Method for rapidly measuring oxalate content in radioactive feed liquid

Abstract

The application belongs to the technical field of spent fuel reprocessing analysis, and particularly relates to a method for rapidly measuring the content of oxalate in radioactive liquid. The method comprises the following steps: adding different volumes of tri-n-octylamine, and obtaining an organic phase sample after extraction; measuring the maximum absorption wavelength of oxalate ions, the optimal sample injection amount and flow rate, and the optimal extraction agent proportion; preparing a series of oxalate standard solutions with different concentration gradients, and measuring the peak area and concentration relationship of the standard solutions under the optimal conditions; and taking a certain amount of pretreated sample, and measuring the sample under the optimal conditions. The application uses tri-n-octylamine to extract and separate oxalic acid to obtain a pretreatment method, simplifies the complex pretreatment steps of oxalate measurement, shortens the sample measurement time, measures the content of oxalate in the post-treatment process sample on a liquid chromatograph, and realizes the effects of rapidness, accuracy, safety and the like.

Description

Technical Field

[0001] This application belongs to the field of spent fuel reprocessing and analysis technology, specifically relating to a method for rapidly measuring the oxalate content in radioactive liquid materials. Background Technology

[0002] The determination of oxalate content is a crucial component of post-processing analytical techniques. Currently, the pretreatment method for determining oxalate content in process feed solutions involves IC-H column chromatography followed by nitrogen purging. First, the sample is adjusted to a suitable acidity. Then, using an IC-H column, alpha radioactivity, beta radioactivity, and some metal elements are removed. Next, the sample is heated and purged with nitrogen until completely dry to further remove nitrate. Finally, the sample is injected into an ion chromatograph for measurement. The entire analytical process takes 3.5 hours. This pretreatment method is cumbersome, time-consuming, inefficient, and has poor repeatability, failing to meet the requirements for rapid and accurate determination. Summary of the Invention

[0003] The purpose of this application is to provide a rapid method for measuring the oxalate content in radioactive liquids. The method uses tri-n-octylamine extraction and separation pretreatment, and takes advantage of the ability of liquid chromatography to directly measure the organic phase. By establishing a standard curve, the method can achieve rapid and accurate determination of oxalate content.

[0004] The technical solution to achieve the purpose of this application is as follows: This application provides a method for rapidly measuring the oxalate content in a radioactive liquid, comprising the following steps: Step 1, Radioactive sample pretreatment: Place the sample to be tested in a glove box, adjust the acidity of the sample, and add extractants of different volume ratios to extract the sample and obtain an organic phase sample. Step 2, liquid chromatography analysis: Select the wavelength of the high performance liquid chromatograph as the maximum absorption wavelength of oxalate ions, and inject organic phase samples with different volume ratios of extractant into the liquid chromatograph under the optimal injection volume and flow rate conditions, and measure the peak area; determine the extractant ratio with the highest peak height and the largest peak area as the optimal extractant ratio. Step 3, Standard curve plotting: Prepare a series of oxalate standard solutions with different concentration gradients, select the wavelength of the high performance liquid chromatograph as the maximum absorption wavelength of oxalate ions, and perform the determination under the optimal injection volume and flow rate conditions to obtain the relationship between the peak area and concentration of the standard solution. Based on this relationship, plot the standard curve and perform linear fitting to obtain the fitting equation. Step 4, Sample determination: Take a certain amount of pretreated sample, select the wavelength of high performance liquid chromatography as the maximum absorption wavelength of oxalate ions, and perform the determination under the optimal injection volume and flow rate conditions. Calculate the oxalate content in the sample based on the fitted equation.

[0005] Optionally, the extractant for the sample in steps one and two may be tri-n-octylamine.

[0006] Optionally, in step one, the sample volume is 0.3 mL to 0.6 mL.

[0007] Optionally, the maximum absorption wavelength of the liquid chromatograph described in steps two to four is the ultraviolet wavelength at which the oxalate group exhibits its maximum absorption peak. This wavelength is obtained by performing an ultraviolet spectral scan on the oxalate standard solution.

[0008] Optionally, the optimal injection volume for liquid chromatography described in steps two to four is determined by setting an injection volume gradient range and measuring the oxalate standard solution at the maximum absorption wavelength.

