Method for measuring content of iodine-129 in aerosol

Abstract

The invention relates to a method for measuring the content of iodine-129 in aerosol, which comprises the following steps: putting a quantitative aerosol sample into a digestion tank, and adding dilute ammonia water and an I-125 tracer agent into the digestion tank; substances in the digestion tank are digested based on microwave digestion, and digestion liquid is filtered and reserved; taking a first volume of digestion solution and an I-125 tracer solution with the same volume, and determining the content of iodide ions entering the digestion solution in the aerosol sample to obtain an iodine recovery rate; acquiring the concentration of I-127 in the digestion solution by adopting an inductively coupled plasma mass spectrometry technology; sequentially adding nitric acid, an iodine standard solution and a silver nitrate solution into the digestion solution to obtain a silver iodide precipitate; the silver iodide precipitate is dried, silver powder is mixed, and the ratio of I-129 to I-127 in the silver iodide precipitate is detected; and calculating the concentration of the I-129. The technical effects that the detection method is simple and the detection time is shortened are achieved.

Description

Technical Field

[0001] This invention relates to the field of radiochemical analysis technology, and in particular to a method for measuring the iodine-129 content in aerosols. Background Technology

[0002] In existing technology, iodine is extracted from the sample by heating it in a sealed sample dissolving vessel with dilute ammonia, and the sample solution is analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to determine the iodine elemental isotopes. 127 Qualitative analysis shows that within a certain concentration range, the mass spectrometry count of iodine is directly proportional to the mass concentration of iodine. The iodine content in a sample can be calculated by measuring the mass spectrometry count of iodine.

[0003] Currently, common methods for separating and purifying iodine from aerosol samples include alkaline ashing and high-temperature pyrolysis. Alkaline ashing involves immersing the aerosol in an alkaline solution, heating it to dryness at 80°C, then ashing it in a muffle furnace. After ashing, it is leached with ultrapure water heated to 70°C. After leaching, the solution is filtered, and a portion of the filtrate is used for analysis. 127 I. Preparation of AMS target samples from the remaining leachate. The high-temperature pyrolysis method uses a tube furnace to oxidize and decompose the organic matter in the sample, converting various forms of iodine into volatile iodine forms. These iodine forms are then transferred via carrier gas to a collection device containing an alkaline solution for absorption. A portion of the collected solution is then analyzed. 127 I. Prepare AMS target samples from the remaining trapping solution.

[0004] Alkaline ashing is based on the property that iodine is relatively stable in an alkaline environment and does not easily transform into volatile gaseous iodine at high temperatures. Combustion removes organic matter, converting organic iodine into inorganic iodine. Then, hot water is used to leach the inorganic iodine from the ash, achieving iodine separation. However, this method is complex and time-consuming. High-temperature pyrolysis, while simple and efficient, is only suitable for low-temperature applications. 129 This method can separate iodine from solid samples at level I, but it has low sample throughput and depends on the number of channels in the tube furnace.

[0005] Existing technologies cannot balance the relationship between the complexity of the detection method, the length of the experimental cycle, and the amount of sample to be detected.

[0006] The above problems urgently need to be addressed. Summary of the Invention

[0007] This invention discloses a method for measuring the iodine-129 content in aerosols, aiming to solve the technical problems existing in the prior art.

[0008] The present invention employs the following technical solution, comprising: placing a quantitative aerosol sample into a digestion vessel; adding dilute ammonia and I-125 tracer to the digestion vessel, wherein the aerosol sample contains I-129 and I-127; digesting the substances in the digestion vessel based on microwave digestion technology, and filtering and retaining the digestion solution, wherein I-129 and I-127 in the aerosol sample are digested into soluble ions and enter the digestion solution, wherein the digestion solution contains I-127, I-129, and I-125; taking a first volume of the digestion solution and an equal volume of I-125 tracer solution... The method involves determining the amount of iodide ions entering the digestion solution from the aerosol sample to obtain the iodine recovery rate; using inductively coupled plasma mass spectrometry (ICP-MS), the concentration of I-127 in the digestion solution is obtained; nitric acid, iodine standard solution, and silver nitrate solution are added sequentially to the digestion solution to obtain silver iodide precipitate, wherein the volume of the iodine standard solution is the first volume; the silver iodide precipitate is dried and mixed with silver powder, and the ratio of I-129 to I-127 in the silver iodide precipitate is detected using an accelerator mass spectrometer; based on the iodine recovery rate, the ratio, and the concentration of I-127, the concentration of I-129 is calculated.

