Method for the isolation and purification of medical pb-212 from natural th-232 and its daughter bodies

Abstract

The application provides a method for separating and purifying medical Pb-212 from natural Th-232 and daughter nuclides thereof, and belongs to the field of medical isotope preparation. The method comprises the following steps: obtaining a Th-232 acid solution; providing a first chromatographic column, performing one-dimensional lead enrichment on the Th-232 acid solution, and obtaining a Pb-212 crude liquid; providing a second chromatographic column, performing two-dimensional refining separation on the Pb-212 crude liquid, and obtaining a Pb-212 purified liquid; providing a third chromatographic column, performing three-dimensional concentration and salt conversion on the Pb-212 purified liquid, and obtaining high-purity and high-concentration Pb-212; the first chromatographic column is filled with coated resin as a stationary phase, and the coated resin is a polymer microsphere coated with a crown ether compound; the second chromatographic column is filled with a cation exchange material as a stationary phase; and the third chromatographic column is filled with a three-dimensional cation exchange resin or coated resin as a stationary phase. The application discloses a method for separating Pb-212 from natural Th-232 and daughter nuclides thereof, and ensures high purity and recovery rate of the Pb-212, thereby meeting the demand of medical radioactive drug application.

Description

Technical Field

[0001] This invention belongs to the technical field of medical radioisotope preparation, and specifically relates to a method for isolating and purifying medical Pb-212 from natural Th-232 and its daughter bodies. Background Technology

[0002] Pb-212 is a popular medical radionuclide used in receptor-targeted alpha particle therapy. With a half-life of approximately 10.64 hours, its decay product, Bi-212, releases high-energy alpha particles with strong cancer-killing capabilities and minimal damage to surrounding healthy tissues. Studies have shown that Pb-212 has good therapeutic effects on malignant tumors such as ovarian, prostate, and pancreatic cancers. However, the clinical application of Pb-212 is limited by its production, separation, and purification technologies.

[0003] Figure 1 The decay chain of Th-232 was demonstrated. Figure 1 It can be seen that Pb-212 is a decay product of Th-232, and it can be directly extracted from natural Th-232. China has abundant Th resources, but the utilization of Th is still relatively underdeveloped, and Th-containing slag is usually directly treated as radioactive waste. Extracting Pb-212 from natural Th-232 can effectively solve the problem of insufficient Pb-212 supply. According to calculations, 1 kg of Th-232 decay equilibrium can produce 0.11 mCi Pb-212, which can be separated every one or two days. Due to the short half-life of Th-232 (1.4 × 10⁻⁶ mCi Pb-212), this process can be very efficient. 10 The long half-life of Th-232 and the short half-life of Pb-212 present a significant challenge in isolating and purifying trace amounts of high-purity Pb-212 from a large amount of Th-232.

[0004] Therefore, developing an efficient, simple, and low-cost Pb-212 separation and purification technology is crucial for improving Pb-212 production capacity and application prospects. This technology not only needs to improve the separation efficiency and purity of Pb-212 but also simplify operational procedures and reduce production costs, providing a reliable guarantee for its widespread application in the medical field. Summary of the Invention

[0005] Therefore, the present invention aims to provide a method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter bodies, in order to solve at least one of the technical problems in the background art.

[0006] This invention is implemented as follows: This invention provides a method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products, comprising the following steps: Obtain Th-232 acid solution.

[0007] A first chromatographic column was provided to perform one-dimensional lead enrichment on the Th-232 acid solution and selectively extract Pb-212 to obtain crude Pb-212 solution.

[0008] A second chromatographic column is provided to perform two-dimensional purification and separation of the crude Pb-212 solution to obtain a purified Pb-212 solution.

[0009] A third chromatographic column is provided to perform three-dimensional concentration and salt conversion of the Pb-212 purification solution to obtain high-purity, high-concentration Pb-212.

[0010] The first chromatographic column is filled with a coating resin as the stationary phase, and the coating resin is a polymer microsphere coated with a crown ether compound.

[0011] The second chromatographic column is filled with cation exchange material as the stationary phase.

[0012] The third chromatographic column is filled with a three-dimensional cation exchange resin or the coated resin as the stationary phase.

[0013] Preferably, the cation exchange material in the second chromatographic column is silica gel modified with sulfonic acid functional groups.

[0014] The three-dimensional cation exchange resin in the third chromatographic column is a resin modified with sulfonic acid functional groups.

[0015] Preferably, the one-dimensional lead enrichment includes column equilibration, sample loading, rinsing, and elution, with the specific operations as follows: The first chromatographic column was equilibrated using inorganic acid solution.

[0016] When the Th-232 acid solution is loaded into the first chromatographic column, Pb-212 is selectively adsorbed onto the first chromatographic column.

[0017] The first chromatographic column was eluted with inorganic acid.

[0018] The crude Pb-212 solution was obtained by eluting the first chromatographic column with an organic salt solution or a weak acid solution as the eluent.

[0019] Preferably, the one-dimensional lead enrichment eluent is selected from α-hydroxyisobutyric acid or diammonium citrate.

[0020] Preferably, the specific operation of the two-dimensional purification and separation is as follows: The second chromatographic column was equilibrated using an organic acid solution.

[0021] A crude Pb-212 solution sample with a preset salt concentration and acidity was obtained. The salt concentration in the crude Pb-212 solution sample was less than 0.2 M, and the pH was 0.5~2.

[0022] The crude Pb-212 sample was loaded into the second chromatographic column.

[0023] Using an organic acid solution as an eluent, Pb-212 was separated from other metal ion impurities to obtain a purified Pb-212 solution.

[0024] Preferably, the eluent in the two-dimensional purification separation is selected from α-hydroxyisobutyric acid or citric acid.

[0025] Preferably, the specific operation of the three-dimensional concentration and salt conversion is as follows: The third chromatographic column was equilibrated using inorganic acid solution.

[0026] A purified Pb-212 solution sample with pH < 2 was obtained.

[0027] The purified Pb-212 sample was loaded into the third chromatographic column, where Pb-212 was selectively adsorbed onto the column.

