Method for combined chemical separation and mass spectrometric measurement of plutonium and neptunium in urine

Abstract

The application relates to a combined chemical separation and mass spectrometric measurement analysis method of Pu and Np in urine. The application establishes a combined, sensitive and reliable analysis and measurement method of Pu and Np in large-volume urine by first co-precipitation and first organic matter digestion, first TK200 column separation and purification, second organic matter digestion and second co-precipitation, second TK200 column separation and purification, and ICP-MS / MS measurement of Pu and Np in the to-be-measured solution 242 Pu, 239 Pu, 240 Pu, 237 Np concentration, solves the problem of Pu and Np internal exposure dose monitoring of personnel, and establishes a combined, sensitive and reliable analysis and measurement method of Pu and Np in large-volume urine. The method provided by the application has been verified to be capable of successfully, reliably, stably and synchronously analyzing Pu and Np in samples. The application optimizes the digestion method of organic matter in urine, the removal method of interfering nuclides and the separation and purification method of chromatographic columns, can realize the ultra-sensitive measurement of Pu and Np by ICP-MS / MS, and obtains the ultra-low level ICP-MS / MS detection limit of Pu and Np in urine.

Description

Technical Field

[0001] The present invention belongs to the technical field of radioactive material analysis, and in particular relates to a combined chemical separation and mass spectrometry analysis method for Pu and Np in urine. Background Art

[0002] 237 Np(T 1 / 2 =2.144×10 6 years) and 239 / 240 Pu isotopes are long-lived α-decay nuclides with high chemical and radioactive toxicity. 239 Pu, 240 Pu and 241 Pu) and neptunium-237( 237 Np) can enter the human body through breathing, ingestion, wounds and other ingestion methods and be deposited in the respiratory tract, bones, liver and other parts, causing serious long-term internal radiation hazards. It is the most important source of occupational internal radiation for radiation workers and is also the focus of internal radiation dose monitoring for occupational workers. As a pure α or pure β radionuclide, the practical and feasible method for monitoring the exposed person in vivo is to detect Pu isotopes and 237 The radioactive activity of Np and the validity, reliability and accuracy of its monitoring results are important data support that affect the accurate evaluation of internal radiation dose and the urgent medical treatment required in accident conditions.

[0003] Based on the sensitivity and accuracy requirements for routine biological assessment methods based on a committed effective dose of 1 mSv in occupational exposure situations, as recommended by the International Commission on Radiological Protection (ICRP), the concentrations of neptunium-237 and plutonium isotopes in urine after human metabolism are extremely low. Currently, sensitive mass spectrometry is the only effective measurement method for routine analytical monitoring. Furthermore, because the excretion of ingested Pu and Np in urine after human metabolism is extremely low, and because the urine matrix is ​​extremely complex and high in organic components, more efficient radiochemical separation methods are still needed to effectively extract neptunium-237 and plutonium from samples and remove interfering matrix components. Summary of the Invention

[0004] In response to the defects existing in the prior art, the purpose of the present invention is to provide a combined chemical separation and mass spectrometry analysis method for Pu and Np in urine. By optimizing the digestion method of organic matter in urine, the removal method of interfering nuclides, and the separation and purification method of the chromatographic column, a test solution with high recovery rate and simple matrix is ​​obtained, and a combined, sensitive, and reliable analysis and measurement method for Pu and Np in large volumes of urine is established. The detection limit of Pu isotopes and Pu in urine is at the sub-femtogram level, which solves the problem of insufficient analytical sensitivity in personnel Pu and Np internal exposure dose monitoring.

[0005] To achieve the above objectives, the present invention adopts a technical solution: a combined chemical separation and mass spectrometry analysis method for Pu and Np in urine, comprising the following steps:

[0006] S1. First co-precipitation and first digestion of organic matter: Pu and Np in urine samples were enriched using a co-precipitant to obtain hydroxide precipitates, and then HNO3+H2O2 was used to digest the organic matter in the sample;

[0007] S2, primary TK200 column separation and purification to obtain primary Pu and Np samples;

[0008] S3, second digestion of organic matter and second co-precipitation;

[0009] S4, secondary TK200 column separation and purification to obtain Pu and Np test solutions;

[0010] S5, measuring the Pu and Np in the test solution by ICP-MS / MS 242 Pu, 239 Pu, 240 Pu, 237 Np concentration.