[0009] Optionally, before taking a quantitative amount of aerosol sample and placing it into the digestion vessel, the following steps are included: taking ammonia water and placing it into the digestion vessel, and digesting the digestion vessel based on microwave digestion technology, wherein the digestion temperature is 200 degrees Celsius and the digestion time is 10 minutes.

[0010] Optionally, the quantitative aerosol sample is an aerosol membrane with a size of 20×25cm; the dilute ammonia solution is a 2.5% solution obtained by diluting 25% ammonia solution tenfold.

[0011] Optionally, the digestion of the substance in the digestion vessel includes: setting the initial digestion temperature to 120 degrees, increasing the temperature by 20 degrees every ten minutes until the temperature reaches 180 degrees, and continuing for ten minutes to complete the digestion.

[0012] Optionally, the step of digesting the substances in the digestion vessel based on microwave digestion technology and filtering and retaining the digestion solution includes: the filtration using a sand core funnel to filter the substances in the digestion vessel; placing a centrifuge tube below the sand core funnel, and the digestion solution flowing into the centrifuge tube; and rinsing the digestion vessel multiple times with ultrapure water, with the rinsing solution transferred to the sand core funnel and combined with the digestion solution.

[0013] Optionally, the step of taking a first volume of digestion solution and an equal volume of I-125 tracer solution to determine the content of iodide ions entering the digestion solution in the aerosol sample and obtaining the iodine recovery rate includes: obtaining a first mass of the first volume of digestion solution and a second mass of the I-125 tracer solution; determining the sample iodine count in the first volume of digestion solution based on a gamma counter, wherein the sample iodine count is the I-125 count; determining the tracer iodine count in the I-125 tracer solution based on a gamma counter; and calculating the iodine recovery rate based on the sample iodine count, the tracer iodine count, the first mass, and the second mass.

[0014] Optionally, the step of calculating the iodine recovery rate based on the iodine count of the sample, the iodine count of the tracer, and the first and second masses includes: the iodine recovery rate is calculated as follows: in, For iodine counting in the sample, For iodine counting as a tracer, To determine the quality of the digested solution after filtration, For the first quality, For the second mass, The mass of I-125 tracer added to the aerosol sample.

[0015] Optionally, the step of using inductively coupled plasma mass spectrometry (ICP-MS) to obtain the concentration of I-127 in the digestion solution includes: taking a third mass of the digestion solution, diluting it with ultrapure water to obtain a diluted solution; using ICP-MS to analyze the concentration of I-127 in the diluted solution; and calculating the concentration of I-127 in the digestion solution based on the concentration of I-127 in the diluted solution.

[0016] Optionally, before calculating the concentration of I-129 based on the iodine recovery rate, the ratio, and the concentration of I-127, the method further includes: obtaining the mass of the aerosol sample before placing a quantitative amount of aerosol sample into the digestion vessel; setting up a blank sample based on the measurement method of I-129 concentration in the aerosol sample, and determining the concentration of I-129 in the blank sample, wherein the blank sample is a sample in which a blank aerosol sampling membrane is placed.

[0017] Optionally, the calculation of the concentration of I-129 based on the iodine recovery rate, the ratio, and the concentration of I-127 includes: the concentration of I-129 is calculated as follows: in, This represents the concentration of I-129 in the aerosol sample. This is the total weight of the centrifuge tubes and the digestion solution. c represents the mass of the centrifuge tube, and c represents the concentration of I-127 in the dilution solution. Let Avogadro's constant be 1. for 129 I / 127 I ratio, for 129 I decay constant, For iodine recovery rate, For the quality of aerosol samples, This represents the concentration of I-129 in the blank sample.