[0028] The third chromatographic column was washed with water.

[0029] Using organic or inorganic acid solutions as eluents, the third chromatographic column is eluted, and Pb-212 is converted into citrate or chloride salt to obtain high-purity, high-concentration Pb-212.

[0030] Preferably, the eluent in the three-dimensional concentrated salt conversion is at least one of citric acid, hydrochloric acid, and diammonium citrate.

[0031] Preferably, Th-232 and its daughter products are dissolved in 0.01M~2M nitric acid to obtain an acidic solution of Th-232.

[0032] Preferably, sodium iodide or zinc cadmium telluride energy dispersive counters are provided in the one-dimensional lead enrichment, two-dimensional purification separation and three-dimensional concentration and salt conversion processes for online detection of Pb-212.

[0033] Compared with the prior art, the present invention has the following beneficial effects. 1. This invention discloses a method for isolating Pb-212 from natural Th-232 and its decay series, ensuring high purity and recovery rate to meet the needs of medical radiopharmaceutical applications.

[0034] 2. This invention focuses on solving the problem of extracting Pb-212 from natural Th-232 using a multidimensional chromatographic separation method, resulting in Pb-212 with high yield and purity and high selectivity.

[0035] 3. The method of the present invention has good repeatability within the allowable error range and has high repeatability.

[0036] 4. The separation process of the present invention is simple and highly operable. Attached Figure Description

[0037] Figure 1 The decay chain of Th-232; Figure 2 This is a flowchart of the separation and purification process; Figure 3 The chromatogram of Pb-212 during the separation process in Example 1; Figure 4 The energy spectrum of Pb-212 during the separation process in Example 1; Figure 5 The chromatogram of Pb-212 during the separation process in Example 2; Figure 6 The chromatogram of Pb-212 during the separation process in Example 3; Figure 7 The chromatogram of Pb-212 during the separation process in Example 4 is shown. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] A method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products, employing multidimensional chromatography to produce high-purity, high-concentration Pb-212. The main steps and operational route of the separation process are as follows: Figure 2 As shown, the method includes the following steps: S1 and Th-232 dissolve in acidic solutions (such as HNO3 solution), and the concentration range of the acidic solution is usually between 0.01 M and 2 M.

[0040] S2. A one-dimensional lead enrichment column was used as the first chromatographic column to selectively extract Pb-212 from a Th-232 solution containing a large number of impurities, thereby achieving one-dimensional lead enrichment and obtaining crude Pb-212 solution. In practice, the first chromatographic column is filled with a coated resin as the stationary phase. The coated resin consists of polymer microspheres coated with crown ether compounds. Pb-212 is selectively extracted from the mixture of Th-232 and its decay products using the coated resin (e.g., polymer microspheres coated with 18-crown-6 material, referred to as PSN-DHC in the following examples). When the Th solution and its decay products pass through the chromatographic column, Pb-212 is selectively adsorbed onto the column, and an appropriate eluent is selected to elute Pb-212. The specifications of the separation column can be adjusted according to the throughput to meet different scale requirements. The one-dimensional lead enrichment process mainly includes four steps: column equilibration, sample loading, elution, and stripping. The Th-232 solution flowing through the column can be extracted again after one or two days. The eluent is generally an organic salt solution, such as α-hydroxyisobutyric acid (α-HIBA) or diammonium citrate. Other weak acids or solvents such as water can also be used as eluents. The Pb-212 sample obtained after one-dimensional lead enrichment usually contains a large amount of Th-232 and other trace metal ions, such as U, Mg, Ca, Fe, Sr, Zr, Ba, La, and Al; these Pb-212 samples are difficult to label and require further separation and purification.

[0041] S3. The Pb-212 sample was further purified by two-dimensional purification separation to remove trace impurities and obtain a purified Pb-212 solution. The crude Pb-212 sample obtained from the one-dimensional lead enrichment column contains impurity metal ions such as Th-232. Therefore, high-performance chromatography (HPLC) is used to purify the crude Pb-212 sample in a two-dimensional purification process. In this specific implementation, the second chromatographic column in this step is filled with a cation exchange material as the stationary phase. The cation exchange material is silica gel modified with sulfonic acid functional groups (such as silica gel with ethylbenzenesulfonic acid groups modified on the surface, referred to as SCX in the following examples). Controlling the sample loading conditions is crucial. First, the salt concentration in the crude Pb-212 sample needs to be controlled, which can be achieved through dilution. Second, the acidity of the sample needs to be controlled; typically, the salt concentration should be less than 0.2 M, and the pH value should be between 0.5 and 2. After loading, the elution process can employ isocratic elution or gradient elution methods. The eluent is generally an organic salt solution, such as α-hydroxyisobutyric acid (α-HIBA) or citric acid, to effectively separate Pb-212 from other metal ions, thereby selectively recovering the Pb-212 fraction. The Pb-212 obtained through this process is of extremely high purity. The final Pb-212 can be used directly for labeling or converted into other organic salt systems or inorganic acid systems.

[0042] S4. Three-dimensional concentration and salt conversion are used to convert the Pb-212 purification solution into citrate or chloride forms, which facilitates labeling and increases the Pb-212 concentration.

[0043] In practice, the third chromatographic column in this step is filled with a three-dimensional cation exchange resin or coated with resin for fixation. The three-dimensional cation exchange resin is a resin modified with sulfonic acid functional groups. Three-dimensional concentration and salt conversion primarily achieves the conversion of Pb-212 purified solution samples (e.g., from citrate to hydrochloride) and increases the concentration of Pb-212. From the Pb-212 purified solution sample obtained through two-dimensional purification, Pb-212 is adsorbed onto a three-dimensional cation exchange resin (e.g., polystyrene-benzenesulfonic acid material, referred to as PSD-SC in the following examples) or a coated resin (e.g., polymer microspheres coated with 18-crown-6 material, referred to as PSN-DHC in the following examples) by controlling the sample's acidity (e.g., pH < 2) and salt concentration (e.g., < 0.2 M). Through rinsing and elution processes, different salt systems can be fully converted. Elution of Pb-212 with organic or inorganic acids yields high-purity, high-concentration Pb-212.

