Method for detecting deuteration rate of deuterium-depleted water

Abstract

The invention belongs to the technical field of deuteration rate detection, and particularly relates to a low-deuteration water deuteration rate detection method, which comprises: 1) preparing a heavy water standard sample with a known deuteration rate, carrying out a nuclear magnetic hydrogen spectrum test, and recording the water peak area; (2) estimating the deuteration rate of the deuterium-depleted water sample to be detected, then mixing a proper amount of the deuterium-depleted water sample with a proper amount of the heavy water standard sample, and preparing a mixed heavy water sample with the estimated deuteration rate of 98% or above; (3) carrying out nuclear magnetic hydrogen spectrum test on the mixed heavy water sample, recording the water peak area, and calculating the deuteration rate by using the water peak area according to an external standard method; and (4) calculating the deuteration rate of the deuterium-depleted water sample. The detection method overcomes the defect that a nuclear magnetic resonance hydrogen spectrum method cannot accurately measure the deuterium-depleted heavy water (deuteration rate lt; the deuterium content in a high range (more than or equal to 98%) is difficult to detect, the limitation that an external standard method can only detect the isotope abundance (more than or equal to 98%) of deuterium in a relatively high range is broken through, and meanwhile, the method is high in analysis precision and accuracy, low in equipment investment, simple and convenient to operate and low in analysis cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of deuterium substitution rate detection, and in particular relates to a method for detecting the deuterium substitution rate of low-deuterium water. Background Art

[0002] Deuterated water (heavy water) is an important deuterium reagent. It is not only a commonly used solvent in nuclear magnetic resonance (NMR) but also has a wide range of applications in other scientific research and production activities, serving as a raw material for the preparation of many other deuterated reagents. Among common deuterated solvents, the spectral line of the residual signal of heavy water is relatively broad, significantly affecting the quality of the spectrum. Therefore, the calibration of the deuteration rate of heavy water is of great practical significance for the evaluation and use of deuterated reagents.

[0003] Existing methods for detecting the deuterated water deuterium rate include density method, infrared spectroscopy, mass spectrometry, nuclear magnetic resonance method, etc. Density method is sensitive to temperature, and poor temperature control will lead to measurement deviation; low-precision density meter (±0.001g / cm 3 ) The error is significant at high deuterium substitution rates, for example, the density difference is 0.001 g / cm at >99%. 3 This can result in an error of approximately 0.3% in the deuterium substitution rate. The density-deuterium substitution rate relationship is based on an ideal model, but hydrogen bonding and molecular forces in real solutions can lead to nonlinear deviations. For example, at high concentrations of D2O (>90%), the actual density can be 0.1% to 0.3% lower than the theoretical value. Infrared spectroscopy is only suitable for the determination of highly concentrated heavy water. Mass spectrometry suffers from separation difficulties, large quantitative analysis errors, and the difficulty in obtaining standard samples.

[0004] Nuclear magnetic resonance (NMR) offers advantages such as high accuracy and excellent stability, making it an effective method for determining the deuterium substitution rate of deuterated water. However, previous NMR methods have encountered difficulties in measuring low-deuterium heavy water (deuterium content <98%). These include difficulties in obtaining standard samples with extremely low deuterium content, the difficulty in finding suitable internal standards, and the nonlinear relationship between peak area and deuterium content in the 1H-NMR spectrum, which can lead to inaccurate test results. Therefore, the determination of the deuterium substitution rate in low-deuterium heavy water has remained an unresolved issue for many years. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a 1H-NMR spiked detection method for the deuterium substitution rate of low-deuterium water, which overcomes the difficulty that the nuclear magnetic resonance hydrogen spectroscopy method cannot accurately measure the deuterium content in low-deuterium heavy water (deuterium substitution rate <98%), and breaks through the limitation that the external standard method can only detect the isotopic abundance of deuterium in a higher range (≥98%). At the same time, the analysis precision and accuracy are high, the equipment investment is small, the operation is simple, the analysis cost is low, and the quantitative analysis of the deuterium substitution rate in the production process of low-deuterium water is convenient. It can not only meet the daily detection requirements of ordinary nuclear magnetic resonance, but also provide a basis for quality control in the production process.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] A method for detecting the deuterium substitution rate of low-deuterium water comprises the following steps:

[0008] (1) Prepare a heavy water standard sample with a known deuterium substitution rate, perform H NMR spectrum testing, and record the water peak area;

[0009] (2) estimating the deuterium substitution rate of the deuterium-depleted water sample to be tested, and then mixing an appropriate amount of the deuterium-depleted water sample with an appropriate amount of a heavy water standard sample to prepare a mixed heavy water sample with an estimated deuterium substitution rate of more than 98%;

[0010] (3) Performing H NMR spectrum testing on the mixed heavy water sample, recording the water peak area, and calculating the deuterium substitution rate based on the water peak area according to the external standard method;

[0011] (4) Calculate the deuterium substitution rate D1 of the deuterium-depleted water sample according to the following formula:

[0012]

[0013] Where m1 is the weight of the deuterium-depleted water sample, g; D 混 is the deuterium substitution rate of the mixed heavy water sample, %; m2 is the weight of the heavy water standard sample, g; D2 is the deuterium substitution rate of the heavy water standard sample, %.

[0014] In the present invention, the low-deuterium water refers to deuterated water with a deuterium substitution rate of less than 98%; the heavy water standard sample is a high-deuterium standard heavy water solution with a deuterium substitution rate of more than 99.85%.

[0015] Preferably, in step (2), the deuterium substitution rate of the deuterium-depleted water sample is measured by density analysis to estimate the deuterium substitution rate of the deuterium-depleted water sample. Although there is a certain error between the deuterium substitution rate obtained by density analysis of the deuterium-depleted water sample and the actual deuterium substitution rate, the estimated deuterium substitution rate can be used as an estimated result to configure a mixed heavy water sample with an estimated deuterium substitution rate of 98% or more.

[0016] Preferably, in step (2), the estimated deuteration rate of the mixed heavy water sample is recorded as D' 混 , calculated according to the following formula:

[0017]

[0018] Where D1′ is the estimated deuterium substitution rate of the deuterium-depleted water sample, %.

[0019] The present invention has no special restrictions on the range of values ​​of the amount m1 of the deuterium-depleted water sample and the amount m2 of the heavy water standard sample used in preparing the heavy water standard sample, as long as the estimated deuterium substitution rate D' of the mixed heavy water sample obtained by mixing is 混 It only needs to meet 98% or more of the requirements.

[0020] As preferred, in step (2), the mass ratio of the low deuterium water sample to the heavy water standard sample is 1:150 or more. If the mass ratio is less than 1:150 (i.e. the proportion of the low deuterium water sample in the mixed heavy water sample is too small), the accuracy of the detection result will be affected.

[0021] As preferred, in step (3), the deuterium substitution rate D of the mixed heavy water sample is 98% or more. 混 , which is calculated according to the following formula:

[0022] D 混 (%) = 1 - A1 x (1 - D2) / A2

[0023] Wherein, A1 is the water peak area of the mixed heavy water sample obtained in step (3); A2 is the water peak area of the heavy water standard sample obtained in step (1).

[0024] The beneficial effects achieved by the present application are:

[0025] (1) The detection method for the deuterium substitution rate of low deuterium water provided by the present application overcomes the difficulty that the nuclear magnetic resonance hydrogen spectrum method cannot accurately measure the deuterium content in low deuterium heavy water (<98%); and breaks through the limitation that the external standard method can only detect the isotopic abundance of deuterium in a higher range (≥98%);

[0026] (2) The detection method for the deuterium substitution rate of low deuterium water provided by the present application has high analysis accuracy and precision, low equipment investment, simple operation, low analysis cost, and is convenient for quantitative analysis of the deuterium content in the production process of low deuterium water, which can not only meet the ordinary detection requirements of nuclear magnetic resonance, but also provide a basis for quality control in the production process;

[0027] (3) The detection method for the deuterium substitution rate of low deuterium water provided by the present application firstly estimates the formula based on a specific deuterium substitution rate, adds standard high deuterium heavy water to low deuterium water, and adjusts it to a high deuterium range (≥98%), which can be accurately detected in the range; then according to the nuclear magnetic resonance result, the deuterium content in the low deuterium water is calculated by using the weight of the low deuterium water, the weight and deuterium substitution rate of the standard high deuterium heavy water, and the deuterium substitution rate of the mixed heavy water solution after adding the standard, which has simple process operation, and the result can be obtained by substituting the calculation formula, which overcomes the defects of low deuterium standard water sample difficult to obtain, internal standard difficult to select, and low accuracy of nuclear magnetic resonance hydrogen spectrum detection of low deuterium water. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flow chart for detecting the deuterium substitution rate of low deuterium water in the examples.