[0011] Furthermore, the first coprecipitation method comprises the following specific steps:

[0012] S111, accurately weigh the acidified urine sample, and add a certain amount of 242 Pu, stirred evenly to obtain a sample containing the tracer;

[0013] S112. Add coprecipitant TiCl3 to the sample containing the tracer and shake well. Then add concentrated NH4OH and shake well. Adjust the pH to 8. After standing for 10 minutes, centrifuge and discard the supernatant to obtain a hydroxide precipitate.

[0014] S113. Wash the hydroxide precipitate with ultrapure water, then centrifuge and discard the supernatant to obtain the washed hydroxide precipitate.

[0015] Furthermore, in the first co-precipitation method, the acidified urine sample is 1.0 to 1.6 L;

[0016] The coprecipitant is 3.0 to 6.0 mL of TiCl3;

[0017] The amount of concentrated NH4OH added is 10-40 mL.

[0018] Furthermore, the method for digesting organic matter for the first time comprises the following steps:

[0019] The washed hydroxide precipitate is dissolved with concentrated HNO 3 , and 30% H 2 O 2 is added to the dissolved solution, and the solution is digested on a hot plate set at a digestion temperature, and then cooled to obtain a first digestion solution.

[0020] Furthermore, in the method of digesting organic matter for the first time, the amount of concentrated HNO3 added is 10 to 30 mL, and the amount of 30% H2O2 added is 0.5 to 2 mL;

[0021] The set digestion temperature is 60-80° C., and the digestion time for the first organic matter digestion is 10-60 minutes.

[0022] Furthermore, before the first digestion solution is subjected to the first-level TK200 column separation and purification, the method further includes the following steps of preparing the sample matrix of the first digestion solution:

[0023] S131, adding concentrated NH4OH to the first digestion solution and shaking until the pH is adjusted to 8, standing for 10 minutes and then centrifuging to collect the first precipitate;

[0024] S132, washing the first precipitate with ultrapure water, then centrifuging, and collecting the washed first precipitate;

[0025] S133, dissolving the washed first precipitate with concentrated HNO3 and diluting it into an 8 mol / L HNO3 matrix; then adding 30% H2O2 and mixing it evenly, then adding 3 mol / L NaNO2 and stirring it evenly, and letting it stand for 10 minutes to obtain a first sample.

[0026] Furthermore, the primary TK200 column separation and purification method includes the following specific steps:

[0027] S21. Install TK200 resin, a syringe, a flow guide tube, and a centrifuge tube pretreated with 8 mol / L HNO3 + 0.02 mol / L NaNO2 solution on a vacuum box;

[0028] S22, transferring the first sample into the prepared syringe;

[0029] S23, after the first sample has completely passed through the TK200 resin, washing the TK200 resin with 8 mol / L HNO3+0.02 mol / L NaNO2 solution;

[0030] S24, drain the TK200 resin, replace the centrifuge tube to collect the effluent, and replace the new guide tube and syringe;

[0031] S25, eluting Th adsorbed on TK200 resin with 12 mol / L HCl + 0.01 mol / L NH2OH·HCl;

[0032] S26, drain the TK200 resin again, replace the centrifuge tube to collect the effluent, and replace the new guide tube and syringe;

[0033] S27. Use 0.1 mol / L HCl+0.05 mol / L HF+0.01 mol / L NH2OH·HCl at a flow rate of 1 mL / min to elute Pu and Np adsorbed on the TK200 resin to obtain the primary Pu and Np samples.

[0034] Furthermore, the method of the second organic matter digestion and the second co-precipitation comprises the following specific steps:

[0035] S31, second digestion of organic matter: adding concentrated HNO3 and 30% H2O2 to the first-level Pu and Np samples, digesting on a hot plate at a certain digestion temperature, and then cooling to obtain a second digestion solution;

[0036] S32, adding TiCl3 to the second digestion solution, shaking, then adding concentrated NH4OH and shaking until the pH is adjusted to 8, standing for 10 minutes and then centrifuging to collect the second precipitate;

[0037] S33, washing the second precipitate, and then centrifuging to collect the washed second precipitate;

[0038] S34. Dissolve the washed second precipitate with concentrated HNO3 and dilute it to 8 mol / L HNO3 matrix; then add 30% H2O2 and mix well, then add 3 mol / L NaNO2 and stir well, let it stand for 10 minutes to obtain a second sample.

