Magnesium and strontium isotope reference materials matched with clinopyroxene matrix and preparation method thereof

Abstract

The present invention discloses a magnesium and strontium isotope reference material matched with a monoclinic pyroxene matrix and a preparation method thereof. The magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix comprises the following raw material components in parts by mass: SiO 2 519 - 522 parts, TiO 2 6.9 - 7.1 parts, Al2O 3 40.0 - 40.2 parts, Fe2O 3 50.4 - 50.6 parts, MgO 149 - 151 parts, CaO 30 - 232 parts, Na2O 4.37 - 4.39 parts, and 2000 - 5000 parts of the Sr standard solution of the National Research Institute of Metrology. The main element composition thereof can be matched with the natural monoclinic pyroxene matrix, and at the same time, the main element content and the magnesium and strontium isotope composition are uniform in the mineral distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical analysis, and particularly relates to a magnesium and strontium isotope reference material matched with a monoclinic pyroxene matrix and a preparation method thereof. Background Art

[0002] Magnesium isotopes, as effective geochemical tracers, have received long-term attention from geologists. By using laser ablation - multi-collector inductively coupled plasma in-situ microanalysis of the lithium and magnesium isotope compositions of single mineral grains at the micron scale, it can provide a unique perspective and evidence for understanding specific geological evolution processes. Among them, in-situ microanalysis of magnesium isotopes is mainly limited by the analysis method and the lack of matrix-matched reference materials. Existing magnesium isotope reference materials include USGS glass, MPI-DING glass, and natural pyroxene, olivine and other substances. However, it is difficult for these synthetic reference materials to match the matrix in monoclinic pyroxene, and natural pyroxene has problems such as small promotion and limited quantity.

[0003] In recent years, laser ablation multi-collector inductively coupled plasma mass spectrometry has been significantly applied in the in-situ measurement of radiogenic Sr isotopes. The multi-collector inductively coupled plasma mass spectrometry method is a fast and economical method for analyzing Sr isotope composition, and can achieve the high spatial resolution and accuracy required for studying various geological processes. In addition to the interference correction that must be considered, accurate in-situ Sr isotope testing requires an external reference material with low Rb / Sr and high Sr content to correct the errors of different laboratory tests and evaluate the feasibility of the correction strategy. Although the commonly used glass reference samples (such as BCR-2G, BHVO-2G, NKT-1G, TB-1G) are used for data quality monitoring and interference deduction of 87Rb, Sr isotope fractionation related to the Rb / Sr relationship has been found in different glasses during the testing process. Therefore, it is very necessary to use matrix-matched reference materials to accurately determine in-situ Sr isotopes. Summary of the Invention

[0004] The main object of the present invention is to propose a magnesium and strontium isotope reference material matched with a monoclinic pyroxene matrix and a preparation method thereof, aiming to provide a monoclinic pyroxene matrix-matched isotope reference material with an element composition matching the natural monoclinic pyroxene matrix and uniform element content and isotope composition distribution (Mg, Sr).

[0005] To achieve the above object, the present invention proposes a magnesium and strontium isotope reference material matched with a monoclinic pyroxene matrix, comprising the following raw material components in parts by mass:

[0006] SiO 2 519 - 522 parts, TiO 2 6.9 - 7.1 parts, Al 2 O3 40.0 to 40.2 parts, Fe 2 O 3 50.4 to 50.6 parts, 149 to 151 parts of MgO, 230 to 232 parts of CaO, Na 2 O 4.37 to 4.39 parts, and 2000 to 5000 parts of the Sr standard solution of the National Research Institute of Metrology.

[0007] The present invention also provides a method for preparing a magnesium and strontium isotope reference material matched with a clinopyroxene matrix, which is used to prepare the magnesium and strontium isotope reference material matched with the clinopyroxene matrix as described above, and includes the following steps:

[0008] Provide raw material components;

[0009] Mix the raw material components and then grind them, adding a primary pure ethanol solution during grinding, and obtaining a powder suspension after grinding;

[0010] Evaporate the powder suspension to dryness, melt it after evaporation, and quench it after melting to obtain a magnesium and strontium isotope reference material matched with a clinopyroxene matrix.

