Application of benzophenone derivative as bipolar matrix-assisted laser desorption ionization matrix in mass spectrometric detection

Abstract

The invention discloses an application of a benzophenone derivative as a bipolar matrix-assisted laser desorption ionization matrix in mass spectrometry detection. The benzophenone derivative matrix provided by the invention can effectively improve desorption ionization efficiency and reduce background interference, is compatible with a positive ion and negative ion bipolar detection mode, and solves the technical bottleneck of single polarity of a traditional matrix detection mode. The matrix has a wide-spectrum absorption characteristic in an ultraviolet region, can be adapted to laser wavelengths of various matrix-assisted laser desorption ionization mass spectrometers, and has a wide application prospect. Besides, when the matrix is used for lipid compound detection, lipid endogenous metabolite spectrum signals with high sensitivity and high coverage rate can be obtained in positive and negative ion modes, the matrix is expected to be widely used for metabonomics and clinical basic research, and key technical support is provided for high-sensitivity and bipolar imaging of small molecule compounds in complex biological samples.

Description

Technical Field

[0001] The present invention belongs to the technical field of mass spectrometry detection, and particularly relates to the application of a benzophenone derivative as a bipolar matrix-assisted laser desorption / ionization matrix in mass spectrometry detection. Background Art

[0002] Matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS) is a soft ionization mass spectrometry technology developed in the 1980s. Its core principle is that matrix molecules absorb laser energy and transfer it to analyte molecules to achieve gentle ionization, which is particularly suitable for the rapid analysis of high molecular weight substances such as proteins, nucleic acids, and synthetic polymers. Compared with traditional ionization technologies such as electron impact ionization, matrix-assisted laser desorption / ionization has significant advantages such as high detection sensitivity, wide molecular weight coverage range, and strong anti-matrix interference ability, and has now become one of the core tools for high-throughput analysis of biological macromolecules.

[0003] In MALDI-MS analysis, the selection of the matrix is a key technical factor determining the success of detection and needs to meet the following functions: (1) forming a uniform co-crystal with the analyte to promote energy transfer; (2) having strong absorption characteristics at the laser wavelength (such as 335 nm); (3) inducing analyte ionization through proton transfer or charge capture mechanism after self-ionization. However, existing commercial MALDI matrices (such as α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (DHB), and sinapic acid (SA), etc.) are mostly designed for biological macromolecules. On the one hand, the background interference is serious in the low molecular weight region and the detection sensitivity of small molecules is low; on the other hand, they only adapt to a single polarity detection mode of positive ions or negative ions, and it is difficult to meet the synchronous detection requirements of bipolar molecules such as lipid compounds in complex samples, which severely restricts the application of MALDI technology in the detection of small molecule compounds.

[0004] Numerous attempts and studies have been made regarding the MALDI analysis and application of small molecule compounds. The existing technical routes can be summarized into two categories: the derivatization of small molecule analytes and the development of new matrices. Among them, reactive MALDI matrices for derivatizing small molecule compounds covalently bind small molecule analytes to reactive matrices (such as hydrazine compounds) through chemical modification to improve their ionization efficiency. This method has inherent defects such as uncontrollable derivatization reactions (by-product interference), molecular spatial displacement (derivatization leads to loss of in-situ information), and poor target universality (only applicable to specific functional groups). New matrices include new nanomaterial matrices and new organic small molecule matrices. Among them, nanomaterial matrices utilize the high specific surface area and photothermal conversion characteristics of nanoparticles such as graphene and metal-organic framework materials to enhance ionization efficiency. Although such matrices can theoretically reduce background interference, their applications are limited by problems such as poor instrument compatibility (nanoparticles are prone to clogging ion transport channels) and low repeatability (large performance fluctuations between batches). Based on the above technical bottlenecks, the development of new bipolar MALDI matrices with broad-spectrum ionization compatibility (positive / negative ion modes), low background interference, and high ionization efficiency has become the core breakthrough for expanding the application of MALDI technology in in-situ detection of small molecules. Summary of the Invention

[0005] The object of the present invention is to provide an application of a benzophenone derivative as a bipolar matrix-assisted laser desorption ionization (MALDI) matrix in mass spectrometry detection.

