Method for analyzing abundance of < 10 > B isotope

Abstract

The invention provides an analysis method of < 10 > B isotope abundance, which comprises the following steps: melting a mixture containing a boron carbide sample and an alkali solvent, and cooling to obtain a frit, the alkali solvent being an alkali metal hydroxide; dissolving the frit with acid to obtain a solution to be detected; and measuring and calculating the abundance of the < 10 > B isotope in the solution to be measured by using a multi-receiving inductively coupled plasma mass spectrometry. The method provided by the invention is simple in processing steps, and the detection accuracy is improved.

Description

Technical Field

[0001] The present invention belongs to the field of analytical testing research, and specifically relates to a 10 B isotope abundance analysis method. Background Art

[0002] Boron has 10 B. 11 B has two stable isotopes with natural abundances of 19.9% ​​and 80.1% respectively. 10 B has an absorption cross section of 3837 for thermal neutrons, and is prone to undergo (n, α) nuclear reactions with thermal neutrons. 11 B is 0.005 target and absorbs almost no neutrons. 10 Boron carbide (boron carbide-10) is a good neutron absorber. It has the advantages of wide absorption energy spectrum, no strong secondary radiation after absorbing neutrons, and easy waste disposal. Therefore, it is used as functional components such as nuclear reactor control rods, regulating rods, accident rods, safety rods, and shielding rods. Fast neutron reactors use 10 Boron carbide pellets with a boron abundance of 92% are used as control rod materials, and boron carbide-aluminum composite materials are used as neutron absorbers in spent fuel storage grids in nuclear power plants.

[0003] Boron carbide is a neutron absorbing material. Its neutron absorption capacity mainly depends on its 10 B content, so 10 The abundance of boron isotope is an important technical indicator of boron carbide products. YS / T250-1994 "Technical Specifications for Nuclear Grade Boron Carbide Powder" stipulates that the 10 The abundance of B isotopes needs to be accurately determined. Therefore, a nuclear grade boron carbide 10 The analysis method of B isotope abundance provides important evaluation data for designing the preparation process of boron carbide materials and product inspection and testing methods, and evaluating neutron absorption performance.

[0004] At present, JB / T7993-2012 Boron Carbide Chemical Analysis Method stipulates the analysis method of the chemical composition of common industrial boron carbide products, but does not specify the chemical composition of boron carbide products. 10 The analytical method of boron isotope abundance is specified. ASTM C791-19 mainly specifies the method of determining boron isotope abundance by thermal ionization mass spectrometry (TIMS), but the TIMS method has the problems of cumbersome sample handling, long analysis time, low work efficiency, and obvious fractionation effect in the ionization process. In particular, when analyzing irradiated boron carbide pellets, the sample is difficult to handle and there are detection interferences.

[0005] Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is another method for isotope abundance analysis with comparable measurement accuracy to TIMS. Currently, for boron carbide samples, most use carbonates such as sodium carbonate and calcium carbonate as alkaline fluxes to decompose the samples, and melt and dissolve them at high temperatures of 900℃-1000℃ before testing. However, this treatment method has a high melting temperature on the one hand, and on the other hand, carbonate alkaline fluxes introduce a large amount of sodium and calcium, which produce matrix effects during measurement and lead to deviations in measurement results. Therefore, when measuring boron isotope abundance, these methods all use ion exchange or precipitation methods to remove a large amount of sodium and calcium ions. For boron carbide-aluminum samples, most of them first use sodium hydroxide solution or hydrochloric acid to dissolve the sample into liquid, then filter and wash, remove the aluminum matrix, and then analyze the filter residue boron carbide according to the above boron carbide treatment method. Alternatively, the boron carbide-aluminum is first melted at 900-1100°C with an alkaline flux such as sodium carbonate, then dissolved with acid, and then a large amount of aluminum ions are precipitated by adjusting the acidity of the solution before analysis. These methods have many experimental steps and cumbersome procedures, and are very likely to cause boron loss and possible boron isotope fractionation. ASTM C791-19 stipulates a method of treating boron carbide with thermal hydrolysis and then determining the boron isotope abundance using inductively coupled plasma mass spectrometry (ICP-MS), but the thermal hydrolysis process is complicated and the conditions are difficult to control. If the boron recovery is not complete, boron isotope fractionation is likely to occur.

