Method for measuring content of 227Ac in 225Ac solution

Abstract

The invention discloses a method for measuring the content of 227Ac in a 225Ac solution, and belongs to the technical field of nuclide analysis. Comprising the following steps: providing a 227Ac diluent solution with known activity concentration; equally dividing a to-be-detected 225Ac solution into two equal parts, adding a quantitative 227Ac diluent solution into one part as a labeled sample, and taking the other part as a non-labeled sample; respectively measuring the isotope ratios of 227Ac / 225Ac in the two samples; based on the principle of isotope dilution mass spectrometry, by comparing two ratios and combining the sampling amount, the diluent solution adding amount and the activity concentration of the diluent solution, a material balance relation is constructed, and the activity concentration of 227Ac and 225Ac in the to-be-detected solution is obtained. According to the invention, absolute measurement is realized through the principles of high-sensitivity measurement, micro-sampling and an isotope dilution method of a mass spectrometer; and by combining a material balance equation, the method for rapidly and accurately measuring the content of 227Ac in the 225Ac solution in a trace amount can be realized.

Description

Technical Field

[0001] This application relates to a measurement 225 Ac solution 227 The method for determining Ac content belongs to the field of radionuclide analysis technology. Background Technology

[0002] 225 Ac (actinium-225) is due to its suitable half-life (T 1 / 2 With its properties of releasing high-energy alpha particles during decay (9.92 days), it is considered one of the most promising radionuclides for targeted alpha therapy (TAT), showing significant efficacy in the treatment of refractory cancers such as prostate cancer and neuroendocrine tumors.

[0003] Currently, globally 225 Ac's supply mainly comes from 229 Th- 225 Ac generator. However, due to 229 Th's mother 233 U is a fissile material controlled by nuclear regulations and its global reserves are limited, leading to 225 Acetate production is extremely low, approximately 1.7 curies per year, far from meeting the growing demand for clinical research and applications. To address the supply shortage, researchers have developed various alternative production methods, such as using high-energy proton irradiation. 232 Th, or by using medium-energy proton / high-energy gamma-ray irradiation. 226 Ra, etc. However, these alternative production methods will inevitably... 225 An Ac product has been introduced with a long-lived radioactive impurity— 227 Ac (Acetium-227, T) 1 / 2 =21.77 years).

[0004] and 227 Ac has extremely high radiotoxicity, and its annual radioactivity limit is higher than that of Ac. 238 U is 80 times lower than, compared to 226 Ra is 10 times lower. A report from the International Atomic Energy Agency (IAEA) recommends medical-grade... 225 Ac products 227 Ac activity should be kept as low as possible to ensure patient safety. Therefore, for 225 Ac products 227 Strict and accurate quality control of Ac content is crucial, especially in the process of... 225 Before Ac can be used to treat patients, it must be confirmed that its impurity levels meet safety standards.

[0005] Measurement in existing technologies 227 Ac's method has obvious shortcomings: Energy dispersive spectroscopy: due to 227 Ac mainly passes through β - The decay (branching ratio 98.62%) has a direct α decay branching ratio of only 1.38%, resulting in low detection sensitivity. To obtain accurate results, the sample typically needs to be stored for several months. 225 Measurements can be taken after Ac has completely decayed, or after waiting... 227 Ac and its daughter products reach a long-term equilibrium. This method is extremely time-consuming and cannot meet the need for rapid detection before medication.

[0006] Energy dispersive spectroscopy: This method measures... 227 daughter of Ac 227 Th (Thorium-227) or 223 Indirectly inferring Ra (radium-223) from its characteristic γ-rays. 227 Ac content. However, this also requires waiting at least 6 months until... 227 Accurate results can only be obtained after Ac and the daughter body reach a long-term equilibrium, resulting in extremely poor timeliness.

[0007] Existing patented technologies (such as WO2024 / 141792A2): disclose a method of separating and measuring 227 Th determine 227 The Ac method. This method requires the purified sample to stand for at least 5 days to allow for... 227 Ac decays to produce a sufficient amount of 227 Then, complex thorium isotope separation, source preparation, and α counting measurements are performed. The entire process is also time-consuming and cumbersome.