[0011] Optionally, the step of mixing the raw material components and then grinding them, adding a primary pure ethanol solution during grinding, and obtaining a powder suspension after grinding includes:

[0012] Add a primary pure ethanol solution to the raw material components for the first grinding, and then add 10 to 15 agate balls for the second grinding to obtain a powder suspension.

[0013] Optionally, the particle size of the powder particles in the powder suspension is less than 5 μm.

[0014] Optionally, the time for the first grinding is 25 to 35 minutes; and / or,

[0015] The time for the second grinding is 5 to 10 hours.

[0016] Optionally, the step of evaporating the powder suspension to dryness, melting it after evaporation, and quenching it after melting to obtain a magnesium and strontium isotope reference material matched with a clinopyroxene matrix includes:

[0017] Evaporate the powder suspension to dryness, heat it from 0 °C to 1500 °C after evaporation, then melt it under the conditions of 1545 to 1555 °C and 1 atm, and quench it in tap water after melting to obtain a magnesium and strontium isotope reference material matched with a clinopyroxene matrix.

[0018] Optionally, the time for melting is 14 to 16 minutes.

[0019] In the technical solution of the present invention, in the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix, SiO 2 、TiO 2 、Al 2 O 3 、Fe 2 O 3 、MgO, CaO and Na 2 O in the elements constitute the matrix components of the reference material. The magnesium element in MgO is used as the magnesium element of the reference material, and the strontium element in the Sr standard solution of National Research Institute of Metrology is used as the strontium element of the reference material. The ratio of each component is scientific, so that the element composition of the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix is matched with the natural monoclinic pyroxene matrix, and the distribution of magnesium, strontium elements and their isotope compositions is uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0021] Figure 1 It is a schematic flow chart of an embodiment of the preparation method of the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix proposed by the present invention;

[0022] Figure 2 It is a test result diagram of the particle size of the powder particles in the powder suspension obtained in Embodiments 1 and 2 provided by the present invention;

[0023] Figure 3 It is a relative standard error diagram of the chemical composition determination of the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix obtained in Embodiments 1 and 2 provided by the present invention;

[0024] Figure 4 It is a test result diagram of the magnesium isotope homogeneity test of the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix obtained in Embodiments 1 and 2 provided by the present invention;

[0025] Figure 5 It is a test result diagram of the strontium isotope homogeneity test of the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix obtained in Embodiments 3, 4, 5, and 6 provided by the present invention.

[0026] The realization, functional characteristics and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0028] It should be noted that for those conditions not specified in the embodiments, they shall be carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes Scenario A, or Scenario B, or the scenario where both A and B are satisfied simultaneously. Furthermore, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or inability to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0029] Magnesium isotopes, as effective geochemical tracers, have received long-term attention from geologists. By using laser ablation-multiple collector inductively coupled plasma in-situ microanalysis of the lithium and magnesium isotope compositions of single mineral grains at the micron scale, it can provide a unique perspective and evidence for understanding specific geological evolution processes. Among them, in-situ microanalysis of magnesium isotopes is mainly limited by the analysis method and the lack of matrix-matched reference materials. Existing magnesium isotope reference materials include USGS glass, MPI-DING glass, and natural pyroxene, olivine, and other substances. However, it is difficult for these synthetic reference materials to match the matrix in clinopyroxene, and natural pyroxene has problems such as small promotion and limited quantity.

[0030] In recent years, laser ablation multiple collector inductively coupled plasma mass spectrometry has been significantly applied in the in-situ measurement of radiogenic Sr isotopes. Multiple collector inductively coupled plasma mass spectrometry is a fast and economical method for analyzing Sr isotope compositions, which can achieve the high spatial resolution and accuracy required for studying various geological processes. In addition to the interference correction that must be considered, accurate in-situ Sr isotope testing requires external reference materials with low Rb / Sr and high Sr content to correct the errors in different laboratory tests and evaluate the feasibility of the correction strategy. Although the commonly used glass reference samples (such as BCR-2G, BHVO-2G, NKT-1G, TB-1G) are used for data quality monitoring and the interference deduction of 87Rb, Sr isotope fractionation related to the Rb / Sr relationship has been found to exist in different glasses during the testing process. Therefore, it is very necessary to use matrix-matched reference materials to accurately determine in-situ Sr isotopes.