[0039] Further, in step S34, the amount of concentrated HNO3 added is 5 to 10 mL;

[0040] The amount of 30% H2O2 added is 0.5-1 mL.

[0041] Further, in step S5, the Pu and Np contents in the test solution are measured by ICP-MS / MS. 242 Pu, 239 Pu, 240 Pu, 237 When the Np concentration was high, the high performance membrane desolvation nebulization injection system Apex Omega was used for injection.

[0042] The beneficial effects of the present invention are as follows: the combined chemical separation and mass spectrometry analysis method of Pu and Np in urine provided by the present invention can be carried out through the first coprecipitation and the first digestion of organic matter, the first-level TK200 column separation and purification, the second digestion of organic matter and the second coprecipitation, the second-level TK200 column separation and purification, and the ICP-MS / MS measurement of Pu and Np in the test solution. 242 Pu, 239 Pu, 240 Pu, 237 Np concentration, establish a combined, sensitive, and reliable analytical measurement method for Pu and Np in large volumes of urine, and solve the problem of instability and insufficient sensitivity of chemical separation methods in personnel Pu and Np internal exposure dose monitoring. Moreover, the method provided by the present invention is verified by urine spiked samples to be able to successfully, reliably, stably, and synchronously analyze Pu and Np in samples. By optimizing the digestion method of organic matter in urine, the removal method of interfering nuclides, and the separation and purification method of the chromatographic column, the present invention can achieve ultra-sensitive measurement of Pu and Np by ICP-MS / MS, and obtain ultra-low level ICP-MS / MS detection limits for Pu and Np in urine. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The figure is a flow chart of the combined chemical separation and mass spectrometry analysis method of Pu and Np in urine according to the present invention. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention will be further clearly and completely described below in conjunction with the drawings and examples. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] In the radiochemical analysis process, in order to ensure the accuracy of the analysis results of the nuclides to be tested, it is usually necessary to add appropriate isotopes as chemical recovery tracers before the chemical treatment of the sample to perform recovery correction on the analysis measurement results. 237 The lack of suitable commercial isotopic tracers for Np has resulted in the absence of a reliable and robust radiochemical separation method and measurement technique for the combined Pu and Np in urine. Based on the identical chemical behavior of Np and Pu on TK200 resin (TOPO), the inventors have developed a stable and reliable radiochemical separation method and measurement technique for the combined Pu and Np in occupational internal dose monitoring.

[0046] This embodiment provides a method for combined chemical separation and mass spectrometry analysis of Pu and Np in urine. The technical solution provided by the method can be used for sensitive analysis and measurement of low levels of Pu and Np in urine, and mainly includes the following inventive concepts:

[0047] 1. To obtain accurate 237 Np analyzed the data using 242 Pu is used as a common yield tracer for Pu and Np. Achieving consistent efficiency of Pu / Np during the separation and purification process is one of the key technologies used in the method.

[0048] 2. The inventors have discovered that urine typically contains a large amount of organic matter, urea. The degree of organic matter degradation will affect the ultrasensitive measurement of Pu and Np by ICP-MS / MS. Therefore, efficient degradation of organic matter is one of the main challenges addressed by the method of the present invention.

[0049] 3. In addition, in order to obtain ultra-low level ICP-MS / MS detection limits for Pu and Np in urine, the radiochemical separation and purification technology scheme provided by the method needs to efficiently remove impurity elements and key interfering nuclides in the sample matrix and obtain a high-purity test solution containing Pu and Np with a high recovery rate.