[0009] Optionally, the optimal flow rate of the liquid chromatography described in steps two to four is determined by adjusting the flow rate of the liquid chromatography under the conditions of maximum absorption wavelength and optimal injection volume, thereby setting a flow rate gradient of the mobile phase.

[0010] Optionally, the linear correlation coefficient of the linear fit in step three should be greater than 0.995.

[0011] Optionally, the pretreated sample in step four should be 4. ~6 .

[0012] The beneficial technical effects of this application are as follows: The pretreatment method of separating oxalic acid by extraction with tri-n-octylamine simplifies the complicated pretreatment steps for oxalate measurement, shortens the sample measurement time, and enables the determination of oxalate content in post-processed samples by liquid chromatography, achieving rapid, accurate, and safe results.

[0013] (1) Rapid and accurate measurement The oxalic acid content in the sample is effectively improved by using tri-n-octylamine extraction and post-processing, reducing the pretreatment speed to approximately 40 minutes. This patented method uses tri-n-octylamine extraction to separate oxalate samples, removing the influence of α-radioactivity, β-radioactivity, some metal elements, nitrate, and sulfate on the oxalic acid measurement results. This simplifies the sample pretreatment steps, reduces errors caused by human operation, and results in a relative standard deviation of better than 5%.

[0014] (2) Safety The sample pretreatment process of this method is carried out in a glove box with radiation shielding function, which meets the radiation protection requirements and can effectively ensure personnel safety. At the same time, the analysis process of this method is relatively fast, reducing the harm of personnel to radiation exposure. Detailed Implementation

[0015] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] A method for rapidly measuring the oxalate content in a radioactive liquid sample includes the following steps: Step 1, Pretreatment of radioactive liquid sample: Place the radioactive liquid sample to be tested in a glove box, adjust the acidity of the sample, and add extractants of different volume ratios to extract the sample and obtain an organic phase sample. Step 2, liquid chromatography analysis: Select the wavelength of the high performance liquid chromatograph as the maximum absorption wavelength of oxalate ions, and inject organic phase samples with different volume ratios of extractant into the liquid chromatograph under the optimal injection volume and flow rate conditions, and measure the peak area; determine the extractant ratio with the highest peak height and the largest peak area as the optimal extractant ratio. Step 3, Standard curve plotting: Prepare a series of oxalate standard solutions with different concentration gradients, select the wavelength of the high performance liquid chromatograph as the maximum absorption wavelength of oxalate ions, and perform the determination under the optimal injection volume and flow rate conditions to obtain the relationship between the peak area and concentration of the standard solution. Based on this relationship, plot the standard curve and perform linear fitting to obtain the fitting equation. Step 4, Sample determination: Take a certain amount of pretreated sample, select the wavelength of high performance liquid chromatography as the maximum absorption wavelength of oxalate ions, and perform the determination under the optimal injection volume and flow rate conditions. Calculate the oxalate content in the sample based on the fitted equation.

[0017] Example 1: Pretreatment of radioactive liquid sample Take 0.3 mL to 0.6 mL of radioactive liquid sample, adjust the acidity, add different volumes of tri-n-octylamine, and extract to obtain organic phase sample.

[0018] Step two involves determining the oxalate standard solution, including the optimal wavelength, injection volume, and flow rate. The optimal extraction solvent volume is then determined using the pretreated radioactive sample. By scanning the ultraviolet spectrum of the oxalate standard solution, the ultraviolet wavelength at which oxalic acid exhibits its maximum absorption peak was identified; therefore, the wavelength range of 200 nm to 230 nm was selected as the wavelength for measuring oxalate. The oxalate standard solution was prepared, and an injection volume gradient range was set. Oxalate was measured at the maximum absorption wavelength, and the optimal injection volume was determined to be 4 μL to 6 μL. Under the conditions of wavelength 200 nm to 230 nm and injection volume of 4 μL to 6 μL, the flow rate of the liquid chromatography was adjusted, and a mobile phase flow rate gradient was set, determining the optimal flow rate to be 0.8 mL / min to 1 mL / min. Under the above optimal wavelength, injection volume, and flow rate conditions, the solution was injected into the high-performance liquid chromatograph, and the optimal extractant volume was determined based on the peak area.