[0018] The technical solution adopted in this invention can achieve at least one of the following beneficial effects: In this embodiment of the invention, a quantitative aerosol sample is placed into a digestion vessel, and dilute ammonia and I-125 tracer are added to the digestion vessel. The aerosol sample contains I-129 and I-127. Based on microwave digestion technology, the substances in the digestion vessel are digested, and the digestion solution is filtered and retained. I-129 and I-127 in the aerosol sample are digested into soluble ions and enter the digestion solution, which contains I-127, I-129, and I-125. A first volume of the digestion solution and an equal volume of I-125 tracer solution are taken to determine the content of iodine ions from the aerosol sample entering the digestion solution, thus obtaining the iodine recovery rate. Inductively coupled plasma mass spectrometry (ICP-MS) was used to obtain the concentration of I-127 in the digestion solution. Nitric acid, iodine standard solution, and silver nitrate solution were added sequentially to the digestion solution to obtain silver iodide precipitate, wherein the volume of the iodine standard solution was the first volume. The silver iodide precipitate was dried and mixed with silver powder. The ratio of I-129 to I-127 in the silver iodide precipitate was detected using an accelerator mass spectrometer. Based on the iodine recovery rate, the ratio, and the concentration of I-127, the concentration of I-129 was calculated. This method reduces the complexity of detection, shortens the experimental cycle, and allows for the detection of a large number of samples, thus achieving the technical effect of a simple detection method and shortened detection time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, forming part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 This is a flowchart of a method for measuring the iodine-129 content in an aerosol according to Embodiment 1 of the present invention; Figure 2 This is a flowchart of an optional method for measuring the iodine-129 content in aerosols according to Embodiment 2 of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or," unless otherwise expressly indicated.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a magnetic connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, in the description of this application, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, "a plurality of" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0022] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] First, to facilitate understanding of the embodiments of the present invention, some terms or nouns involved in the present invention will be explained below: Aerosols are systems formed by tiny solid or liquid particles that are uniformly suspended in a gas (usually air). They are not a single substance, but a mixture of "particles" and "gas".

[0024] Microwave digestion uses microwave energy to heat the sample and digestion solvent (such as a strong acid), causing the analyte in the sample to dissolve rapidly into the solvent, preparing for subsequent chemical analysis (such as heavy metal detection).

[0025] To address the problems existing in related technologies, this application provides a method for measuring the iodine-129 content in aerosols.

[0026] Example 1 This embodiment provides a method for measuring the iodine-129 content in aerosols, such as... Figure 1 As shown, Figure 1This is a flowchart of a method for measuring the iodine-129 content in an aerosol according to Embodiment 1 of the present invention. The method includes: Step S101: Take a quantitative amount of aerosol sample and put it into a digestion vessel. Add dilute ammonia and I-125 tracer into the digestion vessel. The aerosol sample contains I-129 and I-127. Optionally, I-127 and I-129 exist in aerosols. Both are isotopes of iodine, but their key differences lie in their stability and origin. I-127 is a naturally occurring stable isotope, while I-129 is a radioactive isotope with a long half-life. They are often detected together to track environmental changes or the impact of human activities. I-127 represents the "background" iodine in the environment and is an essential trace element for humans, posing no environmental risk. I-129 is radioactive, with a half-life of approximately 15.7 million years. Its decay process releases low-energy beta rays, with relatively weak radiation intensity but an extremely long duration. The main sources of pollution are human activities, such as nuclear reactor emissions, nuclear test residues, and leaks during nuclear waste disposal. I-129 is a "characteristic indicator" for nuclear environmental monitoring and can be used to trace the spread of nuclear contamination. Therefore, detecting I-129 is used to determine the level of pollution in the environment.

[0027] Optionally, I-125 tracer is a tool in radiotracing technology, utilizing its precisely detectable radioactivity to track the movement, distribution, and metabolism of target substances within living organisms or industrial processes. Its half-life of approximately 60.1 days avoids both excessively short half-lives (such as I-131's mere 8 days) leading to rapid radioactivity decay during experiments and excessively long half-lives (such as I-129's millions of years) causing long-term radioactive residue, making it suitable for most experimental cycles (from days to months).

[0028] In some preferred embodiments, before placing a quantitative amount of aerosol sample into the digestion vessel, the following steps are taken: placing ammonia water into the digestion vessel, and digesting the digestion vessel based on microwave digestion technology, wherein the digestion temperature is 200 degrees Celsius and the digestion time is 10 minutes.