[0008] In summary, all existing technologies share the common drawbacks of complex operation and long measurement cycles (typically requiring several days to months), making them unable to achieve [the desired results]. 225 Within the critical time window between the completion of Ac drug preparation and before patient administration, accurate information must be provided rapidly. 227 Ac content data. If it is found after medication... 227 Excessive levels of Ac have caused irreversible health damage to patients. Therefore, the industry urgently needs a method that can address this issue. 225 Ac solution 227 A rapid and accurate method for measuring Ac content is needed to fill the technological gap in pre-medication quality control. Summary of the Invention

[0009] In view of this, the present invention aims to provide a measurement 225 Ac solution 227 Methods for determining Ac content to address existing technologies 225 Ac solution 227 The measurement cycle for Ac content is long and cannot meet the requirements for medical use. 225The issue of rapid quality control before using Ac products. The specific solution is as follows: A sort of 225 Ac solution 227 A method for measuring Ac content, the method comprising the following steps: Provide known activity concentration 227 Ac diluent solution; To be tested 225 The Ac solution was divided into two equal portions, and a quantitative amount of the aforementioned solution was added to one portion. 227 The Ac diluent solution was used to obtain a spiked sample, and another sample was used as an unspiked sample. Mass spectrometry was used to measure the concentrations in the spiked and unspiked samples, respectively. 227 Ac / 225 Ac isotope ratios; Based on the principle of isotope dilution mass spectrometry, by comparing the concentrations in spiked and unspiked samples... 227 Ac / 225 Ac isotope ratio, the measured 225 Sampling volume of Ac solution, 227 By determining the amount of Ac diluent solution added and its activity concentration, a material balance relationship is established, and the test result is calculated. 225 Ac solution 227 Ac and 225 Ac activity concentration.

[0010] Preferably, the 227 Ac diluent solution is a metrically calibrated solution with known activity concentration.

[0011] Preferably, the calibrated... 227 Ac diluent solutions were diluted to multiple different activity concentration gradients for later selection.

[0012] Preferably, the 227 Ac diluent solution can be either purchased or homemade.

[0013] Preferably, preparation 227 The specific process for preparing Ac diluent solution includes: Dry 226 The Ra target material is sealed within the nuclear reactor. Will contain 226 The nuclear reactor for the Ra target material undergoes neutron irradiation in the reactor. The reaction, and through After decay, it contains 227 Ac's materials; For the containing 227 Ac's material is subjected to radiochemical separation and purification to obtain high purity.227 Ac solution, in which high purity 227 Ac solution refers to a purity ≥ 99.9%; After purification 227 The Ac solution was calibrated to obtain its activity concentration; Then, the calibrated solution was purified using 2% HNO3. 227 The Ac solution was diluted to several different activity concentration gradients to obtain the... 227 Ac diluent solution, sealed and stored for later use.

[0014] Preferably, the radiochemical separation and purification includes the treatment of radiochemically charged particles containing... 227 Ac materials were sequentially purified by multi-step chromatographic separation using LN resin, DGA resin, and cation exchange resin.

[0015] Preferably, the 227 Ac / 225 The Ac ratio measurement includes the following steps: Using a multi-receiver inductively coupled plasma mass spectrometer, the unstuck and spiked samples were analyzed. 227 Ac and 225 The Ac signal was detected to obtain the count rate of the mass peak; and the mass fractionation of the uranium standard sample and the efficiency factor of the ion counter were used to determine the... 227 Ac / 225 The Ac ratio was corrected to obtain the corrected values ​​for the unspiked and spiked samples, respectively. 227 Ac / 225 Ac ratio R 227 / 225-0 and R 227 / 225-a .

[0016] Preferably, the test subject 225 Ac solution 227 The content of Ac is calculated using the following set of material balance equations: ; in, C 225 and C 227 They are the ones to be tested 225 Ac solution 225 Ac and 227 Ac activity concentration, in Bq / mL; V The volume of the solution to be tested is in mL. w In the added reference objects 227 The mass of Ac diluent solution added, in grams; M 227 In the added reference objects 227 The activity concentration of Ac diluent solution, in Bq / g;k For the reason 227 Ac and 225 The coefficients that determine the decay constant of Ac.

[0017] Preferably, the following is obtained by solving the material balance equations: ; in: ; yes 227 The decay constant of Ac; yes 225 The decay constant of Ac; k The preferred value is 1.248×10 -3 .

[0018] Compared with the prior art, the beneficial effects of this application are as follows: This application employs the principle of isotope dilution mass spectrometry, by adding a known amount of [method / method] to the sample. 227 Ac diluent solution was used to obtain a spiked sample. The change in isotope ratio before and after spiking was measured to calculate the analyte. 225 Ac solution 227 Ac and 225 The activity concentration of Ac is independent of the concentration of Ac in the sample. 227 The absolute recovery rate of Ac or the absolute intensity of the instrument signal can be obtained by measuring the relative ratio alone. Accurate measurement results can be obtained, and the method described in this application does not require calibration curves, thus avoiding the complex operations and potential errors associated with preparing a series of standard solutions that are perfectly matched to the matrix of the sample to be tested.

