A Complete Dissolution Method of Black Shale by Carius Tube

Abstract

The present application provides a complete digestion method for black shale samples using a Carius tube, which includes: weighing a black shale sample and adding it to a digestion tank, adding HF to the digestion tank and allowing it to stand for digestion to obtain a pre-digested solution; heating the pre-digested solution, adding HCl for acid expulsion when the pre-digested solution is heated to near dryness, and repeating the acid expulsion multiple times to remove HF; adding HCl to the pre-digested solution after acid expulsion, completely transferring the pre-digested solution into a Carius tube, adding a mixed diluent and a digestion reagent to the Carius tube, and performing complete digestion with the Carius tube sealed to obtain a sample digestion solution; separating Re and Os in the sample digestion solution by direct distillation; enriching and purifying Re in the remaining solution after distillation and Os in the distillation absorption solution to obtain Re samples and Os samples to be measured respectively. This method can effectively achieve complete digestion of samples of organic-rich sedimentary rocks such as black shale while ensuring almost no loss of Re and Os.

Description

Technical Field

[0001] The disclosed embodiments belong to the technical field of geological rock dissolution analysis, and specifically relate to a black shale Carius tube complete dissolution method. Background Art

[0002] Black shale is a representative geological sample of organic-rich sedimentary rocks. It is widely found in sedimentary strata and is also an important research object for sedimentary strata dating. In the formation process of organic-rich sedimentary rocks such as black shale, the affinity of Re and Os in seawater for organic matter enables them to be preserved in organic-rich sedimentary rocks such as black shale along with organic matter during the process of sedimentation and diagenesis. This part of Re-Os closely related to organic matter components in this closed system is 187 Re forms daughters through β-radiation 187 Os and starts the Re-Os isotope timer. In addition, there are Re and Os in the clastic (non-organic) component or sulfide component in organic-rich sedimentary rocks such as black shale. This part of Re and Os is considered to be incapable of Re-Os isotope dating in current research, and the dissolution of this part of Re and Os in Re-Os isotope analysis has a small impact on the accuracy of Re-Os isochron age determination.

[0003] At present, in the Re-Os isotope analysis of black shale, the sample powder is weighed and added to the Carius tube, and the Re-Os isotope diluent and sample dissolving reagent are added to the Carius tube under freezing conditions. The mouth of the Carius tube is sealed under an acetylene flame, placed at room temperature, and then put into a steel sleeve, and dissolved in an oven at 220℃~230℃ for 24 hours. After dissolving the sample, the mouth of the Carius tube is opened under freezing conditions, and Re and Os are separated by direct distillation or extraction. Re can be further enriched and purified by acetone extraction or anion exchange, and Os is enriched and purified by micro-distillation technology. In the dissolution process, the dissolution reagents currently used include HCl-HNO3-H2O2 mixed solution (reverse aqua regia system), H2SO4-CrO3 mixed solution, H2SO4-Na2CrO4 mixed solution, and HNO3-H2O2 mixed solution. None of the four dissolution reagents can completely dissolve organic-rich sedimentary rock samples such as black shale. The samples that are not completely dissolved generally contain minerals such as silicate phases, sulfide particles, and feldspar. Different amounts of Re and Os will be encapsulated and mixed in them, and they have isotope ratio characteristics different from those of organic matter components. The Re-Os isotope data obtained cannot confirm the dissolution degree of black shale samples by different dissolution reagents, resulting in great controversy over the dissolution degree of Re and Os from organic matter sources by different dissolution reagents, and at the same time, it is impossible to obtain the potential geological information represented by the Re-Os isotope composition in non-organic matter components.

[0004] In view of the above problems, it is necessary to propose a method for complete dissolution of black shale in a Carius tube with reasonable design and effective solution to the above problems. Summary of the Invention

[0005] An embodiment of the present disclosure aims to solve at least one of the technical problems existing in the prior art, and provides a method for complete dissolution of black shale in a Carius tube.

[0006] An embodiment of the present disclosure provides a method for complete dissolution of black shale in a Carius tube, which

[0007] includes the following steps:

[0008] Step 1: Accurately weigh 0.1 g to 0.2 g of black shale sample and add it to a dissolution tank. Add 1 mL to 2 mL of HF to the dissolution tank and let it stand for dissolution to pre-dissolve the silicate phase in the black shale sample, obtaining a pre-dissolved solution.