[0029] Optional. First, the digestion vessel needs to be cleaned. Transfer 12 mL of 2.5% ammonia solution into the digestion vessel and use a microwave digestion apparatus (a microwave digestion apparatus uses the penetrating power and reaction activation ability of microwaves to heat reagents and samples in a sealed container) to heat to 200℃ for 10 min. (During microwave digestion, there will be a pressure change. If the pressure increases by ten to twenty times, the temperature can be lowered. Ordinary direct heating requires heating to 700-800 degrees Celsius. Microwave digestion technology allows decomposition to be carried out at a lower temperature).

[0030] In some preferred embodiments, the quantitative aerosol sample is an aerosol membrane with a size of 20×25cm; the dilute ammonia solution is a 2.5% solution obtained by diluting 25% ammonia solution tenfold.

[0031] Optionally, the sampling membrane for aerosol samples is 20x25cm, and is cut 9 times using a 3cm diameter annular cutter, yielding approximately 63cm. 2 This is equivalent to 1 / 8 of the total aerosol volume. Record the required aerosol sample mass m after cutting it out. s Place the sample into a cleaned digestion vessel, add I-125 tracer, and record the mass m of the I-125 tracer. t This is used for subsequent calculations of the iodine recovery rate R in aerosols.

[0032] Optionally, a commercially available 25% ammonia solution can be diluted 10 times by volume with ultrapure water to obtain a 2.5% solution. Transfer 12 mL of this 2.5% ammonia solution (volume ratio of concentrated ammonia to water = 1:9) into the digestion vessel, cover it, and secure the vessel to the digestion rack of the microwave digester, tightening the lid to maintain a seal. Adding ammonia helps maintain an alkaline environment, as iodide ions are easily volatilized in acidic environments, thus requiring an alkaline environment. Since the digestion vessel is sealed, the ammonia solution easily decomposes into ammonia gas and water during heating, but these gases remain within the vessel, thus preserving the alkaline environment.

[0033] Step S102: Based on microwave digestion technology, the substances in the digestion vessel are digested and the digestion solution is filtered and retained. In this step, I-129 and I-127 in the aerosol sample are digested into soluble ions and enter the digestion solution. The digestion solution contains I-127, I-129 and I-125. Optionally, after completing the above preparations, the aerosol sample in the digestion vessel is digested, causing iodide ions in the aerosol to separate from the aerosol sample and enter the digestion solution. At this time, the digestion solution contains I-127, I-129, and I-125. Since the aerosol has a particulate structure and the aerosol sample has a slice-like structure, although iodide ions are separated from the aerosol sample, some impurities remain that cannot be decomposed or dissolved in the digestion solution. Therefore, the digestion solution needs to be filtered to retain the isotopes of iodine and remove other impurities.

[0034] In some preferred embodiments, the substances in the digestion vessel are digested by: setting the initial digestion temperature to 120 degrees, increasing the temperature by 20 degrees every ten minutes until the temperature reaches 180 degrees, and continuing for ten minutes to complete the digestion.

[0035] Optionally, place the digestion vessel into a microwave digester, set and run the microwave digestion program as shown in the table below:

[0036] The table above shows the heating temperature settings for the microwave digestion apparatus. Starting at an initial temperature of 120 degrees Celsius, the temperature is increased by 20 degrees Celsius every ten minutes to ensure complete decomposition of iodine isotopes in the aerosol sample into the digestion solution. Once the program is complete, remove the digestion vessel.

[0037] In some preferred embodiments, the substances in the digestion vessel are digested based on microwave digestion technology, and the digestion solution is filtered and retained, including: filtration using a sand core funnel to filter the substances in the digestion vessel; placing a centrifuge tube below the sand core funnel, and the digestion solution flowing into the centrifuge tube; filtration using ultrapure water to rinse the digestion vessel multiple times, and transferring the rinsing solution to the sand core funnel to merge with the digestion solution.

[0038] Optionally, since aerosol particle diameters are typically between 0.01 and 10 μm, to prevent fine particles from clogging the sample inlet tube and nebulizer of the inductively coupled plasma mass spectrometer, the digestion solution needs to be filtered to remove some insoluble particles from the aerosol sample. Specifically, a G4 sintered glass funnel is used for sample filtration. The funnel is mounted on a vacuum chamber via a guide tube, and a 50 mL centrifuge tube (mass m0) is placed inside the chamber. The digestion solution is transferred to the sintered glass funnel for filtration. The digestion vessel is rinsed with a small amount of ultrapure water, and the rinsing solution is transferred to the sintered glass funnel for filtration. This rinse solution is then combined with the digestion solution and rinsed three times to ensure that all iodine isotopes enter the digestion solution, reducing subsequent calculation errors.

