A method for rapid separation of re and pge from organic-rich geological samples

Abstract

The application discloses a method for rapidly separating Re and PGE from an organic matter-rich geological sample. After the sample is dissolved and converted into a sample solution dissolved in 0.2M HCl, first, a cation exchange column is used to realize rapid separation of Re-PGE from a sample matrix and interfering elements (such as Cd, Zr and Hf); second, an LN resin column is used to further remove interfering elements (such as Zr and Hf) and realize mutual separation of Re and PGE. Compared with a traditional separation method, the method can obtain high-purity Re and PGE, and the mutual separation of Re and PGE enables high-precision determination of Re by using MC-ICP-MS for Re-Os dating research, and rapid determination of PGE by using Q-ICP-MS or Element-XR ICP-MS for PGE content analysis.

Description

Technical Field

[0001] The present invention belongs to the fields of element geochemistry, isotopegeochemistry and isotope geochronology, and in particular relates to a method for rapidly separating Re and PGE from organic-rich geological samples. Background Art

[0002] Because Re-Os (rhenium-osmium) and PGE (platinum group elements, primarily Ir, Ru, Pt, and Pd) are strongly siderophilic and sulfide-loving, Re-Os isotopes and PGE (PGE) have important applications in mantle geochemistry, astrochemistry, and mineralogy. Furthermore, Re-Os and PGE exhibit an affinity for organic matter. In recent years, the Re-Os-PGE system has been increasingly applied in the dating and tracing of organic-rich sedimentary rocks and even oil and gas reservoirs. Among them, the Re-Os ratio of organic-rich sedimentary rocks plays an important role in the field of sedimentary strata dating. The initial Os isotope ratio can provide important geological paleoenvironmental information, while PGE can provide important information on the presence of extraterrestrial materials in sedimentary strata. The Re-Os ratio of bitumen and crude oil can limit the age of oil and gas generation / migration / charge or the end of TSR (thermochemical sulfate reduction), while the initial Os ratio and PGE composition can provide information on tracing oil and gas source rocks.

[0003] Re-Os and PGE2 are currently analyzed using the reverse aqua regia-Carius closed dissolution method (Reference 1). Os is then separated from the Re-Os-PGE2 solution by CCl4 extraction or distillation. The residual solution is evaporated to dryness, digested with 6M HCl, evaporated again, and then dissolved with 1M HCl to obtain a sample solution. Re and PGE2 are then separated using anion exchange or cation exchange methods (e.g., References 2 and 3). While Os separation methods are relatively mature, Re and PGE2 separation methods still have the following issues. First, due to the strong adsorption capacity of anion resins for Re and PGE2, especially Pt and Pd, the anion exchange method requires concentrated hydrochloric acid or nitric acid to elute Re and PGE2, which poses operational safety issues and high acid consumption. Furthermore, the anion exchange method suffers from low and unstable recovery rates for Ir, Ru, and Pd. Second: The cation exchange method uses cationic resin to adsorb matrix (such as Fe, Ca, Mg, Al, etc.) and interfering elements (such as Zn, Cd, Zr, Hf, etc.) in dilute hydrochloric acid medium. In dilute hydrochloric acid medium, PGE is in the form of chloride anion, Re is in the form of ReO4- The ionic form is not adsorbed, and the separation of Re and PGE from matrix elements and interfering elements is achieved. The problems with this method are: (1) The current cation exchange separation method is mainly used for the separation of silicate samples (the sample volume is generally more than 2g). In order to adsorb a large amount of matrix elements in the sample solution (although the silicate phase cannot be completely dissolved by reverse aqua regia dissolution, a large amount of matrix elements will still be dissolved), the cation exchange method generally requires a large amount of resin (>40mL, such as reference 3) to meet the exchange capacity requirements; at the same time, the regeneration and washing process requires the use of a large amount of high-purity acid to elute the matrix elements (>120mL 6M HCl), and the acid consumption is relatively large. For organic-rich geological samples (such as organic-rich sedimentary rocks, i.e., source rocks, crude oil, asphalt, etc.), due to their high organic carbon content, in order to prevent excessive CO2 from being generated during the dissolution process of the Carius glass tube, which may cause the tube to explode, the sample volume of organic-rich geological samples is generally only 0.1-0.5g. As a result, the total amount of matrix elements such as Fe, Ca, Mg, and Al in the dissolved sample solution is relatively low. Therefore, in theory, a cationic resin exchange column with a smaller amount of resin can be used, but there is currently no relevant process research report; (2) Re and PGE cannot be separated from each other, which cannot meet the needs of measuring Re and PGE separately for different research needs. In practice, Re-Os dating requires relatively high precision for Re determination, while PGE content dilution analysis requires relatively low precision for isotope mixing ratio determination. Furthermore, while MC determination of PGE (Ir, Ru, Pt, and Pd) offers greater sensitivity and precision, simultaneous multi-element determination is difficult due to the limited number of receivers and the influence of magnetic hysteresis. MC typically requires separate determinations of Re, Ru, Ir-Pt, and Pd. Furthermore, MC makes it difficult to monitor interferences such as ZrO on Pd and HfO on Ir-Pt online. Separating Re and PGE, allowing for high-precision isotopic analysis of Re using MC-ICP-MS (multi-collector plasma mass spectrometry), and rapid multi-element isotope dilution analysis of PGE using Q-ICP-MS (quadrupole plasma mass spectrometry) or Element-XRICP-MS, with simultaneous online monitoring of interfering elements such as Zr, Hf, and Cd, is of great research significance.