[0044] During the separation process of S2 to S4, energy spectrum counting was introduced for online detection of Pb-212.

[0045] Example 1 A method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products includes the following steps: S1. Sample preparation The sample was a 0.54 kg / L Th(NO3)4 solution with an HNO3 concentration of 0.48 M. When the Pb-212 activity reached 93% of the Th-232 activity (every two days), the following steps S2-S4 were performed for separation.

[0046] S2, one-dimensional lead enrichment (2-1) Equilibrate the lead enrichment column (PSN-DHC, 20 mm × 100 mm (inner diameter × height), i.e., the first chromatographic column) with 300 mL of 1 M HNO3; Preparation process of PSN-DHC: 2.75g of crown ether compound (18-crown-6) was dissolved in 30 mL of ethanol, 7.5g of divinylbenzene-N-vinylpyrrolidone copolymer microspheres were added, mixed evenly, and the ethanol was removed by rotary evaporation. The mixture was then rinsed with 7.5 mL of water and dried under vacuum. The filler was then dried (drying temperature 70℃, drying time 20 h).

[0047] Preparation process of divinylbenzene-N-vinylpyrrolidone copolymer microspheres: Weigh 150 g of NaOH and dissolve it in 3 L of pure water to prepare a 1.25M NaOH solution. Measure 500 mL of divinylbenzene into a 2 L separatory funnel, and extract with 500 mL of NaOH solution each time. After shaking and allowing the layers to separate, discard the lower layer. Repeat the alkaline washing 6 times. Then wash with pure water in the same way 6 times. Detect the pH of the aqueous phase after the 6th wash until the pH difference with pure water is ≤0.1. Store the purified divinylbenzene at -40℃ (shelf life 7 days).

[0048] To prepare the oil phase, first mix 8.61 g of N-vinylpyrrolidone with 1 g of pure water, then adjust the pH to 7.0 ± 0.1 with dilute hydrochloric acid (1 mL of 36%-38% concentrated hydrochloric acid to 50 mL). Repeat the above process to prepare a total of 130.24 g of acid-adjusted N-vinylpyrrolidone, which is then sealed at 4°C for later use (shelf life 12 h). Subsequently, add 130.24 g of acid-adjusted N-vinylpyrrolidone, 12.08 g of azobisisobutyronitrile, 319.27 g of xylene, and 454.91 g of purified divinylbenzene to a 2 L round-bottom flask, and stir at 33°C for 30 min until homogeneous.

[0049] Aqueous phase preparation: Add 8L of pure water to a 10L reactor, set the temperature to 50℃ and 380 r / min, add 82.5g of polyvinyl alcohol, 412.5g of sodium chloride and 0.825g of sodium nitrite, rinse the pipeline residue with 250mL of pure water and add it to the reactor, stir and dissolve for 3h.

[0050] The oil phase was poured into the aqueous phase, and the temperature was raised to 80℃ (30–60 min, with a heating time of 45 min in this case), and polymerization was carried out by stirring at 380 rpm for 5 h. After the reaction, the 80℃ liquid was filtered through a 400-mesh vibrating screen and dried. The filter cake was mixed with 6 L of water and washed in a 10 L reactor at 80℃ and 380 rpm for 1 h. The mixture was then filtered using a GC-grade sintered glass funnel and rinsed with 2 L of 80℃ pure water. Next, 6 L of methanol was added and stirred at 50℃ and 380 rpm for 1 h. After discharge, the mixture was allowed to settle for 10–20 min (15 min in this case) until clear stratification was achieved. The upper suspension was discarded, and the settled material was passed through a 400-mesh sieve, washed with 2 L of methanol, and filtered until no liquid flowed out. The above water washing and methanol washing operations were repeated twice, with the stirring time shortened to 30 min in each case. The packing material was then transferred to a 5L beaker, and 3L of ethanol was added for ultrasonic dispersion. The mixture was then dispensed into three 2L beakers (diameter-to-height ratio > 1:1.6). After settling for 15-20 minutes (18 minutes in this case), the upper suspension containing small particles was discarded. Ethanol was added back to the original settling volume, and ultrasonication and settling were repeated 4-5 times (5 times in this case) until no visible suspended particles were visible in the supernatant. Finally, the mixture was filtered using a G4 sintered glass funnel. The filter cake was spread evenly in an enamel dish (material thickness ≤ 2cm) and vacuum dried at 60℃ for 16 hours to obtain polymer microspheres. These microspheres were then sieved to obtain a particle size of 8μm-12μm.

[0051] (2-2) 7.6 L of Th(NO3)4 solution was passed through the first chromatographic column at a flow rate of 40 mL / min, wherein the Pb-212 activity was 200 μCi; (2-3) After loading the sample, wash the first column with 400 mL of 1 M HNO3 at a flow rate of 40 mL / min; (2-4) 140 mL of 1 M α-hydroxyisobutyric acid was used as the eluent at a flow rate of 10 mL / min. A cadmium zinc telluride detector was used for counting. Fraction collection began when the count rate (cps) was higher than the background level and stopped when the count rate returned to the baseline. Ultimately, 28 mL of Pb-212 fraction (i.e., crude Pb-212 solution) was collected, with a Pb-212 activity of approximately 121 μCi (Note: The volume effect on the activity meter's detection error was not considered during the test; the test result is lower than the actual value).

