Method for removing salts in sample for chelate analysis

Abstract

The present invention relates to a method for removing salts in a sample for chelate analysis, which can facilitate analysis of chelates and the like present in the sample. The present invention relates to a method for removing salts in a sample for chelate analysis, the method comprising the steps of: leaching chelates from a sample and centrifuging same to obtain a primary supernatant; centrifuging the primary supernatant to obtain a secondary supernatant; and removing salts from the secondary supernatant.

Description

Method for removing salts from samples for chelate analysis

[0001] The present invention relates to a method for removing salt from a sample for chelate analysis.

[0002] Analyzing chelates in nuclear power plant decommissioning waste is a crucial technology required during the waste disposal process. According to the Korea Radioactive Waste Agency's acceptance standards, any chelating agent remaining at levels exceeding 0.1% must be identified by its chemical name and amount. However, because waste typically contains a variety of salts, analyzing chelating agents alone is difficult, requiring techniques to remove them.

[0003] In addition, the existing analytical methods applied to radioactive waste have technical limitations that make it difficult to specify the chemical name and abundance of multi-component chelating agents, and a chelating analysis method for various types of dismantled waste samples has not been secured, so new analytical technologies are urgently needed.

[0004] The problem to be solved by the present invention is to provide a method for removing salt from a sample for chelate analysis, which can facilitate the analysis of chelates, etc. present in the sample.

[0005] The present invention is a method for removing salt from a sample for chelate analysis, comprising the steps of: leaching a chelate from a sample, centrifuging the sample to obtain a first supernatant; centrifuging the first supernatant to obtain a second supernatant; and removing salt from the second supernatant.

[0006] In the present invention, the step of extracting chelate from the sample and centrifuging to obtain a first supernatant may include the steps of adding 1 to 50 mL of distilled water per 1 g of sample and extracting using ultrasonic waves for 0.5 to 2 hours; and centrifuging at 5,000 to 12,000 g for 5 to 20 minutes to obtain a first supernatant.

[0007] In the present invention, the step of centrifuging the first supernatant to obtain a second supernatant may include the steps of: adding NaOH to the first supernatant to adjust the pH to 10 or higher; centrifuging the first supernatant at 5,000 to 12,000 g for 5 to 20 minutes to obtain a second supernatant; adding Ni(NO3)2 to the second supernatant; adding HCl to the second supernatant to adjust the pH to 6 to 7; and heating the second supernatant at 50 to 70°C for 1 to 3 hours.

[0008] In the present invention, the NaOH may have a concentration of 0.05 to 1 N.

[0009] In the present invention, the HCl may have a concentration of 0.05 to 1 M.

[0010] In the present invention, the step of removing salt from the secondary supernatant may include the steps of adding acetone in a volume 5 to 20 times the volume of the secondary supernatant; centrifuging the secondary supernatant at 8,000 to 15,000 g for 5 to 20 minutes, removing the supernatant, and obtaining a precipitate; removing the solvent remaining in the precipitate; and adding distilled water to the precipitate to dissolve it.

[0011] In the present invention, the temperature of the acetone may be 5°C or lower.

[0012] In the present invention, the step of adding acetone in a volume 5 to 20 times the volume of the second supernatant; and the step of centrifuging the second supernatant at 8,000 to 15,000 g for 5 to 20 minutes, removing the supernatant, and obtaining a precipitate; may be performed one or more times.

[0013] In the present invention, the sample may be soil or radioactive waste.

[0014] In the present invention, the diameter of the sample may be 0.25 mm or less.

[0015] In the present invention, the sample is pretreated, and the pretreatment may include a step of first drying the sample at 20 to 60°C for 12 to 36 hours; a step of second drying the sample at 90 to 120°C for 6 to 24 hours after uniformly dissolving clumped samples among the first dried samples; a step of pulverizing the second dried sample to a diameter of 2 mm or less; a step of obtaining a sample of 50 to 100 g by repeating the cone-quartering method; and a step of pulverizing the sample to a diameter of 0.25 mm or less.