[0019] This application uses a high-sensitivity mass spectrometer (specifically MC-ICP-MS) to measure... 227 Ac / 225 The Ac isotope ratio minimizes the consumption of expensive medical isotope products; This application achieves the simultaneous determination of the content of the sample in a single experiment by establishing a material balance equation and performing mathematical calculations, and by solving a system of simultaneous equations. 227 Ac and 225 The activity concentration of Ac further improves analytical efficiency and information content, and the calculated results are directly traceable to the known activity concentration of the added material. 227 The Ac diluent solution and the measured isotope ratio ensure the accuracy and reliability of the measurement results.

[0020] Preparation in this application 227 The Ac diluent solution was removed step by step using a multi-step chromatographic separation method. 226 Ra target material, transition metal impurities, and organic extractants ensure the final preparation of high-purity materials. 227Ac diluent solution; The calculation took into account 227 Ac decay products 227 The potential impact of Th on the measurement was theoretically verified, and theoretical calculations proved that even if the storage of the diluent solution led to 227 Th growth, its effect on 227 The contribution of the Ac mass peak count rate is only about 0.23%, which is negligible. This analysis proves that the method used... 227 Ac diluent solution has a long shelf life, eliminating the need for frequent calibration and facilitating long-term laboratory use. It allows for continuous measurement of spiked and unspecified samples under identical instrument conditions and measurement sequences. 227 Ac / 225 Ac isotope ratios can effectively offset time-varying systematic errors such as instrument drift, making the difference between the two more accurately reflect the changes brought about by the addition of diluent solution, thereby improving... C 227 The accuracy of the calculation.

[0021] This application utilizes the high sensitivity of MC-ICP-MS to achieve micro-sampling; it employs the principle of isotope dilution to achieve absolute measurement without tracer recovery; and it utilizes material balance equations to achieve simultaneous analysis of principal components and impurities, thus enabling micro-scale, rapid, and accurate analysis. 225 Ac solution 227 A method for measuring Ac content has been developed, thus solving the problem in existing technologies. 225 Ac solution 227 The measurement cycle for Ac content is long and cannot meet the requirements for medical use. 225 The issue of the need for rapid quality control before using Ac products. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating Embodiment 1 of this application; Figure 2 for 227 A schematic diagram of the decay process of Ac. Detailed Implementation

[0023] According to one embodiment of this application, a method is provided. 225 Ac solution 227 A method for measuring Ac content, the method comprising the following steps: Provide known activity concentration 227 Ac diluent solution; To be tested 225 The Ac solution was divided into two equal portions, and a quantitative amount of the aforementioned solution was added to one portion. 227 The Ac diluent solution was used to obtain a spiked sample, and another sample was used as an unspiked sample. Mass spectrometry was used to measure the concentrations in the spiked and unspiked samples, respectively. 227 Ac / 225 Ac isotope ratios; Based on the principle of isotope dilution mass spectrometry, by comparing the concentrations in spiked and unspiked samples... 227 Ac / 225 Ac isotope ratio, the measured 225 Sampling volume of Ac solution, 227 By determining the amount of Ac diluent solution added and its activity concentration, a material balance relationship is established, and the test result is calculated. 225 Ac solution 227 Ac and 225 Ac activity concentration.

[0024] In one embodiment of this application, spiked and unspiked samples are tested. 225 Ac solution sampling and 227 The specific steps for adding the Ac diluent solution are as follows: Quantitatively transfer two equal portions of the test sample 225 Ac solution, to one of the test samples 225 Add 50.00~200.00 mg of Ac solution quantitatively. 227 Ac diluent solution, as the spiked sample; according to the estimated 227 Choose an appropriate activity concentration for the amount of Ac added. 227 Ac diluent solution, so that the volumetric flask contains 227 The amount of Ac increases by 1 to 2 times; Another test result 225 No addition to Ac solution 227 Ac diluent solution, as the unspecified sample; To two copies 225 2% HNO3 solution was added to the Ac solution, and after adjusting the volume, spiked and unspiked samples were obtained.

[0025] In this application, the stated 227 Ac diluent solution is a metrically calibrated solution with known activity concentration.

[0026] In this application, the calibrated... 227 Ac diluent solutions were diluted to multiple different activity concentration gradients for later selection. In one embodiment of this application, high purity was obtained after separation and purification, whether purchased externally or prepared in-house. 227 Ac diluent solutions must be measured by a qualified radiometric metrology station to obtain their concentrations. 227 The radioactivity concentration of Ac is expressed in Bq / g; it is then diluted with 2% HNO3. 227Ac diluent solution, making it 227 Ac radioactivity concentrations ranged from 3.7 to 3700 Bq / g, yielding 3 to 5 different activity concentrations. 227 Ac diluent solution, sealed and stored in PFA plastic bottles for later use.

[0027] This application uses high purity with known activity concentration. 227 Ac solution as 227 Ac diluent solution, in which high purity 227 Ac solution refers to a solution with a purity of ≥99.9%.