[0004] Document 1: Shirey SB and Walker RJ (1995) Carius tube digestion for low-blank rhenium-osmium analysis. Analytical Chemistry, 67, 2136-2141.

[0005] Literature 2: Chu ZY, Yan Y., Chen Z., Guo JH, Yang YH, Li CF and ZhangY.B. (2015) A comprehensive method for precise determination of Re, Os, Ir, Ru, Pt, Pd concentrations and Os isotopic compositions in geological samples. Geostandards and Geoanalytical Research, 39, 151-169.

[0006] Literature 3: Li J., Zhong LF, Xu JF, Wang XC, Wang GQ and Zhao PP (2014) Determination of platinum-group elements and Re-Os isotopes using ID-ICP-MS and N-TIMS from a singledigestion after two-stage columnsseparation. Geostandards and Geoanalytical Research, 38, 37-50. Summary of the Invention

[0007] In response to the above problems, the purpose of the present invention is mainly to analyze the Re-Os isotope and PGE (here referring to the four elements Ir-Ru-Pt-Pd) content of organic-rich geological samples (organic-rich sedimentary rocks, asphalt, crude oil), and to establish a rapid PGE and Re separation method based on a cation exchange column + LN resin column.

[0008] The method of the present invention dissolves the sample and converts it into a sample solution dissolved in 0.2M HCl. A cation exchange column is first used to rapidly separate Re-PGE from the sample matrix and interfering elements (such as Cd, Zr, and Hf). In a second step, an LN resin column is used to further remove interfering elements (such as Zr and Hf) and separate Re and PGE. Compared to traditional separation methods, the method of the present invention can obtain high-purity Re and PGE, and the Re and PGE are separated from each other. This allows Re to be measured with high precision using MC-ICP-MS for Re-Os dating studies, while PGE can be rapidly measured using Q-ICP-MS or Element-XR ICP-MS for PGE content analysis.

[0009] Specifically, the present invention adopts the following technical solutions:

[0010] A method for separating high-purity Re and PGE from an organic-rich geological sample comprises the following steps:

[0011] Sample dissolution: The sample was dissolved by the reverse aqua regia method using the Carius tube method, and the sample solution was obtained by transferring the medium to obtain a sample solution dissolved in 0.2M HCl.

[0012] Chemical separation: First, the sample solution was loaded onto an exchange column filled with 20 mL of cationic resin to separate Re-PGE in the sample solution; the obtained Re-PGE receiving solution was evaporated to dryness and dissolved with 1 mL of 6M HCl. The resulting solution was loaded onto an exchange column filled with 2 mL of LN eluting resin to separate PGE and Re in sequence;

[0013] The PGE and Re separation method is as follows: 0.1-0.5g of organic-rich geological sample, appropriate amount of 185 Re- 190 Os and 191 Ir- 101 Ru- 105 Pd- 196 Pt diluent was added under refrigerated conditions to 3 mL of 12 M HCl and 6 mL of 15 M HNO3, and dissolved at 220°C using the Carius closed sample dissolution method (for details of the sample dissolution steps, see Reference 1); Os was then extracted using CCl4, and the residual liquid was transferred to a Teflon container and evaporated to dryness. 5 mL of 6 M HCl was added to digest the sample, evaporated to dryness again, and then 10 mL of 0.2 M HCl was added to dissolve the sample to obtain a sample solution dissolved in 10 mL of 0.2 M HCl.

[0014] The PGE and Re separation method first loads the sample solution dissolved in 0.2M HCl onto an exchange column loaded with a cationic resin to separate the Re-PGE in the sample solution. The cationic resin-loaded exchange column is prepared by loading 20mL of 200-400 mesh AG50W-X8 resin, manufactured by Bio-Rad, USA, into an empty Econo-Pac chromatography column with an inner diameter of 1.5cm, manufactured by Bio-Rad, USA. The specific steps for separating Re-PGE include: pre-cleaning the cationic resin-loaded exchange column with 60mL of 6M HCl, 10mL of Milli-Q H2O, 30mL of 2M HF, and 10mL of Milli-Q H2O; equilibrating the exchange column with 20mL of 0.2M HCl; loading the sample solution dissolved in 0.2M HCl onto the column; and eluting the Re-PGE with 30mL of 0.2M HCl. Sample matrix elements and interfering elements such as Fe, Ca, Mg, Al, K, Na, Ti, Cr, Ba, Zn, Cd, Zr, and Hf remain on the exchange column.