[0050] like Figure 1 As shown, an embodiment of the present invention provides a combined chemical separation and mass spectrometry analysis method for Pu and Np in urine, the method comprising the following steps:

[0051] S1. First coprecipitation and first digestion of organic matter: Pu and Np in urine samples were enriched with coprecipitants to obtain hydroxide precipitates, and then HNO3+H2O2 was used to digest the organic matter in the hydroxide precipitates;

[0052] The method for the first coprecipitation comprises the following specific steps:

[0053] S111, accurately weigh 1.0 to 1.6 L of an acidified urine sample (pH < 2), and add a certain amount of 242 Pu, stirred evenly to obtain a sample containing the tracer;

[0054] The acidified urine sample is a large-volume acidified urine sample (volume>1 L).

[0055] Specifically, the acidified urine sample is added 242 Pu is about 5pg.

[0056] S112. Add a coprecipitant to the sample containing the tracer and shake well. Then add concentrated NH4OH and shake well. Adjust the pH to 8. Let it stand for 10 minutes and then centrifuge. Discard the supernatant to obtain a hydroxide precipitate.

[0057] Specifically, the coprecipitant is 3.0 to 6.0 mL of TiCl 3 .

[0058] Specifically, in the first co-precipitation method, the amount of concentrated NH4OH added is 10 to 40 mL.

[0059] S113, washing the hydroxide precipitate, then centrifuging and discarding the supernatant to obtain the washed hydroxide precipitate.

[0060] Specifically, the hydroxide precipitate is washed with 30 to 50 mL of ultrapure water.

[0061] Optionally, the method for digesting organic matter for the first time comprises the following steps:

[0062] S121. Dissolve the washed hydroxide precipitate with concentrated HNO3, add 30% H2O2 to the solution, digest on a hot plate set at a digestion temperature, and then cool to obtain a first digestion solution.

[0063] Specifically, in the method of digesting organic matter for the first time, the amount of concentrated HNO3 added is 15-30 mL, and the amount of 30% H2O2 added is 0.5 mL.

[0064] When the first coprecipitation method (adding coprecipitant TiCl3 and concentrated NH4OH) is used to enrich the nuclides Pu and Np in the tracer sample to obtain hydroxide precipitation, the organic matter in the hydroxide precipitation is decomposed by using the HNO3+H2O2 digestion method. The oxidizing property of H2O2 can not only effectively decompose the organic matter, but also react with Ti 4+ Easy to form easily soluble complexes. 4+ Easily hydrolyzed to form TiO 2+ (titanium oxide ion), in acidic solution with pH < 1, it reacts with H2O2 to form a soluble orange-yellow [Ti(O2)(OH)] + However, under high temperature conditions, Ti will form a white TiO2 precipitate, which is both difficult to volatilize and insoluble in water. This will cause the co-precipitated actinides to be lost during the subsequent purification process on the chromatography column (TK200 resin). Therefore, this embodiment further studies the temperature control during the HNO3+H2O2 digestion of organic matter, ensuring both effective digestion of organic matter and preventing the formation of insoluble TiO2 substances, thereby ensuring the efficient separation and purification of actinide nuclides.

[0065] Optionally, in the method for digesting organic matter for the first time, the set digestion temperature is 60-80° C., and the digestion time for the first digestion of organic matter is 10-60 minutes.

[0066] Specifically, 8 portions of hydroxide precipitates obtained from 20 mL of acidified urine sample after the first coprecipitation were dissolved in concentrated nitric acid, and 0.5 mL of 30% H2O2 was added. Pu and Np in the urine were digested at different set digestion temperatures: 60°C (Examples 1 and 2), 80°C (Examples 3 and 4), 100°C (Examples 5 and 6), and 120°C (Example 7). After purification with TK200 resin under the same separation conditions, the chemical recoveries of Pu and Np were calculated. The results are shown in Table 1.

[0067] Table 1 Effect of different digestion temperatures on chemical recovery of Pu and Np

[0068]

[0069] As shown in Table 1, when the digestion temperature is between 60°C and 80°C, the recovery rate of Pu and Np is greater than 99%, indicating that Pu and Np are not significantly lost. When the digestion temperature is greater than 100°C, the recovery rate of Pu and Np is less than 80%, indicating that some Pu and Np are lost during digestion at temperatures greater than 100°C. Therefore, the digestion temperature must be strictly controlled between 60°C and 80°C.