[0028] Multi-acceptor inductively coupled plasma mass spectrometry (MC-ICP-MS) was used to measure the concentrations of spiked and unspiked samples, respectively. 227 Ac / 225 The ratio of Ac; In this application, the stated 227 Ac diluent solutions are purchased from qualified isotope producers, such as the China Institute of Atomic Energy or the China Institute of Radiation Protection, in high-purity form. 227 Ac(NO3)3 powder or solution sample, 227 Ac(NO3)3 powder was dissolved in 2% HNO3 to form 227 Ac diluent solution, or homemade solution 227 After the Ac diluent solution is brought to a final volume, it is sealed and stored in a PFA plastic bottle.

[0029] In this application, the dried 226 The Ra target material is sealed in the nuclear reactor, specifically by drying... 226 RaCl2 or 226 Ra(NO3)2 powder was sealed in the nuclear reactor; Will contain 226 The nuclear reactor for the Ra target material undergoes neutron irradiation in the reactor. 226 Ra target material undergoes changes under neutron irradiation Nuclear reactions, decay quickly transforms into 227 Ac; After irradiation for a certain period of time, the mixture was cooled according to a preset time and then the nuclear reactor was opened. The solution was then dissolved in 0.05 mol / L HNO3 to obtain a solution containing... 227 Ac 226 Ra solution, that is, to obtain a solution containing 227 Ac's materials; For the containing 227 Ac's material was subjected to radiochemical separation and purification to obtain a product meeting the required purity. 227 Ac solution.

[0030] In this application, the radiochemical separation and purification includes a multi-step chromatographic separation process using LN resin, DGA resin, and cation exchange resin sequentially. The specific process is as follows: Step 1: Utilizing LN resin for selective adsorption 227 Ac and its offspring 227 Th, realization and 226 Separation of Ra and transition metal impurities; Step 2: Adsorb the DGA resin separated in Step 1. 227 Ac, removes residue 226 Ra and other impurities are removed to improve purity; Step 3, adsorption via cation exchange resin 227 Ac, washing removes organic extractants, yielding pure product. 227 Ac solution.

[0031] In one embodiment of this application, the LN resin refers to a product of Triskem, France, with a particle size of 100-150 μm. The density is 0.38 g / mL; the LN resin is composed of di-(2-ethylhexyl)phosphoric acid (HDEHP) supported on an inert support, and the molecular structure of HDEHP is as follows: ; The DGA resin mentioned refers to the product of Trishelm, France, with a particle size of 100-150 μm. The chemical formula of DGA resin extractant is ; In the formula: R=C8H 17 ; The AG50W-X8 resin is a cation exchange resin produced by Bio-Rad Laboratories, USA. It is of type H and has a particle size of 100-200 mesh.

[0032] In this application, the stated 227 Ac / 225 The Ac ratio measurement includes the following steps: Using a multi-receiver inductively coupled plasma mass spectrometer, the unstuck and spiked samples were analyzed. 227 Ac and 225 The Ac signal was detected to obtain the count rate of the mass peak; and the mass fractionation of the uranium standard sample and the efficiency factor of the ion counter were used to determine the... 227 Ac / 225 The Ac ratio was corrected to obtain the corrected values ​​for the unspiked and spiked samples, respectively. 227 Ac / 225 Ac ratio R 227 / 225-0 and R 227 / 225-a The specific process is as follows: Two test samples, one spiked and one unspecified, were measured separately using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). 225 Ac solution 227 Ac and 225 The count rate ratio of Ac mass peaks; use 227 Ac diluent solution was used for instrument quality calibration and peak localization; Before measuring the sample, rinse the injection system with 2% HNO3 solution for 60 min. Measurement without addition 227 The test sample of Ac diluent solution 227 Ac and 225 The count rate of the Ac mass peak is recorded accurately at the measurement time, which is taken as time t. Then immediately measure the addition 227 The test sample of Ac diluent solution 227 Ac and 225 Count rate of Ac mass peak; Finally, the mass fractionation of uranium standard samples and the efficiency factor of the ion counter were used to evaluate... 227 Ac / 225 The Ac ratio was corrected to obtain the corrected values ​​for the unspiked and spiked samples, respectively. 227 Ac / 225 Ac ratio R 227 / 225-0 and R 227 / 225-a .

[0033] In this application, based on R 227 / 225-0 and R 227 / 225-a The material balance equations are used to calculate the test result. 225 Ac solution 227 Ac content: The material balance equations are as follows: ; in, C 225 and C 227 They are the ones to be tested 225 Ac solution 225 Ac and 227 Ac activity concentration, in Bq / mL; V The volume of the solution to be tested is in mL. w In the added reference objects 227 The mass of Ac diluent solution added, in grams; M 227 In the added reference objects 227The activity concentration of Ac diluent solution, in Bq / g; k For the reason 227 Ac and 225 The coefficients that determine the decay constant of Ac.