[0009] Step 2: Heat the pre-dissolved solution to 90 °C to 150 °C. When the pre-dissolved solution is heated to near dryness, add 1 mL to 2 mL of HCl to drive off the acid, and repeat the acid driving process multiple times to drive off the HF in the pre-dissolved solution.

[0010] Step 3: Add 1 mL to 2 mL of HCl to the pre-dissolved solution after acid driving. Completely transfer the pre-dissolved solution in the dissolution tank into a Carius tube, and add an accurately weighed Re-Os mixed diluent and a dissolution reagent to the Carius tube for complete sealed dissolution in the Carius tube, obtaining a sample dissolution solution.

[0011] Step 4: Separate Re and Os in the sample dissolution solution by direct distillation method. Re is retained in the distillation residual solution, and Os is retained in the distillation absorption solution.

[0012] Step 5: Further enrich and purify Re in the distillation residual solution and Os in the distillation absorption solution to obtain a Re sample and an Os sample to be measured respectively.

[0013] Optionally, the complete sealed dissolution in the Carius tube in Step 3 includes:

[0014] Completely transfer the pre-dissolved solution in the dissolution tank into a Carius tube under freezing conditions;

[0015] Use 1.5 mL to 2 mL of HCl purified by secondary sub-boiling distillation to completely transfer the accurately weighed 185 Re -190Mix the Os diluent in the Carius tube. After freezing, add 5 mL to 6 mL of HNO3 purified by secondary sub-boiling distillation and 1 mL to 2 mL of H2O2, and then freeze again.

[0016] Optionally, for the complete dissolution and sample digestion in the Carius tube in step three, it further includes:

[0017] Use an acetylene flame to melt and seal the mouth of the frozen Cairus tube. Put on a stainless steel sleeve and place it in an oven. Heat at 220 °C for 12 hours, then heat at 230 °C for 12 hours, and then cool to room temperature.

[0018] Optionally, in step four, to separate Re and Os in the sample dissolution solution by the direct distillation method, with Re remaining in the distillation residue solution and Os remaining in the distillation absorption solution, it includes:

[0019] Open the mouth of the Cairus tube using an acetylene flame under freezing conditions. After returning to room temperature, separate Re and Os by the direct distillation method. Among them, Re remains in the distillation residue solution, and Os remains in the distillation absorption solution of 1:1 HBr:H2O.

[0020] Optionally, in step five, to further enrich and purify Re in the distillation residue solution to obtain a Re sample to be measured, it includes:

[0021] Evaporate the acid from the distillation residue solution on a hot plate at 160 °C to 180 °C until dry;

[0022] Enrich and purify Re in the residual solution after acid evaporation by the acetone extraction method;

[0023] Place the acetone phase containing the Re sample to be measured in a Teflon vial. Nitrify the remaining organic phase with HNO3 and H2O2 at 110 °C to 130 °C. After evaporation to dryness, perform high-precision determination of Re by multi-collector inductively coupled plasma mass spectrometry.

[0024] Optionally, in step five, to further enrich and purify Os in the distillation absorption solution to obtain an Os sample to be measured, it includes:

[0025] Further enrich and purify Os in the distillation absorption solution by the micro-distillation method, and perform high-precision determination of Os by thermal surface ionization mass spectrometry.

[0026] Optionally, in step one, accurately weigh 0.1 g to 0.2 g of black shale sample and add it to the sample dissolution tank, and add 1 mL to 2 mL of HF to the sample dissolution tank, including:

[0027] Accurately weigh 0.1 g to 0.2 g of the black shale sample and add it to an F4 micro round-bottom sample dissolution tank;

[0028] Add 1 mL to 2 mL of MOS grade HF to the sample dissolution tank.