[0031] In view of this, the present invention provides a magnesium and strontium isotope reference material matched with a monoclinic pyroxene matrix, which comprises the following raw material components in parts by mass: SiO 2 519 - 522 parts, TiO 2 6.9 - 7.1 parts, Al 2 O 3 40.0 - 40.2 parts, Fe 2 O 3 50.4 - 50.6 parts, MgO 149 - 151 parts, CaO 230 - 232 parts, Na 2 O 4.37 - 4.39 parts, and 2000 - 5000 parts of the Sr standard solution of the National Research Institute of Metrology.

[0032] In the technical solution of the present invention, in the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix, the elements in SiO 2 , TiO 2 , Al 2 O 3 , Fe 2 O 3 , MgO, CaO and Na 2 O form the matrix components of the reference material. The magnesium element in MgO serves as the magnesium element of the reference material, and the strontium element in the Sr standard solution of the National Research Institute of Metrology serves as the strontium element of the reference material. The proportioning of each component is scientific, making the element composition of the isotope reference material matched with the monoclinic pyroxene matrix match the natural monoclinic pyroxene matrix, and the distribution of the magnesium and strontium elements and their isotope compositions is uniform.

[0033] The present invention also provides a preparation method of the magnesium and strontium isotope reference material matched with the monoclinic pyroxene matrix as described above. As Figure 1 shown, it includes the following steps:

[0034] Step S10: Provide the raw material components.

[0035] It should be noted that the raw material components can be weighed according to the following ratio: SiO 2 519 - 522 parts, TiO 2 6.9 - 7.1 parts, Al 2 O 3 40.0 - 40.2 parts, Fe 2 O 3 50.4 - 50.6 parts, MgO 149 - 151 parts, CaO 230 - 232 parts, Na 2 O 4.37 - 4.39 parts, and 2000 - 5000 parts of the Sr standard solution of the National Research Institute of Metrology.

[0036] Step S20: Mix the raw material components and then grind them. When grinding, add GR ethanol solution. After grinding, a powder suspension is obtained.

[0037] After weighing the raw materials, for the convenience of subsequent melting preparation, the raw materials need to be ground. Step S20 specifically includes: Step S21: Add GR ethanol solution to the raw material components for the first grinding, and then add 10 - 15 agate balls for the second grinding to obtain a powder suspension. During this period, the time for the first grinding is 25 - 35 minutes, such as 25 minutes, 30 minutes, 35 minutes, etc.; the time for the second grinding is 5 - 10 hours, such as 5 hours, 8 hours, 10 hours, etc. Through the first grinding operation, the powder substances in the raw materials are simply mixed and homogenized; and adding GR ethanol solution during grinding helps to improve the grinding efficiency; while through the second grinding operation, the powder substances can be further mixed and homogenized, ensuring that the particle size of the final powder particles is less than 5 μm. Thus, the prepared powder suspension meets the following conditions: the particle size of the powder particles in the powder suspension is less than 5 μm, and the particle size of the powder particles within this range helps to improve the melting effect, thereby improving the quality of the prepared lithium, magnesium, and strontium isotope reference materials matched with the monoclinic pyroxene matrix.

[0038] In the embodiments of the present invention, there are no restrictions on the equipment used for the first grinding. For example, the raw materials can be placed in an agate mortar for the first grinding; there are no restrictions on the equipment used for the second grinding. For example, the raw materials after the first grinding can be placed in an agate jar and then ground for the second time in a MM400 planetary ball mill.

[0039] Step S30: Evaporate the powder suspension to dryness, melt it after drying, and then quench it to obtain magnesium and strontium isotope reference materials matched with the monoclinic pyroxene matrix.

