Method and system for detecting carbon-13 isotope abundance in carbon dioxide

Abstract

The invention discloses a method and a system for detecting carbon-13 isotope abundance in carbon dioxide. The method comprises the following steps: preparing a 13C-benzoic acid sample by using carbon dioxide containing 13C; the method comprises the following steps: dissolving a < 13 > C-benzoic acid sample in a solvent to prepare a solution to be detected; and carrying out liquid chromatography separation on the solution to be detected, and carrying out ion monitoring in a negative ion mode by adopting mass spectrum so as to obtain the < 13 > C isotope abundance. According to the invention, gaseous 13CO2 is converted into solid benzoic acid which is easy to analyze by LC-MS through a specific chemical derivatization reaction, so that abundance measurement of gas isotopes is converted into intensity ratio measurement of specific molecular ion peaks in a liquid sample, and a new path for isotope abundance detection by using conventional analysis equipment is opened up; the method gets rid of dependence on expensive and special IRMS instruments, can be implemented in any laboratory equipped with conventional LC-MS, and greatly reduces the analysis threshold and cost.

Description

Technical Field

[0001] This invention belongs to the field of isotope analysis technology, specifically relating to a method and system for detecting the abundance of carbon-13 isotopes in carbon dioxide. Background Technology

[0002] Carbon-13 ( 13 C) As a stable carbon isotope, it has important applications in metabolic flux analysis, drug development, environmental science, geochronology, and chemical reaction mechanism research. Accurate determination of CO2 gas... 13 C abundance is a key aspect of these studies. Currently, the determination of C abundance is crucial. 13 The gold standard method for C abundance is gas isotope ratio mass spectrometry (IRMS). This method has extremely high precision and accuracy, but its instruments are expensive, its operation and maintenance costs are high, its operation is complex, and it usually requires a relatively large number of samples and complex pretreatment, which limits its popularity and application in routine laboratories.

[0003] Liquid chromatography-mass spectrometry (LC-MS) is a widely used high-sensitivity, high-selectivity analytical tool in analytical laboratories. Compared to gas chromatography-mass spectrometry (GC-MS), LC-MS is more suitable for analyzing polar, thermally unstable, and large molecular compounds. However, due to… 13 C and 12 The mass difference of C is only 1 Da, while the mass resolution and accuracy of LC-MS in conventional operating mode are usually insufficient to accurately distinguish isotope peaks, and instrument mass discrimination effects also exist. Therefore, directly using LC-MS to quantitatively analyze minute isotope abundance changes in gas samples is extremely challenging. Currently, there are few cases of accurately determining CO2 using conventional LC-MS platforms. 13 A report on a simple and reliable method for C abundance. Summary of the Invention

[0004] To address the problems in the prior art, the present invention aims to provide a method and system for detecting the abundance of carbon-13 isotopes in carbon dioxide.

[0005] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows: A method for detecting the abundance of carbon-13 isotopes in carbon dioxide includes the following steps: Step 1: Utilize the ingredients containing 13 C is prepared from carbon dioxide. 13 C-benzoic acid sample; Step 2, 13 The C-benzoic acid sample was dissolved in a solvent to prepare a test solution; Step 3: Separate the test solution by liquid chromatography and monitor the ions using mass spectrometry in negative ion mode to obtain... 13 C isotope abundance.

[0006] Furthermore, in step one, using the ingredient... 13 C is prepared from carbon dioxide. 13 The steps for obtaining C-benzoic acid samples include: 1) Add polished magnesium strips, iodine and a magnetic stir bar to the reaction apparatus. Mix bromobenzene and tetrahydrofuran solution in a dropping funnel. Connect a nitrogen cylinder and a vacuum pump through a three-way valve and pump the gas several times. 2) Turn on the magnetic stirrer and slowly add the bromobenzene and tetrahydrofuran solution. Keep the solution at a gentle boil in a 50-60°C water bath until the amount of magnesium strip no longer changes. Cool it down and set it aside. 3) Containing 13 Carbon dioxide (C) is introduced into the reaction apparatus through a gas delivery needle and reacted at 0~5℃ for 2.5~3.5 hours. 4) Slowly add a saturated ammonium chloride solution, allow it to react completely, then separate and purify to obtain... 13 C-benzoic acid sample.

[0007] Furthermore, in step 1), the amount of magnesium strip added is 1.99~2.04g; the amount of bromobenzene added is 6.5~7.5mL; and the amount of tetrahydrofuran added is 15~18mL.

[0008] Furthermore, in step two, 40-60 mg is dissolved in 0.8-1.2 mL of 50% acetonitrile aqueous solution. 13 C-benzoic acid samples, with a concentration of 40~60 μg / mL.

