Analysis method of 237Np in excrement sample

Abstract

The invention provides a method for analyzing 237Np in a feces sample. The method comprises the following steps: drying the feces sample; carrying out heat treatment on the dried excrement sample; washing and drying the manure sample subjected to heat treatment by distillation; carrying out dissolution and oxidation reduction treatment on the evaporated excrement sample; separating and purifying the excrement sample subjected to oxidation-reduction treatment; and performing 237Np content analysis on the separated and purified excrement sample. According to the method disclosed by the invention, the chemical recovery rate of 237Np is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of radionuclide analysis, and specifically relates to 237 Analysis method of Np. Background Art

[0002] 237 neptunium( 237 Np) is a radioactive isotope, one of the actinide elements, which mainly undergoes alpha decay; its half-life is 2.14 million years, so it is relatively stable in the environment, and its main source is the release of nuclear reactors or radioactive waste. Due to long-term radioactivity and impact on the environment, 237 Np has attracted widespread attention. 237 Np can spread in the air, soil, water and organisms, accumulate through the food chain, and eventually enter the human or animal body. It will be deposited in the bones and liver, causing radiation damage to the organs and possibly causing cancer.

[0003] part 237 After being absorbed by the human body, Np is excreted in the form of urine and feces. 237 Np, can estimate the exposure dose and thus assess the potential risk to health. Currently, high-sensitivity instruments such as inductively coupled plasma mass spectrometers (ICP-MS) or alpha spectrometers are usually used to detect lower concentrations of radioactive isotopes.

[0004] However, it is difficult to directly analyze fecal samples because the matrix composition is very complex and variable. 237 Np content. Summary of the invention

[0005] In view of this, the main purpose of the present invention is to provide 237 The analytical method of Np can effectively separate it from fecal samples 237 Np, which can effectively analyze the 237 Np content.

[0006] To achieve the above object, the present invention provides 237 The method for analyzing Np includes the following operations:

[0007] drying the fecal sample;

[0008] Heat treatment of dried fecal samples;

[0009] The heat-treated fecal samples were washed and evaporated to dryness;

[0010] The evaporated fecal samples were dissolved and redox treated;

[0011] Separating and purifying the redox-treated fecal sample; and

[0012] The purified fecal samples were 237 Np content analysis.

[0013] In some embodiments, the heat treatment includes: performing a first heat treatment on the dried fecal sample; performing a second heat treatment on the fecal sample that has been subjected to the first heat treatment; and performing a third heat treatment on the fecal sample that has been subjected to the second heat treatment. In some embodiments, the first heat treatment is performed at a temperature of 200°C to 400°C. In one embodiment, the first heat treatment is performed at 300°C. In some embodiments, the second heat treatment is performed at a temperature of 500°C to 600°C. In one embodiment, the second heat treatment is performed at 600°C. In some embodiments, the third heat treatment is performed at 80°C.

[0014] In some embodiments, the third heat treatment comprises: dissolving the second heat-treated fecal sample in aqua regia at room temperature, and then heating at 80° C. for 5 hours.

[0015] In some embodiments, the drying is performed at a temperature of 200° C. In some embodiments, during the drying, 242 Pu tracer.

[0016] In some embodiments, 3 mol / L HNO 3 The solution was washed, centrifuged, and the supernatant was taken and then treated with 3 mol / L HNO 3 The precipitate is washed with a solution to obtain a washing solution; the supernatant and the washing solution are combined and then evaporated to dryness. In some embodiments, the precipitate is washed repeatedly 2 to 4 times.

[0017] In some embodiments, 20 mL of 3 mol / L to 5 mol / L HNO 3 In one embodiment, 3 mol / L HNO 3 solution to effect said dissolution.

[0018] In some embodiments, the redox is performed by adding a redox agent, wherein the redox agent comprises Fe(NH 2 SO 3 ) 2 and NaNO 2 .

[0019] In some embodiments, the separation and purification is performed by a TEVA extraction chromatography resin column. In some embodiments, the separation and purification comprises using 20 mL of 3 mol / L HNO 3The TEVA resin was pretreated with the solution, the fecal sample after redox treatment was loaded onto the column, and then 8 mol / L HNO 3 In some embodiments, the separation and purification comprises desorption with 15 mL of a desorption solution of 0.1 mol / L HCl-0.05 mol / L HF.

[0020] In some embodiments, the 237 Np content analysis was performed by ICP-MS. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart of a method according to an embodiment of the present application is shown.

