Method for detecting water free radical cations by using DMPO

Abstract

The invention belongs to the technical field of detection, relates to a free radical detection method, particularly provides a method for detecting water free radical cations by using DMPO, and aims to realize efficient, rapid, simple and convenient water free radical cation detection convenient for analysis. The method comprises the following steps: by taking an electron paramagnetic resonance spectrum technology as a detection tool and 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trapping agent, applying voltage to water, adding a DMPO aqueous solution with a certain concentration into a reacted solution, and carrying out water free radical cation detection on the solution; a corresponding spectrogram is obtained through electron paramagnetic resonance testing, the spectrogram is fitted, and spectrogram characteristic peaks are analyzed to represent water free radical cations. The method can be used for efficiently, quickly and simply detecting the water free radical cations, is convenient for analyzing the water free radical cations, and has popularization value and application prospect.

Description

Technical Field

[0001] The invention belongs to the field of detection technology and relates to a free radical detection method, in particular to a method for detecting water free radical cations by utilizing DMPO. Background Art

[0002] As the foundation and indispensable substance for life on Earth, water plays a vital role in cellular metabolism, nutrient transport, and waste excretion. In recent years, the topic of water-related free radical chemistry has increasingly attracted the attention of experimental and theoretical researchers, with the study of water radical cation chemistry being particularly prominent. The study of water radical cation chemistry is of significant importance in advancing research in a variety of fields, including the origin of life, cell damage, proton transfer, and hydrogen bond formation. However, due to the extremely short lifespan and extremely low abundance of water radical cations, their detection and research have always faced significant difficulties and severe challenges.

[0003] At present, the detection methods of water radical cations mainly include mass spectrometry and spectroscopy. However, these traditional methods have certain limitations. Traditional mass spectrometry detects the trajectory of the ion to be tested in the magnetic field and nuclear electric field, and distinguishes different ions according to the mass-to-charge ratio, but the ion peaks are numerous and difficult to distinguish. Spectroscopy is a technology that uses an ultrafast X-ray probe. Although this technology can detect and track the dynamic changes of water radical cations, the equipment is complex and the operation is cumbersome. In addition, although free radicals have been obtained by spin trapping using electron paramagnetic resonance instruments to obtain spin-trapping agent adducts, the complex and unclear reaction pathways between free radicals and traps have caused the electron paramagnetic resonance signal to be easily confused and classified, thereby hindering the accurate interpretation of the free radical reaction mechanism. Therefore, there is an urgent need to develop a method for detecting water radical cations that is efficient, rapid, simple and easy to analyze. Summary of the Invention

[0004] The purpose of the present invention is to address the many deficiencies of the above-mentioned prior art and provide a method for detecting water radical cations using DMPO to achieve efficient, rapid, simple and easy-to-analyze water radical cation detection.

[0005] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0006] A method for detecting water radical cations using DMPO is disclosed. The method uses electron paramagnetic resonance spectroscopy as a detection tool, uses 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap, applies voltage to water, adds a certain concentration of DMPO aqueous solution to the reaction solution, and performs water radical cation detection on the solution, thereby performing water radical cation detection in water.

[0007] Furthermore, the method for detecting water radical cations specifically comprises the following steps:

[0008] Step S1: Water is placed in a stainless steel tank, which is then placed in a sealed reactor. An array plate is placed above the solution to prepare a 5,5-dimethyl-1-pyrroline-N-oxide solution of a certain concentration to obtain a DMPO solution;

[0009] Step S2: evacuate the air in the reactor, inject inert gas, and apply voltage. After a period of reaction, remove the reaction solution and add the prepared DMPO solution;

[0010] Furthermore, in step S1, the stainless steel tank has a size of 73×51×6 mm, which serves as the negative electrode of the high-voltage source; the array plate is provided with tungsten needles arranged in a grid array, the distance between the needle tip of the tungsten needle and the water level in the stainless steel tank is between 5-15 mm, the curvature radius of the needle tip is between 0.01-0.1 mm, and the array plate is the positive electrode of the high-voltage source.