[0015] The PGE and Re separation method comprises evaporating the Re-PGE obtained by separation using a cation exchange column, dissolving the sample in 1 mL of 7M HCl, and loading the resulting solution onto an exchange column filled with 2 mL of LN resin to sequentially separate PGE and Re. The exchange column loaded with 2 mL of LN resin is prepared by loading 2 mL of LN resin with a particle size of 50-100 microns, produced by Eichrom, USA, into an empty Poly-Prep chromatography column with an inner diameter of 0.8 cm, produced by Eichrom, USA, and capping the upper end of the resin with a polyethylene porous sieve plate. The specific separation steps for sequentially separating PGE and Re include: pre-cleaning an exchange column loaded with 2 mL of the LN resin with 4 mL of Milli-Q H2O, 4 mL of 2M HF, and 4 mL of Milli-Q H2O; adding 4 mL of 7M HCl to equilibrate the exchange column; loading the Re-PGE solution dissolved in 1 mL of 7M HCl onto the column; adding 3 mL of 7M HCl to elute PGE, and then adding 5 mL of 0.2M HCl to elute Re.

[0016] The PGE and Re separation method is described above. Finally, the Re and PGE solutions separated using an exchange column loaded with 2 mL of LN resin are evaporated to dryness and dissolved in 2% HNO. High-precision Re isotope analysis can be performed using MC-ICP-MS, and rapid isotope ratio analysis of each PGE can be performed using Q-ICP-MS or Element-XR ICP-MS. Specific MC-ICP-MS and Q-ICP-MS or Element-XR ICP-MS methods are described in References 2 and 3, respectively.

[0017] The present invention uses an LN resin column for the first time to separate PGE and Re. The mechanism is as follows: in an HCl medium, PGE forms a complex anion that is not retained on the LN resin column, but Re is weakly retained. Furthermore, high-field-strength elements such as Ti, Zr, Hf, and Mo are extremely strongly retained on the LN column and can only be eluted using HF. Therefore, using an LN column to further separate PGE and Re not only separates PGE from Re but also further removes Zr and Hf impurities from PGE. The present invention also discovered for the first time that, although LN resin column retention for Re is not particularly sensitive to acidity, higher HCl acidity increases its retention of Re. The present invention ultimately chose to dissolve the sample onto the column using 7M HCl, eluting PGE with 3mL of 7M HCl, and then eluting Re with 5mL of 0.2M HCl. Therefore, the PGE and Re separation method described in the present invention can rapidly separate high-purity PGE and Re from organic-rich geological samples (sample size <0.5g). High-precision Re isotope analysis can then be performed using MC-ICP-MS, and the isotope ratios of each PGE element can be rapidly determined using Q-ICP-MS or ELEMENT-XR ICP-MS (Q-ICP-MS or ELEMENT-XR ICP-MS can monitor interfering elements such as Zr, Hf, and Cd in real time). The results of the high-precision Re isotope analysis can be used to determine the Re-Os age of the organic-rich geological samples, and the PGE isotope ratio determination results can be used to calculate the PGE content using isotope dilution analysis.

[0018] Since the exchange columns used in the separation process of the present invention all have relatively large inner diameters (the inner diameter of the cation column is 1.5 cm, and the inner diameter of the LN column is 0.8 cm), the eluent flow rate is fast, and thus the separation process has the characteristics of being fast and efficient.

[0019] The present invention is a method for separating PGE and Re from organic-rich geological samples. With slight modifications, such as increasing the amount of cation exchange column resin and correspondingly increasing the amount of acid eluent and acid used for cleaning the exchange column, it can be applied to other types of geological samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1The flow chart of the PGE, Re chemical separation method for the organic-rich geological sample of the embodiment of the present application;

[0021] Figure 2 The matrix elements, interfering elements and Re-PGE effluent curve of the cation exchange column chemical separation step of the preferred embodiment of the present application;

[0022] Figure 3 The PGE, Re effluent curve of the 2 mL LN resin column chemical separation step of the preferred embodiment of the present application

[0023] Main element symbol explanation:

[0024] M represents the concentration unit mol / L DETAILED DESCRIPTION

[0025] The present application will be described in detail below in combination with specific embodiments.