[0016] The present invention provides a method for easily removing salt from a sample, thereby enabling easy chelate analysis of various types of samples.

[0017] Additionally, by removing salt, the life of the device can be increased and analysis at low concentrations can be facilitated.

[0018] Figure 1 shows the HPLC-PDA results of a sample from which salt has been removed according to the present invention.

[0019] Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments, examples, etc. so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments, examples, etc. described herein.

[0020] Additionally, when the terms "about," "approximately," or similar expressions such as "at least" are used in connection with a numerical value in the present invention, it is intended that a theoretical, experimental, statistical, or empirical error of ±10%, ±7%, ±5%, ±3%, ±2%, or ±1% based on the numerical value is allowed.

[0021]

[0022] The present invention is a method for removing salt from a sample for chelate analysis, comprising the steps of: leaching a chelate from a sample, centrifuging the sample to obtain a first supernatant; centrifuging the first supernatant to obtain a second supernatant; and removing salt from the second supernatant.

[0023] In the present invention, the step of extracting chelate from the sample and centrifuging to obtain a first supernatant is a step of extracting chelate from the sample in order to analyze the chelate.

[0024] The step of extracting chelate from the above sample and centrifuging to obtain a first supernatant may include a step of adding 1 to 50 mL of distilled water per 1 g of sample and ultrasonically extracting for 0.5 to 2 hours; and a step of centrifuging at 5,000 to 12,000 g for 5 to 20 minutes to obtain a first supernatant.

[0025] The step of adding 1 to 50 mL of distilled water per 1 g of the sample and ultrasonically leaching for 0.5 to 2 hours may be preferably a step of adding 5 to 15 mL of distilled water per 1 g of the sample and ultrasonically leaching for 0.8 to 1.2 hours, and leaching can proceed easily under the above conditions.

[0026] The above centrifugation can be performed at 5,000 to 12,000 g for 5 to 20 minutes, preferably at 6,000 to 10,000 g for 8 to 12 minutes, and separation of the supernatant can be easily performed under the above conditions.

[0027] In the present invention, the step of centrifuging the first supernatant to obtain a second supernatant is a step of separating a precipitate from the solution and obtaining a Ni chelate.

[0028] The step of centrifuging the first supernatant to obtain a second supernatant may include the steps of: adding NaOH to the first supernatant to adjust the pH to 10 or higher; centrifuging the first supernatant at 5,000 to 12,000 g for 5 to 20 minutes to obtain a second supernatant; adding Ni(NO3)2 to the second supernatant; adding HCl to the second supernatant to adjust the pH to 6 to 7; and heating the second supernatant at 50 to 70° C. for 1 to 3 hours.

[0029] The step of adjusting the pH to 10 or higher by adding NaOH to the first supernatant is a step for precipitating a metal by adjusting the pH to 10 or higher, and NaOH may be added to the first supernatant, and the NaOH may have a concentration of 0.05 to 1 N.

[0030] The step of centrifuging the first supernatant at 5,000 to 12,000 g for 5 to 20 minutes and obtaining the second supernatant is a step for removing sediment, and centrifugation can preferably be performed at 6,000 to 10,000 g for 8 to 12 minutes, and separation of the supernatant can be easily performed under the above conditions.

[0031] The step of adding Ni(NO3)2 to the above secondary supernatant is a step for forming a chelate and a complex with an excess of Ni(nickel). 0.5 to 5 mL of Ni(NO3)2 may be added per 3 mL of the secondary supernatant, and the concentration of the Ni(NO3)2 may be 10 to 20 M. Under the above conditions, complex formation between Ni and the chelate can easily proceed.

[0032] In the step of adjusting the pH to 6 to 7 by adding HCl to the secondary supernatant, the HCl may have a concentration of 0.05 to 1 M, and under the above conditions, complex formation between Ni and the chelate may easily proceed.

[0033] In the present invention, the step of removing salt from the secondary supernatant is a step for removing salt peaks that appear during analysis in order to analyze chelates contained in the sample.