[0006] The present invention provides an application of a benzophenone derivative as a bipolar MALDI matrix in mass spectrometry detection. The benzophenone derivative is a series of derivatives obtained by substituting and modifying the benzene ring of benzophenone, which not only expands the ultraviolet light absorption characteristics of the benzophenone conjugate system but also provides the efficacy of bipolar MALDI detection. The structural formula is as follows: Wherein R1 is independently selected from one of hydrogen or hydroxyl; R2 is independently selected from one of hydroxyl, methoxy, dimethylamino, diethylamino, dipropylamino, or dibutylamino; R3 is independently selected from one of hydrogen, hydroxyl, carboxyl, methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, n-butoxycarbonyl, n-hexyloxycarbonyl, morpholinocarbonyl, N-ethylaminocarbonyl, N-butylaminocarbonyl, N-phenylaminocarbonyl; R4 is independently selected from one of hydrogen, hydroxyl, dimethylamino, or diethylamino.

[0007] When benzophenone derivatives are used as MALDI matrices for detecting compounds, they have the advantages of bipolar detection and high desorption ionization efficiency. In addition, they have lower background interference than traditional small molecule matrices, which is very helpful for the detection of small molecule analytes, especially in the detection of lipid compounds, and are expected to meet the requirements of excellent matrices for matrix-assisted laser desorption ionization mass spectrometry.

[0008] The bipolar MALDI matrix of the benzophenone derivative has good positive / negative ion compatibility, which is very helpful for its later application in the detection of small molecule metabolites. The bipolar MALDI matrix of the benzophenone derivative is used to detect small molecule compounds with a mass-to-charge ratio range between 50 - 2000 Da. The small molecule compounds are lipid compounds, including but not limited to fatty acids, glyceroglycolipids, phospholipids, sphingolipids, sterol lipids and other lipid compounds.

[0009] Specifically, the method of applying the benzophenone derivative as a bipolar MALDI matrix in MALDI mass spectrometry and / or MALDI mass spectrometry imaging analysis includes the following steps: (1) Prepare the benzophenone derivative matrix solution: Weigh 1 mg, 5 mg, 10 mg, 25 mg, 50 mg of the matrix powder and dissolve it in 1 mL of organic solvent to obtain a matrix solution with a concentration of 1 mg / mL - 50 mg / mL. The influence of the matrix solvent on mass spectrometry analysis was investigated, and the results showed that methanol was the best solvent for the matrix solution. The influence of the matrix concentration on mass spectrometry detection was investigated, and the results showed that the mass concentration of the matrix solution was best at 20 mg / mL.

[0010] (2) Prepare the metal target sample for MALDI mass spectrometry analysis, which can be carried out by one of the following two sample dropping methods: a) Sample dropping method 1: Use a pipette to aspirate 1 μL of the analyte solution to be measured and drop it on the target plate, and let it stand for 10 minutes. After waiting for the analyte to dry, then drop 1 μL of the matrix solution to cover the surface of the dried analyte, and let it stand for 20 minutes to form a co-crystal of the matrix and the analyte, and then perform mass spectrometry analysis.

[0011] b) Sample dropping method 2: Use a pipette to aspirate 10 μL of the matrix solution into a 0.2 mL centrifuge tube, then add 10 μL of the analyte solution to be measured, mix and ultrasonicate, and then use a pipette to aspirate 1 μL of the mixed solution of the matrix and the analyte and drop it on the target plate, and let it stand for 20 minutes. After forming a co-crystal of the matrix and the analyte, perform mass spectrometry analysis.

[0012] Through experimental verification, it is preferred to use sample dropping method 1 for the dropping experiment.

[0013] (3)Preparation of tissue section samples for MALDI mass spectrometry imaging analysis: The tissue to be tested is stored at -80 °C for 8 hours to be completely frozen. Subsequently, the frozen tissue is fixed on a cryostat and cut into tissue sections no thicker than 50 μm at -20 °C using the cryostat. Immediately, the sections are pasted onto an ITO-coated glass slide. Finally, the glass slide with the tissue sections is placed into a 50 mL conical centrifuge tube and stored at -20 °C for subsequent matrix deposition and MALDI mass spectrometry imaging analysis.

[0014] For the above-mentioned matrix deposition, one of the following two methods can be adopted: a) Matrix deposition method 1: The matrix is deposited using a vacuum sublimation device. Among them, the glass slide with the tissue sections needs to be placed upside down on the sample holder of the automatic sublimator. 300 mg of the matrix is loaded onto a stainless steel tray, the circuit is connected, and the laser irradiation is adjusted. The oil pump is used to continuously evacuate the air. The matrix can be sublimated under the conditions of vacuum and heating at 60 °C for 20 minutes. The total amount of the matrix deposited on each glass slide is 6 mg, and the thickness of the uniform matrix layer generated is 1.5 μm. After the matrix is sublimated and deposited, the glass slide needs to be subjected to solvent vapor fumigation recrystallization in an organic solvent environment before mass spectrometry imaging analysis.