[0009] Furthermore, in step three, the conditions for liquid chromatography include: An Acquity UPLC BEH C18 column was used, with a column temperature of 38–42 °C. The mobile phase is a mixed solution composed of acetonitrile and an aqueous solution of ammonium formate and formic acid, wherein the volume ratio of ammonium formate, formic acid and water in the aqueous solution of ammonium formate and formic acid is 0.08~0.12:0.8~1.2:900~1100; Isocratic elution was performed, with the volume ratio of acetonitrile to ammonium formate aqueous solution being 55:45 to 65:35, and the flow rate being 0.2 to 0.4 mL / min.

[0010] Furthermore, in step three, the conditions for the mass spectrometry analysis include: Ions with mass-to-charge ratios (m / z) of 120.88 and 121.97 in the sample were monitored using an XEVO TQD liquid chromatography-mass spectrometry (LC-MS) system.

[0011] Furthermore, in step three, the conditions for the mass spectrometry analysis include: The desolventizing temperature is 480~520℃, the desolventizing gas flow rate is 900~1100L / h, and the ion mode is ES-.

[0012] This invention also discloses a system for detecting the abundance of carbon-13 isotopes in carbon dioxide, comprising: Reaction apparatus, used for synthesis 13 C-benzoic acid sample; A liquid chromatography apparatus, including an Acquity UPLC BEH C18 column, for performing liquid chromatography separation; A mass spectrometry analysis device is used to monitor ions with mass-to-charge ratios of m / z: 120.88 and m / z: 121.97 in the sample; The data processing unit is used to receive mass spectrometry data and derive... 13 C isotope abundance.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Method innovation: This invention utilizes gaseous... 13 CO2 is converted into solid carboxylic acid compounds (benzoic acid) through specific chemical derivatization reactions, which are easy to analyze with LC-MS. This transforms the measurement of the abundance of gaseous isotopes into the measurement of the intensity ratio of specific molecular ion peaks in liquid samples, opening up a new path for isotope abundance detection using conventional analytical equipment. (2) Low cost: It eliminates the dependence on expensive and dedicated IRMS instruments, and can be implemented in any laboratory equipped with conventional LC-MS, which greatly reduces the analytical threshold and cost; (3) Simple operation: The derivatization reaction is a classic organic synthesis reaction, and the steps are mature and reliable; LC-MS analysis uses conventional conditions, which are easy to master and repeat; (4) Reliable results: This invention is effective for high abundance. 13 The CO2 sample measurement results showed good repeatability and a high degree of agreement with the theoretical expected value, proving its quantitative accuracy. (5) Wide range of applications: suitable for monitoring CO2. 13 C abundance has significant application value in various scenarios, such as biological metabolism research, catalytic reaction tracing, and environmental carbon cycle research. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a production route diagram for the present invention; Figure 3This is the blank control chromatogram of the present invention; Figure 4-5 The images show chromatograms of two parallel tests performed on the test solution of Example 1 of the present invention. Detailed Implementation

[0015] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0016] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0017] like Figure 1-5 As shown, this invention discloses a method for detecting the abundance of carbon-13 isotopes in carbon dioxide, comprising the following steps: Step 1: Utilize the ingredients containing 13 C is prepared from carbon dioxide. 13 C-benzoic acid sample; Step 2, 13 The C-benzoic acid sample is dissolved in a solvent to prepare the test solution; specifically, 40-60 mg is dissolved in 0.8-1.2 mL of 50% (v / v) acetonitrile-water. 13 C-benzoic acid samples were prepared into test solutions with a concentration of 40-60 μg / mL. Step 3: Separate the test solution by liquid chromatography and monitor the ions by mass spectrometry to obtain... 13 C isotope abundance.

[0018] In some implementations, in step one, a method containing... 13 C is prepared from carbon dioxide. 13 The steps for obtaining C-benzoic acid samples include: 1) Add 1.99~2.04g of polished magnesium strip (Mg), a small grain of iodine (iodine acts as a catalyst, making magnesium and bromobenzene react more easily) and a magnetic stir bar to the reaction apparatus. Mix 6.5~7.5mL of bromobenzene with 15~18mL of tetrahydrofuran (THF) in a dropping funnel. Connect the reaction apparatus to a nitrogen cylinder and a vacuum pump, and evacuate the gas several times. 2) Turn on the magnetic stirrer and slowly add the bromobenzene and tetrahydrofuran solution. Keep the solution at a gentle boil in a 50-60°C water bath until the amount of magnesium strip no longer changes. Cool it down and set it aside. 3) Containing13 C carbon dioxide ( 13 CO2 is introduced into the reaction apparatus through a gas guide needle and reacted at 0~5℃ for 2.5~3.5h; 4) Slowly add saturated ammonium chloride (NH4Cl) solution, allow it to react completely, then separate and purify to obtain... 13 C-benzoic acid sample.