[0034] The step of removing salt from the secondary supernatant may include the steps of adding acetone in a volume 5 to 20 times the volume of the secondary supernatant; centrifuging the secondary supernatant at 8,000 to 15,000 g for 5 to 20 minutes, removing the supernatant, and obtaining a precipitate; removing the solvent remaining in the precipitate; and adding distilled water to the precipitate to dissolve it.

[0035] In the step of adding acetone in a volume 5 to 20 times the volume of the secondary supernatant, the acetone is a solvent for removing salts, and the temperature of the acetone may be 5°C or lower, preferably -10°C or lower, and more preferably -25 to -15°C. It may be easy to remove salts at the above temperature.

[0036] The above acetone can be added in a volume ratio of 5 to 20 times that of the secondary supernatant, and preferably in a volume ratio of 8 to 12 times that of the secondary supernatant. At the above volume ratio, formation of a precipitate is facilitated, and thus, removal of salts can be facilitated.

[0037] In the step of centrifuging the secondary supernatant at 8,000 to 15,000 g for 5 to 20 minutes and removing the supernatant to obtain a precipitate, centrifugation may preferably be performed at 9,000 to 12,000 g for 8 to 12 minutes, and it may be easy to obtain a precipitate within the above range.

[0038] In addition, the step of adding acetone and the step of centrifuging the precipitate may be repeated one or more times, preferably 1 to 4 times, and more preferably 2 to 3 times, and the salt may be removed more with each repetition.

[0039] In the present invention, the sample may be soil or radioactive waste, but is not limited thereto, and the present invention can be performed to remove salt from various samples.

[0040] In the present invention, the diameter of the sample may be 0.25 mm or less, and if the diameter of the sample exceeds 0.25 mm, salt removal may not be easy.

[0041] In the present invention, the sample may be pretreated, and the pretreatment may include a step of first drying the sample at 20 to 60°C for 12 to 36 hours; a step of second drying the sample at 90 to 120°C for 6 to 24 hours after uniformly dissolving clumped samples among the first dried samples; a step of pulverizing the second dried sample to a diameter of 2 mm or less; a step of obtaining a sample of 50 to 100 g by repeating the cone-quartering method; and a step of pulverizing the sample to a diameter of 0.25 mm or less.

[0042] In the present invention, diameter means the longest distance based on the center of the sample.

[0043] In the present invention, the sample is pretreated so that various samples can be made suitable for the salt removal method according to the present invention, and by being pretreated, storage properties can be increased and management can be made easy.

[0044] Hereinafter, specific examples according to the present invention will be described.

[0045]

[0046] Manufacturing example: Sample preparation

[0047] The soil was collected from 0 to 15 cm above the ground surface at five points in a zigzag pattern over a 3 m x 3 m area of ​​the target area.

[0048] The collected soil is dried at approximately 40°C for approximately 24 hours after removing any remaining grass roots. Afterwards, any clumps of the primary dried samples are evenly dispersed and dried a second time at approximately 105°C for approximately 12 hours.

[0049] Afterwards, the secondary dried soil is sieved using a 2 mm sieve, and particles larger than 2 mm are crushed to less than 2 mm using a mixer, mortar, etc. Afterwards, the cone-quartering method is repeated to obtain a sample weighing 50 to 100 g. The cone-quartering method is as follows.

[0050] 1) Mix the samples and stack them in a cone shape. 2) Flatten the cone-shaped stack by pressing vertically from the top. 3) Divide the flattened sample into four equal parts and discard one of the two diagonal sections. 4) Repeat steps 1) through 3) until the desired sample volume is reached.

[0051] Afterwards, prepare the sample by crushing the sample to a diameter of 0.25 mm or less.

[0052]

[0053] Example 1

[0054] Add 10 mL of triple-distilled water to 1 g of the sample prepared in the manufacturing example and extract in a sonic bath (sonic bath, 3510-DTH) for 1 hour. Afterwards, separate the supernatant and the sample using a centrifuge (8000 g, 10 minutes), and collect the first supernatant.