[0015] b) Matrix deposition method 2: The matrix is deposited using a semi-automatic spraying device. Transfer 1 mL of the matrix solution into the spraying device, and evenly spray the matrix solution onto the surface of the tissue section to be tested in a fume hood. After standing for 15 minutes, solvent vapor fumigation recrystallization is carried out in an organic solvent environment, and then mass spectrometry imaging analysis is performed.

[0016] Through experimental verification, the preferred matrix deposition method is deposition method 2.

[0017] The specific process of the above-mentioned solvent vapor fumigation recrystallization is as follows: The glass slide deposited with the matrix is first pre-cooled in an environment at -20 °C for 20 minutes. Filter paper strips are placed in a conventional petri dish, 1 mL of 50% methanol solution is dropped onto the filter paper, and then the petri dish cover is covered to form a saturated vapor. Then, the pre-cooled glass slide is placed into the petri dish and left standing for 5 minutes for recrystallization.

[0018] When the above-mentioned benzophenone derivative bipolar MALDI matrix is used for MALDI mass spectrometry and / or MALDI mass spectrometry imaging analysis, the laser spot size is set to 1, the laser frequency is 1000 Hz, the laser intensity is 12%, the integration times is 1 time / pixel, the detector voltage is 1.89 kV, the positive ion source sample voltage is 3.5 kV, and the negative ion source sample voltage is 3.0 kV.

[0019] The benzophenone derivative bipolar MALDI matrix provided by the present invention can be used for the test and analysis of complex samples, including but not limited to blood samples, microbial samples, water environment or soil environment samples, biological tissue section samples, and plant tissue section samples.

[0020] The benzophenone derivative matrix provided by the present invention can effectively improve the desorption ionization efficiency and reduce background interference. At the same time, it is compatible with the bipolar detection modes of positive ions and negative ions, solving the technical bottleneck of the single polarity of the traditional matrix detection mode. This matrix has a broadband absorption characteristic in the ultraviolet region, can adapt to the laser wavelengths of various matrix-assisted laser desorption ionization mass spectrometry instruments, and has broad application prospects. In addition, when this matrix is used for the detection of lipid compounds, high-sensitivity and high-coverage lipid endogenous metabolite mass spectrometry signals can be obtained in both positive and negative ion modes, and it is expected to be widely used in metabolomics and clinical basic research, providing key technical support for the high-sensitivity and bipolar imaging of small molecule compounds in complex biological samples.

[0021] Compared with the prior art, the beneficial effects of the present invention include but are not limited to: 1. The present invention provides a benzophenone derivative used as a bipolar MALDI matrix. The benzophenone derivative matrix can effectively improve the desorption ionization efficiency and reduce background interference, and can be compatible with the bipolar detection modes of positive ions and negative ions at the same time, which is helpful for the detection of small molecule analytes.

[0022] 2. The present invention provides a benzophenone derivative used as a bipolar MALDI matrix. The benzophenone derivative matrix can achieve the bipolar detection of lipid endogenous metabolites, and high-sensitivity and high-coverage mass spectrometry signals can be obtained in both positive and negative ion modes.

[0023] 3. The present invention provides a benzophenone derivative used as a bipolar MALDI matrix. The benzophenone derivative matrix has a broadband absorption characteristic in the ultraviolet region (200 - 400 nm), can adapt to the laser emission wavelengths of various MALDI-MS instruments, and has high instrument compatibility. Description of the Drawings

[0024] Figure 1 It is the MALDI mass spectrum obtained by using benzophenone derivative compound I as a bipolar MALDI matrix to detect the total lipid extract; Figure 2 It is the MALDI mass spectrum obtained by using benzophenone derivative compound II as a bipolar MALDI matrix to detect the total lipid extract; Figure 3 It is the MALDI mass spectrometry imaging comparison diagram of using benzophenone derivative compound X as a bipolar MALDI matrix and a common MALDI matrix when detecting endogenous lipids in mouse brain tissue sections; Figure 4 It is a comparison chart of the background peaks of benzophenone derivative compound X and common MALDI matrices in the positive ion detection mode; Figure 5 It is a comparison chart of the background peaks of benzophenone derivative compound X and common MALDI matrices in the negative ion detection mode; Figure 6 It is the solid UV spectrum of benzophenone derivative compound X. Detailed implementation manners

[0025] The present invention will be described in detail below in conjunction with embodiments, but the present invention is not limited to these embodiments.