[0026] The present application discloses a method for separating high-purity PGE, Re from organic-rich geological samples. Figure 1 According to the preferred embodiment of the present application, Re-PGE is first separated from the sample solution by using a cation resin exchange column, and then PGE is separated from Re by using a 2 mL LN resin column. The method mainly includes the following steps:

[0027] (1) Dissolution of the organic-rich geological sample (referring to organic-rich sedimentary rock, asphalt, crude oil, etc.):

[0028] According to the organic matter content of the sample, 0.1-0.5 g of organic-rich geological sample powder is weighed in a Carius glass tube (note: the Carius glass tube is a thick-walled borosilicate glass tube with an open end, the main body is 20 cm long, the inner diameter is 18 mm, the outer diameter is 22 mm, the thin neck is 6 cm long, the inner diameter is 7 mm, and the outer diameter is 10 mm), and an appropriate amount of 185 Re- 190 Os and 191 Ir- 101 Ru- 105 Pd- 196Pt mixed diluent. Place the Carius tube in a liquid nitrogen-alcohol slurry and freeze. Then, add 3 mL of concentrated HCl (~12 M) and 6 mL of concentrated HNO3 (~15 M), freeze further, and seal the tube with a liquefied petroleum gas-oxygen flame. Place the Carius tube in an outer steel sleeve and heat it in an oven at 220°C for 72 hours to digest the sample. After the sample cools, place the Carius tube in a liquid nitrogen-alcohol slurry and freeze. Open the Carius tube with a liquefied petroleum gas-oxygen flame, and extract Os from the sample's aqua regia solution with CCl4. The residual liquid is transferred to a Teflon container, evaporated to dryness, and digested with 5 mL of 6 M HCl. Then, evaporate again to dryness, and dissolve the sample in 10 mL of 0.2 M HCl to obtain a sample solution.

[0029] (2) Separation of Re-PGE by cation exchange column

[0030] Cation exchange column: Bio-Rad Econo-Pac empty chromatography column (column inner diameter 1.5 cm), packed with 20 mL of Bio-rad AG50W-X8 resin (200-400 mesh). First, use 60 mL of 6 M HCl, 10 mL of Milli-Q H2O, 30 mL of 2 M HF, and 10 mL of Milli-Q H2O to pre-clean the exchange column; then use 20 mL of 0.2 M HCl to equilibrate the exchange column; the sample solution dissolved in 0.2 M HCl is loaded onto the column; and 30 mL of 0.2 M HCl is added to elute Re-PGE. Sample matrix elements and interfering elements such as Fe, Ca, Mg, Al, K, Na, Ti, Cr, Ba, Zn, Cd, Zr, and Hf remain on the exchange column. The specific chemical separation process is listed in Table 1.

[0031] Table 1: Separation process of matrix elements, interfering elements and Re-PGE by cation exchange method

[0032]

[0033]

[0034] (3) Separation of PGE and Re by 2mL LN resin column

[0035] 2mL LN resin column: An empty Eichrom Poly-Prep chromatography column (inner diameter ~0.8cm) was loaded with 2mL of LN resin (particle size: 50-100 microns) manufactured by Eichrom, USA. The top of the resin was capped with a polyethylene porous frit. The Re-PGE separated using the cation exchange column was evaporated to dryness, dissolved by heating in 1mL of 7M HCl, and the resulting solution was loaded onto the LN resin column to separate PGE and Re in sequence. The specific separation steps were as follows: the column loaded with 2mL of LN resin was pre-cleaned with 4mL of Milli-Q H2O, 4mL of 2M HF, and 4mL of Milli-Q H2O; 4mL of 7M HCl was added to equilibrate the column; the Re-PGE solution dissolved in 1mL of 7M HCl was loaded onto the column; 3mL of 7M HCl was added to elute PGE, followed by 5mL of 0.2M HCl to elute Re.

[0036] The specific chemical separation process is listed in Table 2.

[0037] Table 2: PGE and Re separation process on 2mL LN resin column

[0038] Eluent Eluent volume (mL) Steps <![CDATA[Milli-Q H2O]]> 4 Column washing 2M HF 4 Column washing <![CDATA[Milli-Q H2O]]> 4 Column washing 7M HCl 4 balance 7M HCl 1 Loading 7M HCl 3 Receive PGE 0.2M HCl 5 Receive Re