[0019] In some implementations, the conditions for liquid chromatography in step three include: An Acquity UPLC BEH C18 column was used, with a column temperature of 38–42 °C. The mobile phase is a mixed solution composed of acetonitrile and ammonium formate aqueous solution, wherein the volume ratio of ammonium formate, formic acid and water in the ammonium formate aqueous solution is 0.08~0.12:0.8~1.2:900~1100; Isocratic elution was performed with an acetonitrile to ammonium formate aqueous solution volume ratio of 55:45 to 65:35 and a flow rate of 0.2 to 0.4 mL / min.

[0020] In some implementations, the conditions for mass spectrometry analysis in step three include: Ions with mass-to-charge ratios (m / z) of 120.88 and 121.97 in the sample were monitored using an XEVO TQD liquid chromatography-mass spectrometry (LC-MS) system. The desolventizing temperature is 480~520℃, the desolventizing gas flow rate is 900~1100L / h, and the ion mode is ES-.

[0021] This invention also discloses a system for detecting the abundance of carbon-13 isotopes in carbon dioxide, comprising: Reaction apparatus, used for synthesis 13 C-benzoic acid sample; A liquid chromatography apparatus, including an Acquity UPLC BEH C18 column, for performing liquid chromatography separation; A mass spectrometry analysis device is used to monitor ions with mass-to-charge ratios of m / z: 120.88 and m / z: 121.97 in the sample; The data processing unit is used to receive mass spectrometry data and derive... 13 C isotope abundance.

[0022] Example 1 like Figure 1-5 As shown, a method for detecting the abundance of carbon-13 isotopes in carbon dioxide includes the following steps: Step 1: Utilize the ingredients containing 13 C is prepared from carbon dioxide. 13 For C-benzoic acid samples, the specific steps are as follows: 1) Add 2g of magnesium strip polished with sandpaper, a small iodine crystal and a stirring magnet to a three-necked flask 1. Install a dropping funnel on the three-necked flask 1. Mix 7mL of bromobenzene and 16mL of tetrahydrofuran in the dropping funnel. Connect the nitrogen cylinder and the vacuum device through the three-way valve 2 to introduce nitrogen and vacuum. Vacuum the gas three times. 2) Start the thermostatic magnetic stirrer 3 below the three-necked flask 1, turn on the stirring magnet, slowly drop in the bromobenzene and tetrahydrofuran solution, keep the solution in a gentle boiling state in a 60°C water bath until the amount of magnesium strip no longer changes, then cool it down for later use. 3) Containing 13 Carbon dioxide from C was introduced into three-necked flask 1 through a gas delivery needle, and the reaction was carried out at 0°C for 3 hours. 4) Slowly add saturated ammonium chloride solution dropwise to three-necked flask 1. After the reaction is complete, separate and purify to obtain... 13 C-benzoic acid sample; The production route (chemical derivatization reaction) is as follows: Step 2: Dissolve 50 mg in 1 mL of 50% acetonitrile solution. 13 C-benzoic acid sample was prepared into a test solution with a concentration of 50 μg / mL; Step 3: Separate the solution to be tested by liquid chromatography and monitor the ions by mass spectrometry in negative ion mode; The conditions for liquid chromatography include: An Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 μm) was used at a column temperature of 40 °C. Elution was performed using a mobile phase of acetonitrile and an aqueous solution of ammonium formate and formic acid at a ratio of 60:40. The flow rate was 0.3 mL / min. The volume ratio of ammonium formate, formic acid, and water in the aqueous solution was 0.1:1:1000. The injection volume was 5 μL. The conditions for mass spectrometry analysis include: Ions with mass-to-charge ratios (m / z) of 120.88 and 121.97 in the sample were monitored using an XEVO TQD liquid chromatography-mass spectrometry (LC-MS) system. An electrospray ion source was used, with ES- ion mode, a desolvation temperature of 500℃, and a desolvation gas flow rate of 1000L / h. Finally obtained 13 C isotope abundance 13 The abundance of C was 98.61% and 98.3%, respectively. Figure 4-5 The %TIC value of mass: 121.97 shown in the image is... 13 CO2 13 C abundance value.