[0026] Example 1: Benzophenone derivative compound I is used as a bipolar MALDI matrix for lipid total extract mass spectrometry The present invention provides a benzophenone derivative bipolar MALDI matrix, which can simultaneously be compatible with high-efficiency ionization in both positive and negative ion modes, breaking through the technical limitations of single-polar detection of traditional small molecule matrices. In this example, compound I is selected as a representative benzophenone derivative matrix to test its bipolar detection performance for the total lipid extract of mouse liver, so as to evaluate the application effect of the benzophenone derivative bipolar MALDI matrix in complex samples. First, weigh 10 mg of compound I, add 1 mL of methanol to dissolve and dilute it to prepare a matrix solution; use a pipette to add 1 μL of the total lipid extract, and after drying, add 1 μL of the matrix solution on its surface. After standing for 20 minutes, perform MALDI mass spectrometry detection, and the results are as Figure 1 shown. It is found that when compound I is used as a bipolar MALDI matrix, in the positive ion mode, 533 lipid signal peaks are detected from the total lipid extract; in the negative ion mode, 792 lipid signal peaks are detected from the total lipid extract; a total of 1325 lipid signal peaks, which is the largest number of signal peaks detected in a single experiment using a single organic small molecule matrix known so far. It shows that when benzophenone derivatives are used as bipolar MALDI matrices, they have high desorption ionization efficiency.

[0027] Example 2: Benzophenone derivative compound II is used as a bipolar MALDI matrix for lipid total extract mass spectrometry In this example, compound II was selected as the representative benzophenone derivative matrix to test its bipolar detection performance for the total lipid extract of mouse liver, so as to evaluate the application effect of the bipolar MALDI matrix of benzophenone derivatives in complex samples. First, 10 mg of compound II was weighed and dissolved and diluted with 0.5 mL of methanol to prepare a matrix solution. 1 μL of the total lipid extract was added dropwise using a pipette. After drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. The results are as Figure 2 shown. It was found that when compound II was used as the bipolar MALDI matrix, 321 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 232 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 553 lipid signal peaks.

[0028] Example 3: Benzophenone derivative compound III as a bipolar MALDI matrix for mass spectrometry analysis of total lipid extracts In this example, compound III was selected as the representative benzophenone derivative matrix to test its bipolar detection performance for the total lipid extract of mouse liver, so as to evaluate the application effect of the bipolar MALDI matrix of benzophenone derivatives in complex samples. First, 10 mg of compound III was weighed and dissolved and diluted with 1 mL of acetonitrile to prepare a matrix solution. 1 μL of the total lipid extract was added dropwise using a pipette. After drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. It was found that when compound III was used as the bipolar MALDI matrix, 366 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 432 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 798 lipid signal peaks.

[0029] Example 4 Benzophenone derivative compound IV as a bipolar MALDI matrix for mass spectrometry analysis of total lipid extracts In this example, compound IV was selected as a representative benzophenone derivative matrix to test its bipolar detection performance for the total lipid extract of mouse liver, so as to evaluate the application effect of the bipolar MALDI matrix of benzophenone derivatives in complex samples. First, 10 mg of compound IV was weighed and dissolved and diluted with 0.5 mL of acetonitrile to prepare a matrix solution; 1 μL of the total lipid extract was added dropwise using a pipette, and after drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. It was found that when compound IV was used as a bipolar MALDI matrix, 292 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 79 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 371 lipid signal peaks.

[0030] Example 5: Use of benzophenone derivative compound V as a bipolar MALDI matrix for mass spectrometry analysis of total lipid extracts In this example, compound V was selected as a representative benzophenone derivative matrix to test its bipolar detection performance for the total lipid extract of mouse liver, so as to evaluate the application effect of the bipolar MALDI matrix of benzophenone derivatives in complex samples. First, 5 mg of compound V was weighed and dissolved and diluted with 0.5 mL of dichloromethane to prepare a matrix solution; 1 μL of the total lipid extract was added dropwise using a pipette, and after drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. It was found that when compound V was used as a bipolar MALDI matrix, 304 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 64 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 368 lipid signal peaks.