[0029] The complete sample dissolution method of black shale Carius tube in the embodiment of the present disclosure realizes the complete sample dissolution of black shale by pre-dissolving the black shale sample with HF and then performing sealed sample dissolution in the Carius tube. Among them, HCl needs to be added as a reducing agent to protect Os during the pre-dissolution and acid evaporation of black shale, so that it will not be oxidized to OsO4 and cause loss during this process. Using this sample dissolution method can effectively realize the complete sample dissolution of organic-rich sedimentary rock samples such as black shale while ensuring almost no loss of Re and Os, and this method has an extremely low full-process blank, and the Re and Os data results from all sources in the obtained black shale are reliable. This sample dissolution method provides a new solution for evaluating and comparing the dissolution degree and dissolution characteristics of Re and Os from different sources in black shale samples under different sample dissolution medium conditions by Carius tube sample dissolution, and provides a Re-Os isotope analysis technology for revealing the potential geological information of Re and Os from different sources in black shale, improving the accuracy of Re-Os isotope analysis data of black shale, reducing the dispersion degree of Re-Os isochrones, and improving the accuracy of Re-Os isochrone ages. Description of the Drawings

[0030] Figure 1 It is a schematic flow chart of a complete sample dissolution method of black shale Carius tube in an embodiment of the present disclosure;

[0031] Figure 2 It is a schematic diagram of the process of a complete sample dissolution method of black shale Carius tube in an embodiment of the present disclosure. Detailed Embodiments

[0032] To enable those skilled in the art to better understand the technical solutions of the embodiments of the present disclosure, the following further describes the embodiments of the present disclosure in detail with reference to the drawings and specific embodiments.

[0033] In the existing black shale sample dissolution methods, the following technical problems exist:

[0034] 1) Since the Cairus tube is made of high borosilicate glass and is easily corroded by HF, it is impossible to directly add HF to the Carius tube to achieve complete sample dissolution of organic-rich sedimentary rock samples such as black shale in different sample dissolution media.

[0035] 2) Due to the lack of data on the Re, Os content and isotope ratio obtained from the complete sample dissolution of black shale, it is impossible to accurately evaluate the dissolution degree of Re and Os elements from organic matter sources in organic-rich sedimentary rock samples such as black shale during the Carius tube sample dissolution process.

[0036] 3) Since Os will be oxidized to OsO4 and volatilize and be lost in oxidizing reagents, while Re does not have such characteristics, the Re content can be obtained through traditional total rock dissolution techniques, but accurate Os content and Os isotope ratio data cannot be obtained.

[0037] In summary, there is no reported method for completely dissolving black shale samples and for Re-Os isotope analysis.

[0038] In view of the technical problems existing in the prior art, such as Figure 1 As shown, the embodiment of the present disclosure provides a method S100 for completely dissolving black shale in a Carius tube, and the method includes:

[0039] S110, Step 1, accurately weigh 0.1 g to 0.2 g of black shale sample and add it to a dissolution tank, add 1 mL to 2 mL of HF to the dissolution tank and let it stand for dissolution to pre-dissolve the silicate phase in the black shale sample to obtain a pre-dissolved solution.

[0040] Specifically, in this embodiment, preferably, as Figure 2 shown in a, accurately weigh 0.1 g of black shale sample into an F4 micro round-bottom dissolution tank, add 1 mL of MOS-grade HF to the dissolution tank, as Figure 2 shown in b, let it stand for 24 hours for dissolution. During the standing process, HF will react with the silicate in the black shale to generate volatile SiF4, realizing the pre-dissolution of the silicate phase in the black shale sample to obtain a pre-dissolved solution.

[0041] S120, Step 2, heat the pre-dissolved solution to 90 °C to 150 °C, add 1 mL to 2 mL of HCl for acid expulsion when the pre-dissolved solution is heated to near dryness, and repeat the acid expulsion multiple times to drive away HF in the pre-dissolved solution.

[0042] Specifically, in this embodiment, preferably, as Figure 2 shown in c, heat the dissolution tank on a hot plate at 150 °C, add 1 mL of HCl purified by secondary sub-boiling distillation for acid expulsion when the pre-dissolved solution is heated to near dryness. Repeat the acid expulsion 3 times and then heat to near dryness to drive away HF in the pre-dissolved solution.

[0043] During the above acid expulsion process, first heat HF to near dryness to drive away most of the remaining HF. Since HF is a reducing acid, the near-dry state can ensure that Os in the sample is not lost. Then add HCl to drive away the remaining HF. Since the boiling point of HF is much lower than that of HCl, after several times, HF will be driven away first, while HCl will be retained, and the sample is also transformed into an HCl medium.

[0044] In this embodiment, the pre-dissolved solution is heated on a hot plate at 150 °C. Unreacted HF and the reaction product SiF4 volatilize under the heating condition. Meanwhile, HCl is added to ensure that Os in the sample is in a reduced state and will not be lost under the heating condition, resulting in the deviation of the obtained Os content and isotope ratio results from the true values.