[0055] Add about 50 μL of 0.1 N NaOH per 5 mL of the first supernatant to adjust the pH to about 10 or higher.

[0056] Afterwards, the first supernatant with added NaOH is separated using a centrifuge (8000 g, 10 minutes) to obtain the second supernatant. Add 1 mL of 16 M Ni(NO3)2 per 3 mL of the second supernatant. Then, add about 50 μL of 0.01 M HCl to adjust the pH to 6.5±0.2. Then, heat at about 60°C for 2 hours.

[0057] Add acetone at approximately -20°C in a volume ratio 10 times that of the heated solution. Afterwards, separate the supernatant and the precipitate using a centrifuge (10,000 g, 10 minutes), remove the supernatant, and obtain the precipitate.

[0058] Afterwards, the solvent remaining in the sediment is removed using nitrogen concentration, and distilled water is added to the sediment to complete the removal of salt.

[0059]

[0060] Example 2

[0061] Add 10 mL of triple-distilled water to 1 g of the sample prepared in the manufacturing example and extract in a sonic bath (sonic bath, 3510-DTH) for 1 hour. Afterwards, separate the supernatant and the sample using a centrifuge (8000 g, 10 minutes), and collect the first supernatant.

[0062] Add about 50 ㎕ of 0.1 N NaOH per 5 mL of the first supernatant to adjust the pH to about 10 or higher.

[0063] Afterwards, the first supernatant with added NaOH is separated using a centrifuge (8000 g, 10 minutes) to obtain the second supernatant. Add 1 mL of 16 M Ni(NO3)2 per 3 mL of the second supernatant. Then, add about 50 μL of 0.01 M HCl to adjust the pH to 6.5±0.2. Then, heat at about 60°C for 2 hours.

[0064] Add acetone at approximately -20°C in a volume ratio 10 times that of the heated solution. Afterwards, separate the supernatant and the precipitate using a centrifuge (10,000 g, 10 minutes), remove the supernatant, obtain the precipitate, and repeat the process of adding acetone to the precipitate and centrifuging once in the same manner as for the heated solution.

[0065] Afterwards, the solvent remaining in the sediment is removed using nitrogen concentration, and distilled water is added to the sediment to complete the removal of salt.

[0066]

[0067] Comparative example

[0068] Add 10 mL of triple-distilled water to 1 g of the sample prepared in the manufacturing example and extract in a sonic bath (sonic bath, 3510-DTH) for 1 hour. Afterwards, separate the supernatant and the sample using a centrifuge (8000 g, 10 minutes), and collect the first supernatant.

[0069] Add about 50 μL of 0.1 N NaOH per 5 mL of the first supernatant to adjust the pH to about 10 or higher.

[0070] Afterwards, the first supernatant with added NaOH is separated using a centrifuge (8000 g, 10 minutes) to obtain the second supernatant. Add 1 mL of 16 M Ni(NO3)2 per 3 mL of the second supernatant. Then, add about 50 μL of 0.01 M HCl to adjust the pH to 6.5±0.2. Afterwards, heat at about 60°C for 2 hours and cool to room temperature.

[0071]

[0072] Experimental example

[0073] Chelate analysis was performed using HPLC-PDA. Shimadzu Nexera was used for HPLC-PDA, and the conditions are as shown in Table 1 below, and the results are shown in Figure 1.

[0074] The column used was XBridge BEH Amide column; 5 μm; 4.6 * 250 mm, and the guard column used XBridge BEH Amide VanGuard Cartridge. 10 mM (NH4)HCO3, pH adjusted to 8.50±2 with ammonia water, was used as mobile phase solvent A, and 0.1 M NH4HCO3:ACN = 1:9 was mixed and used as mobile phase solvent B.