[0052] S3, Two-dimensional lead refining and purification (3-1) The sample was 28 mL of crude Pb-212 solution (1 M α-hydroxyisobutyric acid), 223 mL of pure water and 30 mL of 1 M HNO3 were added, and the final volume was about 281 mL with a pH of 1.85 (salt concentration of 0.1 M). (3-2) The second chromatographic column (SCX, 20 mm × 250 mm (inner diameter × height)) was equilibrated using 150 mL of 0.2 M citric acid (pH = 2.68); SCX preparation process: 50g of silica gel (particle size 10μm) was added to 250mL of 1M HCl solution, stirred evenly, and reacted at 100℃ for 2h. After the reaction, the mixture was cooled to below 50℃, filtered, and washed with deionized water until pH = 6-7. It was then washed twice with 100mL of methanol and completely dried. The silica gel was evenly spread in a 500mL beaker, and the mouth of the beaker was covered with perforated aluminum foil. It was first vacuum dried at 80℃ for 16h, then dried by forced air drying at 160℃ for 16h. After drying, it was cooled to 40℃ and placed in a constant temperature and humidity chamber (35℃, 40% humidity) to absorb water for 16h, controlling the moisture content to be 5.0%-5.5%, yielding pretreated silica gel for later use. The apparatus (round-bottom flask) was cleaned and dried, the tubing was connected, the airtightness was checked, and a tail gas absorption device was installed. Nitrogen gas was introduced to purge the air from the system. Add 20g of the pretreated silica gel and 40mL of xylene to a 250mL round-bottom flask and stir. Weigh 2.5g of 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane and 1.5g of methyltrichlorosilane, add 20mL of xylene and mix well. Slowly add the mixture dropwise to the reaction system. Rinse the dropping funnel twice with 10mL of xylene to ensure that the silane reagent is completely added. Maintain the reaction temperature at 40℃ and stir for 3h. After the reaction is complete, filter until the sample is almost dry. Wash twice with 50mL of methanol and dry under vacuum. Finally, spread the sample evenly on the bottom of the container, cover the mouth of the container with perforated aluminum foil, and dry at 80℃ for 16h. The preparation is complete (the amount of sulfonic acid functional group modification is 0.3mmol / g).

[0053] (3-3) Pass the sample through the second column at a flow rate of 20 mL / min; (3-4) After the sample loading is completed, use 660 mL of 0.2 M citric acid (pH = 2.68) at a flow rate of 20 mL / min to rinse and remove impurities for 33 min; (3-5) 0.4 M citric acid (pH = 2.68) was used as the eluent, eluted at a flow rate of 20 mL / min for 20 min, with a wash volume of 400 mL. A cadmium zinc telluride detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. Finally, 34 mL of Pb-212 fraction (i.e., purified Pb-212 solution) was collected, with a Pb-212 activity of approximately 85 μCi in the sample (Note: The volume effect on the activity meter's detection error was not considered during the test; the test result is lower than the actual value).

[0054] S4, Three-dimensional lead concentration and salt conversion (4-1) The sample was about 34 mL of Pb-212 purified solution. 14.45 mL of pure water was added, followed by 10 mL of 1 MHNO3. The final sample was 59 mL with a pH of 1.05. (4-2) Equilibrate the third chromatographic column (PSD-SC, 10 mm × 50 mm (inner diameter × height)) with 40 mL of 0.1 M HNO3; PSD-SC preparation process: 3 L of 0.5% (w / w) polyvinyl alcohol aqueous solution, 12 g of azobisisobutyronitrile, 210 g of divinylbenzene, and 420 g of xylene were mixed evenly and heated at 90 °C with stirring for 5 h. The reaction solution was filtered, washed with water and ethanol sequentially, and dried at 55 °C for 12 h to obtain polystyrene microspheres. The microspheres with a particle size of 8 μm to 12 μm were obtained by sieving. 100 mL of 96%-98% (w / w) concentrated sulfuric acid and 5 g of polystyrene microspheres were mixed evenly and reacted at 5 °C for 24 h. The reaction solution was diluted with water, filtered, washed with water and ethanol sequentially, and dried at 60 °C for 24 h to obtain sulfonated cation exchange packing material (sulfonic acid group modification amount of 1.7 mmol / g).

[0055] Pass 59 mL of Pb-212 sample through the third column at a flow rate of 10 mL / min; After sample loading, the third column was eluted with 20 mL of H2O at a flow rate of 20 mL / min. 0.1 M diammonium citrate (pH ≈ 5) was used as the eluent at a flow rate of 10 mL / min, with an elution volume of 20 mL. A cadmium zinc telluride detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. A final 5 mL Pb-212 fraction was collected, with a Pb-212 activity of 105 μCi. This procedure validated the concentration and salt conversion of Pb-212 using diammonium citrate. 27 μCi was extracted in this step for drug labeling experiments; therefore, in this example, the Pb-212 sample used for subsequent chloride conversion was 78 μCi (3.71 mL).

[0056] (4-3) In this embodiment, the remaining sample was also used to concentrate and convert Pb-212 to salt using hydrochloric acid. 3.71 mL of 78 μCi Pb-212 was taken, 20 mL of H2O was added, and then the pH was adjusted to 1.05 with 1 M concentrated nitric acid. The final sample volume was 40 mL. First, the third chromatographic column was equilibrated using 40 mL of 0.1 M HNO3; Then, 40 mL of sample was passed through the third column at a flow rate of 20 mL / min; After loading the sample, rinse with 20 mL of H2O at a flow rate of 20 mL / min; Next, 3 M HCl was used as the eluent at a flow rate of 10 mL / min, with an elution volume of 100 mL. A cadmium zinc telluride detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. A final 2 mL Pb-212 fraction was collected, with a Pb-212 activity of approximately 122 μCi in the sample.

[0057] Verification showed that after one-dimensional lead enrichment, the radionuclear purity in the crude Pb-212 sample was very high (>99%). Therefore, the signal collected by the cadmium zinc telluride detector mainly originated from Pb-212, which provides feasibility for online detection during sample separation. The Pb-212 chromatogram shown in the cadmium zinc telluride energy dispersive spectroscopy of this embodiment is as follows... Figure 3 As shown, the energy spectrum is as follows: Figure 4 As shown, the chromatogram can guide the time for fraction extraction, and the energy dispersive spectroscopy confirms that the collected sample is Pb-212.

[0058] Example 2 A method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products includes the following steps: S1. Sample preparation The sample was a 0.35 kg / L Th(NO3)4 solution with an HNO3 concentration of 1 M. Separation was carried out when the Pb-212 activity reached the Ra-224 equilibrium.