[0023] A system for detecting the abundance of carbon-13 isotopes in carbon dioxide includes: The reaction apparatus, including a three-necked flask 1, is used for synthesis. 13 The C-benzoic acid sample is connected to a nitrogen cylinder and a vacuum device via a three-way valve 2 in a three-necked flask 1 to access nitrogen and vacuum. A thermostatic magnetic stirrer 3 is installed below the three-necked flask 1. A liquid chromatography apparatus, including an Acquity UPLC BEH C18 column, for performing liquid chromatography separation; A mass spectrometry analysis device is used to monitor ions with mass-to-charge ratios of m / z: 120.88 and m / z: 121.97 in the sample; The data processing unit is used to receive mass spectrometry data and derive... 13 C isotope abundance.

[0024] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0025] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method of detecting carbon- 13 isotope abundance in carbon dioxide, characterized by, The method comprises the following steps: Step one, preparation of C-carboxylic acid sample using carbon dioxide containing 13 C- benzoic acid sample 13 C- benzoic acid sample Step two, dissolve 13 The C-benzoic acid sample is dissolved in a solvent to prepare a test solution. Step three, the solution to be tested is separated by liquid chromatography, and ion monitoring is carried out by mass spectrometry, so as to obtain 13 C Isotope abundance.

2. The method of claim 1, wherein the method is used to detect the abundance of carbon- 13 isotope in carbon dioxide. In step one, carbon dioxide containing 13 C was used to prepare 13 C-benzoic acid samples included the steps of: 1) adding a polished magnesium strip, iodine and a stirring magnet in a reaction device, mixing a bromobenzene and tetrahydrofuran solution in a dropping funnel, connecting a nitrogen cylinder and a vacuum device through a three-way valve, and replacing the gas several times; 2) starting the stirring magnet, slowly dropping the bromobenzene and tetrahydrofuran solution, keeping the solution in a slightly boiling state in a 50-60℃ water bath, until the amount of the magnesium strip no longer changes, and cooling for use; 3) Containing 13 Carbon dioxide (C) is introduced into the reaction apparatus through a gas delivery needle and reacted at 0~5℃ for 2.5~3.5 hours. 4) Slowly drop saturated ammonium chloride solution, separate and purify after full reaction, get 13 C-benzoic acid sample.

3. The method of claim 2, wherein the method is used to detect the abundance of carbon- 13 isotope in carbon dioxide. In step 1), the amount of the magnesium strip added is 1.99-2.04g; the amount of the bromobenzene added is 6.5-7.5mL; and the amount of the tetrahydrofuran added is 15-18mL.

4. The method of claim 1, wherein the method is used to detect the abundance of carbon- 13 isotope in carbon dioxide. In step two, 40-60 mg of C-benzoic acid sample was dissolved in 0.8-1.2 mL of 50% acetonitrile aqueous solution 13 C-benzoic acid sample, sample concentration 40-60 μg / mL.

5. The method of claim 1, wherein the method is used to detect the abundance of carbon- 13 isotope in carbon dioxide. In step three, the conditions of the liquid chromatography include: An Acquity UPLC BEH C18 chromatographic column is used, and the column temperature is 38-42℃; The mobile phase is a mixed solution of acetonitrile and an ammonium formate aqueous solution, and the volume ratio of ammonium formate, formic acid and water in the ammonium formate aqueous solution is 0.08-0.12:0.8-1.2:900-1100; Isocratic elution is performed, and the volume ratio of acetonitrile to ammonium formate aqueous solution is 55:45-65:35, and the flow rate is 0.2-0.4mL / min.

6. The method of claim 1, wherein the method is used to detect the abundance of carbon- 13 isotope in carbon dioxide. In step three, the conditions of the mass spectrometry include: An XEVO TQD liquid chromatography-mass spectrometry instrument is used to perform ion monitoring on the mass-to-charge ratio m / z:120.88 and m / z:121.97 in the sample.

7. The method of claim 1, wherein the method is used to detect the abundance of carbon- 13 isotope in carbon dioxide. In step three, the conditions of the mass spectrometry include: The desorption temperature is 480-520℃, the desorption gas flow rate is 900-1100L / h, and the ion mode is ES-.

8. A system for detecting carbon-13 isotope abundance in carbon dioxide, characterized by, It comprises: Reaction apparatus for the synthesis of 13 C-benzoic acid sample; A liquid chromatography device comprising an Acquity UPLC BEH C18 chromatographic column for performing liquid chromatography separation; A mass spectrometry device for performing ion monitoring on the mass-to-charge ratio m / z:120.88 and m / z:121.97 in the sample; a data processing unit for receiving mass spectrometry data and deriving 13 C isotope abundance.

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