Detection and analysis method of carotenoid space metabolome

Abstract

The invention relates to a detection and analysis method of carotenoid space metabolome, and belongs to the field of agricultural chemical component analysis. According to the method, sweet corn and pepper are taken as examples, a desorption electrospray ionization mass spectrometry (DESI-MSI) technology is utilized, and a used spray solvent comprises acetonitrile, isopropanol, water and a formic acid solution according to the volume ratio of (40-60): (30-50): 10: 0.1. According to the method, the distribution characteristics of carotenoids in plants can be visually observed. The spatial metabolome difference and tissue specificity of different carotenoid metabolites are obtained by analyzing the response value of the imaging distribution diagram of carotenoid metabolite distribution, the difference of active metabolites in different tissues is analyzed, and valuable reference basis is provided for extracting carotenoid metabolites in plants.

Description

Technical Field

[0001] The invention belongs to the field of agricultural chemical component analysis, and specifically relates to a method for detecting and analyzing a carotenoid spatial metabolome. Background Art

[0002] Carotenoids are natural pigments that are widely found in plants, algae and certain microorganisms in nature. At present, there are more than 700 known natural carotenoids, which are mainly divided into two categories, namely, xanthophylls containing oxygen atoms in the molecules and carotenes containing no oxygen atoms but only carbon and hydrogen. They not only give plants bright colors, but also have multiple physiological functions such as anti-oxidation, immunomodulation, and anti-cancer. Unfortunately, the human body cannot synthesize carotenoids by itself and must be ingested from the outside. In daily diet, carotenoids are mainly obtained by eating plant foods rich in these pigments (such as sweet corn and peppers). Peppers and sweet corn are both good sources of carotenoids. They contain many types of carotenoids, which are self-evident for human health. The spatial distribution characteristics of carotenoids in plant tissues have an important influence on their biosynthesis, accumulation and bioavailability. This information has important application value in food processing, nutrition research and crop breeding.

[0003] Although traditional carotenoid analysis methods, such as high performance liquid chromatography (HPLC), can accurately determine the composition and content of carotenoids, these methods usually require complex sample preparation steps and cannot provide information on the spatial distribution of carotenoids in plant tissues.

[0004] With the development of spatial metabolomics, a new analytical technology that can reveal the spatial distribution of biomolecules at the microscopic level has emerged. Desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) technology can directly analyze the compounds on the surface of tissues while maintaining the in situ structure of biological tissues, and obtain the spatial distribution information of the compounds. However, DESI-MSI technology faces some challenges in analyzing carotenoids. Because carotenoids belong to tetraterpenoid compounds and have long-chain conjugated polyene structures, this structure gives carotenoids color, but also leads to their weak ionization ability. The electrons in the conjugated polyene chain are delocalized, which makes the overall electron cloud density distribution of the molecule more uniform, reducing the ability of the molecule to ionize at a specific position. In the prior art, there is currently no literature reporting the application of mass spectrometry imaging technology (especially DESI-MSI technology) to the spatial analysis of carotenoids and reporting its results.

[0005] Therefore, it is crucial to explore the spray solvents that can respond to carotenoids during spatial metabolomics analysis. Summary of the invention

[0006] The purpose of the present invention is to overcome at least one disadvantage of the prior art and to provide a spray solvent for a carotenoid spatial metabolome analysis method and a method for detecting and analyzing the carotenoid spatial metabolome.

[0007] The technical solution adopted by the present invention is:

[0008] A spray solvent for a carotenoid spatial metabolome analysis method, wherein the spray solvent is a spray solvent used in an ionization source in desorption electrospray ionization mass spectrometry imaging (DESI-MSI), and the spray solvent is an acetonitrile:isopropanol:water:formic acid solution with a volume ratio of (40-60):(30-50):10:0.1.

[0009] In some preferred embodiments, the spray solvent is an acetonitrile:isopropanol:water:formic acid solution in a volume ratio of (45-55):(35-45):10:0.1.

[0010] In some embodiments, the carotenoids include at least one of capsanthin, capsanthin, zeaxanthin, and lutein.

[0011] A method for detecting and analyzing the spatial metabolome of carotenoids, the method comprising the following steps:

[0012] The sample to be tested was placed on a glass slide, dried, and then subjected to spatial metabolome analysis using a mass spectrometer equipped with a DESI ion source. The spray solvent used was as described above.

[0013] In some embodiments, the mass spectrometer includes a tandem quadrupole mass spectrometer or a high-resolution mass spectrometer.