[0034] By solving the aforementioned set of material balance equations, we obtain: ; The specific derivation process is as follows: According to the measured R 227 / 225-0 and R 227 / 225-a Calculate 225 Ac solution 227 Ac and 225 Ac activity ratio, 225 Ac activity concentration and 227 The specific process of Ac activity concentration is as follows: 227 The decay constant of Ac: =1.010×10 -9 227 The decay constant of Th: =4.291×10 -7 225 The decay constant of Ac: =8.087×10 -7 because 225 The Ac solution was measured immediately after separation and purification, and the decay was negligible. The measured R... 227 / 225-0 In solution 227 Ac and 225 The ratio of the number of atoms of Ac is then 225 Ac solution 227 Ac and 225 Ac activity ratio can be calculated using the following formula: ; 227 Ac diluent solution 227 Ac will decay and generate 227 Th, add to the test sample that has been stored for a certain period of time 227 Ac diluent solution, generated 227 Th impact 227 Ac and 225 The count rate ratio of the Ac mass peak causes the measured value to be too large.

[0035] Assumption 227 The Ac diluent solution was stored for t days after separation and purification before use. 227 Ac diluent solution 227The number of Th atoms is: ; In the formula: N 227Th for 227 Ac diluent solution 227 The number of Th atoms; N 227Ac-0 for 227 Ac diluent solution at the moment of completion of separation and purification 227 The number of atoms in Ac; for 227 Ac decay 227 The branch ratio of Th =98.62%.

[0036] As can be seen from the calculation formula, with 227 The storage time of Ac diluent solution increases, among which 227 The number of Th atoms increases rapidly, as 227 The decay rate of Th gradually approaches 227 The growth rate of Th after 180 days 227 Ac diluent solution 227 Number of Th atoms and 227 The change in the Ac atom number ratio is less than 1‰, ultimately 227 Number of Th atoms and 227 The ratio of Ac atoms is close to a constant value, at which point... 227 Ac and 227 Th decay reaches a long-term equilibrium.

[0037] when 227 Ac diluent solution can be stored for a long time. 227 Ac and 227 When Th decay reaches long-term equilibrium, then 227 Ac diluent solution 227 The number of Th atoms is: ; In the formula: N 227Ac for 227 Ac diluent solution after long-term storage 227 The number of atoms in Ac.

[0038] when 227 Ac diluent solution can be stored for a long time. 227 Number of Th atoms and 227 The ratio of Ac atoms is: ; Therefore, 227The decay products in the Ac diluent solution 227 The effect of Th atoms on the measurement of the count rate ratio of the 227 and 225 mass peaks is small and can be ignored.

[0039] Let the measurement at time t be... 225 Ac solution 225 The activity concentration of Ac is C 225 Unit: Bq / mL; 227 The activity concentration of Ac is C 227 Unit: Bq / mL; to be tested 225 The sampling volume of Ac solution is V Unit: mL; decay-corrected value at time t 227 Ac diluent solution 227 The activity concentration of Ac is M 227 Unit: Bq / g; 227 The amount of Ac diluent solution added is w The unit is g; then: ; ; Combining the two equations above, we can solve the equation to obtain: ; ; The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0040] Example 1 This embodiment is used to measure a certain batch. 225 Ac solution 227 Ac content. The specific process is attached. Figure 1 As shown, specifically: conduct 227 Preparation of Ac diluent solution: Open a bottle of high-purity liquor purchased from outside 227 Ac(NO3)3 solution was transferred to a 15 mL PFA plastic bottle after acid washing with 2% HNO3. The net weight of the solution was accurately measured using a 0.01 g analytical balance, and then sealed and stored. Approximately 0.2 g of this solution was transferred to a vial and sent to a qualified radiometric metrology station for measurement. The concentration of the solution was measured at time t0. 227 The radioactivity concentration of Ac is 327.5 Bq / g. Before use, dilute the solution with 2% HNO3 to prepare an activity concentration of approximately 4 Bq / g. 227 Ac diluent solution, sealed and stored in PFA plastic bottle for later use.

[0041] conduct 225 Sampling of Ac solution and 227 Addition of Ac diluent solution: Precisely transfer using a micropipette The test 225 Two portions of Ac solution were placed in two clean 5 mL quartz volumetric flasks.

[0042] According to estimates, in the sample to be tested 227 The Ac content is low, so the above-mentioned activity concentration of approximately 4 Bq / g was selected. 227 Ac diluent solution. Using a 0.01 g / mL analytical balance, precisely add 105.47 mg (w) of this diluent solution to one volumetric flask using the differential method as the spiked sample. The other volumetric flask contains no diluent solution as the unspecified sample.