[0006] Therefore, it is necessary to develop a method that can measure accurately and is easy to operate. 10 B isotope abundance analysis method. Summary of the invention

[0007] In view of this, the main purpose of the present invention is to provide an accurate and easy-to-operate neutron absorbing material containing boron carbide. 10 B isotope abundance analysis method.

[0008] To this end, the present invention provides a boron carbide-containing material 10 The analytical method for the isotope abundance of B comprises the following steps:

[0009] Melting and cooling a mixture containing a boron carbide sample and an alkali flux to obtain a frit, wherein the alkali flux is an alkali metal hydroxide;

[0010] Dissolving the frit with acid to obtain a solution to be tested;

[0011] The multi-collector inductively coupled plasma mass spectrometry method is used to determine and calculate the 10 B isotope abundance.

[0012] In some embodiments, the boron carbide-containing sample includes one or more of boron carbide, boron carbide-aluminum, and boron carbide-aluminum oxide.

[0013] In some embodiments, the boron carbide-containing sample is boron carbide.

[0014] In some embodiments, the alkali flux is at least one of sodium hydroxide and lithium hydroxide.

[0015] In some embodiments, the ratio of the amount of the boron carbide-containing sample to the amount of the alkali flux added is 1:10 to 1:20.

[0016] In some embodiments, the melting temperature is 550°C-600°C.

[0017] In some embodiments, the melting is achieved by step-by-step heating; preferably, the step-by-step heating program is: heating to 350°C-400°C at a first heating rate of 2-3°C / min, and keeping warm for 0.5-1h, heating to the melting temperature at a second heating rate of 4-5°C / min, and keeping warm for 0.5-1h.

[0018] In some embodiments, the acid is 3.6 mol / L-4.8 mol / L hydrochloric acid, or 4.8 mol / L-6.4 mol / L nitric acid.

[0019] In some embodiments, the test solution is obtained by diluting and fixing the volume of a solution obtained by dissolving a frit with an acid, preferably by diluting and fixing the volume with water or 0.32 mol / L.

[0020] In some embodiments, the analysis method uses a multi-collector inductively coupled plasma mass spectrometer for measurement.

[0021] The present application uses alkali metal oxides as alkaline flux, wherein the melting point of sodium hydroxide is 318.4°C, and the melting point of lithium hydroxide is 462°C. The boron carbide sample powder is melted at a smaller dosage, lower melting temperature, and shorter melting time, which can avoid the loss of boron during sample pretreatment and completely melt the boron carbide sample, with a boron recovery rate of more than 99.6%. The solution obtained after dissolving the molten block is directly measured, and the alkali metal ion matrix introduced by the alkaline flux has no effect on the measurement of boron isotope abundance. By adopting a step-by-step heating method, the sample gradually melts at a lower melting temperature, which is not easy to cause sample loss during the melting process. The process is simple, easy to control, and has strong repeatability. The equipment used in the method of the present application is generally available, and simplifies the sample pretreatment process and analysis process, which can be achieved. 10 The abundance of B isotope was determined with an accuracy of 0.1‰. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The test results of the effect of the lithium ion matrix on the boron isotope abundance when the boron ion concentration is 200 μg / L in Example 4 of the present application;

[0023] Figure 2 The test results of the effect of the sodium ion matrix on the boron isotope abundance when the boron ion concentration is 200 μg / L in Example 5 of the present application;

[0024] Figure 3 These are the test results of the effect of the coexistence of lithium ions and aluminum ions on boron isotope abundance when the boron ion concentration is 200 μg / L in Example 6 of the present application. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0027] It should be noted that, in the embodiments of the present invention, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a method or device including a series of elements includes not only the elements explicitly stated, but also other elements not explicitly listed, or also includes elements inherent to the implementation of the method or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other related elements in the method or device including the element.