[0039] The principle of the chemical separation process is as follows: First, refer to the attached Figure 2 , Figure 2 The Re-PGE elution curve obtained by the inventors through creative work shows that on a cation exchange resin column, under the condition of 0.2M HCl medium, matrix elements and interfering elements such as Fe, Ca, Mg, Al, K, Na, Ti, Cr, Ba, Zn, Cd, Zr, and Hf exist in the form of cations and are retained on the column, while PGE exists in the form of chloride anions and Re exists in the form of ReO4 - The form exists, but none of them are on the pillar; Figure 2 It can be seen that after loading the sample and eluting the exchange column with 30mL 0.2M HCl, Re-PGE is basically completely eluted (Re is close to 100%, PGE>80%), while Fe, Ca, Mg, Al, K, Na, Ti, Cr, Ba, Zn, Cd, Zr, and Hf are not eluted, thereby achieving the separation of Re-PGE from the sample matrix elements and interfering elements; It should be pointed out that the lower the acidity of the column, the stronger the retention of interfering elements such as Zn and Cd on the cation exchange column, and the smaller the possibility of being eluted into Re-PGE. However, if the acidity is too low, such as using 0.1M HCl medium for loading the column, the tailing of some PGE elements such as Ru will be extended, and 30mL 0.1M HCl after loading the sample cannot completely elute Ru. Therefore, the present invention uses 0.2M HCl to load and elute PGE. Under this acidity condition, it can basically ensure that Cd is not eluted with PGE ( 106Cd interference 106 Pd)( Figure 2 After eluting PGE, 60mL 6M HCl can completely elute most of the matrix elements, but Fe, Zr, and Hf are strongly retained and can be completely eluted using 30mL 2M HF. The resin can be used again. Figure 3 , Figure 3 The elution curves of PGE and Re on an LN resin column, obtained through the inventors' creative work, show that PGE forms a chloride complex anion on an LN resin column under HCl medium conditions and is weakly retained on the LN resin. However, we discovered that Re is somewhat retained on the LN column under 0.5M to 7M HCl medium conditions, thus enabling the separation of PGE and Re. The inventors discovered that although the retention of Re on the LN column is not particularly sensitive to the acidity of the HCl eluent, generally, the higher the HCl concentration, the stronger the retention of Re on the LN resin column. Using 1 mL of 4-7 M HCl for loading and 3 mL of 4-7 M HCl for elution of PGE, Re is essentially not eluted, while PGE is almost completely eluted. After eluting PGE, Re can be completely eluted using 5 mL of 0.2 M HCl. Finally, we chose to load 1 mL of 7 M HCl for loading and 3 mL of 7 M HCl for elution of PGE, followed by 5 mL of 0.2 M HCl for elution of Re, achieving complete separation of PGE and Re. Interfering elements such as Zr and Hf are strongly retained on the LN column and can only be eluted using HF. Therefore, the LN column also serves to further remove Zr and Hf interference from PGE. After eluting Re, Zr, Hf, Ti, and Mo can be completely eluted using 4 mL of 2M HF, making the column reusable.

[0040] Advantages of the present invention: Compared with traditional methods, the present method achieves high Re and PGE recovery rates, can separate Re and PGE from each other, and completely removes Zr-Hf interference. Furthermore, due to the large inner diameters of the exchange columns employed (cation columns, 1.5 cm inner diameter; LN columns, 0.8 cm inner diameter), the eluent flow rate is fast, resulting in rapid separation and high efficiency. The present method is particularly suitable for determining Re and PGE using MC-ICP-MS and Q-ICP-MS or ELEMENT-XR ICP-MS, respectively, to meet different research needs. The former is used for Re-Os dating, and the latter is used for PGE content analysis.

[0041] The chemical process for separating high-purity PGE and Re from organic-rich geological samples according to the present invention will be further described below with reference to specific examples.

[0042] In all embodiments of the present invention, in order to obtain low blank background values ​​of PGE and Re processes, the reagents, water, laboratory utensils and laboratory environment used are described as follows:

[0043] (1) Sample dissolution and chemical separation experiments were performed on a Class 100 clean bench and a Class 100 fume hood within a Class 1000 clean room.

[0044] (2) Ultrapure water: prepared by Millipore-Q Element system from Millipore Corporation, USA, with an outlet resistivity of 18.2 MΩ / cm (25°C);

[0045] (3) The hydrochloric acid and nitric acid used were electronic grade (CMOS pure) products produced by China National Pharmaceutical Group Chemical Reagent Co., Ltd. and were all tested by Savillex. TM DST-1000 sub-boiling distiller (produced by Minnetonka, USA) for sub-boiling distillation purification;

[0046] (4) The vessels for receiving the sample solution during the dissolution and chemical separation process were Teflon PFA vessels produced by Savillex Company of the United States, mainly including 15 mL round-bottom and 30 mL round-bottom PFA Teflon vessels with screw caps, which were soaked in 50% diluted reverse aqua regia (HNO3:HCl=2:1) ​​and washed with Milli-Q water before use. Finally, the 15 mL round-bottom and 30 mL round-bottom PFA bottles were washed with HNO3 purified by sub-boiling distillation and the 5 mL conical-bottom PFA conical flask was washed with HBr reflux.

[0047] Example 1:

[0048] Oil shale international rock standard USGS SGR-1b Re-Os and PGE analysis

[0049] The oil shale standard sample SGR-1b has a high organic carbon content of 24.8 wt%. To avoid explosion of the Carius tube during the dissolution process, the sample weight for each analysis was 0.2 g.

