Black shale Carius tube complete sample dissolving method

Abstract

The invention provides a black shale Carius pipe complete sample dissolving method which comprises the following steps: weighing a black shale sample, adding the black shale sample into a sample dissolving tank, adding HF into the sample dissolving tank, and standing to dissolve the sample to obtain a pre-dissolved solution; the pre-dissolved solution is heated, HCl is added for acid removal when the pre-dissolved solution is heated to be nearly dry, and acid removal is repeated for multiple times so that HF can be removed; adding HCl into the pre-dissolved solution after acid removal, completely transferring the pre-dissolved solution into a Carius tube, adding a mixed diluent and a sample dissolving reagent into the Carius tube, and carrying out Carius tube sealing and complete sample dissolving to obtain a sample dissolving solution; separating Re and Os in the sample dissolving solution by adopting a direct distillation method; and enriching and purifying Re in the distillation residual solution and Os in the distillation absorption liquid to respectively obtain a to-be-measured Re sample and an Os sample. According to the method, it is guaranteed that Re and Os are almost not lost, and meanwhile complete sample dissolving of organic matter-rich sedimentary rock samples such as black shale is effectively achieved.

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 black shale Carius tube complete sample dissolution method that is reasonably designed and effectively solves the above problems. Summary of the invention

[0005] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a method for complete sample dissolution of black shale Carius tubes.

[0006] The present disclosure provides a method for complete dissolution of black shale Carius tubes.

[0007] The methods include:

[0008] 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;

[0009] 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;

[0010] 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;

[0011] 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;

[0012] 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.

[0013] Optionally, the Carius tube is sealed and completely dissolved in step 3, including:

[0014] The pre-dissolved solution in the sample dissolution tank is completely transferred into a Carius tube under a freezing condition;

[0015] Use 1.5mL~2mL of HCl purified by secondary sub-boiling distillation to completely transfer the accurately weighed 185 Re -190The 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.

[0016] Optionally, the Carius tube is sealed and the sample is completely dissolved in step 3, and further includes:

[0017] The Cairus tube mouth after freezing was melted and sealed by using 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.

[0018] Optionally, in step 4, a direct distillation method is used to separate Re and Os in the sample solution, Re is retained in the distillation residual solution, and Os is retained in the distillation absorption liquid, comprising:

[0019] The Cairus 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.

[0020] Optionally, in step 5, the Re of the distillation residual solution is further enriched and purified to obtain a Re sample to be measured, comprising:

[0021] The residual solution from the distillation was evaporated to dryness at 160° C. to 180° C. on a hot plate;

[0022] The Re in the residual solution after the acid removal was enriched and purified by acetone extraction.

[0023] 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.

[0024] Optionally, in step 5, further enriching and purifying the Os in the distilled absorption liquid to obtain an Os sample to be measured comprises:

[0025] 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.

[0026] Optionally, 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, comprising:

[0027] 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;

[0028] 1 mL to 2 mL of MOS-grade HF is added to the sample dissolving tank.

[0029] The black shale Carius tube complete dissolution method of the embodiment of the present invention realizes the complete dissolution of black shale by subjecting the black shale sample to HF pre-dissolution and then subjecting the black shale sample to Carius tube closed dissolution. HCl is added as a reducing agent during the HF pre-dissolution and acid removal process of the black shale to protect Os so that it will not be oxidized to OsO4 and cause loss in the process. The dissolution method can effectively achieve complete dissolution of organic-rich sedimentary rock samples such as black shale while ensuring almost no loss of Re and Os, and the method has extremely low blank in the entire process, and the Re and Os data results of all sources in the black shale are reliable; the 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 dissolution medium conditions through Carius tube 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 discrete degree of Re-Os isochrons, and improving the accuracy of Re-Os isochron ages. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of a process of a black shale Carius tube complete sample dissolution method according to an embodiment of the present disclosure;

[0031] Figure 2 This is a schematic diagram of the process of a black shale Carius tube complete sample dissolution method according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present disclosure, the embodiments of the present disclosure are further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0033] The existing black shale dissolution method has the following technical problems:

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

[0035] 2) Due to the lack of Re, Os content and isotope ratio data obtained from complete dissolution of black shale, the dissolution degree of organic-derived Re and Os elements in organic-rich sedimentary rock samples such as black shale cannot be accurately evaluated by the four mixed solutions during the Carius tube dissolution process.