[0028] It should be noted that the terms "first\second\third" involved in the embodiments of the present invention are only used to distinguish similar objects, and do not represent a specific order for the objects. It is understandable that the specific order or sequence of "first\second\third" can be interchanged where permitted. It should be understood that the objects distinguished by "first\second\third" can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0029] In the prior art, multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) or thermal ionization mass spectrometry (TIMS) is used to 10 When measuring the boron isotope abundance, for boron carbide samples, carbonates such as sodium carbonate and calcium carbonate are usually used as alkaline fluxes to melt and dissolve the samples at high temperatures of 900℃-1000℃, and then a large amount of sodium and calcium ions are removed by ion exchange or precipitation before testing. Due to the addition of a large amount of sodium and calcium alkaline fluxes, the matrix effect is generated during the measurement, resulting in deviations in the measurement results. Therefore, when measuring the boron isotope abundance, these methods all use ion exchange or precipitation to remove a large amount of sodium and calcium ions. The matrix effect refers to the inaccuracy of the measurement results caused by the high concentration of matrix elements in the sample, which causes the ion flow intensity of the analyzed element to be suppressed or enhanced. For example, Zhu Liuchao et al. used calcium carbonate as a flux for high-temperature decomposition, leached with nitric acid, and then used sulfuric acid to precipitate a large amount of calcium ions to pretreat the boron carbide sample to eliminate the influence of a large amount of calcium matrix on the measurement of boron isotope abundance. This method is the same as the method using other carbonates. In addition of more calcium carbonate, the introduction of a large amount of calcium ions will affect the measurement of boron isotope abundance. However, adding sulfuric acid to precipitate a large amount of calcium ions has many problems, such as complicated experimental operation, introduction of new impurity elements, and the precipitation process is prone to boron loss and boron isotope fractionation. For another example, CN 116893216 A discloses a method of melting boron carbide-alumina materials at 900°C-1100°C with an alkali flux such as sodium carbonate, then leaching with water, adjusting the pH value with hydrochloric acid so that a large amount of aluminum ions form aluminum hydroxide precipitation, and then performing boron isotope analysis on the supernatant. However, hydroxide precipitation is generally a colloidal precipitation, which is easy to carry over the coexisting elements in the solution and cause boron loss. In addition, it is difficult to accurately control the pH value, which is easy to cause incomplete precipitation of aluminum and affect the measurement results.

[0030] In view of this, the present invention provides a 10 The analytical method for the isotope abundance of B comprises the following steps:

[0031] Melting and cooling a mixture containing a boron carbide sample and an alkali flux to obtain a frit, wherein the alkali flux is an alkali metal hydroxide;

[0032] Dissolving the frit with acid to obtain a solution to be tested; and

[0033] The multi-collector inductively coupled plasma mass spectrometry method is used to determine and calculate the 10 B isotope abundance.

[0034] In the present application, alkali metal hydroxide is used as an alkali flux, which can reduce the amount of alkali flux and the melting temperature required for melting the boron carbide sample, and achieve complete melting of the boron carbide sample. The boron carbide form that cannot be directly measured is converted into a measurable borate form through the melting process. The melting process adopts step-by-step heating, and the sample gradually melts at a lower melting temperature and a shorter melting time, which is not easy to cause sample loss during the melting process. The process is simple, easy to control, and has strong repeatability. The method of the present application can directly use the melted block for measurement after it is dissolved, without the need to remove the alkali metal ions introduced in the alkali flux or the matrix elements contained in the sample itself. And for the subsequent 10 The measurement of the B isotope abundance has no effect.

[0035] In some embodiments, the boron carbide-containing sample includes boron carbide, boron carbide-aluminum, and boron carbide-aluminum oxide. The boron carbide-containing sample is used as a neutron absorbing material for functional elements such as control rods, regulating rods, accident rods, safety rods, shielding rods, etc. of nuclear reactors or a spent fuel storage grid of a nuclear power plant. In some embodiments, the boron carbide-containing sample is boron carbide.

[0036] In some embodiments, the boron carbide-containing sample is ground and dried before mixing with the alkali flux. By grinding and drying the boron carbide-containing sample, it is beneficial to improve the melting efficiency, facilitate the subsequent complete dissolution of the melt, and avoid sample loss. In a specific embodiment, the grinding includes grinding in a grinder at 3000r / min for 2min. Optionally, after grinding the boron carbide-containing sample, the sample powder is sieved, for example, with a 160-mesh to 200-mesh sample sieve. In a specific embodiment, the drying includes drying in an oven at a drying temperature of 100°C-110°C and a drying time of 1h.