[0043] Subsequently, 2% HNO3 solution was added to each of the two volumetric flasks, and the volume was adjusted to the 5 mL mark. Shake well to obtain the solution to be tested.

[0044] conduct 227 Ac / 225 Measurement of the Ac ratio: The measurement was performed on a multi-receiver inductively coupled plasma mass spectrometer (MC-ICP-MS).

[0045] Instrument preparation and calibration: After confirming that the laboratory environment (temperature 18-25℃, relative humidity ≤60%) and instrument status (argon pressure, cooling water, vacuum) are normal, ignite to stabilize the plasma. 227 Ac diluent solution was used for instrument mass calibration and peak centering. Measurement results using uranium standard samples (such as NBL U-500) were used to obtain the instrument's mass fractionation correction factor and the efficiency factor between the ion counter and subsequent measurements. 227 Ac / 225 The Ac ratio is corrected.

[0046] Background cleaning: Before measurement, clean the injection system with 2% HNO3 solution for 60 minutes and perform baseline correction.

[0047] Sample measurement: First, measure without adding... 227 The test sample of Ac diluent 227 Ac and 225 The count rate of the Ac mass peak, after mass fractionation and efficiency factor correction, is the ratio of the count rates, denoted as [value missing]. R 227 / 225-0 =0.056288, and accurately record this moment as measurement time t; then immediately measure the addition under the same conditions. 227The test sample of Ac diluent 227 Ac and 225 The count rate of the Ac mass peak, after mass fractionation and efficiency factor correction, yields the count rate ratio, which is the corrected isotope ratio, denoted as . R 227 / 225-a =0.12023.

[0048] After the measurement is completed, clean the system with 2% HNO3 and ultrapure water in sequence, then turn off the machine.

[0049] The test result is calculated using the following formula. 225 Ac solution 227 Ac and 225 The activity ratios of Ac and their respective activity concentrations are as follows: First, calculate the amount added at time t. 227 Activity concentration of Ac diluent solution M 227 Decay correction was applied to it. The activity concentration of the diluent solution at time t was measured and decay corrected at the metrology station and was found to be 4.125 Bq / g. Known 227 Ac decay constant =1.010×10 -9 , 225 Ac decay constant =8.087×10 -7 Then the coefficient .

[0050] 227 Ac and 225 Ac activity ratio ;

[0051] 227 Ac activity concentration ;

[0052] 225 Ac activity concentration ;

[0053] This embodiment, from sampling to obtaining the final result, takes less than 1 hour in total, achieving [the goal of] [the following]. 225 Ac solution 227 Rapid and accurate measurement of Ac content.

[0054] Example 2 In this embodiment, compared to Example 1, the radioactivity concentration at time t0 is 327.5 Bq / g. 227An Ac solution was quantitatively transferred and diluted with 2% HNO3 to a concentration of 58.32 Bq / g at time t. 227 Ac diluent solution was added to the sample at a concentration of 0.06859 g for measurement. The isotope ratios of the unspecified and spiked samples were measured sequentially using the same MC-ICP-MS instrument conditions and measurement procedure as in Example 1. ， The measured values ​​are as follows: The unspiked sample was measured 227 Ac / 225 Ac isotope ratio R 227 / 225-0 =0.16272.

[0055] The spiked sample was measured 227 Ac / 225 Ac isotope ratio R 227 / 225-a =0.41721.

[0056] The tests were performed using the same formula and decay constant as in Example 1. 225 Ac solution 227 Ac and 225 The activity ratios of Ac and the calculation of their respective activity concentrations are as follows: 227 Ac and 225 Ac activity ratio ;

[0057] 227 Ac activity concentration ;

[0058] 225 Ac activity concentration ;

[0059] This embodiment further verifies the applicability of the method of the present invention to samples with different activity levels, and the measurement process is fast and simple.

[0060] Example 3 This embodiment measures yet another batch. 225 Ac solution 227 The content of Ac, and the method of irradiation. 226 Ra's homemade 227 Ac diluent solution.

[0061] 227 The specific process for preparing the Ac diluent solution is as follows: Irradiation: to dry 226RaCl2 powder was sealed in a quartz tube and placed in a reactor for neutron irradiation, resulting in... nuclear reaction, 227 The half-life of Ra is 42.2 min. Decay quickly transforms into 227 Ac. After irradiation, allow to cool for one day.

[0062] to be transformed 227 The Ac material was separated and purified as follows: the quartz tube was opened, and the solution was dissolved in 15 mL of 0.05 mol / L HNO3 to obtain the product containing... 227 Ac 226 Ra solution. This solution was subjected to multi-step separation using chromatographic columns in series: In an LN resin column, the contents of the column will be... 227 Ac 226 Ra solution was introduced into a 2 ml LN resin column ( Adsorption 227 Ac and its offspring 227 Th, 226 Ra and transition metal impurities are not adsorbed, and the residue is washed with 20 mL of 0.05 mol / L HNO3. 226 Ra and other impurities; The LN resin column adsorbed by desorption was desorbed using 10 mL of 2 mol / L HNO3. 227 Ac, 227 Th remains adsorbed on the column, resulting in... 227 Ac primary solution.