[0039] Step S103: Take the first volume of digestion solution and the same volume of I-125 tracer solution to determine the content of iodine ions entering the digestion solution in the aerosol sample and obtain the iodine recovery rate. Optionally, I-125 tracer can be used as a control solution. I-125 tracer is added to the digestion vessel at the beginning. After digestion and filtration, some iodine isotopes may not have entered the digestion solution, resulting in iodine loss. Based on the concentration of I-125 tracer in the current filtered digestion solution, it is compared with the concentration of the standard I-125 tracer solution to determine the amount of iodine that failed to enter the digestion solution (i.e., iodine recovery rate). Based on the iodine recovery rate, it can be determined that some I-129 failed to enter the digestion solution, thereby determining the accurate I-129 content in the aerosol sample and effectively reducing errors.

[0040] In some preferred embodiments, a first volume of digestion solution and an equal volume of I-125 tracer solution are taken to determine the content of iodide ions entering the digestion solution from the aerosol sample, and to obtain the iodine recovery rate. This includes: obtaining a first mass of the first volume of digestion solution and a second mass of the I-125 tracer solution; determining the sample iodine count in the first volume of digestion solution based on a gamma counter, wherein the sample iodine count is the I-125 count; determining the tracer iodine count in the I-125 tracer solution based on a gamma counter; and calculating the iodine recovery rate based on the sample iodine count, the tracer iodine count, and the first and second masses.

[0041] Optionally, the centrifuge tubes need to be weighed first, and then the total mass m of the centrifuge tubes and digestion solution needs to be recorded. 总 Take 0.5 mL of digestion solution and 0.5 mL of I-125 tracer respectively (for control experiments, both volumes should be the same to reduce variability), and record the mass of the digestion solution (m1) and the mass of the standard I-125 tracer (m2). Use a γ-counter to measure the I-125 counts (counts1) in the digestion solution sample and the I-125 counts (counts2) in the I-125 tracer for recovery calculation. Where: m s For aerosol sample mass, g; m t For joining 125 I is the tracer mass, g; m0 is the mass of the empty centrifuge tube, g; m 总 m1 represents the total mass of the centrifuge tube and digestion solution after filtration, in grams; m1 is the mass of the solution used for... 125 I is the mass of the digestion solution measured in g; m2 is the mass of the I-125 tracer solution used for I-125 measurement in g; counts1 is the I-125 count in the digestion solution; counts2 is the I-125 count in the digestion solution; and R is the iodine recovery rate in the sample.

[0042] In some preferred embodiments, the iodine recovery rate is calculated based on the sample iodine count, the tracer iodine count, and the first and second masses, including: the iodine recovery rate is calculated as follows: in, For iodine counting in the sample, For iodine counting as a tracer, To determine the quality of the digested solution after filtration, For the first quality, For the second mass, The mass of I-125 tracer added to the aerosol sample.

[0043] Step S104: The concentration of I-127 in the digestion solution is obtained using inductively coupled plasma mass spectrometry. Optionally, the digestion solution is filtered, so that fine particulate matter will no longer clog the sample inlet tube and nebulizer of the inductively coupled plasma mass spectrometer. In this case, the concentration of I-127 in the digestion solution can be directly detected by the inductively coupled plasma mass spectrometer. At this time, both I-125 and I-127 in the digestion solution can be calculated. Since only three iodine isotopes exist in the digestion solution, the content of I-129 can be obtained by calculating the total iodine isotope content, or the content of I-129 can be determined based on the ratio of I-127 to I-129.

[0044] In some preferred embodiments, inductively coupled plasma mass spectrometry (ICP-MS) is used to obtain the concentration of I-127 in the digestion solution, including: taking a third mass of the digestion solution, diluting it with ultrapure water to obtain a diluted solution; using ICP-MS to analyze the concentration of I-127 in the diluted solution; and calculating the concentration of I-127 in the digestion solution based on the concentration of I-127 in the diluted solution.