[0029] Figure 2 The nuclear magnetic hydrogen spectrum of the mixed heavy water sample prepared by using low deuterium water sample 1 and heavy water standard sample of Qingdao Tenglong Microwave Technology Co., Ltd. in specific case 1.

[0030] Figure 3 This is the H NMR spectrum of the mixed heavy water sample prepared by using deuterium-depleted water sample 2 and heavy water standard sample from Qingdao Tenglong Microwave Technology Co., Ltd. in specific case 1.

[0031] Figure 4 Specific case 1 is the H NMR spectrum of the mixed heavy water sample prepared by using deuterium-depleted water sample 3 and heavy water standard sample from Qingdao Tenglong Microwave Technology Co., Ltd.

[0032] Figure 5 This is the H NMR spectrum of the mixed heavy water sample prepared by using deuterium-depleted water sample 4 and heavy water standard sample from Qingdao Tenglong Microwave Technology Co., Ltd. in specific case 1.

[0033] Figure 6 This is the H NMR spectrum of the mixed heavy water sample prepared using deuterium-depleted water sample 5 and heavy water standard sample from Qingdao Tenglong Microwave Technology Co., Ltd. in specific case 1. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0035] Example

[0036] A method for detecting the deuterium substitution rate of low-deuterium water, see Figure 1 , the steps are as follows:

[0037] (1) Prepare a heavy water standard sample with a known deuterium substitution rate D2, and detect it by nuclear magnetic resonance (NMR) method (NMR spectrometer, detection conditions are detection sequence zg30, scan number 16 times, D1 is 1 second, DS is 2; the same below), and mark the peak of heavy water, and the peak area is A2;

[0038] (2) First, the deuterium substitution rate D′1 of the deuterium-depleted water sample to be tested was estimated using the density method. Specifically, the density method was performed using an Anton Paar DMA501 density meter (with an accuracy of 0.001 g / cm 3 ) and prepared heavy water standard samples of varying concentrations (mixed by weight of pure water and heavy water of known deuterium substitution rate) to establish density-deuterium substitution rate standard curves for different concentration ranges. The density of the unknown sample is measured using a densitometer and then substituted into the density-deuterium substitution rate standard curve to calculate the deuterium substitution rate, D′1. Next, a deuterium-depleted water sample (weight m1) is added to a heavy water standard sample (weight m2) and shaken to prepare a mixed heavy water sample. The ratio of m1 to m2 must be controlled to ensure an estimated deuterium substitution rate of 98% or higher for the mixed heavy water sample.

[0039] The estimated deuterium substitution rate was calculated according to the following formula:

[0040]

[0041] In the formula:

[0042] D′ 混 : estimated deuterium enrichment of mixed heavy water sample, %.

[0043] m1: weight of low deuterium water sample, g.

[0044] D′1: estimated deuterium enrichment of low deuterium water sample, %.

[0045] m2: weight of heavy water standard sample, g.

[0046] D2: deuterium enrichment of heavy water standard sample, %.

[0047] (3) The prepared mixed heavy water sample is injected into a nuclear magnetic spectrometer for detection, and the peak area of heavy water is A1. The deuterium enrichment is calculated by the peak area according to an external standard method, and the calculation formula is as follows:

[0048] D 混 (%) = 1 - A1 x (1 - D2) / A2

[0049] In the formula:

[0050] D 混 : deuterium enrichment of mixed heavy water sample detected by a nuclear magnetic method, %;

[0051] D2: deuterium enrichment of heavy water standard sample, %.

[0052] A1: water peak area of mixed heavy water sample.

[0053] A2: water peak area of heavy water standard sample.