[0022] Figure 2 A picture of the fecal sample after calcination in Example 1 is shown.

[0023] Figure 3 A bar graph showing the nuclide chemical recovery in Example 1.

[0024] Figure 4 A bar graph showing the nuclide chemical recovery in Example 2.

[0025] Figure 5 A bar graph showing the nuclide chemical recovery in Example 3.

[0026] Figure 6 The device for separation and purification in the present application is shown, which is equipped with TEVA resin.

[0027] Figure 7 A graph of the chemical recovery data of cumulative desorption volume in Example 4 is shown.

[0028] Figure 8 The graph shows the chemical recovery rate data of nuclides obtained from the reproducible analysis performed in Example 5 (No. 0 is a blank sample). DETAILED DESCRIPTION

[0029] The following specific embodiments are discussed in conjunction with the accompanying drawings to exemplary embodiments. The specific embodiments included herein should not be construed as limitations of the present invention. Further, although specific language may be used to describe features, actions and / or structures in the embodiments described herein, the claims are not limited to the described features, actions and / or structures. It will be appreciated by those skilled in the art that other embodiments including improvements are within the spirit and scope of the present invention.

[0030] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0031] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the invention belongs.

[0032] The method of internal radiation monitoring and assessment is mainly through the processing and measurement of excreta such as urine and feces, which is characterized by high sensitivity. 237 The concentration of Np in the environment and biological samples is very low, so the sensitivity and accuracy of detection technology become the key to research. More specifically, 237 When Np is excreted from the body in the form of urine and feces, the content in the excreta is extremely low. In addition, due to differences in dietary structure, and the type of diet each person eats will also change over time, which makes the matrix composition of fecal samples very complex and variable, thus increasing the 237 The difficulty of Np analysis.

[0033] Reference Figure 1 , the method proposed in this application includes:

[0034] S1: Dry the stool sample;

[0035] S2: heat treatment of the dried fecal sample;

[0036] S3: Wash and evaporate the heat-treated fecal sample;

[0037] S4: dissolving and redox treating the evaporated fecal sample;

[0038] S5: separating and purifying the redox-treated fecal sample; and

[0039] S6: The separated and purified fecal samples were 237 Np content analysis.

[0040] In this application, a method for efficient analysis of fecal samples was established. By conducting a full-process experiment on fecal samples, it is possible to establish 237 The analytical monitoring process of Np was carried out, thereby achieving a chemical recovery rate of up to 79.07%. On this basis, it should be understood that the method provided in this application can be used to separate 237 Np method, or can also be used to recover fecal samples 237 Np's method.

[0041] The method of the present application will be described in detail below.

[0042] In the present application, the fecal sample is dried at 200° C. In this operation, if the temperature is too high, the fecal sample will volatilize too much organic matter, which will cause excessive odor in an open instrument such as an electric furnace used for drying, affecting the environment and operators; if the temperature is too low, the purpose of heating and drying cannot be achieved.

[0043] During the drying step, in order to facilitate subsequent detection, 242 Pu tracer. Optionally, add 242 The radioactivity of Pu standard solution is 2.68Bg / L.

[0044] In the present application, the heat treatment S2 may include three sub-steps, namely, a first heat treatment S2a, a second heat treatment S2b and a third heat treatment S2c.

[0045] In the present application, the first heat treatment S2a is performed at a temperature of 200° C. to 400° C., such as 300° C., to remove organic matter in the fecal sample, thereby reducing the impact of organic matter on the analysis process. In a specific embodiment, the first heat treatment can be performed on the sample at 300° C. in a carbonization and ashing integrated furnace.

[0046] The second heat treatment S2b is performed at a temperature of 500° C. to 600° C., such as 600° C. Specifically, the second heat treatment S2b is a calcination step, for example, performed in a muffle furnace, to further reduce the presence of moisture and volatiles, so that the organic matter in the fecal sample is thermally decomposed or converted into carbides, carbon dioxide or other gases, water vapor, etc., while improving the stability of the valence state of the metal oxide.

[0047] Through the first heat treatment and the second heat treatment, the volatile substances in the sample can be further reduced, and the valence state of the substances in the sample can be stabilized, which is beneficial to the subsequent analysis process. In a specific embodiment, the sample can be calcined at 600° C. in a muffle furnace.

[0048] In the present application, the third heat treatment S2c is performed by aqua regia. The term "aqua regia" has a meaning known to those skilled in the art, and refers to concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO 3 ) is a mixture composed of 3:1 by volume.