[0063] In DGA resin columns: 227 Ac primary solution was introduced into a 2 ml DGA resin column ( Adsorption 227 Ac, 226 Ra and other impurities were not adsorbed, and the residue was washed with 20 mL of 2 mol / L HNO3. 226 Ra and other impurities; The DGA resin column adsorbed was desorbed using 10 mL of 0.01 mol / L HNO3. 227 Ac, obtained 227 Ac secondary solution; In the AG50W-X8 cation exchange resin column: 227 Ac secondary solution was introduced into a 0.5 mL AG50W-X8 resin column ( Adsorption 227 Ac, then wash with 10 mL of 0.01 mol / L HNO3 to remove residual organic extractant; desorb the adsorbed AG50W-X8 resin column with 5 mL of 4 mol / L HNO3.227 Ac, evaporated to dryness, then dissolved in a certain volume of 2% HNO3, to obtain 227 Ac solution, sealed and stored in PFA plastic bottles.

[0064] Calibration: The self-purified product 227 The Ac solution was sent to a qualified radiometric station for measurement to obtain its activity concentration, and then diluted with 2% HNO3 to the required concentration. After decay correction to the measurement time t, the solution used in this embodiment... 227 The activity concentration M of the Ac diluent solution at time t 227 It is 326.8 Bq / g.

[0065] conduct 225 Ac solution sampling and 227 Add Ac diluent solution: Precise transfer To be tested 225 Two portions of Ac solution were placed in two 5 mL quartz volumetric flasks.

[0066] 112.63 mg (w) of the self-made active concentration at time t (326.8 Bq / g) was precisely added to one of the volumetric flasks using the differential method. 227 One sample was prepared with Ac diluent and used as the spiked sample; the other sample was prepared without Ac and used as the unspecified sample.

[0067] Both samples were diluted to 5 mL with 2% HNO3 and shaken well.

[0068] In this embodiment 227 Ac / 225 Ac ratio measurements were performed under the exact same MC-ICP-MS instrument conditions and measurement procedures as in Example 1, sequentially measuring the isotope ratios of unspiked and spiked samples. ， The measured values ​​are as follows: The isotope ratios of the unspiked sample were measured. R 227 / 225-0 =0.29355.

[0069] The isotope ratios of the spiked samples were measured. R 227 / 225-a =0.85059.

[0070] In this embodiment, the same formula and decay constant as in Example 1 are used to perform the tests. 225 Ac solution 227 Ac and 225 The activity ratios of Ac and the calculation of their respective activity concentrations are as follows: 227 Ac and 225 Ac activity ratio ;

[0071] 227 Ac activity concentration ;

[0072] 225 Ac activity concentration ;

[0073] This embodiment demonstrates that regardless of whether purchased or homemade materials are used... 227 Ac diluent solution, the method of the present invention can be used for both Ac diluent solution and Ac diluent solution. 225 Ac solution 227 This method allows for rapid and accurate measurement of Ac content, and has good universality and reliability.

[0074] The mass spectrometry measurement time for a single sample in Examples 1-3 above is typically within a few minutes. Combined with sample pretreatment, the total time is less than 1 hour, achieving truly rapid measurement. 225 The measurement results of the Ac solution sample are shown in Table 1.

[0075] Table 1

[0076] From Table 1 M 227 , w,V,R 227 / 225-0 , R 227 / 225-a The original measurement data and the final calculated activity ratio A , C 227 , C 225 The calculation results show that the measurement method described in this application can directly calculate the target impurities in the solution to be tested. 227 Ac activity concentration C 227 The main nuclide was also calculated simultaneously. 225 Ac activity concentration C 225 The ratio of the two values ​​indicates that this method can be performed without relying on other measuring equipment. 225 Comprehensive quality control for Ac products.

[0077] The measurements obtained from Examples 1-3 225 Ac activity concentration C 225 Covering 10 8 ~10 9 Bq / mL level, while 227 Ac activity concentration C 227 Covering from 10 4 Bq / mL to 105 With concentrations in the range of Bq / mL, it can be seen that the method described in this application can adapt to different activity concentration levels. 225 Ac products meet testing needs and have a wide dynamic detection range, suitable for various samples ranging from low to high activity concentrations; And the calculations of the three embodiments 227 Ac / 225 The activity ratios of Ac were 7.025 × 10⁻⁶. -5 2.031×10 -4 and 3.664×10 -4 This means the impurity content is between 0.007% and 0.036%, demonstrating that this method can accurately measure extremely low levels of impurities, far below the 0.1% impurity limit typically required by the European Pharmacopoeia. 227 Ac impurities meet the stringent requirements for in-depth impurity analysis in medical radionuclides.