[0045] S130. Step 3: Add 1 mL to 2 mL of HCl to the pre-dissolved solution after acid evaporation. Completely transfer the pre-dissolved solution in the sample dissolution tank into a Carius tube, and add an accurately weighed Re-Os mixed diluent and a sample dissolution reagent to the Carius tube, and perform complete dissolution in the sealed Carius tube to obtain a sample dissolution solution.

[0046] In this embodiment, preferably, as Figure 2 shown in d, the specific process of step 3 includes the following:

[0047] First, add 1 mL of HCl purified by secondary sub-boiling distillation to the pre-dissolved solution after acid evaporation, and completely transfer the pre-dissolved solution in the sample dissolution tank into a Carius tube under freezing conditions through a glass funnel.

[0048] Secondly, use 1.5 mL to 2 mL of HCl purified by secondary sub-boiling distillation to completely transfer the accurately weighed 185 Re -190 Os mixed diluent into the Carius tube. After freezing, add 5 mL to 6 mL of HNO3 purified by secondary sub-boiling distillation and 1 mL to 2 mL of H2O2, and freeze.

[0049] Specifically, use 1.5 mL of HCl purified by secondary sub-boiling distillation to completely transfer the accurately weighed 185 Re -190 Os mixed diluent into the Carius tube. After freezing, add 6 mL of HNO3 purified by secondary sub-boiling distillation and 1 mL of MOS-grade H2O2, and freeze to dissolve the organic phase in the black shale sample, thereby achieving complete dissolution of the black shale sample. That is to say, a total of 2.5 ml of HCl is used, of which 1 ml is used to transfer the pre-dissolved solution and 1.5 ml is used to transfer the mixed diluent.

[0050] In this embodiment, HCl, HNO3, and H2O2 are required for sample dissolution in the Carius tube. When HCl and HNO3 are added in a ratio of about 1:3, they can form a reverse aqua regia system, which has a good dissolution effect on the sample. The addition of H2O2 can increase the oxidizing property of the mixed reagent and improve the signal amount of Os. HCl has a reducing property. The sample pretreated with HF contains Os, and the use of HCl for transfer can ensure that Os is not lost during the transfer process.

[0051] Next, use an acetylene flame to melt and seal the opening of the Cairus tube after it has been frozen solid. Put on a stainless steel sleeve and place it in an oven. Heat it at 220 °C for 12 hours, then at 230 °C for 12 hours, and then cool it to room temperature.

[0052] S140, Step Four: Separate Re and Os in the sample dissolution solution by direct distillation. Re remains in the distillation residue solution, and Os remains in the distillation absorption solution.

[0053] Specifically, as Figure 2 shown in e, open the opening of the Cairus tube with an acetylene flame under freezing conditions, and after returning to room temperature, separate Re and Os by direct distillation. Among them, Re remains in the distillation residue solution, and Os remains in the distillation absorption solution of 1:1 HBr:H2O.

[0054] S150, Step Five: Further enrich and purify Re in the distillation residue solution and Os in the distillation absorption solution to obtain Re samples and Os samples to be measured respectively.

[0055] Among them, further enriching and purifying Re in the distillation residue solution in Step Five to obtain a Re sample to be measured includes:

[0056] Evaporate the acid in the distillation residue solution to dryness on a hot plate at 160 °C - 180 °C. Enrich and purify Re in the residual solution after acid evaporation by acetone extraction. Place the acetone phase containing the Re sample to be measured in a Teflon vial, nitrify the remaining organic phase with HNO3 and H2O2 at 110 °C - 130 °C, and after evaporation to dryness, perform high-precision determination of Re by multi-collector inductively coupled plasma mass spectrometry.

[0057] Specifically, as Figure 2 shown in f, in this embodiment, preferably, evaporate the distillation residue solution to dryness on a hot plate at 160 °C, add 10 ml of 10 mol / L NaOH solution purified by acetone, add 10 ml of acetone and extract twice and centrifuge, take out the acetone phase and place it in a 15 ml Teflon digestion vessel, evaporate to dryness at 110 °C, nitrify the remaining organic phase with HNO3 and H2O2 at 130 °C, and after evaporation to dryness, perform high-precision determination of Re by multi-collector inductively coupled plasma mass spectrometry.

