 16 Faraday cups. Antimony isotope analysis uses nine Faraday cups, including H7, H6, H5, H4, H3, Ax, L2, L4, and L5, to collect data simultaneously. 125 Te, 123 Sb, 122 Sn, 121 Sb, 120 Sn, 117 Sn, 115 In, 113 In, 111 The ion signal of Cd. The analysis procedure uses the sample-standard bracketing (SSB) method combined with the indium (In) internal standard method to correct the isotope fractionation produced by the instrument itself during the test process.

[0051] Example 1

[0052] This embodiment provides a method for detecting antimony isotopes in seawater.

[0053] The specific steps include:

[0054] (1) Acidification and pre-reduction of seawater samples: 25 mL of high-purity hydrochloric acid solution and 2.5 g of potassium iodide were added to 475 mL of seawater sample to acidify and pre-reduce the sample solution for 5 hours, so that antimony exists completely in trivalent form; the specific seawater samples are seawater from Laoshan Bay, Lingshan Bay, western Pacific Ocean, and standard simulated seawater with known antimony isotope composition, the salt content in the samples is about 3.5%, the antimony content in Laoshan Bay seawater is about 0.28 ng / mL, the antimony content in Lingshan Bay seawater is about 0.47 ng / mL; the antimony content in western Pacific Ocean seawater is about 0.18 ng / mL, and the antimony content in simulated seawater is about 0.1 ng / mL.

[0055] (2) The sample solution and hydride reducing agent were respectively heated at 20 mL min -1 and 3 mL min -1 The hydride reducing agent was selected as a 1.0% potassium borohydride solution, and the waste pump was always pumped at a rate of 23 mL min -1 to 25mL min -1 The waste liquid is continuously discharged from the gas-liquid separator at a rate of 100%. After the sample solution is completely introduced, the carrier gas is maintained for 5 minutes to ensure that all the antimony hydrogen in the U-shaped gas-liquid separator is transported to the capture liquid and captured completely. The total time is about 30 minutes.

[0056] (3) Transfer 10 mL of the aqua regia capture solution to a 15 mL polytetrafluoroethylene sample cup, evaporate to dryness at 90°C to 95°C, and then redissolve. Repeat this process three times. Finally, dissolve the sample in 1.9 mL of 0.5 mol L -1 of hydrochloric acid solution.

[0057] (4) 0.1 mL was taken out and placed in a 3 mL polytetrafluoroethylene sample cup. After being evaporated to dryness at 90°C to 95°C, the sample was re-dissolved in 3 mL of 2% nitric acid. The element recovery rate of the major matrix elements in the seawater sample after HG purification was tested using an inductively coupled plasma spectrometer (ICP-OES). As shown in Table 1, the recovery rates of Na, K, Ca, and Mg in the seawater sample were close to 0, indicating that the major matrix elements were effectively removed.

[0058] (5) At the same time, 0.2 mL of 10% potassium iodide-ascorbic acid mixed solution was added to the remaining 1.8 mL of sample solution in (4) to fully pre-reduce Sb for 5 hours. A commercial thiol chemically bonded silica gel column was used to separate Sb from interfering elements such as Cd, In, As, and Sn. First, 5 mL of 6 mol L -1 The column was cleaned with 6 mL of 0.5 mol L -1Adjust the column environment to the loading acidity with 10% hydrochloric acid. Load 2 mL of sample solution onto the column and use 11 mL of 2.5 mol L -1 Finally, 7 mL of 6 mol L -1 The antimony element retained in the hydrochloric acid elution column was collected in a 15 mL polytetrafluoroethylene sample cup and evaporated to dryness at 90°C to 95°C, and then re-dissolved in 2 mL of 2% nitric acid.

[0059] (6) The recovery rates of the column purification and separation process of Laoshan Bay seawater, Lingshan Bay seawater, western Pacific Ocean seawater and standard simulated seawater with known antimony isotope composition were analyzed by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). As shown in Tables 2 and 3, the second step of column purification can effectively remove Cd, In, As, and Sn from the sample solution, and the recovery rates of the four elements are close to 0%, while the antimony recovery rate reaches 97.9% to 101.2%.

[0060] (7) Dilute the sample solution to a concentration of 100 to 150 ng mL -1 , using a multi-collector inductively coupled plasma mass spectrometer to analyze the antimony isotope composition of the sample, simulating the δ 123 Sb test value and reference value (δ 123 Sb=0‰) and the δ 123 The Sb test accuracy is better than 0.02‰, indicating that this method can obtain accurate and high-precision seawater antimony isotope composition data (as shown in Table 3).

[0061] Table 1. Element recovery data of major matrix elements in seawater samples after HG purification

[0062]

[0063] Table 2. Element recovery data of trace matrix elements in seawater samples after column purification

[0064]

[0065] Table 3. Recovery rate of antimony in the whole purification process and antimony isotope test results in seawater samples

[0066]

[0067] Example 2

[0068] This embodiment provides a method for detecting antimony isotopes in a matrix complex sediment sample with a low antimony content.