[0070] Before the obtained first digestion solution is subjected to primary TK200 column separation and purification, a sample matrix of the first digestion solution needs to be prepared to obtain a first sample suitable for TK200 column separation. The preparation method of the first sample includes the following steps:

[0071] S131, adding concentrated NH4OH to the first digestion solution and shaking until the pH is adjusted to 8, letting it stand for 10 minutes and then centrifuging to collect the first precipitate;

[0072] Specifically, in the preparation method of the first sample, the amount of concentrated NH4OH added is 10 to 30 mL.

[0073] S132, washing the first precipitate, then centrifuging, and collecting the washed first precipitate;

[0074] Specifically, the first precipitate is washed with 30 to 50 mL of ultrapure water.

[0075] S133. Dissolve the washed first precipitate with concentrated HNO3 and dilute it to 8 mol / L HNO3 matrix; then add 30% H2O2 and mix well. The solution becomes clear and turns dark red. Then add 3 mol / L NaNO2 and stir well. Let it stand for 10 minutes to obtain the first sample.

[0076] Specifically, when dissolving the washed first precipitate, the amount of concentrated HNO3 added is 10-30 mL; the amount of 30% H2O2 added is 0.5-2 mL; and the amount of 3 mol / L NaNO2 added is 0.2-0.5 mL.

[0077] S2, separation and purification using a primary TK200 column to obtain primary Pu and Np samples; including the following specific steps:

[0078] S21. Install TK200 resin pretreated with 15 mL of 8 mol / L HNO3 + 0.02 mol / L NaNO2 solution, a 50 mL syringe, white and yellow flow tubes, and a 50 mL centrifuge tube on the vacuum box;

[0079] S22, transferring the first sample into the prepared 50 mL syringe;

[0080] S23. After the first sample has completely passed through the TK200 resin, wash the TK200 resin with 15-30 mL of 8 mol / L HNO3 + 0.02 mol / L NaNO2 solution to elute the remaining sample matrix;

[0081] S24, drain the TK200 resin, replace the effluent with a new 50 mL centrifuge tube, and replace the new flow tube and syringe;

[0082] S25, elute Th adsorbed on TK200 resin with 15-40 mL of 12 mol / L HCl + 0.01 mol / L NH2OH·HCl;

[0083] S26. Drain the TK200 resin again, replace the effluent with a new 50 mL centrifuge tube, and replace the new flow tube and syringe.

[0084] S27. Use 15-40 mL of 0.1 mol / L HCl + 0.05 mol / L HF + 0.01 mol / L NH2OH·HCl at a flow rate of 1 mL / min to elute Pu and Np adsorbed on the TK200 resin to obtain a primary Pu and Np sample.

[0085] The average daily urine volume of an adult is 1400 mL, of which the content of uric acid is about 0.6 g and the content of urea is about 25.5 g. Uric acid is the main end product of nitrogenous substance (protein) metabolism. Under strong acid conditions, H2O2 has a good digestion effect on organic matter. However, since the present embodiment adopts the coprecipitant TiCl3 to carry out the first coprecipitation, in order to avoid the production of insoluble TiO2 and the loss of Pu / Np, the temperature and time of digestion need to be strictly controlled during the first digestion process. However, during the experiment of this embodiment, it was found that if only the first organic matter digestion and the first-level TK200 resin chromatography column separation and purification were performed, the obtained first-level Pu and Np samples contained a large amount of organic foam. The small amount of organic matter present during ICP-MS / MS measurement caused the measurement sensitivity to decrease by at least 3 times, and a layer of oily substance accumulated on the injection cone. The detection limit obtained was more than 10 times that of the reagent process (the reagent process refers to the replacement of urine in the sample with ultrapure water, and the first co-precipitation, first organic matter digestion, and first-level TK200 resin chromatography column separation and purification process provided in this embodiment under the same experimental conditions).

[0086] Therefore, this embodiment targets large-volume acidified urine samples (>1 L). After the initial coprecipitation, a first organic matter digestion with HNO3 and H2O2 is performed, followed by separation and purification using a primary TK200 chromatography column. Concentrated HNO3 and H2O2 are then added to the resulting primary Pu and Np samples, followed by a second high-temperature digestion to remove organic matter. Purification is then performed using a secondary TK200 chromatography column, ultimately yielding a high-purity Pu and Np test solution.