[0050] (1) Dissolve the sample: weigh ~0.2 g of SGR-1b oil shale standard powder into a Carius tube, and weigh an appropriate amount 185 Re- 190 Os and 191 Ir- 101 Ru- 196 Pt- 105Pd was mixed with diluent in a 15 mL Teflon beaker. The Carius tube was placed in a liquid nitrogen-alcohol slurry and frozen. Then, 3 mL of concentrated HCl (~12 M) was added to the Teflon beaker containing the diluent. The diluent was transferred to the Carius tube, and 6 mL of concentrated HNO3 (~15 M) was added and further frozen. The Carius tube was sealed with a liquefied petroleum gas-oxygen flame, placed in an outer steel sleeve, and heated in an oven at 220°C for 72 hours to digest the sample. After the sample cooled, the Carius tube was placed in a liquid nitrogen-alcohol slurry and frozen. The Carius tube was opened with a liquefied petroleum gas-oxygen flame, and Os was extracted from the aqua regia solution of the sample using CCl4. Os was micro-distilled and used for Os isotope analysis by NTIMS (see Reference 2). The residual liquid was evaporated to dryness, digested with 5 mL of 6 M HCl, and then evaporated again. The sample was dissolved in 10 mL of 0.2 M HCl to obtain a sample solution ready for column loading.

[0051] (2) Chemical separation:

[0052] In the first step, a cationic resin exchange column is used to separate Re-PGE from the sample solution. The separation process is shown in Table 1. Exchange column: Bio-rad Econo-Pac chromatography empty column (column inner diameter 1.5 cm), filled with 20 mL 200-400 mesh resin. First, 60 mL 6M HCl, 10 mL Milli-Q H2O, 30 mL 2M HF, and 10 mL Milli-Q H2O are used to pre-clean the exchange column; then 20 mL 0.2M HCl is used to equilibrate the exchange column; the sample solution dissolved in 10 mL 0.2M HCl is loaded onto the column; 30 mL 0.2M HCl is added to elute the Re-PGE. Sample matrix elements and interfering elements such as Fe, Ca, Mg, Al, K, Na, Ti, Cr, Ba, Zn, Cd, Zr, and Hf are still retained on the exchange column. The Re-PGE separated by the above-mentioned cation exchange column is evaporated to dryness, and the sample is dissolved in 1 mL 7M HCl for subsequent separation;

[0053] In the second step, Re and PGE were separated using an LN resin column. The separation process is shown in Table 2. The column consisted of an empty Eichrom Poly-Prep chromatography column (inner diameter ~0.8 cm) loaded with 2 mL of LN resin (particle size: 50-100 μm) manufactured by Eichrom Corporation (USA). The resin was capped with a polyethylene porous frit. The specific separation steps were as follows: the column loaded with 2 mL of LN resin was pre-cleaned with 4 mL of Milli-Q H2O, 4 mL of 2M HF, and 4 mL of Milli-Q H2O; the column was equilibrated with 4 mL of 7M HCl; the Re-PGE solution dissolved in 1 mL of 7M HCl was loaded onto the column; 3 mL of 7M HCl was added to elute PGE, followed by 5 mL of 0.2M HCl to elute Re. The Re and PGE fractions were evaporated to dryness, dissolved in 1 mL of 0.8M HNO3, and analyzed by mass spectrometry.

[0054] (3) MC-ICP-MS determination of Re and Q-ICP-MS determination of PGE

[0055] Re was measured using a Neptune Plus MC-ICP-MS, and PGE was measured using an iCap-Q quadrupole mass spectrometer (Q-ICP-MS). Because PGEs, particularly Ir and Ru, are present in organic-rich geological samples at very low concentrations, the nebulizer, spray chamber, torch, and cone of the instrument were cleaned prior to Q-ICP-MS PGE determination to minimize instrumental memory effects.

[0056] The MC-ICP-MS method for determining Re is described in Reference 2. A brief description is as follows: Re is measured using a Faraday cup, and 30 cycles of data are collected for each sample. 192 Os signal monitoring 187 Os pair 187 The interference of Re is generally very low. Os signal is very low and the interference to Re can be completely ignored. In addition, 2% v / v HNO3 acid blank was monitored before the determination until the Re signal was reduced to a negligible level. During the determination, Re (10 ng ml -1 ) Mass deviation effect of standard solution monitoring instrument.

[0057] The Ir, Ru, Pt, and Pd isotopes and potential interferences monitored during mass spectrometry analysis are listed in Table 3. Although the interferences can be reduced to insignificant levels by chemical procedures, they are still detected during mass spectrometry. 90 Zr + and 111 Cd + To monitor 90 Zr 16 O + and106 Cd + right 106 Pd + Interference, determination 177 Hf + 、 178 Hf + and 180 Hf + To correct Hf 16 O + right 193 Ir + interference, 178 Hf 16 O + right 194 Pt+ interference and 180 Hf 16 O + right 196 Pt + The dwell time of each isotope was set to 0.05 s, and each sample was measured in three runs, each consisting of 50 scans. Before each sample was measured, the background signal was monitored by measuring 2% v / v HNO3 solution. -1 ) mixed standard solution monitoring instrument mass deviation effect, the measured sample - diluent mixture 191 Ir / 193 Ir, 101 Ru / 99 Such as 196 Pt / 194 Pt and 105 Pd / 106 The isotope ratio of Pd was corrected by isotope fractionation. In addition, the Zr, Hf and Cd standard solutions (all 10 ng ml -1 ) to monitor ZrO during mass spectrometry + / Zr、HfO + / Hf and 106 Cd + / 111 Cd + Ratio, used for interference correction calculation.