[0069] The specific steps are as follows:

[0070] (1) Sediment digestion: Accurately weigh three 1.0-1.2g ground mudstone sediment samples (mudstone sediment 1, mudstone sediment 2 and mudstone sediment 3) in a 50mL polytetrafluoroethylene sample bomb. Each sample was processed three times in parallel. 10mL concentrated nitric acid and 10mL hydrofluoric acid were added. The sample bomb was sealed with a steel sleeve and placed in an oven and heated at 190℃ for 48 hours until the sediment was completely digested and the solution was clear. Evaporate and redissolve at 90℃-95℃, and the operation was repeated three times. Finally, the sample was dissolved in 5mL of 5% hydrochloric acid solution, and 0.1g potassium iodide was added to it for pre-reduction for 5 hours. At this time, the salt content in the three mudstone sediment samples was about 20%, the antimony content in mudstone sediment 1 was about 0.27μg / mL, the antimony content in mudstone sediment 2 was about 0.10μg / mL, and the antimony content in mudstone sediment 3 was about 0.08μg / mL.

[0071] (2) Turn on the solution pumping device and the carrier gas, pump 5 mL of sample solution and 5 mL of reducing agent into the gas-liquid separator, and keep the waste pump in the closed state, so that the solution stays in the gas-liquid separator to fully react and release antimony hydrogen. The difference from Example 1 is that the sample solution is 5 mL of solution obtained by digesting 1 g of sediment sample. Since there is a high concentration of transition metal elements in geological samples, which affects the chemical reaction rate of hydride generation, 5 mL of sample solution and 5 mL of hydride reducing agent solution are heated at 1 mL min -1 The rate of 1.5 wt % was introduced into the U-shaped gas-liquid separator within 5 minutes for a long reaction period of 90 minutes, ensuring that antimony was completely separated from the sample solution.

[0072] (3) After 90 minutes, start the waste pump to discharge the waste liquid in the gas-liquid separator, and at the same time start the solution pumping device to pump in 5% high-purity hydrochloric acid and reducing agent to clean the device.

[0073] (4) Transfer 10 mL of the aqua regia capture solution to a 15 mL polytetrafluoroethylene sample cup, evaporate to dryness at 90°C to 95°C, and then redissolve. Repeat this process three times. Finally, dissolve the sample in 1.9 mL of 0.5 mol L -1 of hydrochloric acid solution.

[0074] (5) 0.1 mL was taken out and placed in a 3 mL polytetrafluoroethylene sample cup. After evaporation at 90°C to 95°C, the sample was re-dissolved in 3 mL of 2% nitric acid. The element recovery rate of the major matrix elements in the sample after HG purification was tested using an inductively coupled plasma spectrometer (ICP-OES). As shown in Table 4, the recovery rates of eight major matrix elements, Na, K, Ca, Mg, Fe, Mn, Al, and Ti in the mudstone sediment sample were close to 0, indicating that the major matrix elements in the mudstone sediment were effectively removed.

[0075] (6) At the same time, 0.2 mL of 10% potassium iodide solution was added to the remaining 1.8 mL of the sample solution in (5) to fully pre-reduce the antimony for another 5 hours.

[0076] (7) After the main matrix elements were separated by hydride generation, the sample solution was further separated from the interfering elements such as antimony and Cd, In, As, and Se using a commercial thiol chemically bonded silica gel column. First, 5 mL of 6 mol L -1 The column was cleaned with 6 mL of 0.5 mol L -1 Adjust the column environment to the loading acidity with 10% hydrochloric acid. Load 2 mL of sample solution onto the column and use 11 mL of 2.5 mol L -1 Finally, 7 mL of 6 mol L -1 The antimony element retained in the hydrochloric acid elution column was collected in a 15 mL polytetrafluoroethylene sample cup and evaporated to dryness at 90°C to 95°C, and then re-dissolved in 2 mL of 2% nitric acid.

[0077] (8) ICP-QMS was used to analyze the element recoveries of the column purification process of the three mudstone sediments. As shown in Tables 5 and 6, the second step of column purification can effectively remove the interfering elements in the mudstone sediment samples. The recoveries of the four elements Cd, In, As, and Sn are all close to 0%, and the antimony recovery rate reaches 97.5% to 100.8%.

[0078] (9) Dilute the sample solution to a concentration of 100 to 150 ng mL -1 The antimony isotope composition of the samples was analyzed using a multi-collector inductively coupled plasma mass spectrometer. The δ 123 The Sb test accuracy is better than 0.02‰, which can effectively identify small differences in the antimony isotope composition of mudstone sediments (as shown in Table 6).