[0087] S3, second digestion of organic matter and second co-precipitation, including the following specific steps:

[0088] S31. Second digestion of organic matter: Add concentrated HNO3 and 30% H2O2 to the first-level Pu and Np samples, digest on a hot plate at a certain digestion temperature, and then cool to obtain the second digestion solution;

[0089] Specifically, during the second digestion of organic matter, the amount of concentrated HNO3 added is 15-30 mL, and the amount of 30% H2O2 added is 0.5-2 mL.

[0090] Specifically, during the second digestion of organic matter, the certain digestion temperature is 60 to 80° C., and the second digestion time of the organic matter is 10 to 60 minutes.

[0091] S32. Add 1-3 mL of TiCl3 to the second digestion solution, shake well, then add 10-30 mL of concentrated NH4OH and shake well until the pH is adjusted to 8. Let stand for 10 minutes and then centrifuge to collect the second precipitate;

[0092] S33, washing the second precipitate, then centrifuging to collect the washed second precipitate;

[0093] Specifically, the second precipitate is washed with 30 to 50 mL of ultrapure water.

[0094] S34. Dissolve the washed second precipitate with concentrated HNO3 and dilute it to 8 mol / L HNO3 matrix; then add 30% H2O2 and mix well. The solution becomes clear and turns dark red. Then add 3 mol / L NaNO2 and stir well. Let it stand for 10 minutes to obtain the second sample.

[0095] Specifically, when using concentrated HNO3 to dissolve the washed second precipitate, the amount of concentrated HNO3 added is 5-10 mL; the amount of 30% H2O2 added is 0.5-1 mL; and the amount of 3 mol / LNaNO2 added is 0.1-0.3 mL.

[0096] S4, secondary TK200 column separation and purification; including the following specific steps:

[0097] S41. Install TK200 resin pretreated with 5-10 mL of 8 mol / L HNO3 + 0.02 mol / L NaNO2 solution, a 30 mL syringe, white and yellow flow tubes, and a 50 mL centrifuge tube on the vacuum box;

[0098] S42, transferring the second sample into the prepared 30 mL syringe;

[0099] S43. After the second sample has completely passed through the TK200 resin, 10 to 15 mL of 8 mol / L HNO3 + 0.02 mol / L NaNO2 solution is used to wash the TK200 resin to elute the residual sample matrix;

[0100] S44, drain the TK200 resin, replace the effluent with a new 50 mL centrifuge tube, and replace the flow tube and syringe;

[0101] S45. Elute Th adsorbed on the TK200 resin with 10-15 mL of 12 mol / L HCl + 0.01 mol / L NH2OH·HCl;

[0102] S46. Drain the TK200 resin again, replace the effluent with a new 50 mL centrifuge tube, and replace the flow tube and syringe.

[0103] S47. Use 5-10 mL of 0.1 mol / L HCl + 0.05 mol / L HF + 0.01 mol / L NH2OH·HCl at a flow rate of 1 mL / min to elute Pu and Np adsorbed on the TK200 resin to obtain Pu and Np test solutions.

[0104] S5. Measure the Pu and Np contents in the test solution by ICP-MS / MS. 242 Pu, 239 Pu, 240 Pu, 237 Np concentration.

[0105] Specifically, in step S5, the Pu and Np contents in the test solution are measured by ICP-MS / MS. 242 Pu, 239 Pu, 240 Pu, 237 When the Np concentration was high, the high performance membrane desolvation nebulization injection system Apex Omega was used for injection.

[0106] Verification Example 1

[0107] In order to verify the separation efficiency of the method provided by the embodiment of the present invention, 5 pg of 242 Pu tracer, using the combined chemical separation and purification of Pu and Np in urine provided by this embodiment, and using ICP-MS / MS measurement to obtain 239 Pu, 240 Pu, 237 The detection limits of Np were 0.8 fg (0.0018 mBq), 0.3 fg (0.0084 mBq) and 0.7 fg (0.00002 mBq) respectively. This is lower than the concentration of Np excreted in human urine after 180 days when occupational personnel ingested and caused an accumulated effective dose of 1 mSv in routine monitoring ( 239 Pu (0.019 mBq), 240 Pu (0.019 mBq) and 237 Np (0.15mBq)) is low, meeting the detection limit requirements for internal radiation dose monitoring of occupational personnel.