[0019] Step 3: Plotting the oxalate standard curve Prepare a series of oxalate standard solutions of 0.01 mg / L, 0.2 mg / L, 0.5 mg / L, 2.0 mg / L, 5.0 mg / L, and 10 mg / L, respectively, in the range of 4 μL to 6 μL. Inject these solutions into the liquid chromatograph under the optimal wavelength, injection volume, and flow rate conditions determined in step two. Plot a standard curve based on the relationship between the obtained standard concentration and peak area. Obtain the fitting equation based on linear fitting and determine that the linear correlation coefficient of the standard curve should be greater than 0.995.

[0020] Step 4: Determination of oxalate content in radioactive liquid samples Take 4 μL to 6 μL of the pretreated sample from step one, select the wavelength of the high performance liquid chromatography instrument as the maximum absorption wavelength of oxalate ions, and perform the determination under the optimal injection volume and flow rate conditions. After measuring the peak area, calculate the oxalate content of the sample according to the fitting equation of the standard curve.

[0021] The sample measurement precision is better than 5%, and the accuracy is better than 10%.

[0022] The present application has been described in detail above with reference to the embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application. All content not described in detail in this application can be derived from existing technology.

Claims

1. A method for rapidly measuring the oxalate content in a radioactive liquid, characterized in that, Includes the following steps: Step 1, Pretreatment of radioactive liquid sample: Place the radioactive liquid sample to be tested in a glove box, adjust the acidity of the sample, and add extractants of different volume ratios to extract the sample and obtain an organic phase sample. Step 2, liquid chromatography analysis: Select the wavelength of the high performance liquid chromatograph as the maximum absorption wavelength of oxalate ions, and inject organic phase samples with different volume ratios of extractant into the liquid chromatograph under the optimal injection volume and flow rate conditions, and measure the peak area; determine the extractant ratio with the highest peak height and the largest peak area as the optimal extractant ratio. Step 3, Standard curve plotting: Prepare a series of oxalate standard solutions with different concentration gradients, select the wavelength of the high performance liquid chromatograph as the maximum absorption wavelength of oxalate ions, and perform the determination under the optimal injection volume and flow rate conditions to obtain the relationship between the peak area and concentration of the standard solution. Based on this relationship, plot the standard curve and perform linear fitting to obtain the fitting equation. Step 4, Sample determination: Take a certain amount of pretreated sample, select the wavelength of high performance liquid chromatography as the maximum absorption wavelength of oxalate ions, and perform the determination under the optimal injection volume and flow rate conditions. Calculate the oxalate content in the sample based on the fitted equation.

2. The method for rapidly measuring the oxalate content in a radioactive liquid according to claim 1, characterized in that, The extractant selected for the samples in steps one and two is tri-n-octylamine.

3. A method for rapidly measuring the oxalate content in a radioactive liquid according to claim 1 or 2, characterized in that, In step one, the sample volume is 0.3 mL to 0.6 mL.

4. The method for rapidly measuring the oxalate content in a radioactive liquid according to claim 3, characterized in that, The maximum absorption wavelength of the liquid chromatograph described in steps two to four is the ultraviolet wavelength at which the oxalate group exhibits its maximum absorption peak. This wavelength is obtained by performing an ultraviolet spectral scan on the oxalate standard solution.

5. The method for rapidly measuring the oxalate content in a radioactive liquid according to claim 4, characterized in that, The optimal injection volume for liquid chromatography described in steps two to four is determined by setting an injection volume gradient range and measuring the oxalate standard solution at the maximum absorption wavelength.

6. The method for rapidly measuring the oxalate content in a radioactive liquid according to claim 5, characterized in that, The optimal flow rate for liquid chromatography described in steps two to four is determined by adjusting the flow rate of the liquid chromatography under the conditions of maximum absorption wavelength and optimal injection volume, and setting the flow rate gradient of the mobile phase.

7. The method for rapidly measuring the oxalate content in a radioactive liquid according to claim 6, characterized in that, In step three, the linear correlation coefficient of the linear fit should be greater than 0.

995.

8. The method for rapidly measuring the oxalate content in a radioactive liquid according to claim 7, characterized in that, The pretreatment sample described in step four should be 4. ~6 .