[0011] Furthermore, in step S2, the injected inert gas is argon, the applied voltage is 5.5 kV, and different reaction times are adjusted to increase the intensity of the target signal.

[0012] Furthermore, in step S3, when the spin trapping agent is 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), the parameters for the electron paramagnetic resonance (EPR) test are set as: central magnetic field: 3420G, scan width: 100G, and scan time: 5min.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The present invention uses 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a scavenger, which reacts rapidly with water radical cations, has a clear reaction path, and is easy to distinguish in the spectrum;

[0015] 2. The present invention adopts a discharge device, which uses an electric field to apply voltage to water to form water radical cations. The reaction inert gas is argon, which eliminates the influence of oxygen in the air. The operation is simple and the instrument device is low in price.

[0016] 3. The present invention is based on electron paramagnetic resonance spectroscopy, which has high sensitivity and low detection limit;

[0017] In summary, the present invention provides a method for detecting water radical cations using DMPO, which can efficiently, quickly and simply process and detect water radical cations, and has promotion value and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above advantages of the present invention will become apparent and easily understood in conjunction with the following drawings, in which:

[0019] Figure 1 This is a diagram of a water radical cation synthesis device; wherein, 1-array plate, 2-discharge needle, 3-stainless steel tank, 4-high voltage source, 5-paramagnetic resonance instrument;

[0020] Figure 2 This is the electron paramagnetic resonance spectrum of water radical cations captured by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) aqueous solution;

[0021] Figure 3 This is a diagram showing the mechanism of the reaction between 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and water radical cations. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0023] The instrument used in the following embodiments of the present invention is a Bruker EMX electron paramagnetic resonance instrument, and the parameters are set as follows: central magnetic field: 3420G, scan width: 100G, and scan time: 5min.

[0024] Reference detection device on which the detection method is based Figure 1 Specifically, it includes an array plate 1 and a stainless steel tank 3 arranged in a closed reactor, a discharge needle 2 is provided below the array plate 1, and the stainless steel tank 3 is located below the discharge needle 2. The array plate 1 is connected to the positive electrode of the high-voltage source 4, and the stainless steel tank 3 is connected to the negative electrode of the high-voltage source 4. It also includes a paramagnetic resonance instrument for detecting and analyzing the reaction products obtained in the stainless steel tank 3.

[0025] The following describes the above method of detecting water radical cations using DMPO with several examples:

[0026] Example 1

[0027] This embodiment provides a method for detecting water radical cations using DMPO, comprising the following steps:

[0028] S1: Prepare 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) solution using ultrapure water as solvent at a concentration of 60 μL / mL;

[0029] S2: Place water in a stainless steel tank and adjust the height of the array plate to keep the distance between the needle tip and the water surface at 90 mm. Then, evacuate the air from the sealed reactor, inject argon gas, and apply a voltage of 5.5 kV for 5 minutes to form water radical cation clusters in the electric field.

[0030] S3: adding a certain concentration of DMPO solution to the aqueous solution after the reaction, and transferring it to an EPR sample tube for electron paramagnetic resonance testing;

[0031] S4: The EPR spectrum was fitted and analyzed by Bruker Xenon fitting software, and characteristic peaks with hyperfine coupling constants of AN = 15-16G and AHβ = 22-23G were obtained, such as Figures 2 and 3 As shown, Figure 2 This is the electron paramagnetic resonance spectrum of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) aqueous solution capturing water radical cations, indicating the generation of water radical cations. The reaction mechanism of water radical cations with DMPO is as follows: Figure 3 shown.

[0032] Example 2

[0033] This embodiment provides a method for detecting water radical cations using DMPO, comprising the following steps:

[0034] S1: Prepare 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) solution using ultrapure water as solvent at a concentration of 60 μL / mL;

[0035] S2: Place water in a stainless steel tank and adjust the height of the array plate to keep the distance between the needle tip and the water surface at 90 mm. Then, evacuate the air from the sealed reaction chamber, inject argon gas, and apply a voltage of 5.5 kV for 10 minutes to form water radical cation clusters in the electric field.