[0108] Verification Example 2

[0109] Since the ng-level U and Th in urine will affect the ICP-MS / MS measurement of ultra-low levels of Pu and Np in urine, it is necessary to confirm the removal of U and Th in urine by the chemical separation method used before the sample measurement. In this embodiment, in order to verify the decontamination factor of TK200 resin for U and Th, 20mL of urine was configured into an 8mol / L HNO3-0.02mol / L NaNO2 system, and 100μg of U and 100μg of Th were added thereto. After the above urine was separated and purified by TK200 resin column, the concentrations of U and Th in 10mlPu and Np eluent (0.1mol / L HCl+0.01mol / L HF+0.1mol / L NH2OH) were measured using ICP-MS / MS, and the decontamination factor D for U was calculated. w (U) is 9.1×10 4 , the decontamination factor for Th is D w (Th) is 4.2×10 4 By adopting two-stage purification, the above-mentioned U and Th removal factors can meet the requirements for the removal of U and Th in urine samples.

[0110] Verification Example 3

[0111] In order to verify the accuracy of the analytical results obtained by the method provided in this embodiment, a tracer was added to three 1.0L acidified urine samples. 242 Pu, a certain amount 239 Pu and 237 Np, and marked as Verification Example 3-1, Verification Example 3-2, Verification Example 3-3, respectively, the method provided in this embodiment was used to measure and analyze the above three spiked urine samples. 239 Pu and 237 Np content. Based on tracer 242 The amount of Pu added and the final concentration measured by ICP-MS / MS can be used to calculate the concentration of Pu in the three spiked urine samples. 239 Pu and 237 The chemical recovery of Np and the analysis results are shown in Table 2. The results show that 242 The recovery rate of Pu is >70%, 239 Pu and 237 The added amount of Np was consistent with the measured value, with a deviation below ±10%, indicating that the method provided in this embodiment can successfully, reliably, stably and synchronously analyze Pu and Np in urine samples.

[0112] Table 2 Spiked urine samples 239 Pu and 237 Analysis results of Np

[0113]

[0114] The methods described herein are not limited to the specific embodiments described. The above embodiments are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or in other specific forms without departing from the gist or essential characteristics of the present invention. Therefore, the embodiments described herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is to be determined by the appended claims, and any variations that are equivalent to the intent and scope of the claims are intended to be within the scope of the present invention.

Claims

1. A combined chemical separation and mass spectrometry analysis method for Pu and Np in urine, characterized in that: The steps include: S1. First coprecipitation and first digestion of organic matter: Pu and Np in the urine sample are enriched using a coprecipitant to obtain a hydroxide precipitate, and then HNO3+H2O2 is used to digest the organic matter in the sample; the coprecipitant is 3.0-6.0 mL of TiCl3; The method for digesting organic matter for the first time comprises the following steps: Dissolve the washed hydroxide precipitate with concentrated HNO3 and add 30% H2O2 is digested on a hot plate at a set digestion temperature, and then cooled to obtain a first digestion solution; the set digestion temperature is 60-80°C; S2, primary TK200 column separation and purification to obtain primary Pu and Np samples; S3, second digestion of organic matter and second co-precipitation; S4, secondary TK200 column separation and purification to obtain Pu and Np test solutions; S5, measuring the Pu and Np in the test solution by ICP-MS / MS 242 Pu, 239 Pu, 240 Pu, 237 Np concentration.

2. The combined chemical separation and mass spectrometry analysis method for Pu and Np in urine according to claim 1, characterized in that: The method for the first coprecipitation comprises the following specific steps: S111, accurately weigh the acidified urine sample, and add a certain amount of 242 Pu, stirred evenly to obtain a sample containing the tracer; S112. Add coprecipitant TiCl3 to the sample containing the tracer and shake well. Then add concentrated NH4OH and shake well. Adjust the pH to 8. After standing for 10 minutes, centrifuge and discard the supernatant to obtain a hydroxide precipitate. S113. Wash the hydroxide precipitate with ultrapure water, then centrifuge and discard the supernatant to obtain the washed hydroxide precipitate.