[0040] Step S30 specifically includes: Step S31: Evaporate the powder suspension to dryness, heat it from 0 °C to 1500 °C after drying, then melt it under the conditions of 1545 - 1555 °C and 1 atm, and quench it in tap water after melting to obtain magnesium and strontium isotope reference materials matched with the monoclinic pyroxene matrix. And the melting time is 14 - 16 minutes. It should be noted that the heating process can be carried out in a platinum crucible; while the melting process can be carried out in the furnace chamber of a high-temperature single-atmosphere furnace, and the volume of the furnace chamber is 36 liters (30 cm × 40 cm × 30 cm). By quenching in tap water, it is convenient to observe the formation of magnesium and strontium isotope reference materials matched with the monoclinic pyroxene matrix.

[0041] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0042] Example 1

[0043] (1)Provide raw materials: SiO 2 521 mg, TiO 2 7 mg, Al 2 O 3 40.1 mg, Fe 2 O 3 50.5 mg, MgO 150 mg, CaO 231 mg, Na 2 O 4.38 mg.

[0044] (2)Perform the first grinding on the raw materials (grind for 30 minutes). Add analytical reagent grade ethanol solution during the first grinding. After the first grinding, add 12 agate balls, and then perform the second grinding (grind for 8 hours). A powder suspension is obtained after the second grinding.

[0045] (3)Evaporate the powder suspension to dryness. After evaporation, heat from 0 °C to 1500 °C, and then melt at 1550 °C and 1 atm for 15 minutes. Quench in tap water after melting to obtain a magnesium isotope reference material matched with the clinopyroxene matrix.

[0046] The prepared magnesium isotope reference material matched with the clinopyroxene matrix is denoted as CPXA01.

[0047] Example 2

[0048] (1)Provide raw materials: SiO 2 521 mg, TiO 2 8 mg, Al 2 O 3 40.1 mg, Fe 2 O 3 50.7 mg, MgO 152 mg, CaO 230 mg, Na 2 O 4.38 mg.

[0049] (2)Perform the first grinding on the raw materials (grind for 25 minutes). Add analytical reagent grade ethanol solution during the first grinding. After the first grinding, add 10 agate balls, and then perform the second grinding (grind for 10 hours). A powder suspension is obtained after the second grinding.

[0050] (3)Evaporate the powder suspension to dryness. After evaporation, heat from 0 °C to 1500 °C, and then melt at 1555 °C and 1 atm for 14 minutes. Quench in tap water after melting to obtain a magnesium isotope reference material matched with the clinopyroxene matrix.

[0051] The prepared magnesium isotope reference material matched with the clinopyroxene matrix is denoted as CPXB01.

[0052] Example 3

[0053] (1) Provide raw materials: SiO 2 519 mg, TiO 2 6.9 mg, Al 2 O 3 40.2 mg, Fe 2 O 3 50.6 mg, 149 mg of MgO, 230 mg of CaO, Na 2 O 4.39 mg and 2 g of Sr standard solution of National Research Institute of Metrology.

[0054] (2) Grind the raw materials for the first time (grind for 35 minutes). Add analytical reagent ethanol solution during the first grinding. After the first grinding, add 15 agate balls, and then conduct the second grinding (grind for 5 hours). After the second grinding, a powder suspension is obtained.

[0055] (3) Evaporate the powder suspension to dryness. After evaporation, heat from 0 °C to 1500 °C, and then melt at 1545 °C and 1 atm for 16 minutes. After melting, quench in tap water to obtain a strontium isotope reference material matched with monoclinic pyroxene matrix.

[0056] The prepared magnesium and strontium isotope reference materials matched with monoclinic pyroxene matrix are denoted as CPXSR1.

[0057] Example 4

[0058] The difference from Example 3 is that: the raw materials provided in step (1) are SiO 2 521 mg, TiO 2 7 mg, Al 2 O 3 40.1 mg, Fe 2 O 3 50.5 mg, 150 mg of MgO, 231 mg of CaO, Na 2 O 4.38 mg and 3 g of Sr standard solution of National Research Institute of Metrology.

[0059] The prepared magnesium and strontium isotope reference materials matched with monoclinic pyroxene matrix are denoted as CPXSR2.