[0031] Example 6: Use of benzophenone derivative compound VI as a bipolar MALDI matrix for mass spectrometry analysis of total lipid extracts In this example, compound VI was selected as a representative benzophenone derivative matrix to test its bipolar detection performance for the total lipid extract of mouse liver, so as to evaluate the application effect of the bipolar MALDI matrix of benzophenone derivatives in complex samples. First, 5 mg of compound VI was weighed and dissolved and diluted with 0.5 mL of ethanol to prepare a matrix solution; 1 μL of the total lipid extract was added dropwise using a pipette, and after drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. It was found that when compound VI was used as a bipolar MALDI matrix, 118 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 40 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 158 lipid signal peaks.

[0032] Example 7: Diphenylmethanone derivative compound VII as a bipolar MALDI matrix for mass spectrometry analysis of total lipid extracts In this example, compound VII was selected as a representative diphenylmethanone derivative matrix to test its bipolar detection performance for total lipid extracts from mouse liver, so as to evaluate the application effect of diphenylmethanone derivative bipolar MALDI matrix in complex samples. First, 5 mg of compound VII was weighed and dissolved and diluted with 1 mL of ethanol to prepare a matrix solution; 1 μL of total lipid extract was added dropwise using a pipette, and after drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. It was found that when compound VII was used as a bipolar MALDI matrix, 67 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 80 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 147 lipid signal peaks were detected.

[0033] Example 8: Diphenylmethanone derivative compound VIII as a bipolar MALDI matrix for mass spectrometry analysis of total lipid extracts In this example, compound VIII was selected as a representative diphenylmethanone derivative matrix to test its bipolar detection performance for total lipid extracts from mouse liver, so as to evaluate the application effect of diphenylmethanone derivative bipolar MALDI matrix in complex samples. First, 15 mg of compound VIII was weighed and dissolved and diluted with 0.5 mL of methanol to prepare a matrix solution; 1 μL of total lipid extract was added dropwise using a pipette, and after drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. It was found that when compound VII was used as a bipolar MALDI matrix, 296 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 266 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 562 lipid signal peaks were detected.

[0034] Example 9: Diphenylmethanone derivative compound IX as a bipolar MALDI matrix for mass spectrometry analysis of total lipid extracts In this example, compound IX was selected as the representative benzophenone derivative matrix to test its bipolar detection performance for the total lipid extract of mouse liver, so as to evaluate the application effect of the benzophenone derivative bipolar MALDI matrix in complex samples. First, 5 mg of compound IX was weighed and dissolved and diluted with 1 mL of dichloromethane to prepare a matrix solution. 1 μL of the total lipid extract was added dropwise using a pipette gun. After drying, 1 μL of the matrix solution was added dropwise on its surface. After standing for 20 minutes, MALDI mass spectrometry detection was carried out. It was found that when compound IX was used as the bipolar MALDI matrix, 115 lipid signal peaks were detected from the total lipid extract in the positive ion mode; 17 lipid signal peaks were detected from the total lipid extract in the negative ion mode; a total of 132 lipid signal peaks were detected.

[0035] Example 10: Use of benzophenone derivative compound X as a bipolar MALDI matrix for mass spectrometric imaging analysis of mouse brain tissue sections The present invention provides a benzophenone derivative bipolar MALDI matrix, which shows excellent performance in the detection of lipid compounds and can obtain high-sensitivity and high-coverage lipid endogenous metabolite mass spectrometry signals in both positive and negative ion modes. In this example, we took mouse brain tissue sections as the representative analysis object to further study the mass spectrometric imaging analysis effect of the benzophenone derivative provided by the present invention as a bipolar MALDI matrix in biological tissue samples, and compared it with the commonly used matrix-assisted laser desorption ionization (MALDI) matrices α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (DHB), and 1,5-dihydroxynaphthalene (DAN). First, male Kunming mice were sacrificed and their brain organs were collected. The organs were washed with pre-cooled physiological saline solution and quickly frozen in liquid nitrogen. The obtained mouse brain organs were stored at -80 °C for later use. When in use, the brain organs were taken out from -80 °C and stored in a cryostat at -20 °C for 30 minutes. After the temperature of the mouse brain organs was stable, the mouse brain organs were fixed on the frozen sample tray of the cryostat using an OCT cryostat embedding machine, cut into continuous sections with a thickness of 14 μm and transferred to an ITO-coated glass slide. Then, the glass slide loaded with the sections was taken out from the cryostat and waited for the sections to return to room temperature; 20 mg of the matrix was weighed and dissolved and diluted with 1 mL of methanol to prepare a matrix solution; the matrix solution was transferred to a spray gun and sprayed to make the matrix evenly deposited on the surface of the brain tissue sections; finally, after the matrix was completely dried, a recrystallization operation was carried out for MALDI mass spectrometric imaging analysis, and the results are as Figure 3 shown. It was found that the in-situ detection effect of compound X in biological tissues was significantly better than that of commonly used MALDI matrices such as CHCA, whether in the positive ion detection mode or in the negative ion detection mode.