3. The combined chemical separation and mass spectrometry analysis method for Pu and Np in urine according to claim 2, characterized in that: In the first co-precipitation method, the acidified urine sample is 1.0 to 1.6 L; The amount of concentrated NH4OH added is 10-40 mL.

4. The method for combined chemical separation and mass spectrometry analysis of Pu and Np in urine according to claim 1, characterized in that: In the method of digesting organic matter for the first time, the amount of concentrated HNO3 added is 10 to 30 mL, and the amount of 30% H2O2 added is 0.5 to 2 mL; The digestion time of the first organic matter digestion is 10 to 60 minutes.

5. The combined chemical separation and mass spectrometry analysis method for Pu and Np in urine according to claim 1, characterized in that: Before the first digestion solution is subjected to the first-level TK200 column separation and purification, the method further includes the following steps of preparing a sample matrix of the first digestion solution: S131, adding concentrated NH4OH to the first digestion solution and shaking until the pH is adjusted to 8, standing for 10 minutes and then centrifuging to collect the first precipitate; S132, washing the first precipitate with ultrapure water, then centrifuging, and collecting the washed first precipitate; S133, dissolving the washed first precipitate with concentrated HNO3 and diluting it into an 8 mol / L HNO3 matrix; then adding 30% H2O2 and mixing it evenly, then adding 3 mol / L NaNO2 and stirring it evenly, and letting it stand for 10 minutes to obtain a first sample.

6. The combined chemical separation and mass spectrometry analysis method for Pu and Np in urine according to claim 5, characterized in that: The method of separation and purification using a primary TK200 column comprises the following specific steps: S21. Install TK200 resin, a syringe, a flow guide tube, and a centrifuge tube pretreated with 8 mol / L HNO3 + 0.02 mol / L NaNO2 solution on a vacuum box; S22, transferring the first sample into the prepared syringe; S23, after the first sample has completely passed through the TK200 resin, washing the TK200 resin with 8 mol / L HNO3+0.02 mol / L NaNO2 solution; S24, drain the TK200 resin, replace the centrifuge tube to collect the effluent, and replace the new guide tube and syringe; S25, eluting Th adsorbed on TK200 resin with 12 mol / L HCl + 0.01 mol / L NH2OH·HCl; S26, drain the TK200 resin again, replace the centrifuge tube to collect the effluent, and replace the new guide tube and syringe; S27. Use 0.1 mol / L HCl+0.05 mol / L HF+0.01 mol / L NH2OH·HCl at a flow rate of 1 mL / min to elute Pu and Np adsorbed on the TK200 resin to obtain the primary Pu and Np samples.

7. The method for combined chemical separation and mass spectrometry analysis of Pu and Np in urine according to claim 1, characterized in that: The method for the second organic matter digestion and the second co-precipitation comprises the following specific steps: S31, second digestion of organic matter: adding concentrated HNO3 and 30% H2O2 to the first-level Pu and Np samples, digesting on a hot plate at a certain digestion temperature, and then cooling to obtain a second digestion solution; S32, adding TiCl3 to the second digestion solution, shaking, then adding concentrated NH4OH and shaking until the pH is adjusted to 8, standing for 10 minutes and then centrifuging to collect the second precipitate; S33, washing the second precipitate, and then centrifuging to collect the washed second precipitate; S34. Dissolve the washed second precipitate with concentrated HNO3 and dilute it to 8 mol / L HNO3 matrix; then add 30% H2O2 and mix well, then add 3 mol / L NaNO2 and stir well, let it stand for 10 minutes to obtain a second sample.

8. The method for combined chemical separation and mass spectrometry analysis of Pu and Np in urine according to claim 7, characterized in that: In step S34, the amount of concentrated HNO3 added is 5 to 10 mL; The amount of 30% H2O2 added is 0.5-1 mL.

9. The method for combined chemical separation and mass spectrometry analysis of Pu and Np in urine according to claim 1, characterized in that: In step S5, the Pu and Np contents in the test solution are measured by ICP-MS / MS. 242 Pu, 239 Pu, 240 Pu, 237 When the Np concentration was high, the high performance membrane desolvation nebulization injection system Apex Omega was used for injection.

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