[0054] (4) The deuterium enrichment D1 of the low deuterium water sample is calculated by the weight of the low deuterium water sample, the weight and deuterium enrichment of the heavy water standard sample, and the deuterium enrichment of the mixed heavy water sample:

[0055]

[0056] In the formula:

[0057] D1: deuterium enrichment of low deuterium water sample, %.

[0058] m1: weight of low deuterium water sample, g.

[0059] D 混 : deuterium enrichment of mixed heavy water sample detected by a nuclear magnetic method, %;

[0060] m2: weight of heavy water standard sample, g.

[0061] D2: Deuterium enrichment of heavy water standard sample, %.

[0062] Specific case 1

[0063] In this case, first, configure the known deuterium enrichment of low deuterium water sample, and then use the method described in the application to detect, through the comparison of results, to verify the feasibility of the method described in the application. The specific steps are as follows:

[0064] 0.5g pure water was mixed with 5.3g, 6.7g, 9.2g, 11g, 14g of heavy water standard solution (deuterium enrichment of 99.85%), respectively, to prepare the low deuterium water samples 1-5 with deuterium enrichment of 90.38%, 92.21%, 94.16%, 90.05%, 96.04%, respectively.

[0065] The heavy water standard sample of Qingdao Tenglong Microwave Technology Co., Ltd. (deuterium enrichment of 99.85%) was used as the heavy water standard sample, and the deuterium enrichment of the low deuterium water samples 1-5 was detected according to the method of the above embodiment, and the results are as shown in Table 1. Figure 2-6 The nuclear magnetic hydrogen spectrum of the mixed heavy water sample prepared by using low deuterium water samples 1-5 and heavy water standard sample of Qingdao Tenglong Microwave Technology Co., Ltd. is shown in Table 1.

[0066] Table 1

[0067] Sample name [D1'] <![CDATA[m2(g)]]> m1(g) [D2] D 混 ’]]> <![CDATA[D 混 ]]> [D1] Deuterium-depleted water sample 1 89.98％ 10.6033 0.999 99.85％ 98.99％ 99.02％ 90.34％ Deuterium-depleted water sample 2 92.03％ 8.3011 0.9996 99.85％ 99.00％ 99.02％ 92.21％ Deuterium-depleted water sample 3 94.05％ 5.9036 1.0003 99.85％ 99.01％ 99.02％ 94.17％ Deuterium-depleted water sample 4 95.11％ 4.7195 0.9988 99.85％ 99.02％ 99.02％ 95.09％ Deuterium-depleted water sample 5 96.01％ 3.5107 0.9996 99.85％ 99.00％ 99.00％ 96.04％

[0068] As can be seen from the results of Table 1, using the method described in the application, the obtained deuterium enrichment result is almost consistent with the true deuterium enrichment.

[0069] Specific case 2

[0070] In this case, first, configure the known deuterium enrichment of low deuterium water sample, and then use the method described in the application to detect, through the comparison of results, to verify the feasibility of the method described in the application. The specific steps are as follows:

[0071] 1g pure water was mixed with 0.76g, 1.12g, 1.7g, 2.65g, 4.49g, 10.5g of heavy water standard solution (deuterium enrichment of 99.89%), respectively, to prepare the low deuterium water samples 6-11 with deuterium enrichment of 40.58%, 50.15%, 60.41%, 70.38%, 80.08%, 90.33%, respectively.

[0072] The heavy water standard sample of Qingdao Tenglong Microwave Technology Co., Ltd. (deuterium enrichment of 99.85%) was used as the heavy water standard sample, and the deuterium enrichment of the low deuterium water samples 1-5 was detected according to the method of the above embodiment, and the results are as shown in Table 1.