[0037] In some embodiments, the alkali flux is at least one of sodium hydroxide and lithium hydroxide. Sodium hydroxide and lithium hydroxide can effectively reduce the melting temperature of the boron carbide-containing sample and reduce the amount of alkali flux used. It is not necessary to remove sodium ions or lithium ions, which is beneficial for subsequent multi-collector inductively coupled plasma mass spectrometry determination. 10B isotope abundance does not have an impact. In one embodiment, the alkali flux is sodium hydroxide. When the alkali flux is sodium hydroxide, the amount of alkali flux can be reduced and the melting temperature of the boron carbide sample can be reduced, reagent and energy costs can be saved, and the sodium ions introduced will not produce a matrix effect when measuring. In one embodiment, the alkali flux is lithium hydroxide. Using lithium hydroxide as an alkali flux, the melting temperature can be significantly reduced and the amount of alkali flux can be reduced for samples such as boron carbide, boron carbide-aluminum, and boron carbide-aluminum oxide, and lithium ions will not cause a matrix effect when measuring, thereby ensuring the accuracy of detection. On the other hand, since lithium ions do not need to be removed after melting, the loss of boron in the sample processing process, boron isotope fractionation, and other elements introduced interfere, thereby further improving the accuracy of detection.

[0038] In some embodiments, when the boron carbide-containing sample includes one or more of boron carbide, boron carbide-aluminum, and boron carbide-aluminum oxide, the alkali flux is lithium hydroxide.

[0039] In some embodiments, when the boron carbide-containing sample includes boron carbide, the alkali flux is sodium hydroxide.

[0040] In some embodiments, the ratio of the amount of the boron carbide-containing sample to the amount of the alkali flux is 1:10 to 1:20. By having the ratio of the amount of the boron carbide-containing sample to the amount of the alkali flux within the above range, it is beneficial to ensure the complete melting of the boron carbide sample, reduce the amount of the alkali flux and the subsequent dissolving acid, and minimize the matrix content. Exemplarily, the ratio of the amount of the boron carbide-containing sample to the amount of the alkali flux can be 1:10, 1:15, 1:20, or a value between the ranges consisting of any two of them.

[0041] In some embodiments, the melting is performed at a melting temperature of 550°C-600°C. By making the melting temperature in the above range, it is beneficial to melt at a lower melting temperature and a shorter melting time, and it is not easy to cause the loss of boron in the melting process, thereby improving the measurement accuracy and saving experimental time. Exemplarily, the melting temperature can be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C or a value between the ranges consisting of any two of them.

[0042] In some embodiments, the melting is performed by gradually increasing the temperature to reach the temperature. The melting is performed by gradually increasing the temperature, and the sample gradually melts at a lower melting temperature, which is conducive to the complete melting of the boron carbide sample and is not prone to sample loss caused by sample overflow due to rapid temperature increase. The melting process is simple, easy to control, and highly repeatable.

[0043] In some embodiments, the step-by-step heating program is: heating to 350-400°C at a first heating rate of 2-3°C / min, and keeping warm for 0.5-1h, heating to the melting temperature at a second heating rate of 4-5°C / min, and keeping warm for 0.5-1h.

[0044] In a preferred embodiment, the step-by-step heating program is: heating to 400°C at a heating rate of 3°C / min, keeping warm for 0.5h; heating to the melting temperature at a heating rate of 5°C / min, keeping warm at the melting temperature for 1h.

[0045] In some embodiments, the acid is 3.6mol / L-4.8mol / L hydrochloric acid, or 4.8mol / L-6.4mol / L nitric acid. Using the above-mentioned concentration of acid, the solid sample can be converted into an aqueous solution sample of lithium borate or sodium borate for subsequent measurement. Exemplarily, the acid can be 3.6mol / L, 3.8mol / L, 4.0mol / L, 4.2mol / L, 4.4mol / L, 4.6mol / L, 4.8mol / L or a concentration of hydrochloric acid between the ranges consisting of any two of them; it can also be 4.8mol / L, 5.0mol / L, 5.2mol / L, 5.4mol / L, 5.6mol / L, 5.8mol / L, 6.0mol / L, 6.2mol / L, 6.4mol / L or a concentration of nitric acid between the ranges consisting of any two of them.