[0058] Among them, further enriching and purifying Os in the distillation absorption solution in Step Five to obtain an Os sample to be measured includes:

[0059] Further enrich and purify Os in the distillation absorption solution by micro-distillation method, and perform high-precision determination of Os by thermal surface ionization mass spectrometry.

[0060] Specifically, asFigure 2 As shown in g, in this embodiment, preferably, transfer the Os distillation absorption solution to a 150 ml Teflon bowl, heat it on a hot plate at 150 °C until about 50 μL remains, and transfer it to the lid of a Teflon conical bottom vial. Evaporate it to dryness on a hot plate at 120 °C, cover it with 50 μL of the distilled and purified H2SO4-CrO3 mixed solution, add purified HBr 4 times as the Os absorption solution to the conical bottom part of the conical bottom vial, invert the conical bottom part on the lid and tighten it, wrap it with aluminum foil, place it on a hot plate, and keep it warm at 80 °C for 4 hours. Then, after cooling to room temperature, discard the H2SO4-CrO3 on the lid, right the conical bottom vial, tighten the lid, keep it warm in an oven at 80 °C for 2 hours, concentrate it, spot it on a high-purity Pt tape, and perform high-precision determination of Os using thermal surface ionization mass spectrometry.

[0061] The complete digestion method of black shale Carius tube in the embodiments of the present disclosure realizes the complete digestion of black shale by pre-digesting the black shale sample with HF and then performing sealed digestion in a Carius tube; wherein, during the pre-digestion and acid expulsion of black shale with HF, HCl needs to be added as a reducing agent to protect Os, so that it will not be oxidized to OsO4 and cause loss during this process. Using this complete digestion method can effectively realize the complete digestion of black shale and other organic-rich sedimentary rock samples while ensuring almost no loss of Re and Os, and this method has an extremely low overall process blank, and the obtained Re and Os data results from all sources in black shale are reliable; this digestion method provides a new solution for evaluating and comparing the dissolution degree and dissolution characteristics of Re and Os from different sources in black shale samples digested in a Carius tube under different digestion medium conditions, provides a Re-Os isotope analysis technology for revealing the potential geological information of Re and Os from different sources in black shale, improves the accuracy of Re-Os isotope analysis data of black shale, reduces the dispersion degree of Re-Os isochrones, and improves the accuracy of Re-Os isochrone ages.

[0062] The following specifically illustrates the specific process of the complete digestion method S100 of black shale Carius tube in the embodiments of the present disclosure through relevant embodiments.

[0063] In this embodiment, the average Re content of the internal monitoring sample B47 of black shale obtained by Carius tube digestion using the reverse aqua regia system, H2SO4-Na2CrO4, and H2SO4-CrO3 is 27.34 ng / g, and the average Os content is 0.7328 ng / g. 187 Re / 188 The average value of the Os ratio is 246.7. 187 Os / 188The average Os ratio is 2.980 (as shown in Table 1). There are no sulfide particles and few silicate detrital minerals in this internal monitoring sample, which can be used to evaluate the recovery rate of Re-Os isotope data obtained after the HF pretreatment process of the present invention.

[0064] Using the complete digestion method S100 of black shale Carius tube in the embodiments of the present disclosure, that is, the black shale is first pretreated with HF, and the HF in the sample is removed and converted into HCl medium under four temperature gradient conditions of 90 °C, 110 °C, 130 °C, and 150 °C, and then the Re-Os data of the internal monitoring sample of black shale obtained after digestion with Cairus tube are shown in Table 1. Compared with the Re-Os data obtained from the internal monitoring sample B47 of black shale in the laboratory obtained by digesting with Carius tube using three digestion media, under the four temperature gradient acid removal conditions, the recovery rate of Re content is greater than 97%, and the recovery rate of Os content is greater than 96%. Among them, when the acid removal temperature is 150 °C, the recovery rate of Os is the highest, which is 99.6%, confirming that Re and Os are hardly lost during the process of transferring the sample to the Cairus tube for digestion after HF pretreatment, and the influence on the test results is small. The highest acid removal temperature of HF acid can be set to 150 °C. The Re blank level of this method in the whole process is 0.0015 ng / g, and the Os blank level is 0.0009 ng / g.