[0060] Example 5

[0061] The difference from Example 3 is that: the raw materials provided in step (1) are SiO 2 519 mg, TiO 2 6.9 mg, Al 2 O 3 40.2 mg, Fe 2 O 350.6 mg, 149 mg of MgO, 230 mg of CaO, Na 2 O 4.39 mg, and 4 g of the Sr standard solution of GRNAC.

[0062] The magnesium and strontium isotope reference materials matched with the clinopyroxene matrix prepared are denoted as CPXSR3.

[0063] Example 6

[0064] The difference from Example 3 lies in that: the raw materials provided in step (1) are SiO 2 522 mg, TiO 2 7.1 mg, Al 2 O 3 40.0 mg, Fe 2 O 3 50.4 mg, 151 mg of MgO, 232 mg of CaO, Na 2 O 4.37 mg, and 5 g of the Sr standard solution of GRNAC.

[0065] The magnesium and strontium isotope reference materials matched with the clinopyroxene matrix prepared are denoted as CPXSR4.

[0066] Taking the magnesium and strontium isotope reference materials matched with the clinopyroxene matrix prepared in Examples 1 to 6 as examples, their various indexes are tested. Please refer to Figures 2 - 5 and Table 1-2. Table 1 is the accurate Mg isotope composition of CPXA01 and CPXB01 samples (SN-MC-ICP-MS method), and Table 2 is the accurate Sr isotope composition of CPXSR1-4 samples (obtained by LA-ICP-MS method); Figure 2 This is the test result diagram of the particle size of the powder particles in the powder suspension obtained in Examples 1 and 2 provided by the present invention; Figure 3 This is the relative standard error diagram of the chemical composition determination of the isotope reference materials matched with the clinopyroxene matrix obtained in Examples 1 and 2 provided by the present invention; Figure 4 This is the result diagram of the magnesium isotope homogeneity test of the isotope reference materials matched with the clinopyroxene matrix obtained in Examples 1 and 2 provided by the present invention; Figure 5 This is the result diagram of the strontium isotope homogeneity test of the isotope reference materials matched with the clinopyroxene matrix obtained in Examples 3, 4, 5, and 6 provided by the present invention.

[0067] From Figures 2 - 5 and Table 1-2, it can be seen that for CPXA01 and CPXB01, their element compositions can all match the natural clinopyroxene matrix, and the contents of their magnesium and strontium isotopes are uniform in the mineral.

[0068] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the patent protection scope of the present invention.

[0069] Table 1 Accurate Mg isotope compositions of CPXA01 and CPXB01 samples (SN-MC-ICP-MS method)

[0070]

[0071] Table 2 Accurate Sr isotope compositions of CPXSR1-4 samples (obtained by LA-ICP-MS method)

[0072]

Claims

1. A preparation method of a magnesium and strontium isotope reference material matched with a monoclinic pyroxene matrix, characterized in that, it includes the following steps: Provide raw material components including the following mass parts: SiO 2 519 - 522 parts, TiO 2 6.9 - 7.1 parts, Al 2 O 3 40.0 - 40.2 parts, Fe 2 O 3 50.4 - 50.6 parts, MgO 149 - 151 parts, CaO 230 - 232 parts, Na 2 O 4.37 - 4.39 parts, and 2000 - 5000 parts of the Sr standard solution of the National Research Institute of Metrology; Mix the raw material components, add a superior pure ethanol solution for the first grinding, and then add 10 - 15 agate balls for the second grinding to obtain a powder suspension; wherein, the time for the first grinding is 25 - 35 minutes, the time for the second grinding is 5 - 10 hours, and the particle size of the powder particles in the powder suspension is less than 5 μm; Evaporate the powder suspension to dryness, melt it after evaporation, and quench it after melting to obtain a magnesium and strontium isotope reference material matched with a monoclinic pyroxene matrix; wherein, after evaporation, heat it from 0 °C to 1500 °C, then melt it under the conditions of 1545 - 1555 °C and 1 atm, and quench it in tap water after melting, and the melting time is 14 - 16 minutes.

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