[0045] Optionally, a commercially available ammonia reagent with a concentration of 25% and a molar concentration of 13.33 mol / L is used. During inductively coupled plasma mass spectrometry (ICP-MS) measurement, the ammonia concentration in the sample is 0.02 mol / L, and the ammonia concentration in the digestion solution is approximately 1.33 mol / L. To achieve accurate iodine measurement, the digestion solution needs to be diluted approximately 70 times. Take approximately 0.2 g of the digestion solution, record its mass (m³), dilute it 70 times with ultrapure water, and analyze the concentration of iodine in the digestion solution using ICP-MS. 127 I concentration c.

[0046] Step S105: Nitric acid, iodine standard solution and silver nitrate solution are added to the digestion solution in sequence to obtain silver iodide precipitate, wherein the volume of iodine standard solution is the first volume; Optionally, slowly add 1.5 mL of 8 mol / L HNO3 to the remaining digestion solution and mix well; then add 0.5 g of 1 mg / g iodine standard solution and mix well; add 1 mL of 1 mol / L AgNO3, shake thoroughly, let stand for 30 min, centrifuge for 20 min at 10000 rpm, decant the supernatant, and retain the precipitate (I... - +Ag + →AgI). Transfer the precipitate to a 2 mL centrifuge tube using ultrapure water, centrifuge for 10 min at 10000 rpm, discard the supernatant, and retain the precipitate.

[0047] Step S106: Dry the silver iodide precipitate and mix it with silver powder. Use an accelerator mass spectrometer to detect the ratio of I-129 to I-127 in the silver iodide precipitate. Optionally, the resulting precipitate needs to be dried. The hot plate temperature is set to 60℃, and the precipitate is dried for 12 hours. The mass of the precipitate is recorded, and it is mixed with silver powder at a mass ratio of 1:1. The addition of silver powder improves the conductivity of the solid, thereby improving the detection accuracy of the subsequent accelerator mass spectrometer. An accelerator mass spectrometry (AMS) target sample is prepared, and the I-129 / I-127 ratio in the target sample is analyzed using AMS.

[0048] Step S107: Calculate the concentration of I-129 based on the iodine recovery rate, ratio, and concentration of I-127.

[0049] In some preferred embodiments, before calculating the concentration of I-129 based on the iodine recovery rate, ratio, and I-127 concentration, the method further includes: obtaining the mass of the aerosol sample before placing a quantitative amount of aerosol sample into the digestion vessel; setting up a blank sample based on the measurement method of I-129 concentration in the aerosol sample, and determining the concentration of I-129 in the blank sample, wherein the blank sample is a sample in which a blank aerosol sampling membrane is placed, and wherein the blank aerosol sampling membrane is a sampling membrane cut from an aerosol sample that does not contain iodine.

[0050] Optionally, a blank sample is prepared and measured according to the above steps. The blank sample is the experiment in step S101 where no aerosol sample is placed in the digestion vessel. This serves as a control experiment to detect errors in the control process.

[0051] In some preferred embodiments, the concentration of I-129 is calculated based on the iodine recovery rate, the ratio, and the concentration of I-127, including: the concentration of I-129 is calculated as follows: in, This represents the concentration of I-129 in the aerosol sample. This is the total weight of the centrifuge tubes and the digestion solution. c represents the mass of the centrifuge tube, and c represents the concentration of I-127 in the dilution solution. Let Avogadro's constant be 1. for 129 I / 127 I ratio, for 129 I decay constant, For iodine recovery rate, For the quality of aerosol samples, This represents the concentration of I-129 in the blank sample.

[0052] Optional, the concentration of I-129 in the digestion solution: Concentration of I-129 in aerosol samples: AS =AA bl .

[0053] Where c is the iodine concentration in the diluted digestion solution, g / g; 70 is the dilution factor of the digestion solution; N A is Avogadro's constant, equal to 6.023 × 10⁻⁶. 23 The ratio represents the ratio of the sample obtained from accelerator mass spectrometry measurements. 129 I / 127 I ratio; λ is 129 The decay constant of I, I-129 is 1.40 × 10⁻⁶. -15 A S I-129 concentration in the sample, Bq / g; A bl The value represents the concentration of I-129 in the blank sample, in Bq / g.

[0054] Through the above steps S101 to S107, the complexity of detection is reduced, the experimental cycle is shortened, and a large number of samples can be detected, thus achieving the technical effect of simple detection method and shortened detection time.