[0065] Table 1 Re and Os content data and isotope ratio data of the internal monitoring sample of black shale obtained under different acid removal temperature conditions

[0066]

[0067] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the embodiments of the present disclosure. However, the embodiments of the present disclosure are not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the embodiments of the present disclosure, and these modifications and improvements are also regarded as the protection scope of the embodiments of the present disclosure.

Claims

1. A method for complete dissolution of black shale Carius tubes, characterized in that: The method comprises: Step 1, accurately weighing 0.1 g to 0.2 g of a black shale sample and adding it to a sample dissolving tank, adding 1 mL to 2 mL of HF to the sample dissolving tank and standing the sample to dissolve, so as to pre-dissolve the silicate phase in the black shale sample to obtain a pre-dissolved solution; Step 2, heating the pre-dissolved solution to 90°C to 150°C, adding 1 mL to 2 mL of HCl to remove the acid when the pre-dissolved solution is heated to nearly dry, and repeating the acid removal multiple times to remove the HF in the pre-dissolved solution; Step 3: Add 1 mL to 2 mL of HCl to the pre-dissolved solution after removing the acid, transfer the pre-dissolved solution in the sample dissolving tank completely into a Carius tube, add accurately weighed Re-Os mixed diluent and sample dissolving reagent to the Carius tube, close the Carius tube to completely dissolve the sample, and obtain a sample solution; Step 4: Separate Re and Os in the sample solution by direct distillation, wherein Re is retained in the distillation residual solution and Os is retained in the distillation absorption liquid; Step 5: further enrich and purify the Re in the distillation residual solution and the Os in the distillation absorption liquid to obtain Re samples and Os samples to be measured, respectively.

2. The method according to claim 1, characterized in that In step 3, the Carius tube is sealed and the sample is completely dissolved, including: The pre-dissolved solution in the sample dissolution tank is completely transferred into a Carius tube under a freezing condition; Use 1.5 mL to 2 mL of HCl purified by secondary sub-boiling distillation to completely transfer the accurately weighed 185 Re- 190 The Os mixed diluent is placed in the Carius tube, and after freezing, 5 mL to 6 mL of HNO3 purified by secondary sub-boiling distillation and 1 mL to 2 mL of H2O2 are added and frozen.

3. The method according to claim 2, characterized in that Step 3 is to seal the Carius tube and completely dissolve the sample, and also includes: The frozen Carius tube was melted and sealed with an acetylene flame, and then covered with a stainless steel sleeve. The tube was placed in an oven and heated at 220° C. for 12 hours and then at 230° C. for 12 hours, and then cooled to room temperature.

4. The method according to any one of claims 1 to 3, characterized in that: In step 4, Re and Os in the sample solution are separated by direct distillation, Re is retained in the distillation residual solution, and Os is retained in the distillation absorption liquid, comprising: The Carius tube is opened with an acetylene flame under freezing conditions, and after returning to room temperature, Re and Os are separated by a direct distillation method, wherein Re is retained in the distillation residual solution and Os is retained in the distillation absorption liquid of 1:1 HBr:H2O.

5. The method according to any one of claims 1 to 3, characterized in that: In step 5, the Re of the residual solution from the distillation is further enriched and purified to obtain a Re sample to be measured, comprising: The residual solution from the distillation was evaporated to dryness at 160° C. to 180° C. on a hot plate; The acetone extraction method was used to enrich and purify Re in the residual solution after removing the acid; The acetone phase containing the Re sample to be measured is placed in a Teflon vial, and the remaining organic phase is nitrated with HNO3 and H2O2 at 110°C to 130°C. After evaporation, Re is measured with high precision using a multi-collector plasma mass spectrometer.

6. The method according to any one of claims 1 to 3, characterized in that: In step 5, the Os in the distilled absorption liquid is further enriched and purified to obtain an Os sample to be measured, comprising: The Os in the distilled absorption liquid is further enriched and purified by a micro-distillation method, and the Os is determined with high precision by thermal surface ionization mass spectrometry.

7. The method according to any one of claims 1 to 3, characterized in that: In step 1, 0.1 g to 0.2 g of black shale sample is accurately weighed and added to a sample dissolving tank, and 1 mL to 2 mL of HF is added to the sample dissolving tank, including: Accurately weigh 0.1 g to 0.2 g of the black shale sample and add it into the F4 micro round bottom sample dissolution tank; 1 mL to 2 mL of MOS-grade HF is added to the sample dissolution tank.

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