[0014] In some embodiments, when the sample to be tested is a solution, 1-2 μl of the solution to be tested is placed on a glass slide.

[0015] In some embodiments, the sample to be tested is corn kernels or pepper fruits.

[0016] In some of the embodiments, when the sample to be tested is pepper fruit, the pepper fruit is pre-treated, and the pre-treatment method includes cutting the pepper into small segments of 0.8-1.2 cm; embedding with a gelatin solution with a mass percentage of 10-15%, and then freezing at or below -80°C for a freezing time of not less than 12 hours; and cutting the frozen and embedded pepper segments into 15-25 um sheets.

[0017] In some of the embodiments, when the sample to be tested is corn kernels, the corn kernels are pre-treated, and the pre-treatment method includes embedding the corn kernels with a gelatin solution with a mass percentage of 10-15%, and then freezing them at or below -80°C for a freezing time of not less than 12 hours; and cutting the frozen and embedded corn kernels into 15-25um flakes.

[0018] In some of the embodiments, when a high-resolution mass spectrometer is used for detection, the flow rate is set to 2-3 ul / min, the ion source temperature is 140-160° C., and the mass spectrometry data is collected in a positive ion scanning mode.

[0019] The beneficial effects of the present invention are:

[0020] This application uses sweet corn and pepper as examples, using mass spectrometry imaging technology - analytical electrospray ionization mass spectrometry imaging (DESI-MSI), and the spray solvent used is acetonitrile:isopropanol:water:formic acid solution with a volume ratio of (40-60):(30-50):10:0.1. This method can intuitively observe the distribution characteristics of carotenoids in plants.

[0021] The present application realizes the spatial analysis of carotenoids by improving the spray solvent used in the ionization source in desorption electrospray ionization mass spectrometry imaging (DESI-MSI). This is the first reported spatial analysis technology of carotenoids, filling this gap. This is an innovation in the spatial analysis technology of carotenoids.

[0022] This application analyzes the response value of the imaging distribution map of carotenoid metabolites, obtains the spatial metabolome differences and tissue specificity of different carotenoid metabolites, analyzes the differences between active metabolites in different tissues, and provides a valuable reference for extracting carotenoid metabolites in plants. At the same time, it provides a new perspective for understanding the role and metabolic pathways of carotenoids in different plant tissues.

[0023] In the field of mass spectrometry imaging technology, especially DESI-MSI technology, although there have been many studies, they have not been applied to the spatial analysis of carotenoids and the results have not been reported. Therefore, the technical solution of this application is an important supplement in the field of carotenoid research.

[0024] This application not only achieves innovation in DESI-MSI technology, but also provides new analytical methods and perspectives in the field of carotenoid research, which is of great significance for promoting in-depth research on carotenoids. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Spatial distribution mass spectra of the three active compounds (capsaicin, zeaxanthin and lutein) in Examples 1-6 using different spray solvents.

[0026] Figure 2 Figure 2 is the spatial distribution mass spectrum of zeaxanthin and lutein in sweet corn samples.

[0027] Figure 3 This is the spatial distribution mass spectrum of capsanthin and capsorubin in sweet pepper fruit samples. DETAILED DESCRIPTION

[0028] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0029] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0030] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.

[0031] Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) technology is implemented in an open environment. It does not require complex pretreatment of the samples to be tested, and does not require the addition of matrix. It is convenient to operate and avoids the displacement of the molecules of the test object, thus ensuring the in-situ nature and accuracy of the imaging analysis.

[0032] The entire process includes applying high voltage to the electrospray capillary nozzle, atomizing the spray solvent to form charged spray droplets, the droplets bombarding the sample surface for desorption and ionization, the charged droplets desolvated and then entering the mass spectrometer for detection, the sample platform moving for two-dimensional scanning, and the mass spectrometer recording the signal intensity to obtain a spatial distribution map of the molecules and their content.

[0033] Therefore, the choice of spray solvent is crucial to the results of DESI-MSI.

[0034] A spray solvent for a carotenoid spatial metabolome analysis method, wherein the spray solvent is a spray solvent used in an ionization source in desorption electrospray ionization mass spectrometry imaging (DESI-MSI), and the spray solvent is an acetonitrile:isopropanol:water:formic acid solution with a volume ratio of (40-60):(30-50):10:0.1.

[0035] In some embodiments, the spray solvent is an acetonitrile:isopropanol:water:formic acid solution in a volume ratio of (45-55):(35-45):10:0.1.

[0036] In some embodiments, the spray solvent is an acetonitrile:isopropanol:water:formic acid solution in a volume ratio of 50:40:10:0.1.