[0036] 3) Since Os will be oxidized to OsO4 and volatilized and lost in oxidizing agents, while Re does not have such characteristics, the traditional whole karst sampling technology can obtain the Re content but cannot obtain accurate Os content and Os isotope ratio data.

[0037] In summary, there is currently no report on the complete dissolution method of black shale and Re-Os isotope analysis.

[0038] Aiming at the technical problems existing in the prior art, such as Figure 1 As shown, the embodiment of the present disclosure provides a black shale Carius tube complete sample dissolution method S100, the method comprising:

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

[0040] Specifically, in this embodiment, preferably, Figure 2 As shown in a, accurately weigh 0.1g of black shale sample into a F4 micro round bottom dissolving tank, and add 1mL of MOS grade HF into the dissolving tank. Figure 2 As shown in b, the sample was left to stand for 24 hours for dissolution. During the standing process, HF reacted with silicates in the black shale to generate volatile SiF4, which pre-dissolved the silicate phase in the black shale sample and obtained a pre-dissolved solution.

[0041] S120, 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.

[0042] Specifically, in this embodiment, preferably, Figure 2 As shown in Figure c, the sample dissolving tank is heated at 150°C on a hot plate, and when the pre-dissolved solution is heated to nearly dryness, 1 mL of HCl purified by secondary sub-boiling distillation is added to remove the acid. Repeat the acid removal 3 times and heat to nearly dryness to remove the HF in the pre-dissolved solution.

[0043] In the above acid removal process, HF is first heated to near dryness to remove most of the residual HF. Since HF is a reducing acid, the near dry state can ensure that Os in the sample is not lost. Then HCl is added to remove the remaining HF. Since the boiling point of HF is much lower than that of HCl, after several times, HF will be removed first, while HCl will be retained, and the sample will be converted into an HCl medium.

[0044] In this embodiment, the pre-dissolved solution is heated at 150° C. on a hot plate, and unreacted HF and the reaction product SiF4 are volatilized under the heating conditions. HCl is added at the same time to ensure that the Os in the sample is in a reduced state and will not be lost under the heating conditions, resulting in the final Os content and isotope ratio results deviating from the true values.

[0045] S130, step 3, adding 1mL to 2mL HCl to the pre-dissolved solution after removing the acid, completely transferring the pre-dissolved solution in the sample dissolution tank into the Carius tube, and adding accurately weighed Re-Os mixed diluent and sample dissolution reagent to the Carius tube, sealing the Carius tube to completely dissolve the sample, and obtaining the sample solution.

[0046] In this embodiment, preferably, Figure 2 As shown in FIG. 4 , the specific process of step three includes the following:

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

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

[0049] Specifically, 1.5 mL of HCl purified by secondary sub-boiling distillation was used to completely transfer the accurately weighed 185 Re -190 Os mixed diluent was placed in a Carius tube, and after freezing, 6 mL of HNO3 purified by secondary sub-boiling distillation and 1 mL of MOS-grade H2O2 were added, and then frozen to dissolve the organic phase in the black shale sample, thereby achieving complete dissolution of the black shale sample. In other words, a total of 2.5 ml of HCl was used, of which 1 ml was used to transfer the pre-dissolved solution and 1.5 ml was used to transfer the mixed diluent.

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

[0051] Again, the frozen Cairus tube was melted and sealed with an acetylene flame, and a stainless steel sleeve was placed on the tube. The tube was placed in an oven and heated at 220°C for 12 hours and at 230°C for 12 hours, and then cooled to room temperature.

[0052] S140, step 4, using a direct distillation method to separate Re and Os in the sample solution, Re is retained in the distillation residual solution, and Os is retained in the distillation absorption liquid.

[0053] Specifically, Figure 2 As shown in Fig. e, the Cairus tube is opened with an acetylene flame under freezing conditions, and after returning to room temperature, Re and Os are separated by direct distillation, wherein Re is retained in the residual solution of distillation, and Os is retained in the distillation absorption liquid of 1:1 HBr:H2O.

[0054] S150, step five, further enriching and purifying 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.