[0078] Meanwhile, as can be seen from Examples 1-3, when the activity concentration of the added diluent solution... M 227 The isotope ratio measured after spiking from 4.125 Bq / g to 326.8 Bq / g. R 227 / 225-a The value increased significantly from 0.12023 to 0.85059, indicating that this method is effective for... 227 The linear response to changes in Ac content demonstrates that the principle of isotope dilution is accurately applied in practice and the measurement data are reliable.

[0079] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A measurement 225 Ac solution 227 The method for determining Ac content is characterized by... The measurement method includes the following steps: Provide known activity concentration 227 Ac diluent solution; To be tested 225 The Ac solution was divided into two equal portions, and a quantitative amount of the aforementioned solution was added to one portion. 227 The Ac diluent solution was used to obtain a spiked sample, and another sample was used as an unspiked sample. Mass spectrometry was used to measure the concentrations in the spiked and unspiked samples, respectively. 227 Ac / 225 Ac isotope ratios; Based on the principle of isotope dilution mass spectrometry, by comparing the concentrations in spiked and unspiked samples... 227 Ac / 225 Ac isotope ratio, the measured 225 Sampling volume of Ac solution, 227 By determining the amount of Ac diluent solution added and its activity concentration, a material balance relationship is established, and the test result is calculated. 225 Ac solution 227 Ac and 225 Ac activity concentration.

2. A measurement according to claim 1 225 Ac solution 227 The method for determining Ac content is characterized by... The 227 Ac diluent solution is a metrically calibrated solution with known activity concentration.

3. A measurement according to claim 2 225 Ac solution 227 The method for determining Ac content is characterized by... The calibrated 227 Ac diluent solutions were diluted to multiple different activity concentration gradients for later selection.

4. A measurement according to claim 1 225 Ac solution 227 The method for determining Ac content is characterized by... The 227 Ac diluent solution can be either purchased or homemade.

5. A measurement according to claim 4 225 Ac solution 227 The method for determining Ac content is characterized by... preparation 227 The specific process for preparing Ac diluent solution includes the following steps: Dry 226 The Ra target material is sealed within the nuclear reactor. Will contain 226 The nuclear reactor for the Ra target material undergoes neutron irradiation in the reactor, resulting in… The reaction, and through After decay, it contains 227 Ac's materials; For the containing 227 Ac's material is subjected to radiochemical separation and purification to obtain high purity. 227 Ac solution, in which high purity 227 Ac solution refers to a purity ≥ 99.9%; After purification 227 The Ac solution was calibrated to obtain its activity concentration; Then, the calibrated solution was purified using 2% HNO3. 227 The Ac solution was diluted to several different activity concentration gradients to obtain the... 227 Ac diluent solution, sealed and stored for later use.

6. A measurement according to claim 5 225 Ac solution 227 The method for determining Ac content is characterized by... The radiochemical separation and purification includes the treatment of... 227 Ac materials were sequentially purified by multi-step chromatographic separation using LN resin, DGA resin, and cation exchange resin.

7. A measurement according to claim 1 225 Ac solution 227 The method for determining Ac content is characterized by... The 227 Ac / 225 The Ac ratio measurement includes the following steps: Using a multi-receiver inductively coupled plasma mass spectrometer, the unstuck and spiked samples were analyzed. 227 Ac and 225 The Ac signal was detected to obtain the count rate of the mass peak; and the mass fractionation of the uranium standard sample and the efficiency factor of the ion counter were used to determine the... 227 Ac / 225 The Ac ratio was corrected to obtain the corrected values ​​for the unspiked and spiked samples, respectively. 227 Ac / 225 Ac ratio R 227 / 225-0 and R 227 / 225-a .

8. A measurement according to claim 2 225 Ac solution 227 The method for determining Ac content is characterized by... The test 225 Ac solution 227 The content of Ac is calculated using the following set of material balance equations: ； in, C 225 and C 227 They are the ones to be tested 225 Ac solution 225 Ac and 227 Ac activity concentration, in Bq / mL; V The volume of the solution to be tested is in mL. w In the added reference objects 227 The mass of Ac diluent solution added, in grams; M 227 In the added reference objects 227 The activity concentration of Ac diluent solution, in Bq / g; k For the reason 227 Ac and 225 The coefficients that determine the decay constant of Ac.

9. A measurement according to claim 8 225 Ac solution 227 The method for determining Ac content is characterized by... By solving the aforementioned set of material balance equations, we obtain: ； in: ; yes 227 The decay constant of Ac; yes 225 The decay constant of Ac; k The preferred value is 1.248×10 -3 .

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