[0037] In some embodiments, the carotenoids include capsanthin, capsanthin, zeaxanthin, and lutein.

[0038] The reasons why substances such as capsanthin, capsanthin, zeaxanthin and lutein are not easily ionized are mainly related to their chemical structure and physicochemical properties:

[0039] (1) Carotenoids belong to the tetraterpenoid class of compounds and have a long-chain conjugated polyene structure. This structure gives carotenoids their color, but it also leads to their weak ionization ability. The electrons in the conjugated polyene chain are delocalized, which makes the overall electron cloud density of the molecule more uniform, reducing the ability of the molecule to ionize at a specific position.

[0040] (2) Carotenoids are a class of non-polar compounds. Their molecular structures contain multiple conjugated double bonds. These double bonds result in a lack of obvious charge distribution within the molecule, making it difficult for it to ionize. Carotenoids are relatively stable chemically and do not easily undergo chemical reactions with other substances, including ionization reactions.

[0041] In summary, the stability of carotenoids such as capsanthin, capsanthin, zeaxanthin and lutein is determined by their molecular structure and electron configuration, so they face challenges in the ionization process and are therefore not easily ionized.

[0042] In order to overcome these challenges and improve the extraction efficiency and mass spectrometry signal response of carotenoids, this application proposes a method for detecting and analyzing carotenoids based on spatial metabolomics. This method optimizes the selection of spray solvents to analyze the spatial distribution characteristics of carotenoid compounds in sweet corn and peppers. Through this method, we can have a deeper understanding of the distribution of carotenoids in plant tissues and provide a scientific basis for the extraction, application and nutritional research of carotenoids.

[0043] A method for detecting and analyzing the spatial metabolome of carotenoids, the method comprising the following steps:

[0044] The sample to be tested is placed on a glass slide, dried, and then subjected to spatial metabolome analysis using a mass spectrometer equipped with a DESI ion source. The spray solvent used in the ionization source of the mass spectrometer is as described in any of the above items.

[0045] In some embodiments, the mass spectrometer includes but is not limited to a tandem quadrupole mass spectrometer (such as Waters Xevo TQ Absolute), a high-resolution mass spectrometer (such as Waters' Xevo G2-XS QTof, Waters' Synapt XS).

[0046] In some embodiments, when the sample to be tested is a solution, 1-2 μl of the solution to be tested is placed on a glass slide.

[0047] For example, when the solution is a carotenoid standard solution, the concentration of the solution is adjusted to 0.8-1.2 mg / ml. The purpose is to examine the ionization degree of the standard solution with the same concentration in different spray solvents.

[0048] For example, the standard solution of carotenoids includes capsanthin, zeaxanthin, lutein, etc. The standard solution is first loaded on the machine, and the spray solvent parameters with strong response are compared and selected, and then the samples (sweet corn and pepper) are loaded on the machine to analyze the distribution characteristics of carotenoid metabolites in the samples.

[0049] In some embodiments, the sample to be tested is (sweet) corn kernels or pepper fruits.

[0050] In some embodiments, when the sample to be tested is pepper fruit, the pepper fruit is pre-treated, and the pre-treatment method includes cutting the pepper into small segments of 0.8-1.2 cm; embedding with a gelatin solution of 10-15% by mass, and then freezing at or below -80°C for no less than 12 hours; cutting the frozen embedded pepper segments into 15-25um flakes. The 15-25um pepper flakes after freeze embedding are obtained and quickly attached to a glass slide.

[0051] In some of the embodiments, when the sample to be tested is corn kernels, the corn kernels are pre-treated, and the pre-treatment method includes embedding the corn kernels with a gelatin solution with a mass percentage of 10-15%, and then freezing them at or below -80°C for a freezing time of not less than 12 hours; and cutting the frozen and embedded corn kernels into 15-25um flakes.

[0052] In some of the embodiments, when a high-resolution mass spectrometer is used for detection, the flow rate is set to 2-3 ul / min, the ion source temperature is 140-160° C., and the mass spectrometry data is collected in a positive ion scanning mode.

[0053] In some of the embodiments, when a Synapt XS high-resolution mass spectrometer is used for detection, the flow rate is set to 2 ul / min, the ion source temperature is 150° C., and the mass spectrometry data are collected in a positive ion scanning mode.

[0054] In some of the embodiments, the HD Imaging v1.6 software used in conjunction with the Synapt XS high-resolution mass spectrometer is used to perform high-resolution imaging analysis on the collected mass spectrometry data.

[0055] The following is a description with reference to specific embodiments.