[0049] Further, the third heat treatment S2c includes dissolving the fecal sample subjected to the second heat treatment in aqua regia at room temperature, and then heating at 80°C for 5 hours to fully dissolve the solid oxides in the fecal sample so that the elements therein are present in the aqua regia solution in the form of ions as much as possible, so as to remove the solid oxides contained therein. 237 Np and 242 Pu is completely released.

[0050] Subsequently, the heat-treated fecal samples were washed and evaporated to dryness. S3 included: 3 The solution was washed and then centrifuged, the supernatant was taken and then washed with 3 mol / L HNO 3 The precipitate is washed with a solution to obtain a washing solution, the supernatant and the washing solution are combined and then evaporated to dryness.

[0051] In some embodiments, washing of the precipitate is repeated 2 to 4 times to reduce 237 Np and 242 The loss of Pu during centrifugation causes 237 Np and 242 Pu enters the solution system, and then is combined with the supernatant and evaporated to dryness. In this application, the process of evaporation-dissolution-evaporation can effectively remove the influencing factors in the fecal sample. 237 Impurities in Np.

[0052] In the present application, 3 mol / L to 5 mol / L, especially 3 mol / L mol / L HNO 3 The solution is used to dissolve the evaporated sample to facilitate oxidation-reduction of the sample.

[0053] In a solution system, the sample is subjected to redox treatment. Redox agents commonly used in the art can be used, such as Fe(NH 2 SO 3 ) 2 and NaNO 2 Using Fe(NH 2 SO 3 ) 2 and NaNO 2 Together they act as redox agents, thus converting Np and Pu in fecal samples into Np(IV) and Pu(IV), which is beneficial for separating them from complex systems. For example, Np(IV) and Pu(IV) can be better adsorbed onto TEVA resin, thereby achieving their separation.

[0054] In the separation and purification of S5, TEVA extraction chromatography resin column can be used to extract 237 Np is separated and purified. The "TEVA extraction chromatographic resin column" is an extraction resin column with a quaternary ammonium salt as an extractant. The separation and purification S5 generally includes: S5a, using 3 mol / L HNO 3 The TEVA resin was activated and pretreated with 8 mol / L HNO 3 Elution was performed to remove uranium (U), and then elution was performed with 9 mol / L HCl to remove thorium (Th); S5c, Np and Pu were desorbed from the TEVA resin using a low concentration mixed acid of 0.1 mol / L HCl-0.05 mol / L HF.

[0055] In this operation, 3 mol / L HNO 3 The solution was used to wash the container containing the sample several times to reduce the loss of Np and Pu, and the washing solution was transferred to the resin column.

[0056] In this operation, 3 mol / L HNO 3 The solution was separated by column, at which time the distribution coefficient of TEVA resin for Np(IV) and Pu(IV) reached the maximum (K' was 10 3 Up to 10 4 ), and the distribution coefficient for U is K'<10. Therefore, at this time, the TEVA resin has the strongest adsorption capacity for Np(IV) and Pu(IV), while the adsorption capacity for U is relatively weak, so that the heterometallic ions in the sample can be washed away by a higher concentration of acid, and as the acidity decreases, the distribution coefficients of Np(IV) and Pu(IV) also decrease rapidly (K'<10), and then the low concentration mixed acid of the present invention can be used to desorb Np and Pu from the TEVA resin. Therefore, the TEVA extraction chromatographic resin column used in the present invention can effectively separate and purify fecal samples. 237 Np, thereby increasing the extraction rate.

[0057] In the content analysis operation, it is performed by ICP-MS. "ICP-MS" is an analytical instrument that combines inductively coupled plasma (ICP) technology and mass spectrometry, and has high sensitivity.

[0058] The present invention is described in more detail below by examples. It should be understood that the examples described below are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially. The chemical reagents and drugs used in the examples are all of high grade purity.

[0059] Example 1: Effect of calcination temperature on recovery rate

[0060] Experiment 1.1

[0061] S1: Add 2.68mBq to 1g of fecal sample 242 The Pu tracer was then dried in an electric furnace at 200 °C for 6 h.

[0062] S2a: The sample obtained from S1 was placed in a carbonization-ashing integrated furnace and calcined at 300°C for 6 hours.

[0063] S2b: After taking the sample out of the carbonization and ashing furnace, place it in a muffle furnace and calcine it at 400° C. for 2 hours.

[0064] S2c: The calcined sample was taken out from the muffle furnace and placed in a beaker, and then 12 mL of aqua regia was added. The beaker was then placed in an electric furnace and heated at 80° C. for 5 hours for thermal digestion.