[0059] S2, one-dimensional lead enrichment (2-1) The lead enrichment column (PSN-DHC (material from Example 1), 10 mm × 60 mm (inner diameter × height), i.e., the first chromatographic column) was equilibrated using 50 mL of 1 M HNO3; (2-2) Then, 0.17 L of Th(NO3)4 solution was passed through the first chromatographic column at a flow rate of 5 mL / min; (2-3) After loading the sample, wash the first column with 50 mL of 1 M HNO3 at a flow rate of 5 mL / min; (2-4) 24 mL of 1 M α-hydroxyisobutyric acid (pH=5) was used as the eluent at a flow rate of 5 mL / min. A sodium iodide detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. Approximately 5 mL of Pb-212 fraction (i.e., crude Pb-212 solution) was ultimately collected.

[0060] S3, Two-dimensional lead refining and purification (3-1) The sample was approximately 5 mL of crude Pb-212 solution (1 M α-hydroxyisobutyric acid), 46 mL of pure water and 0.34 mL of HNO3 (mass fraction 65%~68%) were added, resulting in a final volume of approximately 51 mL and a pH value of 1.80 (salt concentration of 0.1 M). (3-2) The second chromatographic column (SCX (material from Example 1), 10 mm × 250 mm (inner diameter × height)) was equilibrated using 200 mL of 0.2 M citric acid (pH = 2.4); (3-3) Pass the sample through the second column at a flow rate of 4 mL / min; (3-4) After loading the sample, elute with 120 mL of 0.2 M citric acid (pH = 2.68) at a flow rate of 4 mL / min for 30 min. (3-5) 0.4 M citric acid (pH = 2.83) was used as the eluent at a flow rate of 4 mL / min for 20 min, with a wash volume of 80 mL. A sodium iodide detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. Approximately 10 mL of Pb-212 fraction (i.e., purified Pb-212 solution) was ultimately collected.

[0061] S4, Three-dimensional lead concentration and salt conversion (4-1) The sample to be loaded is about 10 mL of Pb-212 purified solution, 4.25 mL of pure water is added, and then 0.19 mL of HNO3 (mass fraction 65%~68%) is added, the final volume is 14.44 mL, and the pH value is 1.1; (4-1) Equilibrate the third chromatographic column (PSD-SC (material from Example 1), 10 mm × 60 mm (inner diameter × height)) with 50 mL of 0.1 M HNO3; (4-1) Pass 14.44 mL of Pb-212 sample through the third column at a flow rate of 5 mL / min; (4-1) After sample loading, 0.5 M citric acid (pH = 5) was used as the eluent at a flow rate of 5 mL / min and an elution volume of 10 mL. A sodium iodide detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. Approximately 2 mL of Pb-212 fraction was collected, representing high-purity, high-concentration, medically viable Pb-212.

[0062] Verification showed that the radionuclear purity in the Pb-212 sample was very high after one-dimensional lead enrichment. Therefore, the signal collected by the sodium iodide detector mainly originated from Pb-212, which provides feasibility for online detection during sample separation. The Pb-212 chromatogram shown in the sodium iodide energy dispersive spectroscopy of this embodiment is as follows. Figure 5 As shown.

[0063] Example 3 A method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products includes the following steps: S1. Sample preparation The sample was a 0.35 kg / L Th(NO3)4 solution with an HNO3 concentration of 1 M. Separation was carried out when the Pb-212 activity reached the Ra-224 equilibrium.

[0064] S2, one-dimensional lead enrichment (2-1) The lead enrichment column (PSN-DHC (material from Example 1), 10 mm × 60 mm (inner diameter × height), i.e., the first chromatographic column) was equilibrated using 50 mL of 1 M HNO3; (2-2) 0.17 L of Th(NO3)4 solution was passed through the first chromatographic column at a flow rate of 5 mL / min; (2-3) After loading the sample, wash the first column with 50 mL of 1 M HNO3 at a flow rate of 5 mL / min; (2-4) Using 30 mL of 1 M α-hydroxyisobutyric acid (pH=5) as the eluent, at a flow rate of 5 mL / min, about 6 mL of Pb-212 fraction (i.e. crude Pb-212 liquid) was collected.

[0065] S3, Two-dimensional lead refining and purification (3-1) The sample was approximately 6 mL of crude Pb-212 solution (1 M α-hydroxyisobutyric acid), 55.2 mL of pure water and 0.41 mL of HNO3 (mass fraction 65%~68%) were added, resulting in a final volume of approximately 61.6 mL and a pH value of 1.84 (salt concentration of 0.1 M). (3-2) The second chromatographic column (SCX (material from Example 1), 10 mm × 250 mm (inner diameter × height)) was equilibrated using 200 mL of 0.2 M citric acid (pH = 2.4); (3-3) Pass the sample through the second column at a flow rate of 4 mL / min; (3-4) After loading the sample, elute with 120 mL of 0.2 M citric acid (pH = 2.68) at a flow rate of 4 mL / min for 30 min. (3-5) 0.4 M citric acid (pH = 2.83) was used as the eluent, eluted at a flow rate of 4 mL / min for 20 min, with a wash volume of 80 mL. A sodium iodide detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. Approximately 5.2 mL of Pb-212 fraction (i.e., purified Pb-212 solution) was ultimately collected.

[0066] S4, Three-dimensional lead concentration and salt conversion (4-1) In order to simulate the large volume of sample loading in three dimensions, 0.4 M citric acid (pH = 2.68) was added to the 5.2 mL Pb-212 purified sample obtained in two dimensions to dilute it to 60 mL, then 24.5 mL of pure water was added, and then 1.14 mL of HNO3 (mass fraction 65%~68%) was added, with a final volume of about 85.6 mL and a pH value of 1.0; (4-2) The third chromatographic column (PSD-SC (material from Example 1), 4.6 mm × 250 mm (inner diameter × height)) was equilibrated using 40 mL of 0.1 M HNO3; (4-3) Pass 85.6 mL of Pb-212 sample through the third column at a flow rate of 3 mL / min; (4-4) 0.1 M HNO3 was used as the eluent, the flow rate was 10 mL / min, and the elution volume was 100 mL; (4-5) After sample loading, 3 M HCl was used as the eluent at a flow rate of 3 mL / min, with an elution volume of 10 mL. A sodium iodide detector was used for counting; fraction collection began when the count rate (cps) was higher than the background level and stopped when the count rate returned to the baseline. Approximately 2.5 mL of Pb-212 fraction was collected, representing high-purity, high-concentration medical-grade Pb-212.