[0056] The instruments and equipment involved in the examples are shown in Table 1.

[0057] Table 1. Instruments and equipment used in the examples

[0058]

[0059]

[0060] The reagents in the following examples are derived from commercially available products, for example:

[0061] Chlorophyll standard: Beijing Beina Chuanglian Biotechnology Research Institute; zeaxanthin standard: Northern Weiye Metrology Group Co., Ltd.; capsanthin standard: Shanghai MacLean Biochemical Technology Co., Ltd.; capsanthin standard: Cayman Chemical Company, Inc; gelatin: Shanghai MacLean Biochemical Technology Co., Ltd.; acetonitrile, methanol, isopropanol: Thermo Fisher Scientific.

[0062] Example 1

[0063] The analysis of three carotenoids (capsanthin, zeaxanthin and lutein) standards includes the following steps:

[0064] S1. Preparation of standard solution: Dissolve three standards of capsanthin, zeaxanthin and lutein in a mixed solvent of isopropanol and acetonitrile (volume ratio 1:1) to prepare a standard solution with a concentration of 1 mg / ml. Take 1-2 microliters of the standard solution and place it on a slide and dry it in the dark.

[0065] S2. Standard spot coating and spray solvent treatment: 1-2 μl of the standard solution obtained in step S1 was spot coated on the slide. Subsequently, the three standards were loaded on the machine, and the spray solvent was acetonitrile: isopropanol: water: formic acid solution with a volume ratio of 50:40:10:0.1, with a flow rate of 2 ul / min, to evaluate its effect on the standard signal.

[0066] The entire process includes applying high voltage to the electrospray capillary nozzle, atomizing the spray solvent to form charged spray droplets, the droplets bombarding the sample surface for desorption and ionization, the charged droplets desolvated and then entering the mass spectrometer for detection, the sample platform moving for two-dimensional scanning, and the mass spectrometer recording the signal intensity to obtain a spatial distribution map of the molecules and their content.

[0067] S3. Mass spectrometry imaging data acquisition: Data acquisition was performed using a Synapt XS HDMS 4k high-resolution mass spectrometer detector (Waters, USA) equipped with a DESI ion source. The flow rate was set to 2ul / min, the ion source temperature was 150°C, and the gas pressure was 0.4 MPa. Full scan mode was used, and mass spectrometry data were collected in positive ion mode.

[0068] S4. Mass spectrometry imaging data analysis: Use HD Imaging v1.6 software (Waters, USA) to perform high-resolution imaging analysis on the collected mass spectrometry data. The software will automatically calculate and list the precise molecular weights of all detected compounds and their total response values. By clicking on the precise molecular weight of the ion of the compound to be tested, the software will display the total response value of the compound in the entire mass spectrometry imaging diagram, thereby achieving a visual analysis of the compound distribution.

[0069] Among them, qualitative: through mass-to-charge ratio and standard; quantitative: the color depth of the image, the color changes from blue to yellow and the response gradually becomes stronger; positioning: the color display position of the image.

[0070] By adjusting the spray solvent, the other steps are the same as Example 1 to obtain Examples 2-6.

[0071] The spray solvent compositions of Examples 1-6 and the corresponding results are shown in the attached drawings. Figure 1 part, see Figure 1 and Table 2.

[0072] Table 2. Spray solvent composition and results of Examples 1-6

[0073]

[0074] Examples 1-6 are spray solvent selections for standard products, and the results are shown in Table 3. The images are normalized to obtain Figure 1 .

[0075] Table 3. Total response values ​​corresponding to standard mass peaks

[0076]

[0077] By comparing AC and DF, it was concluded that the mixed solution of acetonitrile and isopropanol played a synergistic role, and the response of the single acetonitrile solution to the carotenoid standard was weak. The response intensity was determined based on the color of the image, and the spray solvent was finally determined to be an acetonitrile:isopropanol:water:formic acid solution with a volume ratio of (40-60):(30-50):10:0.1. Among them, the spray solvent of acetonitrile:isopropanol:water:formic acid = 50:40:10:0.1 had the best effect.

[0078] Example 7

[0079] When the corn sample is sweet corn kernels, the detection and analysis method comprises the following steps:

[0080] S1. Preparation of standard: embed the sweet corn kernels with a gelatin solution of 10-15% by mass, and then freeze them at or below -80°C for no less than 12 hours; cut the frozen embedded corn kernels into 15-25um flakes. The 15-25um corn kernel flakes after freeze embedding are quickly attached to a glass slide.