[0065] S3: Then add 24mL of deionized water to the beaker for dilution to ensure safe operation of the staff, and then centrifuge at 8000rpm for 3 minutes in a high-speed centrifuge to remove the supernatant.

[0066] Then, 3 mol / L HNO 3 The precipitate was repeatedly washed with the solution and combined with the supernatant to reduce 237 Np and 242 Loss of Pu during centrifugation. Subsequently, the resulting solution was evaporated to dryness.

[0067] S4: Use 20mL of 3mol / L HNO 3 The evaporated sample was dissolved in a solution, and then 100 μL of 0.05 mol / LFe (NH 2 SO 3 ) 2 and 100 μL of 4 mol / L NaNO 2 , so that Np and Pu in the fecal sample are adjusted to Np(IV) and Pu(IV), thereby obtaining the column sample.

[0068] S5: Use 20mL 3mol / L HNO3 For example Figure 6 The TEVA extraction chromatography resin column shown in FIG. 1 (the particle size of the TEVA resin is 100 to 150 μm, the inner diameter of the column is 5 mm, and the column height is 20 mm) was activated and pretreated, and then the upper column sample in S4 was transferred to the resin column; then 15 mL of 3 mol / L HNO 3 The beaker containing the sample was washed several times to reduce the loss of Np and Pu, and the washing solution was transferred to the resin column; then, the flow rate was adjusted to 0.5 mL / min, and 20 mL of 8 mol / L HNO 3 Rinse to remove U, and rinse to remove Th with 20mL 9mol / L HCl to reduce the content of impurities in the feces sample; finally, use 15mL 0.1mol / L HCl-0.05mol / L HF low-concentration mixed acid to desorb Np and Pu from TEVA resin to obtain 15mL containing 237 Np and 242 The Pu desorption solution was concentrated and evaporated to dryness, and then washed with 3 mL of 2% HNO 3 dilution.

[0069] S6: Then ICP-MS was used to analyze the 237 Np and 242 The Pu solution was analyzed and calculated to obtain 237 Chemical recovery of Np.

[0070] Experiments 1.2 to 1.7

[0071] Each experiment was conducted in the same manner as in Example 1, except that in S2b, the sample obtained from S2a was calcined in a muffle furnace at 500° C., 600° C., 700° C., 800° C., 900° C. and 1000° C. for 2 hours.

[0072] In Example 1, when the calcined samples were taken out from the muffle furnace, the morphology of each sample was observed and photographed. The results are shown in Figure 2 In. By Figure 2 It can be seen that as the calcination temperature increases, the color of the obtained sample gradually changes from black to white, indicating that within the temperature range of this application, the organic matter in the feces sample is carbonized, and in the process of heating, it gradually changes from carbon material to gases such as carbon dioxide, leaving the sample and becoming ash.

[0073] In addition, after ICP-MS measurement, we get 237 Np chemical recovery rate. In experiments 1.1 to 1.7, three repeated experiments were performed and the average values ​​were taken. The results are shown in Figure 3 middle.

[0074] Depend on Figure 3It can be seen that with the increase of calcination temperature, 237 The chemical recovery rate of Np gradually increased, then decreased, and finally stabilized. The chemical recovery rate reached the maximum when the calcination temperature was 600°C. It is speculated that the chemical recovery rate of the sample decreased again when the temperature continued to increase. This may be because the excessively high temperature may cause the fecal sample to form refractory particles and fail to effectively leach the target elements.

[0075] Example 2: Effect of redox agent on recovery rate

[0076] Experiment 2.1

[0077] S1: Add 0.889 mBq of 237 Np and 2.68mBq 242 The Pu tracer was then dried in an electric furnace at 200 °C for 6 h.

[0078] Then, the operations from S2a to S6 were performed in the same manner as in Experiment 1.3.

[0079] Experiment 2.2

[0080] Except in S4, no Fe(NH 2 SO 3 ) 2 and NaNO 2 , except that, this experiment was carried out in the same way as Experiment 2.1.

[0081] Experiment 2.3

[0082] In addition to S4, only 100 μL of 0.05 mol / L Fe(NH 2 SO 3 ) 2 Otherwise, this experiment was conducted in the same manner as Experiment 2.1.

[0083] After ICP-MS measurement, we can get 237 The chemical recovery of Np was calculated by ICP-MS after three repeated experiments. The average value was obtained and the results are shown in Figure 4 middle.