[0046] In some embodiments, the solution to be tested is obtained by diluting and constant volume a solution in which a frit is dissolved with an acid, preferably with water or 0.32 mol / L HNO3 for dilution and constant volume. This enables the analytical method of the present application to measure and accurately calculate the boron isotope abundance values ​​in different boron carbide samples. The concentration of boron ions in the solution to be tested can be 200 μg / L to 800 μg / L, which is conducive to measuring boron isotopes within the full abundance range, and can clean the boron without affecting the measurement results of subsequent samples.

[0047] In some embodiments, the measurement is performed using a multi-collector inductively coupled plasma mass spectrometer. Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is a method for rapidly and accurately measuring isotope abundance.

[0048] In some embodiments, the measurement is performed in a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) in the order of cleaning-boron isotope standard solution-cleaning-sample solution-cleaning-isotope standard solution-cleaning. The purpose of testing in the above order is to calculate the mass discrimination correction factor and correct the instrument signal drift. Thus, the measured value of the sample solution can be corrected according to the mass discrimination correction factor, thereby obtaining the actual value of the boron isotope abundance.

[0049] In the present application, the boron isotope standard solution is used to calibrate the instrument and the measurement results of the sample, and is a commercially available certified standard material. The boron isotope standard solution has a known boron isotope abundance, for example, an abundance of 0.2473±0.0002.

[0050] In this application, the instrument mass discrimination correction factor = 1 / 2 (reference value of standard material / previous measurement value of standard material + reference value of standard material / later measurement value of standard material). The true value of boron isotope abundance in the sample = mass discrimination correction factor * sample measurement value.

[0051] The present application will be described in detail below with reference to specific embodiments.

[0052] Example

[0053] Feasibility testing of detection methods

[0054] In order to verify the feasibility of the analytical method of the present application, the melting process was studied using GBW06606 boron carbide standard material (with a total boron mass content of 75.68%) as the research object.

[0055] Example 1: Determination of boron isotope abundance in boron carbide standard GBW06606 sample

[0056] 1) The commercially available boron carbide standard GBW06606 sample was placed in a grinder as the test sample, ground at 2000 r / min for 3 min, then dried in an oven at 100°C for 1 h, and passed through a 200-mesh sieve to obtain a boron carbide powder sample.

[0057] 2) Weigh 0.1000 g of boron carbide powder sample and 1.00 g of lithium hydroxide into a platinum crucible and mix them evenly.

[0058] 3) Place the platinum crucible containing the sample to be tested in a muffle furnace and melt the sample using a step-by-step heating program: increase the temperature to 400°C at a heating rate of 3°C / min, then keep it at 400°C for 0.5h; then increase the temperature to 600°C at a heating rate of 4°C / min, and keep it at 600°C for 0.5h. Take out the crucible while it is hot and cool it at room temperature to obtain a molten block.

[0059] 4) Add 10 mL of 3.6 mol / L HCl to the above crucible and dissolve the frit on a hot plate at 60°C.

[0060] 5) Transfer all the sample solution and cleaning solution in the crucible into a 50mL PFA volumetric flask, dilute to scale with deionized water, and dilute with water to 200μg / L for instrument measurement.

[0061] 6) On MC-ICP-MS, in the "Wet plasma" detection mode, the above-mentioned sample solution to be tested is measured in the order of cleaning-boron isotope standard solution-cleaning-test sample solution cleaning-boron isotope standard solution. The instrument mass discrimination correction factor is calculated based on the boron isotope abundance value measured by the standard solution and the reference value of the boron isotope abundance of the standard substance, and the measured value of the sample solution is corrected with the mass discrimination correction factor to obtain the actual value of the boron isotope abundance. Among them, the boron isotope standard solution is a standard substance for the boron isotope abundance of boric acid (SRM 951a, the boron concentration is 200μg / L).

[0062] The MC-ICP-MS model used was Nu plasma II, and the operating parameters are shown in Table 1.