[0055] Example 2 Based on the above embodiments and optional embodiments, the present invention also proposes an optional implementation method. Figure 2 This is a flowchart of an optional method for measuring the iodine-129 content in aerosols according to Embodiment 2 of the present invention, as shown below. Figure 2 As shown, the method includes: Digestion tank cleaning; Sample preparation: Use a 3cm diameter ring cutter to cut the sample 9 times, weigh it, the sample mass is 0.23g, and put it into a clean digestion vessel; Add 0.10 g of I-125 tracer to the digestion vessel; Add 12 mL of 2.5% ammonia solution, cover the container, place the digestion vessel on the digestion rack, and tighten the lid. Place the digestion rack into the microwave digester and run the program; Once the program is complete, remove the digestion vessel. The digest was filtered, and the centrifuge tube weighed 13.10 g. After filtration, the total weight of the centrifuge tube and the digest was 37.68 g. The I-125 count was measured using the digestion solution corresponding to 0.88 g of aerosol sample. The sample count was 9556. The I-125 count was measured using 0.20 g of standard I-125 tracer solution. The standard sample count was 533968. The recovery rate R = 99.97%.

[0056] Take 0.19 g of digestion solution and dilute it with ultrapure water to 13.30 g. Measure the iodine concentration in the digestion solution using ICP-MS. The concentration of iodine in the diluted solution is 12.68 × 10⁻⁶. -12 g / g; Slowly add 1.5 mL of 8 mol / L HNO3 to the remaining digestion solution and mix well; then add 1.001 g of 1 mg / g iodine standard solution and mix well.

[0057] Add 1 mL of 1 mol / L AgNO3, shake well, let stand for 30 min, centrifuge for 20 min at 10000 rpm. Pour off the supernatant and retain the precipitate.

[0058] Transfer the precipitate to a 2 mL centrifuge tube using ultrapure water and centrifuge for 10 min at 10,000 rpm. Discard the supernatant and retain the precipitate.

[0059] The resulting precipitate was dried by heating for 12 hours, with the electric heating plate temperature set to 60℃. Weigh and record the mass of the precipitate. Mix it thoroughly with silver powder at a 1:1 mass ratio to prepare an accelerator mass spectrometry (AMS) target sample. Analyze the target sample using AMS. 129 I / 127 I ratio = 2.62 × 10 -12 .

[0060] According to the formula, the concentration of I-129 in the digestion solution is 3.78 × 10⁻⁶. -9 Bq / g, the concentration of I-129 in the blank sample was 6.95 × 10⁻⁶. -10 If Bq / g, then the concentration of I-129 in the aerosol sample is 3.08 × 10⁻⁶. -9 Bq / g.

[0061] Through steps S1 to S6 above, the analysis and measurement of I-129 in aerosols mainly includes two parts: the separation and extraction of iodine from the sample and the preparation of iodine AMS target samples. The extraction method used is simpler and more convenient, mainly due to its simple reagents and high efficiency.

[0062] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for measuring the iodine-129 content in aerosols, characterized in that, include: A quantitative amount of aerosol sample is placed into a digestion vessel, and dilute ammonia and tracer I-125 are added to the digestion vessel. The aerosol sample contains I-129 and I-127. Based on microwave digestion technology, the substances in the digestion vessel are digested and the digestion solution is filtered and retained. In this process, I-129 and I-127 in the aerosol sample are digested into soluble ions and enter the digestion solution, which contains I-127, I-129 and I-125. Take a first volume of digestion solution and an equal volume of I-125 tracer solution to determine the content of iodine ions entering the digestion solution in the aerosol sample, and obtain the iodine recovery rate; The concentration of I-127 in the digestion solution was obtained using inductively coupled plasma mass spectrometry. Nitric acid, iodine standard solution, and silver nitrate solution are added sequentially to the digestion solution to obtain silver iodide precipitate, wherein the volume of the iodine standard solution is the first volume; The silver iodide precipitate was dried and mixed with silver powder. The ratio of I-129 to I-127 in the silver iodide precipitate was detected by accelerator mass spectrometry. The concentration of I-129 is calculated based on the iodine recovery rate, the ratio, and the concentration of I-127.