[0075]

[0076] Time (min)Mobile phase solvent AMobile phase solvent B00100104060154060200100350100Column temperature: 50℃Auto sampler temperature: 10℃Flow rate: 1 mL / minInjection volume: 10 ㎕Wavelength: 224 nm

[0077] Figure 1 shows the HPLC-PDA results of a sample from which salt has been removed according to the present invention. Referring to Figure 1, it can be confirmed that in the case where salt has been removed according to the present invention (Examples 1 and 2), the salt peak has been removed more than in the case where salt has not been removed (Comparative Example), and it can be confirmed that the chelate peak is similar to the case where salt has not been removed.

[0078]

[0079] The present invention provides a method for easily removing salt from a sample, thereby enabling easy chelate analysis of various types of samples.

[0080] Additionally, by removing salt, the life of the device can be increased and analysis at low concentrations can be facilitated.

Claims

1. A step of leaching chelate from a sample and centrifuging to obtain a first supernatant; A step of centrifuging the first supernatant to obtain a second supernatant; and A step of removing salt from the secondary supernatant; A method for removing salts from a sample for chelate analysis, comprising:

2. In paragraph 1, The step of leaching the chelate from the above sample and centrifuging to obtain the first supernatant is as follows: A step of adding 1 to 50 mL of distilled water per 1 g of sample and ultrasonic leaching for 0.5 to 2 hours; and A step of centrifuging at 5,000 to 12,000 g for 5 to 20 minutes and obtaining the first supernatant; A method for removing salt from a sample for chelate analysis, comprising:

3. In paragraph 1, The step of centrifuging the first supernatant to obtain the second supernatant is as follows: A step of adjusting the pH to 10 or higher by adding NaOH to the first supernatant; A step of centrifuging the first supernatant at 5,000 to 12,000 g for 5 to 20 minutes and obtaining the second supernatant; A step of adding Ni(NO3)2 to the above secondary supernatant; A step of adjusting the pH to 6-7 by adding HCl to the above secondary supernatant; and A step of heating the above secondary supernatant at 50 to 70 ℃ for 1 to 3 hours; A method for removing salt from a sample for chelate analysis, comprising:

4. In paragraph 3, A method for removing salt from a sample for chelate analysis, wherein the above NaOH has a concentration of 0.05 to 1 N.

5. In paragraph 3, A method for removing salt from a sample for chelate analysis, wherein the above HCl has a concentration of 0.05 to 1 M.

6. In paragraph 1, The step of removing salt from the above secondary supernatant is: A step of adding acetone in a volume 5 to 20 times the volume of the second supernatant; A step of centrifuging the above secondary supernatant at 8,000 to 15,000 g for 5 to 20 minutes, removing the supernatant, and obtaining a sediment; A step of removing the solvent remaining in the above sediment; and A step of dissolving the above precipitate by adding distilled water; A method for removing salt from a sample for chelate analysis, comprising:

7. In paragraph 6, A method for removing salt from a sample for chelate analysis, wherein the temperature of the acetone is 5°C or lower.

8. In paragraph 6, A step of adding acetone in a volume 5 to 20 times the volume of the second supernatant; and A step of centrifuging the above secondary supernatant at 8,000 to 15,000 g for 5 to 20 minutes, removing the supernatant, and obtaining a sediment; A method for removing salt from a sample for chelate analysis, which is performed one or more times.

9. In paragraph 1, A method for removing salts from a sample for chelate analysis, wherein the sample is soil or radioactive waste.

10. In paragraph 1, A method for removing salt from a sample for chelate analysis, wherein the diameter of the sample is 0.25 mm or less.

11. In paragraph 1, The above sample is pretreated, The above preprocessing is, A step of primary drying the sample at 20 to 60 ℃ for 12 to 36 hours; A step of evenly dispersing clumped samples from the first dried samples and then drying them for a second time at 90 to 120°C for 6 to 24 hours; A step of grinding the secondary dried sample into pieces with a diameter of 2 mm or less; A step of obtaining a sample of 50 to 100 g by repeating the cone-four method; and A step of grinding the sample to a diameter of 0.25 mm or less; A method for removing salt from a sample for chelate analysis, comprising:

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