[0055] Wherein, in step 5, the Re of the residual solution of the distillation is further enriched and purified to obtain a Re sample to be measured, comprising:

[0056] The residual solution of the distillation was evaporated to dryness at 160°C to 180°C on a hot plate. The Re in the residual solution after the acid removal was enriched and purified by acetone extraction. The acetone phase containing the Re sample to be measured was placed in a Teflon vial, and the remaining organic phase was nitrated with HNO3 and H2O2 at 110°C to 130°C. After evaporation, Re was measured with high precision by multi-collector plasma mass spectrometry.

[0057] Specifically, Figure 2 As shown in f, in this embodiment, preferably, the residual solution of the distillation is evaporated to dryness at 160°C on a hot plate to remove the acid, 10 ml of 10 mol / L NaOH solution purified by acetone is added, 10 ml of acetone is added to extract twice and centrifuge, the acetone phase is taken out and placed in a 15 ml Teflon sample dissolving tank, evaporated to dryness at 110°C, the remaining organic phase is nitrated with HNO3 and H2O2 at 130°C, and after evaporation, Re is measured with high precision using multi-collector plasma mass spectrometry.

[0058] Wherein, in step 5, further enriching and purifying the Os in the distilled absorption liquid to obtain the Os sample to be measured comprises:

[0059] 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.

[0060] Specifically, Figure 2 As shown in FIG. 1 , in this embodiment, preferably, the Os distilled absorption liquid is transferred to a 150 ml Teflon bowl, heated on a hot plate at 150° C. until about 50 μL remains and transferred to a Teflon pointed bottom bottle cap, evaporated to dryness on a hot plate at 120° C., covered with 50 μL of H2SO4-CrO3 mixed solution purified by distillation, and 4 times of purified HBr is added to the pointed bottom part of the pointed bottom bottle as the Os absorption liquid, the pointed bottom part is turned upside down on the lid and tightened, wrapped with aluminum foil, placed on the hot plate, and kept warm at 80° C. for 4 hours. After cooling to room temperature, the H2SO4-CrO3 on the bottle cap is discarded, the pointed bottom bottle is straightened, the lid is tightened, and it is kept warm at 80° C. in an oven for 2 hours. After concentration, it is spotted on a high-purity Pt tape, and Os is measured with high precision using thermal surface ionization mass spectrometry.

[0061] The black shale Carius tube complete dissolution method of the embodiment of the present invention realizes the complete dissolution of black shale by subjecting the black shale sample to HF pre-dissolution and then subjecting the black shale sample to Carius tube closed dissolution. HCl is added as a reducing agent during the HF pre-dissolution and acid removal process of the black shale to protect Os so that it will not be oxidized to OsO4 and cause loss in the process. The complete dissolution method can effectively achieve complete dissolution of organic-rich sedimentary rock samples such as black shale while ensuring that there is almost no loss of Re and Os. The method has extremely low blank in the entire process, and the Re and Os data results of all sources in the black shale are reliable. The 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 dissolution medium conditions through Carius tube 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 discrete degree of Re-Os isochrons, and improving the accuracy of Re-Os isochron ages.

[0062] The specific process of the black shale Carius tube complete sample dissolution method S100 of the disclosed embodiment is described in detail below through relevant embodiments.

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

[0064] The black shale Carius tube complete dissolution method S100 of the embodiment of the present disclosure is adopted, that is, the black shale is first pretreated with HF, and the HF in the sample is driven out and converted into HCl medium under four temperature gradient conditions of 90°C, 110°C, 130°C, and 150°C. The Re-Os data of the black shale internal monitoring sample obtained after the Cairus tube dissolution are shown in Table 1. Compared with the Re-Os data of the black shale laboratory internal monitoring sample B47 obtained by Carius tube dissolution using three dissolution media, under the four temperature gradient acid-driving conditions, the Re content recovery rates were all greater than 97%, and the Os content recovery rates were all greater than 96%. Among them, when the acid-driving temperature was 150°C, the Os recovery rate was the highest, which was 99.6%. This confirmed that there was almost no loss of Re and Os in the sample after HF pretreatment and then transferred to the Cairus tube dissolution process, and the effect on the test results was small. The HF acid-driving temperature can be set to a maximum of 150°C. The Re blank level of the whole process of this method is 0.0015ng / g, and the Os blank level is 0.0009ng / g.

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

[0066]

[0067] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the embodiments of the present disclosure, but 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 considered to be within 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 1.5mL~2mL 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 Cairus tube mouth after freezing was melted and sealed by using 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 Cairus 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 of 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 6, 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 dissolving tank.

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