[0036] S3: adding a certain concentration of DMPO solution to the aqueous solution after the reaction, and transferring it to an EPR sample tube for electron paramagnetic resonance testing;

[0037] S4: The EPR spectrum was fitted and analyzed using Bruker Xenon fitting software, and characteristic peaks with hyperfine coupling constants of AN = 15-16 G and AHβ = 22-23 G were obtained.

[0038] Example 3

[0039] This embodiment provides a method for detecting water radical cations using DMPO, comprising the following steps:

[0040] S1: Prepare 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) solution using ultrapure water as solvent at a concentration of 60 μL / mL;

[0041] S2: Place water in a stainless steel tank and adjust the height of the array plate to keep the distance between the needle tip and the water surface at 90 mm. Then, evacuate the air from the sealed reactor, inject argon gas, and apply a voltage of 5.5 kV for 20 minutes to form water radical cation clusters in the electric field.

[0042] S3: adding a certain concentration of DMPO solution to the aqueous solution after the reaction, and transferring it to an EPR sample tube for electron paramagnetic resonance testing;

[0043] S4: The EPR spectrum was fitted and analyzed by Bruker Xenon fitting software, and the characteristic peaks with hyperfine coupling constants of AN = 15-16G and AHβ = 22-23G were obtained. Figures 2 and 3 As shown, it indicates the generation of water radical cations, and the reaction mechanism of water radical cations and DMPO is shown in the figure.

[0044] The reagents used in Examples 1 to 3 above were all commercially available analytical grade reagents.

[0045] In summary, the method for detecting water radical cations using DMPO proposed in this embodiment achieves efficient, rapid, simple and easy-to-analyze water radical cation detection.

[0046] The above-described embodiments merely represent several specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for detecting water radical cations using DMPO, characterized in that: The detection method uses electron paramagnetic resonance spectroscopy as a detection tool and 5,5-dimethyl-1-pyrroline-N-oxide as a spin trapping agent. A voltage is applied to water, and a certain concentration of DMPO aqueous solution is added to the solution after the reaction and water radical cation detection is performed on the solution. Water radical cation detection is performed in water; a corresponding spectrum is obtained, the spectrum is fitted, and characteristic peaks of the spectrum are analyzed to characterize the water radical cation.

2. A method for detecting water radical cations using DMPO according to claim 1, characterized in that, The detection method of the water radical cation specifically comprises the following steps: Step S1: Water is placed in a stainless steel tank, which is then placed in a sealed reactor with an array plate placed above the stainless steel tank; a 5,5-dimethyl-1-pyrroline-N-oxide solution of a certain concentration is prepared to obtain a DMPO solution; Step S2: evacuating the air in the reactor, injecting inert gas, and applying voltage; after a period of reaction, taking out the reaction solution and adding DMPO solution; Step S3: transferring the solution to which DMPO is added into a quartz sample tube for electron paramagnetic resonance testing to obtain a corresponding spectrum; fitting the spectrum and analyzing the characteristic peaks of the spectrum to characterize the water radical cation.

3. A method for detecting water radical cations using DMPO according to claim 1, characterized in that, In step S1, the stainless steel tank has a size of 73×51×6 mm and serves as the negative electrode of the high-voltage source; the array board is provided with tungsten needles arranged in a grid array, the distance between the needle tip and the water level in the stainless steel tank is between 5-15 mm, and the curvature radius of the needle tip is between 0.01-0.1 mm. The array board serves as the positive electrode of the high-voltage source.

4. A method for detecting water radical cations using DMPO according to claim 1, characterized in that, In step S1, the concentration of the DMPO solution is 50-70 μL / mL.

5. A method for detecting water radical cations using DMPO according to claim 1, characterized in that, In step S2, the injected inert gas is argon, the applied voltage is 5-6 kV, and the intensity of the target signal is increased by adjusting different reaction times.

6. A method for detecting water radical cations using DMPO according to claim 1, characterized in that, In step S3, when the spin trapping agent is 5,5-dimethyl-1-pyrroline-N-oxide, the parameters for the electron paramagnetic resonance test are set as follows: central magnetic field: 3420G, scan width: 100G, and scan time: 5 minutes.

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