[0058] Table 3: Mass numbers and potential interfering ions of PGE ICP-MS

[0059]

[0060]

[0061] (4) NTIMS determination of Os isotopes

[0062] Os isotopes were determined using a TRITON Plus thermal ionization mass spectrometer. Peak jump analysis using a scanning electron multiplier (SEM) was generally employed. For detailed determination methods, see Reference 2.

[0063] (5) Blank in the entire process

[0064] This method has the characteristic of low process blank. The blank value of the whole process is: Re 1.9±1.1pg; Os0.11±0.12pg, 187 Os / 188 Os~0.16; Ir 2.8±1.9pg; Ru 6.1±1.0pg; Pt 4.0±1.1pg; Pd 8.0±2.2pg

[0065] SGR-1b Re-Os and PGE determination results

[0066] The Re-Os isotope and PGE test results of the oil shale standard sample SGR-1b are listed in Table 4. The test results are consistent with the values ​​reported in the literature within the error range.

[0067] Table 4: USGS SGR-1b Re-PGE results for oil shale standard samples*

[0068]

[0069]

[0070] *SE is the internal error, which is calculated based on the mass spectrometry error and background subtraction error; SD is the external error, which is calculated based on the results of multiple repeated measurements of the same sample.

[0071] Literature 4: Yin L., Li J., Liu JG, Li C., Sun SL, Liang HYand Xu JF (2017) Precise and accurate Re-Os isotope dating of organic-rich sedimentaryrocks by thermal ionization mass spectrometry with an improved H2O2-HNO3digestion procedure. International Journal of Mass Spectrometry, 421, 263-270.

[0072] Document 5: Wang, MJ, Chu, ZY, Meisel, TC, Guo, JH (2022) Determination of Re, Os, Ir, Ru, Pt, Pd Mass Fractions and 187Os / 188Os Ratios of Organic-RichGeological Reference Materials. Geostandards and Geoanalytical Research 46(2), 333-349.

[0073] Example 2:

[0074] Analysis of Re-Os and PGE in marine shale standard samples using USGS SBC-1

[0075] The chemical process for Example 2 was essentially the same as that for Example 1, except that, due to the lower organic carbon content of SBC-1 (1.23 wt%), a 0.5 g sample was weighed for each analysis. The Re-Os isotope and PGE analysis results for the USGS SBC-1 marine shale standard are listed in Table 5. These results agree within the error range with those reported in the literature.

[0076] Table 5: Determination results of Re-Os and PGE in marine shale standard sample SBC-1*

[0077]

[0078]

[0079] *SE is the internal error, which is calculated based on the mass spectrometry error and background subtraction error; SD is the external error, which is calculated based on the results of multiple repeated measurements of the same sample.

[0080] Document 6: Li J. and Yin L. (2019) Rhenium-osmium isotope measurements inmarine shale reference material SBC-1: Implications for method validation and quality control. Geostandards and Geoanalytical Research, 43, 497-507.

[0081] Document 7: Li X.W., Li C., Pei H.X., Zhou L.M., Qu W.J. and Du A.D. (2021) Purified Na2Cr04-H2S04: A new low-blank medium for Re-Os dating of black shale. Geostandards and Geoanalytical Research, 45, 313-323.

[0082] Example 3: Re-Os, PGE determination results of crude oil standard NIST RM 8505

[0083] Example 3 The chemical process of Example 1 is basically the same, except that the crude oil standard has a high organic matter content (such as RM8505 organic carbon ~ 85wt%), and the Re-PGE content is extremely low. Since Re-PGE in crude oil is mainly present in asphaltene in it, for crude oil standard RM8505, we first extract the asphaltene in crude oil with n-heptane, and then analyze the Re-Os and PGE of the asphaltene. To avoid tube blasting, 0.1 g of asphaltene is analyzed each time.

[0084] Among them, the principle of separating asphaltene from crude oil with n-heptane is: crude oil is the result of mixing multiple sub-components, and organic reagents can be used to separate the sub-components in crude oil. Generally, 40 times the volume of n-heptane is added to the crude oil to separate the crude oil into two parts, where the heavy components asphaltene that is insoluble in n-heptane will precipitate, and the light components maltene will dissolve in n-heptane to achieve the purpose of separation. N-heptane is used to extract asphaltene from NIST RM 8505 crude oil, and the specific method is as follows: (1) Add 1 g of crude oil and 40 mL of n-heptane to a 50 mL centrifuge tube; (2) Shake thoroughly in a dark light-free environment for more than 12 hours at room temperature; (3) After centrifugation at 2000 rpm for 20 minutes using a centrifuge, remove the n-heptane that dissolves the maltene using a pipette; The asphaltene obtained by first extraction can be further purified with n-heptane (to further wash out the light components maltene) to obtain purer asphaltene. (4) The remaining insoluble asphaltene at the bottom of the centrifuge tube is evaporated to dryness at a temperature below 60°C, and is ground into powder for Re-Os and PGE analysis.