[0063] Table 1 Working parameter settings for Nu PlasmaⅡMC-ICP-MS determination of boron isotopes

[0064]

[0065]

[0066] Calculation of boron isotope abundance

[0067] Correction factor calculation:

[0068] The instrument mass discrimination correction factor is calculated according to formula (1):

[0069] K=R c / R m ……………………………………(1)

[0070] Where:

[0071] K——Instrument mass discrimination correction factor;

[0072] R c ——Boron isotope standard solution 10 B / 11 The standard value of B;

[0073] R m ——Boron isotope standard solution 10 B / 11 The measured value of B.

[0074] right 10 B / 11 B isotope abundance ratio correction.

[0075] After calibration, the sample 10 B / 11 The B value R correction is calculated according to formula (2):

[0076] R 校正 =R 测量 ×K……………………………………(2)

[0077] Where:

[0078] R 校正 ——In the sample to be tested 10 B / 11 Correction value of B;

[0079] R 测量 ——In the sample to be tested 10 B / 11 The measured value of B.

[0080] The boron carbide standard GBW06606 sample was measured by the above method. 10 The B isotope abundance is 19.824%.

[0081] Example 2

[0082] Example 2 was tested in a similar manner to Example 1, except that sodium hydroxide was used as the alkali flux. The boron isotope abundance in the boron carbide standard GBW06606 sample was measured to be 19.825%.

[0083] Example 3

[0084] Example 3 was tested in a similar manner to Example 1, except that the sample was a boron carbide-aluminum experimental sample. The boron isotope abundance in the boron carbide-aluminum sample was measured to be 19.826%.

[0085] Example 4

[0086] Effect of lithium ion matrix on boron isotope abundance

[0087] Using 200μg / L SRM 951a boron isotope standard solution as the standard, 200μg / L SRM 951a and GSB G62001-90Li single element standard solution were mixed to prepare a series of mixed solutions with Li / B (concentration ratio) of 0:1, 1:1, 2:1, 3:1, 4:1, 5:1, 10:1, 20:1, and 40:1 as samples, and the boron isotope abundance was determined by the sample-standard interpolation method. The experimental results are shown in Figure 2. Figure 1As shown, when the boron ion concentration in the sample is 200 μg / L and Li / B≤40, the measured boron isotope abundance is within the range of 0.2473±0.0002, indicating that lithium ions have no effect on the measurement of boron isotope abundance. During actual sample processing, the lithium ion content is far lower than this value, so it has no effect on the measurement of boron isotope abundance in the sample.

[0088] Example 5

[0089] Effect of sodium ion matrix on boron isotope abundance

[0090] Using 200μg / L SRM 951a boron isotope standard solution as the standard, 200μg / L SRM 951a and GSB G62004-90Na single element standard solution were mixed to prepare a series of mixed solutions with Na / B (concentration ratio) of 0:1, 1:1, 2:1, 3:1, 4:1, 5:1, 10:1, 20:1, and 40:1 as samples, and the boron isotope abundance was determined by the sample-standard interpolation method. The experimental results are shown in Figure 2. Figure 2 As shown in the figure, when the boron ion concentration in the sample is 200 μg / L and Na / B≤40, the measured boron isotope abundance is within the range of 0.2473±0.0002, indicating that sodium ions have no effect on the measurement of boron isotope abundance. During actual sample processing, the sodium ion content is far lower than this value, so it has no effect on the measurement of boron isotope abundance in the sample.

[0091] Example 6

[0092] Effects of Lithium and Aluminum Ion Matrix on Boron Isotope Abundance

[0093] Using 200μg / L SRM 951a boron isotope standard solution as the standard, SRM 951a and GSB G62001-90Li and GSB G 62006-90Al single element standard solutions were mixed to prepare a series of mixed solutions with a boron ion concentration of 200μg / L and Li / B and Al / B (concentration ratios) of 0:1, 1:1, 2:1, 3:1, 4:1, 5:1, 10:1, 20:1, and 40:1 as samples, and the boron isotope abundance was determined using the sample-standard interpolation method. The experimental results are shown in Figure 2. Figure 3 As shown, when the boron ion concentration in the sample is 200 μg / L, Li / B≤40 and Al / B≤40, the measured boron isotope abundance is in the range of 0.2473±0.0002, indicating that the simultaneous presence of lithium ions and aluminum ions in the above concentration range has no effect on the measurement of boron isotope abundance. During actual sample processing, the lithium ion and aluminum ion contents are far lower than this value, so they have no effect on the measurement of boron isotope abundance in the sample.