[0067] Verification showed that the radionuclear purity of the Pb-212 sample was very high after one-dimensional lead enrichment. Therefore, the signal collected by the sodium iodide detector mainly originated from Pb-212, providing feasibility for online detection during sample separation. The Pb-212 chromatogram shown in the sodium iodide energy dispersive spectroscopy of this embodiment is as follows... Figure 6 As shown.

[0068] Example 4 A method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products includes the following steps: S1. Sample preparation The sample was a 0.61 kg / L Th(NO3)4 solution with an HNO3 concentration of 1 M.

[0069] S2, one-dimensional lead enrichment (2-1) The lead enrichment column (PSN-DHC (material from Example 1), 50 mm × 100 mm (inner diameter × height), i.e., the first chromatographic column) was equilibrated using 1 M HNO3; (2-2) 35 L of Th(NO3)4 solution was passed through the first chromatographic column at a flow rate of 100~140 mL / min; (2-3) After the sample loading is completed, the first column is rinsed with 1500 mL of 1 M HNO3 at a flow rate of 140 mL / min; then the column is rinsed with 140 mL of pure water. (2-4) 1 M α-hydroxyisobutyric acid (pH=5) was used as the eluent at a flow rate of 100 mL / min. A cadmium zinc telluride detector was used for counting. Fraction collection began when the count rate (cps) was higher than the background level and stopped when the count rate returned to the baseline. Approximately 260 mL of Pb-212 fraction (i.e., crude Pb-212 solution) was collected, and 150 mL of the sample was taken for two-dimensional loading.

[0070] S3, Two-dimensional lead refining and purification (3-1) The sample was 150 mL of crude Pb-212 solution (1 M α-hydroxyisobutyric acid), 1350 mL of pure water and 10 mL of HNO3 (mass fraction 65%~68%) were added, the final volume was about 1510 mL, and the pH value was 1.83 (salt concentration was 0.1M). (3-2) First, the second chromatographic column (SCX (material from Example 1), 20 mm × 250 mm (inner diameter × height)) was equilibrated with 400 mL of 0.2 M citric acid (pH = 2.72); (3-3) Then, the sample was passed through the second column at a flow rate of 30 mL / min; (3-4) After loading the sample, elute with 700 mL of 0.2 M citric acid (pH = 2.73) at a flow rate of 20 mL / min for 35 min. (3-5) Next, 0.15 M citric acid (pH = 3.56) was used as the eluent, eluted at a flow rate of 20 mL / min for 20 min, with a wash volume of 400 mL. A cadmium zinc telluride detector was used for counting; fraction collection began when the count rate (cps) was higher than the background and stopped when the count rate returned to the baseline. Approximately 120 mL of Pb-212 fraction (Pb-212 purified solution) was ultimately collected.

[0071] S4, Three-dimensional lead concentration and salt conversion (4-1) The sample to be loaded was about 120 mL of Pb-212 purified solution. 51 mL of pure water was added, followed by 2.28 mL of HNO3 (mass fraction 65%~68%). The final volume was about 173 mL, and the pH value was 1.1. (4-2) The third chromatographic column (PSD-SC (material from Example 1), 10 mm × 100 mm (two 10 mm × 50 mm in series) (inner diameter × height)) was equilibrated using 0.1 M HNO3; (4-3) Pass 173 mL of Pb-212 sample through the third column at a flow rate of 15 mL / min; (4-4) 0.1 M HNO3 was used as the eluent, the flow rate was 10 mL / min, and the elution volume was 100 mL; (4-5) After the sample loading was completed, 3 M HCl was used as the eluent at a flow rate of 3 mL / min and an elution volume of 20 mL. About 8 mL of Pb-212 fraction was collected. The fraction was then heated and dried with an infrared lamp. The final activity was 360 μCi, which is high-purity, high-concentration medical-grade Pb-212.

[0072] Verification showed that the radionuclear purity in the Pb-212 sample was very high after one-dimensional lead enrichment. Therefore, the signal collected by the cadmium zinc telluride detector mainly originated from Pb-212, providing feasibility for online detection during sample separation. The Pb-212 chromatogram shown in the sodium iodide energy dispersive spectroscopy of this embodiment is as follows... Figure 7 As shown.

[0073] Example 5 The process and conditions in this embodiment are basically the same as S1 and S2 in Example 1. The difference is that 0.01M α-hydroxyisobutyric acid is used for elution in this embodiment.

[0074] S2, one-dimensional lead enrichment (2-1) The lead enrichment column (PSN-DHC (material from Example 1), 10 mm × 60 mm (inner diameter × height), i.e., the first chromatographic column) was equilibrated using 50 mL of 1 M HNO3; (2-2) Then, 0.17 L of Th(NO3)4 solution was passed through the first chromatographic column at a flow rate of 5 mL / min; (2-3) After loading the sample, wash the first column with 50 mL of 1 M HNO3 at a flow rate of 5 mL / min; (2-4) 50 mL of 0.01 M α-hydroxyisobutyric acid (pH=5) was used as the eluent at a flow rate of 5 mL / min. Ultimately, no Pb-212 nuclide was collected from the 50 mL eluent.

[0075] This example demonstrates that using an eluent concentration that is too low results in poor elution.

[0076] Example 6 The process and conditions in this embodiment are basically the same as those in S1, S2 and S3 in Embodiment 3. The difference is that 0.2M citric acid is used for elution in the S3 two-dimensional lead purification process in this embodiment.