[0085] Re-Os, PGE determination results of crude oil standard NIST RM 8505

[0086] The Re-Os and PGE test results of crude oil standard NIST RM 8505 are listed in Table 6. The Re-Os and PGE test results of asphaltene are consistent with those reported in the literature within the error range.

[0087] Table 6: Determination of Re-Os and PGE in crude oil standard NIST RM8505 asphaltene*

[0088]

[0089] *SE is the internal error, which is calculated based on the mass spectrometry error and background subtraction error; SD is the external error, which is calculated based on the results of multiple repeated measurements of the same sample.

[0090] **Reference 9 Asphaltene was washed twice with n-heptane to remove light components such as malachite.

[0091] Document 8: Liu JJand Selby D. (2018) Amatrix-matched reference material for validating petroleum Re-Os measurements. Geostandards and Geoanalytical Research, 42, 97-113.

[0092] Literature 9: Hurtig NC, Georgiev SV, Zimmerman A., Yang G., Goswami V., Hannah JLand Stein HJ (2020) Re-Os geochronology for the NIST RM 8505crudeoil: The importance of analytical protocol and uncertainty. Chemical Geology, 539, 119381.

[0093] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for rapidly separating Re and PGE from organic-rich geological samples, characterized in that: The following steps are involved: Sample dissolution steps: Dissolve the sample to obtain a sample solution dissolved in 0.2M HCl; specifically, first, dissolve 0.1-0.5 g of organic-rich geological sample using the Carius closed sample dissolution method in 3 mL of 12M HCl and 6 mL of 15M HNO3 at 220°C. Then, extract Os with CCl4. Transfer the residual liquid to a Teflon container and evaporate to dryness. Add 5 mL of 6M HCl to digest the sample, evaporate to dryness again, and then add 10 mL of 0.2M HCl to dissolve the sample to obtain a sample solution dissolved in 10 mL of 0.2M HCl. Chemical separation steps: A1, first, the sample solution is loaded onto an exchange column loaded with 20 mL of cationic resin to separate the Re-PGE therein; A2: The obtained Re-PGE receiving solution was evaporated to dryness and then dissolved in 1 mL of 7M HCl. The obtained sample solution was loaded onto an exchange column filled with 2 mL of 50-100 mm LN resin to separate PGE and Re in sequence.

2. The method according to claim 1, characterized in that In step A1, the sample solution dissolved in 0.2 M HCl is first loaded onto an exchange column filled with a cationic resin to separate Re-PGE in the sample solution; The exchange column loaded with cationic resin is prepared by filling 20 mL of 200-400 mesh AG50W-X8 resin produced by Bio-rad Company of the United States into an Econo-Pac chromatography empty column with an inner diameter of 1.5 cm produced by Bio-rad Company of the United States; The specific separation steps for separating Re-PGE include: pre-cleaning the exchange column loaded with the cationic resin with 60 mL of 6M HCl, 10 mL of Milli-Q H2O, 30 mL of 2M HF, and 10 mL of Milli-Q H2O in sequence; equilibrating the exchange column with 20 mL of 0.2M HCl; loading the sample solution dissolved in 10 mL of 0.2M HCl onto the column; and eluting the Re-PGE with 30 mL of 0.2M HCl.

3. The method according to claim 2, characterized in that In step A2, the Re-PGE obtained by separation using the cation exchange column is evaporated to dryness, dissolved in 1 mL of 7M HCl, and the obtained sample solution is loaded on an exchange column filled with LN resin to separate PGE and Re in sequence; The exchange column loaded with LN resin is prepared by filling 2 mL of LN resin with a particle size of 50-100 μm produced by Eichrom, USA, into a PP chromatography empty column with an inner diameter of 0.8 cm produced by Eichrom, USA, and covering the upper end of the resin with a polyethylene porous sieve plate; The specific separation steps for sequentially separating PGE and Re include: pre-cleaning an exchange column loaded with 2 mL of the LN resin with 4 mL of Milli-Q H2O, 4 mL of 2M HF, and 4 mL of Milli-Q H2O; adding 4 mL of 7M HCl to equilibrate the exchange column; loading the Re-PGE solution dissolved in 1 mL of 7M HCl onto the column; adding 3 mL of 7M HCl to elute PGE, and then adding 5 mL of 0.2M HCl to elute Re.

4. The method according to any one of claims 1 to 3, characterized in that: The separated Re can be used for high-precision Re isotope analysis by MC-ICP-MS (multi-collector plasma mass spectrometry) and for Re content analysis by the isotope dilution method for Re-Os dating. The separated PGE can be used for multi-element rapid isotope ratio determination by Q-ICP-MS (quadrupole plasma mass spectrometry) or Element-XR ICP-MS and for PGE element content analysis by the isotope dilution method.

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