[0073] Table 2

[0074] Sample name [D1'] <![CDATA[m2(g)]]> <![CDATA[m1(g)]]> <![CDATA[D2]]> D 混 ’]]> <![CDATA[D 混 ]]> <![CDATA[D1]]> Deuterium-depleted water sample 6 39.02％ 10.2408 0.1275 99.89％ 99.09％ 99.12％ 40.88％ Deuterium-depleted water sample 7 51.03％ 6.5616 0.1069 99.89％ 99.07％ 99.05％ 50.13％ Deuterium-depleted water sample 8 59.13％ 6.4631 0.1281 99.89％ 99.07％ 99.09％ 60.37％ Deuterium-depleted water sample 9 68.83％ 4.1057 0.1113 99.89％ 99.05％ 99.10％ 70.84％ Deuterium-depleted water sample 10 81.04％ 2.7738 0.1185 99.89％ 99.10％ 99.06％ 80.08％ Deuterium-depleted water sample 11 89.08％ 1.4734 0.1319 99.89％ 98.99％ 99.11％ 90.48％

[0075] It can be seen from the results in Table 2 that the deuterium substitution rate obtained by the method of the present invention is almost consistent with the true deuterium substitution rate.

[0076] Specific case 3

[0077] In this case, a low-deuterium water sample with an unknown deuterium substitution rate was first tested using the method described in this invention. The deuterium substitution rate was then tested using deuterium nuclear magnetic resonance spectroscopy. The results were compared to verify the feasibility of the method described in this invention. The specific steps are as follows:

[0078] The deuterium substitution rate of the low-deuterium water samples 12-15 with unknown deuterium substitution rate was determined using the heavy water standard sample (deuterium substitution rate 99.86%) produced by Qingdao Tenglong Microwave Technology Co., Ltd. as the heavy water standard sample. The results are shown in Table 3 below.

[0079] Table 3

[0080]

[0081]

[0082] Deuterium nuclear magnetic resonance spectroscopy was used to detect the low-deuterium water samples 12-15 to be tested. The instrument parameters were adjusted and a special probe was used to observe the deuterium signal. The deuterium substitution rates measured by deuterium nuclear magnetic resonance spectroscopy were 60.15%, 70.13%, 79.99%, and 96.00%, respectively, which were almost consistent with the deuterium substitution rate results in Table 3, indicating that the analysis precision and accuracy of the present invention are high.

[0083] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for detecting the deuterium substitution rate of low-deuterium water, characterized in that: The following steps are involved: (1) Prepare a heavy water standard sample with a known deuterium substitution rate, perform H NMR spectrum testing, and record the water peak area; (2) estimating the deuterium substitution rate of the deuterium-depleted water sample to be tested, and then mixing an appropriate amount of the deuterium-depleted water sample with an appropriate amount of a heavy water standard sample to prepare a mixed heavy water sample with an estimated deuterium substitution rate of more than 98%; (3) Performing H NMR spectrum testing on the mixed heavy water sample, recording the water peak area, and calculating the deuterium substitution rate based on the water peak area according to the external standard method; (4) Calculate the deuterium substitution rate D1 of the deuterium-depleted water sample according to the following formula: Where m1 is the weight of the deuterium-depleted water sample, g; D 混 is the deuterium substitution rate of the mixed heavy water sample, %; m2 is the weight of the heavy water standard sample, g; D2 is the deuterium substitution rate of the heavy water standard sample, %.

2. The method for detecting the deuterium substitution rate of low-deuterium water according to claim 1, wherein: In step (2), the deuterium substitution rate of the deuterium-depleted water sample is detected by density method, which is used as the estimated deuterium substitution rate of the deuterium-depleted water sample.

3. The method for detecting the deuterium substitution rate of low-deuterium water according to claim 1 or 2, characterized in that: In step (2), the estimated deuteration rate of the mixed heavy water sample is recorded as D' 混 , calculated according to the following formula: Where D1′ is the estimated deuterium substitution rate of the deuterium-depleted water sample, %.

4. The method for detecting the deuterium substitution rate of low-deuterium water according to claim 1 or 2, wherein: In step (2), the mass ratio of the deuterium-depleted water sample to the heavy water standard sample is greater than 1:

150.

5. The method for detecting the deuterium substitution rate of low-deuterium water according to claim 1 or 2, wherein: In step (3), the deuterium substitution rate D of the mixed heavy water sample is 混 , calculated according to the following formula: D 混 (%)=1-A1×(1-D2) / A2 Wherein, A1 is the water peak area of ​​the mixed heavy water sample obtained in step (3); A2 is the water peak area of ​​the heavy water standard sample obtained in step (1).

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