[0077] S3, Two-dimensional lead refining and purification (3-1) The sample was approximately 6 mL of crude Pb-212 solution (1 M α-hydroxyisobutyric acid), 55.2 mL of pure water and 0.41 mL of HNO3 (mass fraction 65%~68%) were added, resulting in a final volume of approximately 61.6 mL and a pH value of 1.84 (salt concentration of 0.1 M). (3-2) The second chromatographic column (SCX (material from Example 1), 10 mm × 250 mm (inner diameter × height)) was equilibrated using 200 mL of 0.2 M citric acid (pH = 2.4); (3-3) Pass the sample through the second column at a flow rate of 4 mL / min; (3-4) After loading the sample, elute with 120 mL of 0.2 M citric acid (pH = 2.68) at a flow rate of 4 mL / min for 30 min. (3-5) 0.2 M citric acid (pH = 2.68) was used as the eluent, and elution was carried out at a flow rate of 4 mL / min for 20 min, with a wash volume of 80 mL. In the end, no Pb-212 was collected in the 80 mL eluent.

[0078] This example demonstrates that using an eluent concentration that is too low results in poor elution.

[0079] Example 7 The process and conditions in this embodiment are basically the same as those in S1, S2 and S3 in embodiment 3. The difference is that the pH of the sample in the S4 three-dimensional lead concentration and salt conversion loading solution used in this embodiment was not adjusted.

[0080] S4, Three-dimensional lead concentration and salt conversion (4-2) The third chromatographic column (PSD-SC (material from Example 1), 4.6 mm × 250 mm (inner diameter × height)) was equilibrated using 40 mL of 0.1 M HNO3; (4-3) Pass 5.2 mL of Pb-212 sample (0.4 M citric acid (pH = 2.68)) through the third column at a flow rate of 3 mL / min; (4-4) 0.1 M HNO3 was used as the eluent, the flow rate was 10 mL / min, and the elution volume was 100 mL; (4-5) After sample loading, 3 M HCl was used as the eluent at a flow rate of 3 mL / min and an elution volume of 10 mL. Ultimately, no Pb-212 fraction was collected, as the sample experienced leakage during loading.

[0081] This embodiment confirms that Pb-212 samples that do not meet the loading conditions are difficult to be effectively adsorbed by the chromatographic column used.

[0082] Example 8 The process and conditions in this embodiment are basically the same as S1, S2, S3 and S4 in Embodiment 2. The difference is that the three-dimensional lead concentration and salt conversion in this embodiment uses 0.1M HCl to elute Pb-212.

[0083] S4, Three-dimensional lead concentration and salt conversion (4-1) The sample to be loaded is about 10 mL of Pb-212 purified solution, 4.25 mL of pure water is added, and then 0.19 mL of HNO3 (mass fraction 65%~68%) is added, the final volume is 14.44 mL, and the pH value is 1.1; (4-1) Equilibrate the third chromatographic column (PSD-SC (material from Example 1), 10 mm × 60 mm (inner diameter × height)) with 50 mL of 0.1 M HNO3; (4-1) Pass 14.44 mL of Pb-212 sample through the third column at a flow rate of 5 mL / min; (4-1) After sample loading, 0.1 M HCl was used as the eluent at a flow rate of 5 mL / min and an elution volume of 50 mL. Ultimately, no Pb-212 fraction was collected, and Pb-212 remained adsorbed on the column.

[0084] This example demonstrates that using an eluent concentration that is too low results in poor elution.

[0085] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products, characterized in that, The method includes the following steps: 1) Obtain Th-232 acid solution; 2) Provide a first chromatographic column to perform one-dimensional lead enrichment on the Th-232 acid solution and selectively extract Pb-212 to obtain crude Pb-212 solution; 3) Provide a second chromatographic column to perform two-dimensional purification and separation on the crude Pb-212 solution to obtain a purified Pb-212 solution; 4) Provide a third chromatographic column to perform three-dimensional concentration and salt conversion of the Pb-212 purification solution to obtain high-purity, high-concentration Pb-212; The first chromatographic column is filled with a coating resin as the stationary phase, and the coating resin is a polymer microsphere coated with a crown ether compound. The second chromatographic column is filled with cation exchange material as the stationary phase. The third chromatographic column is filled with a three-dimensional cation exchange resin and / or the coated resin as a stationary phase.

2. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products according to claim 1, characterized in that, The cation exchange material in the second chromatographic column is silica gel modified with sulfonic acid functional groups; the sulfonic acid functional groups are one or more of phenylsulfonic acid groups and alkylsulfonic acid groups (alkyl carbon number is 1~8), and the modification amount is 0.1 mmol / g~2.0 mmol / g; the silica gel particle size is 3.5 μm~15 μm; The three-dimensional cation exchange resin in the third chromatographic column is a resin modified with sulfonic acid functional groups; The modification amount is 0.5 mmol / g to 3.0 mmol / g; the resin is one or more of the following: polyvinylbenzene microspheres, divinylbenzene-vinylbenzene copolymer microspheres, or divinylbenzene-N-vinylpyrrolidone copolymer microspheres, with a particle size of 5 μm to 80 μm.

3. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter bodies according to claim 1 or 2, characterized in that, Step 2) describes one-dimensional lead enrichment, which includes column equilibration, sample loading, rinsing, and elution. The specific operations are as follows: The first chromatographic column was equilibrated using inorganic acid solution; When the Th-232 acid solution is loaded into the first chromatographic column, Pb-212 is selectively adsorbed onto the first chromatographic column. The first chromatographic column was eluted with inorganic acid at a rate of 1 BV to 20 BV (preferably 5 BV to 15 BV, more preferably 10 BV to 13 BV). The crude Pb-212 solution was obtained by eluting the first chromatographic column with an organic salt solution or a weak acid solution as the eluent.

4. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products according to claim 3, characterized in that, The inorganic acid solution is one or more of nitric acid and hydrochloric acid, with a molar concentration of 0.01M to 1M (preferably 0.5M to 1M, more preferably 0.8M to 1M). The one-dimensional lead enrichment eluent is selected from α-hydroxyisobutyric acid (0.1M~2M, preferably 0.5M~1.5M, more preferably 0.8M~1.2M) and / or diammonium citrate (0.01M~1M, preferably 0.05M~0.8M, more preferably 0.08M~0.5M). The first or third chromatographic column is filled with a coated resin as the stationary phase, wherein the coated resin is a polymer microsphere coated with a crown ether compound. The polymer microspheres coated with crown ether compounds are one or more of the following: polyvinylbenzene microspheres, divinylbenzene-vinylbenzene copolymer microspheres, or divinylbenzene-N-vinylpyrrolidone copolymer microspheres; the crown ether compounds are one or more of the following: 15-crown ether-5, 18-crown ether-6, di-tert-butyldicyclohexyl-18-crown-6, di-tert-butyldicyclohexyl-15-crown ether-5, or di-tert-butyldiphenyl-18-crown-6; and the coating amount is 50 mg / g to 300 mg / g. The polymer microspheres are one or more of the following: divinylbenzene-vinylbenzene copolymer microspheres or divinylbenzene-N-vinylpyrrolidone copolymer microspheres; and the particle size is 5 μm to 80 μm.

5. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter bodies according to claim 1 or 2, characterized in that, The specific operation of the two-dimensional purification and separation is as follows: The second chromatographic column was equilibrated using an organic acid solution. A crude Pb-212 solution sample with a preset salt concentration and acidity is obtained by adjusting with water and an inorganic acid. The salt concentration in the crude Pb-212 solution sample is less than or equal to 0.2M (preferably 0.01M~0.19M, more preferably 0.05M~0.15M), and the pH is 0.5~2 (preferably pH=1.0~1.9, more preferably pH=1.8~1.9). The inorganic acid solution is one or more of nitric acid and hydrochloric acid, and its molar concentration is 0.01M~15.2M (preferably 1M~10M, more preferably 5M~8M). The crude Pb-212 sample was loaded into the second chromatographic column. Elute with 0.1M~0.3M (preferably 0.15M~0.25M, more preferably 0.18M~0.22M) organic acid (pH=1.0~2.8, preferably pH=1.5~2.8, more preferably pH=2.5~2.8) solution for 1BV~15BV (preferably 4BV~10BV, more preferably 6BV~9BV). Pb-212 is separated from other metal ion impurities by using a 0.3M~1.0M (preferably 0.3M~0.5M, more preferably 0.35M~0.45M) organic acid solution (pH=2.8~6.0, preferably pH=2.8~4.0, more preferably pH=2.8~3.0) as an eluent (1BV~10BV, preferably 2BV~8BV, more preferably 4BV~6BV).

6. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products according to claim 5, characterized in that, The eluent and eluting agent used in the two-dimensional purification separation are selected from α-hydroxyisobutyric acid and / or citric acid.

7. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter bodies according to claim 1 or 2, characterized in that, The specific operation of the three-dimensional concentration and salt conversion is as follows: The third chromatographic column was equilibrated using inorganic acid solution. A Pb-212 purification solution sample with pH < 2 (preferably pH = 0.5~1.5, more preferably pH = 1.0~1.2) was obtained by adjusting the pH with water and inorganic acid; The inorganic acid solution is one or more of nitric acid and hydrochloric acid, with a molar concentration of 0.01M to 15.20M (preferably 1M to 10M, more preferably 5M to 8M). The purified Pb-212 sample was loaded into the third chromatographic column, where Pb-212 was selectively adsorbed onto the third chromatographic column. A third chromatographic column is eluted with water or inorganic acid (the inorganic acid solution is one or more of nitric acid and hydrochloric acid, with a molar concentration of 0.01M~0.30M (preferably 0.05M~0.20M, more preferably 0.08M~0.12M) for 1 BV~30 BV, preferably 5 BV~20 BV, more preferably 8 BV~12 BV); Using one or more of the following: organic acid solution (0.001M~1.0M (preferably 0.05M~0.50M, more preferably 0.09M~0.11M) diammonium citrate (pH=2.0~7.0, preferably pH=3.0~6.0, more preferably pH=4.5~5.5), 0.1M~1.0M (preferably 0.2M~0.8M, more preferably 0.4M~0.6M) citric acid (pH=2.0~7.0, preferably pH=3.0~6.0, more preferably pH=4.5~5.5)) or inorganic acid solution (0.5M~10M) Using 1M to 6M (preferably 2M to 4M) as the eluent, Pb-212 is eluted from a third chromatographic column (1BV to 30BV, preferably 1BV to 20BV, more preferably 2BV to 5BV) to convert Pb-212 into citrate and / or chloride salts, resulting in high-purity, high-concentration Pb-212.

8. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter products according to claim 7, characterized in that, The eluent in the three-dimensional concentrated salt conversion is at least one or more of citric acid, hydrochloric acid, and diammonium citrate. The polymer microspheres coated with crown ether compounds are one or more of divinylbenzene-vinylbenzene copolymer microspheres or divinylbenzene-N-vinylpyrrolidone copolymer microspheres. The crown ether compounds are one or more of 15-crown ether-5, 18-crown ether-6, di-tert-butyldicyclohexyl-18-crown-6, di-tert-butyldicyclohexyl-15-crown ether-5, and di-tert-butyldiphenyl-18-crown-6. The coating amount is 50 mg / g to 300 mg / g. The polymer microspheres are one or more of divinylbenzene-vinylbenzene copolymer microspheres or divinylbenzene-N-vinylpyrrolidone copolymer microspheres. The particle size is 10 μm to 80 μm.

9. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter bodies according to claim 1, characterized in that, In step 1), one or more of Th-232 and its daughter products, or their salts, are dissolved in 0.01 M to 10 M (preferably 0.1 M to 5 M, more preferably 0.4 M to 1.0 M) of nitric acid to obtain a Th-232 acid solution. The concentration of Th-232 and its daughter products, or their salts, in the Th-232 acid solution is 0.1 kg / L to 1 kg / L (preferably 0.2 kg / L to 0.8 kg / L, more preferably 0.3 kg / L to 0.6 kg / L). The daughter organism is one or more of Ra-228, Th-228, and Ra-224.

10. The method for isolating and purifying medical-grade Pb-212 from natural Th-232 and its daughter bodies according to claim 1, characterized in that, Sodium iodide or zinc cadmium telluride energy dispersive counters are set up in the one-dimensional lead enrichment, two-dimensional purification and separation, and three-dimensional concentration and salt conversion processes for online detection of Pb-212.

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