[0084] Depend on Figure 4 It can be seen that when no redox agent Fe(NH 2 SO 3 ) 2 and NaNO 2 When 237 Np and 242 The chemical recovery rate of Pu was the lowest, while Fe(NH 2 SO 3 ) 2 and NaNO2 When both Fe(NH 2 SO 3 ) 2 Its chemical recovery rate is only at a medium level compared with the other two. 2 SO 3 ) 2 Np(V) in the solution can be oxidized to Np(IV), and then the added NaNO 2 It can ensure that Pu in the solution is completely converted into Pu(IV), so that they can be better adsorbed on TEVA resin, reduce sample loss and improve chemical recovery rate.

[0085] Example 3: Effect of column acidity on recovery

[0086] Experiment 3.1

[0087] In addition to S4, 1 mol / L HNO 3 This example was carried out in the same manner as Experiment 2.1 except that the solution dissolved the sample.

[0088] Experiment 3.2

[0089] In addition to S4, 2 mol / L HNO 3 This example was carried out in the same manner as Experiment 3.1 except that the solution dissolved the sample.

[0090] Experiment 3.3

[0091] In addition to S4, 3 mol / L HNO 3 This example was carried out in the same manner as Experiment 3.2 except that the solution dissolved the sample.

[0092] Experiment 3.4

[0093] In addition to S4, 4 mol / L HNO 3 This example was carried out in the same manner as Experiment 3.3 except that the solution dissolved the sample.

[0094] Experiment 3.5

[0095] In addition to S4, 5 mol / L HNO 3 This example was carried out in the same manner as Experiment 3.4 except that the solution dissolved the sample.

[0096] After ICP-MS measurement, we can get 237 The chemical recovery of Np was calculated by ICP-MS after three repeated experiments. The average value was obtained and the results are shown in Figure 5 middle.

[0097] Depend on Figure 5 It can be seen that in HNO 3 When the concentration ranged from 1 mol / L to 3 mol / L, the chemical recovery rates of Np and Pu increased with the increase of HNO 3 The concentration of HNO 3 When the concentration is 3mol / L to 5mol / L, 237 Np and 242 The chemical recovery of Pu increases with the increase of HNO 3 The chemical recovery rate of the product tended to be stable with the increase of concentration. After three repeated experiments, the chemical recovery rate could be maintained at about 75%. 242 Pu tracer 237 The chemical recovery rate of Np has a small error and the result is relatively accurate; since the mixed acid concentration used for elution is low, Np and Pu can be efficiently desorbed under low acidity conditions.

[0098] Example 4: Effect of desorption liquid volume on recovery rate

[0099] S1: Dry 1 g of fecal sample in an electric furnace at 200°C for 6 hours, then divide it into 6 equal parts and add 1 mL of 237 Np standard solution (0.889 mBq) and 1 mL of 242 Pu (2.68 mBq) tracer, forming 6 samples.

[0100] S2a: Six samples obtained from S1 were placed in a carbonization-ashing integrated furnace and calcined at 300° C. for 6 hours.

[0101] S2b: After taking the sample out of the carbonization and ashing integrated furnace, place it in a muffle furnace and calcine it at 600° C. for 2 hours.

[0102] S2c: Each calcined sample was taken out from the muffle furnace and placed in a beaker, and then 12 mL of aqua regia was added. The beaker was then placed in an electric furnace and heated at 80° C. for 5 hours for thermal digestion.

[0103] S3: Then add 24mL of deionized water to the beaker for dilution to ensure safe operation of the staff, and then centrifuge at 8000rpm for 3 minutes in a high-speed centrifuge to remove the supernatant.

[0104] Then, 3 mol / L HNO 3 The precipitate was repeatedly washed with the solution and combined with the supernatant to reduce 237 Np and 242 Loss of Pu during centrifugation. Subsequently, the resulting solution was evaporated to dryness.

[0105] S4: Use 20mL of 3mol / L HNO3 The dried samples were dissolved in 100 μL of 0.05 mol / L Fe(NH 2 SO 3 ) 2 and 100 μL of 4 mol / L NaNO 2 NaNO 2 , so that Np and Pu in the fecal sample are adjusted to Np(IV) and Pu(IV), thereby obtaining 6 column samples.