[0094] Example 7

[0095] A nuclear grade boron carbide sample from a domestic enterprise 10 Determination of B isotope abundance

[0096] 1) Place the boron carbide sample in a grinder and grind it at 3000 r / min for 2 min, then dry it in a 100°C oven for 1 h, and pass it through a 200-mesh sieve to obtain a boron carbide powder sample.

[0097] 2) Weigh 0.0500 g of boron carbide powder sample and 1.00 g of LiOH into a platinum crucible and mix them evenly.

[0098] 3) Place the platinum crucible containing the sample to be tested in a muffle furnace and melt the sample using a step-by-step heating program: increase the temperature to 400°C at a heating rate of 2°C / min, then keep it at 400°C for 1 hour; then increase the temperature to 550°C at a heating rate of 5°C / min, and keep it at 550°C for 1 hour. Take out the crucible while it is hot and cool it at room temperature to obtain a molten block.

[0099] 4) Add 5 mL of 6.4 mol / L HNO3 to each of the above crucibles and dissolve the frit on a hot plate at 60°C.

[0100] 5) Transfer all the sample solution and cleaning solution in the crucible into a 50mL PFA volumetric flask, dilute to scale with 0.32mol / L HNO3, and dilute to 800μg / L for testing.

[0101] 6) On the MC-ICP-MS, in the "Wet plasma" detection mode, the sample solutions to be tested are measured in the order of cleaning-boron isotope standard solution-cleaning-sample solution-cleaning-boron isotope standard solution. The instrument mass discrimination correction factor is calculated by the boron isotope abundance value measured by the standard solution and the reference value of the boron isotope abundance of the standard substance, and the mass discrimination correction factor is used to correct the measured value of the sample solution to obtain the actual value of the boron isotope abundance.

[0102] The MC-ICP-MS model used was Nu plasma II, and the operating parameters were as shown in Table 1 of Example 1.

[0103] 8) Repeat the test 6 times. 10 The results of the B isotope abundance test are shown in Table 2.

[0104] Table 2 Sample precision measurement

[0105]

[0106]

[0107] The boron isotope abundance measured by the method of the present application is 19.826%, which is in line with expectations. The repeatability test results show that the test accuracy is 0.1‰, and the test method of the present application has high accuracy.

[0108] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. 10 The method for analyzing the abundance of B isotopes is characterized in that: The steps include: Melting and cooling a mixture containing a boron carbide sample and an alkali flux to obtain a frit, wherein the alkali flux is an alkali metal hydroxide; Dissolving the frit with acid to obtain a solution to be tested; and The multi-collector inductively coupled plasma mass spectrometry method is used to determine and calculate the 10 B isotope abundance.

2. The analysis method according to claim 1, characterized in that The boron carbide-containing sample includes one or more of boron carbide, boron carbide-aluminum and boron carbide-aluminum oxide.

3. The analysis method according to claim 2, characterized in that The boron carbide-containing sample is boron carbide.

4. The analysis method according to claim 1, characterized in that The alkali flux is at least one of sodium hydroxide and lithium hydroxide.

5. The analysis method according to claim 1, characterized in that The weight ratio of the boron carbide-containing sample to the alkali flux is 1:10 to 1:

20.

6. The analysis method according to claim 1, characterized in that The melting is performed at a melting temperature of 550°C to 600°C.

7. The analysis method according to claim 6, characterized in that The melting reaches the temperature by step-by-step heating; preferably, the step-by-step heating program is: heating to 350°C-400°C at a first heating rate of 2-3°C / min, and keeping warm for 0.5-1h, heating to the melting temperature at a second heating rate of 4-5°C / min, and keeping warm for 0.5-1h.

8. The analysis method according to claim 1, characterized in that The acid is 3.6mol / L-4.8mol / L hydrochloric acid, or 4.8mol / L-6.4mol / L nitric acid.

9. The analysis method according to claim 1, characterized in that The test solution is obtained by diluting and fixing the solution obtained by dissolving the frit with acid, preferably by diluting and fixing the solution with water or 0.32 mol / L HNO3.

Images