[0036] Figure 4 and Figure 5 The background peaks of Compound X and three common MALDI matrices were respectively compared in the positive-ion and negative-ion detection modes. As can be seen from the figure, regardless of whether it is the positive-ion mode or the negative-ion mode, the background ion peaks of Compound X are significantly fewer than those of the three common MALDI matrices. Especially in the low molecular weight range (<500 Da), the background peaks of Compound X are cleaner, making it very suitable for the bipolar MALDI mass spectrometry detection of small molecule compounds.

[0037] Figure 6 Figure [7-digit tag] is the solid UV spectrum of Compound X. Compound X has high absorbance values in the range of 200 nm to 400 nm, which can be adapted to the laser wavelengths of various MALDI instruments and has broad application prospects.

[0038] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A use of a benzophenone derivative as a bipolar matrix-assisted laser desorption ionization matrix in mass spectrometry detection, characterized in that: The structural formula of the benzophenone derivative is as follows: Wherein R1 is independently selected from one of hydrogen and hydroxyl; R2 is independently selected from one of hydroxyl, methoxy, dimethylamino, diethylamino, dipropylamino or dibutylamino; R3 is independently selected from one of hydrogen, hydroxyl, carboxyl, methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, n-butoxycarbonyl, n-hexyloxycarbonyl, morpholinylcarbonyl, N-ethylaminocarbonyl, N-butylaminocarbonyl, N-phenylaminocarbonyl; R4 is independently selected from one of hydrogen, hydroxyl, dimethylamino and diethylamino.

2. The use according to claim 1, characterized in that: The benzophenone derivative is compatible with bipolar detection in both positive ion mode and negative ion mode in matrix-assisted laser desorption ionization mass spectrometry detection.

3. The use according to claim 1 or 2, characterized in that: The benzophenone derivative is used to detect small molecule compounds with a mass-to-charge ratio ranging from 50 to 2000 Da.

4. The use according to claim 3, characterized in that: The small molecule compound is a lipid compound, including fatty acids, glycerol glycolipids, phospholipids, sphingolipids or sterol lipids.

5. The use according to any one of claims 1 to 4, characterized in that: The mass spectrometry detection method is any one of the following: Prepare a matrix solution, drip the analyte solution to be tested onto the target plate and dry it, then drip the matrix solution onto the surface of the analyte to form a co-crystal of the matrix and the analyte for mass spectrometry analysis; Prepare a matrix solution, and mix the matrix solution and the analyte solution to be tested in a volume ratio of 1:1 to obtain a mixed solution; The mixed solution is dropped onto a target plate to form co-crystals of matrix and analyte for mass spectrometry analysis; Weigh the matrix powder, and use vacuum sublimation to evenly deposit the matrix on the tissue surface. After sublimation, let it stand to cool down, take out the glass slide for solvent fumigation recrystallization, and then perform mass spectrometry imaging analysis; Prepare the matrix solution, transfer the matrix solution to the spraying device, spray it evenly onto the surface of the tissue to be tested, let it stand to dry, perform solvent fumigation and recrystallization, and perform mass spectrometry imaging analysis.

6. The use according to claim 5, characterized in that: The matrix solution is prepared by dissolving a benzophenone derivative in methanol; the mass concentration of the benzophenone derivative in the matrix solution is 1-50 mg / mL.

7. The use according to claim 5, characterized in that: The mass spectrometry imaging analysis conditions are as follows: the laser spot size is set to 1, the laser frequency is 1000 Hz, the laser intensity is 12%, the integration number is 1 time / pixel, the detector voltage is 1.89 kV, the positive ion source sample voltage is 3.5 kV, and the negative ion source sample voltage is 3.0 kV.

8. The use according to any one of claims 1 to 7, characterized in that: The detection samples of benzophenone derivatives as bipolar matrix-assisted laser desorption ionization matrix include blood samples, microbial samples, water environment samples, soil environment samples, biological tissue slice samples or plant tissue slice samples.

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