[0106] S5: Use 20mL 3mol / L HNO 3 The TEVA extraction chromatography resin column (TEVA resin particle size is 100-150 μm, column inner diameter is 5 mm, column height is 20 mm) was activated and pretreated, and then the upper column sample in S4 was transferred to the resin column; then 15 mL 3 mol / L HNO 3 The beaker containing the sample was washed several times to reduce the loss of Np and Pu, and the washing solution was transferred to the resin column; then, the flow rate was adjusted to 0.5 mL / min, and 20 mL of 8 mol / L HNO 3 Rinse to remove U, and rinse to remove Th with 20mL 9mol / L HCl to reduce the content of impurities in the fecal sample; finally, use a mixed acid of 0.1mol / LHCl-0.05mol / L HF at a flow rate of 0.5mL / min to elute, and take one sample for every 2mL for ICP-MS testing. The results are as follows: Figure 7 shown.

[0107] Depend on Figure 7 It can be seen that 237 The chemical recovery rate of Np first increased with the increase of the desorption volume of the solution, and then gradually decreased; and when the desorption volume reached 12mL, 237 The chemical recovery rate of Np has tended to the maximum and stabilized; the standard deviation of the chemical recovery rate of the experiment repeated 6 times was calculated, and it was found that the standard deviation s<5%. It can be seen that when the volume of the desorption liquid reaches 12mL, Np and Pu can be completely desorbed. In the analysis, choosing 15mL of desorption liquid can completely achieve the optimal desorption effect.

[0108] Example 5 Reproducibility Analysis

[0109] In this embodiment, a total of 11 groups of full-process experiments were conducted, of which sample No. 0 was a blank sample without fecal sample, and the rest were fecal samples containing radionuclides (serial numbers were 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, respectively). In order to ensure the accuracy of the experiment, 3 groups were performed for each experiment and the average value was taken.

[0110] Each experimental group was analyzed by the analysis method described in Experiment 2.1. The results are shown in Figure 8 middle.

[0111] Depend on Figure 8 It can be seen that the chemical recovery rate of the fecal sample in the 10 full-process experiments is relatively stable. 237 The chemical recovery rate of Np was basically maintained at 70.85% to 79.07%, indicating that the method of the present application is feasible and reproducible.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. In a fecal sample 237 The analysis method of Np includes the following operations: drying the fecal sample; Heat treatment of dried fecal samples; The heat-treated fecal samples were washed and evaporated to dryness; The evaporated fecal samples were dissolved and redox treated; Separating and purifying the fecal samples after redox treatment; as well as The purified fecal samples were 237 Np content analysis.

2. The analysis method according to claim 1, wherein The heat treatment comprises: performing a first heat treatment on the dried feces sample; performing a second heat treatment on the feces sample subjected to the first heat treatment; and performing a third heat treatment on the feces sample subjected to the second heat treatment; Optionally, the first heat treatment is performed at a temperature of 200°C to 400°C, preferably at 300°C; the second heat treatment is performed at a temperature of 500°C to 600°C, preferably at 600°C; and the third heat treatment is performed at 80°C.

3. The method according to claim 2, wherein: The third heat treatment comprises: dissolving the fecal sample subjected to the second heat treatment in aqua regia at room temperature, and then heating at 80° C. for 5 hours.

4. The method according to any one of claims 1 to 3, wherein: The drying is carried out at a temperature of 200°C, and during the drying, 242 Pu tracer.

5. The method according to any one of claims 1 to 4, wherein: The washing was performed with a 3 mol / L HNO3 solution, followed by centrifugation to obtain a supernatant; The precipitate was then washed with a 3 mol / L HNO3 solution to obtain a washing solution; combining the supernatant and the washing solution, and then evaporating to dryness; Optionally, washing the precipitate is repeated 2 to 4 times.

6. The method according to any one of claims 1 to 5, wherein: The dissolution is carried out using 20 mL of 3 mol / L to 5 mol / L, preferably 3 mol / L HNO3 solution.

7. The method according to any one of claims 1 to 6, wherein: The redox is performed by adding a redox agent, wherein the redox agent includes Fe(NH2SO3)2 and NaNO2.

8. The method according to any one of claims 1 to 7, wherein: The separation and purification is carried out by using a TEVA extraction chromatography resin column, Preferably, the separation and purification comprises pre-treating the TEVA resin with 20 mL of 3 mol / L HNO3 solution, loading the redox-treated fecal sample onto the column, and then eluting with 8 mol / L HNO3 solution and 9 mol / L HCl solution in sequence.

9. The method according to any one of claims 1 to 8, wherein: The separation and purification includes desorption using 15 mL of a desorption solution of 0.1 mol / L HCl-0.05 mol / L HF.

10. The method according to any one of claims 1 to 9, wherein: Said 237 Np content analysis was performed by ICP-MS.

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