[0079] Table 4. Element recovery data of major matrix elements in mudstone sediment samples after HG purification

[0080]

[0081] Table 5. Element recovery data of major matrix elements in mudstone sediment samples after HG purification

[0082]

[0083] Table 6. Antimony recovery and antimony isotope test results of the whole purification process in mudstone sediment samples

[0084]

[0085] For matters not mentioned above, the prior art applies.

[0086] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make modifications or supplements to the described specific embodiments or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above implementations based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A pretreatment method for detecting antimony isotopes in high-salt samples, characterized in that: The antimony content in the high-salt sample ranged from 0.01 μg kg -1 ~10 μg kg -1 , the salinity range is 1% to 35%, and the pre-treatment method specifically comprises the following steps: S1. Pretreatment of high-salt samples The high-salinity samples include seawater samples and mudstone sediment samples; Acidifying and pre-reducing the seawater sample so that antimony in the seawater sample exists in a trivalent form, thereby obtaining a first solution; Alternatively, the mudstone sediment sample is digested and pre-reduced so that the antimony in the digested solution exists in a trivalent form, thereby obtaining a second solution; S2. Separation and purification of antimony elements The trivalent antimony element in the first solution or the second solution is converted into gaseous antimony hydrogen by using hydride generation technology, the gaseous antimony hydrogen is separated out by gas-liquid separation, and is captured by using a capture liquid to obtain a third solution; S3, evaporate the third solution obtained in step S2 at 90°C to 95°C and then redissolve it, repeat the operation several times, and dissolve the dry sample in a solution with a concentration of 0.5 to 0.55 mol L -1 A 10-12% potassium iodide solution is added to the hydrochloric acid solution to fully pre-reduce the antimony for 5-6 hours to obtain a fourth solution; S4. The fourth solution obtained in step S4 is eluted, enriched and purified by column chromatography separation and purification technology, and the eluate is collected and dried to obtain a sample after pretreatment.

2. The pre-treatment method according to claim 1, characterized in that: In step S1, the pretreatment process of the seawater sample is to add concentrated hydrochloric acid solution to the seawater sample so that the volume proportion of hydrochloric acid in the sample is 5-5.5%, and add 1g-10g of potassium iodide solid powder to acidify and pre-reduce the seawater sample solution for 5-6 hours to obtain a first solution.

3. The pre-treatment method according to claim 1, characterized in that: In step S1, the digestion process of the mudstone sediment sample is to add the ground mudstone sediment sample into a high-pressure digestion tank, add concentrated nitric acid and hydrofluoric acid, keep it at 180-190° C. for at least 48 hours until the sediment is completely digested and the solution is clear, then evaporate and redissolve, and repeat the operation for multiple times to obtain a dry product.

4. The pre-treatment method according to claim 3, characterized in that: In step S1, the pre-reduction process of the mudstone sediment sample is to dissolve the dried material in a 5-6% hydrochloric acid solution, and add a 10-12% potassium iodide solution by volume for pre-reduction for 5-6 hours to obtain a second solution.

5. The pre-treatment method according to claim 1, characterized in that: In step S2, a separation and purification device is used to separate and purify the antimony element. The separation and purification device includes a hydride generating unit, a gas-liquid separation unit and a gas collector which are connected in sequence through pipelines. The hydride generating unit includes a hydride reducing agent reagent bottle, a sample bottle and a peristaltic pump. The hydride reducing agent reagent bottle and the sample bottle are respectively connected to the inlet of the peristaltic pump. The gas-liquid separation unit is a U-shaped gas-liquid separator. The inlet of the U-shaped gas-liquid separator is connected to the outlet of the peristaltic pump, the gas outlet of the U-shaped gas-liquid separator is connected to the gas collector, and the liquid outlet of the U-shaped gas-liquid separator is connected to a waste liquid bottle.

6. The pre-treatment method according to claim 5, characterized in that: The inlet of the U-shaped gas-liquid separator is connected with a carrier gas pipeline, and the carrier gas pipeline contains inert gas.

7. The pre-treatment method according to claim 5, characterized in that: The gas trap is filled with a trapping liquid, which is a strong oxidizing solution.

8. The pre-treatment method according to claim 5, characterized in that: The hydride reducing agent reagent bottle is filled with potassium borohydride or sodium borohydride solution.

9. The pre-treatment method according to claim 1, characterized in that: In step S4, the chromatographic column used in the column chromatography separation and purification technology includes a thiol cotton fiber column, a cellulose powder column or a Cleanert SH thiol resin column.

10. A method for detecting antimony isotopes in high-salt samples, characterized in that: The method comprises the following steps: after pre-treating the high-salt sample according to the pre-treatment method described in any one of claims 1 to 9, detecting the antimony isotope by using a multi-receiving cup inductively coupled plasma mass spectrometer.

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