2. The method for measuring the iodine-129 content in aerosols according to claim 1, characterized in that, Before taking a quantitative amount of aerosol sample and placing it into the digestion vessel, the following steps are included: Ammonia water is placed into a digestion vessel, and the digestion vessel is digested using microwave digestion technology. The digestion temperature is 200 degrees Celsius, and the digestion time is 10 minutes.

3. The method for measuring the iodine-129 content in aerosols according to claim 1, characterized in that, The quantitative aerosol sample is an aerosol membrane with a size of 20×25cm; The dilute ammonia solution is prepared by diluting 25% ammonia solution tenfold to obtain a solution with a concentration of 2.5%.

4. The method for measuring the iodine-129 content in aerosols according to claim 1, characterized in that, The digestion of the substances in the digestion vessel includes: Set the initial digestion temperature to 120 degrees Celsius, and increase the temperature by 20 degrees Celsius every ten minutes until the temperature reaches 180 degrees Celsius. Continue this process for ten minutes to complete the digestion.

5. The method for measuring the iodine-129 content in aerosols according to claim 1, characterized in that, The process of digesting substances in the digestion vessel using microwave digestion technology and filtering and retaining the digestate includes: The filtration process employs a sand core funnel to extract the substances within the digestion vessel. A centrifuge tube is placed below the sand core funnel, and the digestion solution flows into the centrifuge tube; The filtration process involves rinsing the digestion tank multiple times with ultrapure water, and the rinsing solution is transferred to the sand core funnel and flows into the digestion solution to combine with it.

6. The method for measuring the iodine-129 content in aerosols according to claim 1, characterized in that, The process involves taking a first volume of digestion solution and an equal volume of I-125 tracer solution to determine the content of iodine ions entering the digestion solution from the aerosol sample, thereby obtaining the iodine recovery rate. This includes: Obtain the first mass of the first volume of digestion solution and the second mass of the I-125 tracer solution; The sample iodine count in the first volume of digestion solution is determined based on a gamma counter, wherein the sample iodine count is a count of 1-125; The tracer iodine count in the I-125 tracer solution was determined based on a gamma counter. Iodine recovery rate is calculated based on the iodine count of the sample, the iodine count of the tracer, and the first and second masses.

7. The method for measuring the iodine-129 content in aerosols according to claim 6, characterized in that, The calculation of iodine recovery rate based on the iodine count of the sample, the iodine count of the tracer, and the first and second masses includes: The iodine recovery rate is calculated as follows: in, For iodine counting in the sample, For iodine counting as a tracer, To determine the quality of the digested solution after filtration, For the first quality, For the second mass, The mass of I-125 tracer added to the aerosol sample.

8. The method for measuring the iodine-129 content in aerosols according to claim 1, characterized in that, The method of using inductively coupled plasma mass spectrometry to obtain the concentration of I-127 in the digestion solution includes: Take the third mass of the digestion solution and dilute it with ultrapure water to obtain a diluted solution; The concentration of I-127 in the diluted solution was analyzed using inductively coupled plasma mass spectrometry. The concentration of I-127 in the digestion solution is calculated based on the concentration of I-127 in the diluted solution.

9. The method for measuring the iodine-129 content in aerosols according to claim 5, characterized in that, Before calculating the concentration of I-129 based on the iodine recovery rate, the ratio, and the concentration of I-127, the method further includes: Before placing a fixed amount of aerosol sample into the digestion vessel, obtain the mass of the aerosol sample; Based on the measurement method of I-129 concentration in aerosol samples, a blank sample is set up, and the concentration of I-129 in the blank sample is determined. The blank sample is a sample in which a blank aerosol sampling membrane is placed.

10. The method for measuring the iodine-129 content in aerosols according to claim 9, characterized in that, The calculation of the concentration of I-129 based on the iodine recovery rate, the ratio, and the concentration of I-127 includes: The concentration of I-129 is calculated as follows: in, This represents the concentration of I-129 in the aerosol sample. This is the total weight of the centrifuge tubes and the digestion solution. c represents the mass of the centrifuge tube, and c represents the concentration of I-127 in the dilution solution. Let Avogadro's constant be 1. for 129 I / 127 I ratio, The decay constant is For iodine recovery rate, For the quality of aerosol samples, This represents the concentration of I-129 in the blank sample.

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