[0081] S2. Spray solvent treatment: The samples were loaded onto the machine with a spray solvent of acetonitrile:isopropanol:water:formic acid solution in a volume ratio of 50:40:10:0.1 at a flow rate of 2ul / min to evaluate its effect on the standard signal.

[0082] S3. Mass spectrometry imaging data acquisition: Data acquisition was performed using a Synapt XS HDMS 4k high-resolution mass spectrometer detector (Waters, USA) equipped with a DESI ion source. The flow rate was set to 2ul / min, the ion source temperature was 150°C, and the gas pressure was 0.4 MPa. Full scan mode was used, and mass spectrometry data were collected in positive ion mode.

[0083] S4. Mass spectrometry imaging data analysis: Use HD Imaging v1.6 software (Waters, USA) to perform high-resolution imaging analysis on the collected mass spectrometry data. The software will automatically calculate and list the precise molecular weights of all detected compounds and their total response values. By clicking on the precise molecular weight of the ion of the compound to be tested, the software will display the total response value of the compound in the entire mass spectrometry imaging diagram, thereby achieving a visual analysis of the compound distribution.

[0084] Among them, qualitative: through mass-to-charge ratio and standard; quantitative: the color depth of the image, the color changes from blue to yellow and the response gradually becomes stronger; positioning: the color display position of the image.

[0085] Results Figure 2 .

[0086] Figure 2 is the spatial distribution map of zeaxanthin and lutein in sweet corn kernel samples. Figure 2 It can be seen that zeaxanthin and lutein metabolites are mainly distributed in the endosperm part of sweet corn.

[0087] Analyzing the distribution of zeaxanthin and lutein in sweet corn kernels can help agricultural scientists cultivate sweet corn varieties with higher amounts of zeaxanthin and lutein through breeding techniques. During food processing, understanding the distribution of nutrients can help develop more effective processing methods to ensure that the loss of these beneficial ingredients is minimized during processing. These data provide basic information for scientific research and help further explore the biosynthesis, accumulation and degradation mechanisms of carotenoids in plants. Therefore, analyzing the distribution of zeaxanthin and lutein in sweet corn kernels using DESI mass spectrometry imaging technology not only helps to improve the edible value of sweet corn, but also has important significance for agricultural scientific research and food industry development.

[0088] Example 8

[0089] When the pepper sample is pepper fruit, the detection and analysis method comprises the following steps:

[0090] S1. Sample cryoembedding: Select fresh pepper fruit samples and cut them into small segments of about 1 cm in length with a sharp blade. Use 13% gelatin solution by mass for embedding, and then freeze in an ultra-low temperature refrigerator at -80°C for at least 12 hours.

[0091] S2. Sample sectioning and drying: The cryo-embedded samples were taken out and 20-micron thick sections were prepared using a Leica CM1950 cryo-tome, which was quickly attached to a glass slide. The sections were then dried for 2 hours in a dark environment.

[0092] S3. Spray solvent treatment: The samples were loaded onto the machine with a spray solvent of acetonitrile:isopropanol:water:formic acid solution in a volume ratio of 50:40:10:0.1 at a flow rate of 2ul / min to evaluate its effect on the standard signal.

[0093] S4. Mass spectrometry imaging data acquisition: Data acquisition was performed using a Synapt XS HDMS 4k high-resolution mass spectrometer detector (Waters, USA) equipped with a DESI ion source. The flow rate was set to 2ul / min, the ion source temperature was 150°C, and the gas pressure was 0.4 MPa. The full scan mode was used, and mass spectrometry data were collected in the positive ion mode.

[0094] S5. Mass spectrometry imaging data analysis: Use HD Imaging v1.6 software (Waters, USA) to perform high-resolution imaging analysis on the collected mass spectrometry data. The software will automatically calculate and list the precise molecular weights of all detected compounds and their total response values. By clicking on the precise molecular weight of the ion of the compound to be tested, the software will display the total response value of the compound in the entire mass spectrometry imaging diagram, thereby achieving a visual analysis of the compound distribution.

[0095] Among them, qualitative: through mass-to-charge ratio and standard; quantitative: the color depth of the image, the color changes from blue to yellow and the response gradually becomes stronger; positioning: the color display position of the image.

[0096] Results Figure 3 .

[0097] Figure 3 is the spatial distribution map of capsanthin and capsorubin in pepper fruit samples, Figure 3 It can be seen that capsanthin and capsanthin metabolites are mainly distributed in the epidermis and placenta of pepper fruits, respectively.

[0098] Capsanthin and capsanthorubin are important bioactive ingredients in peppers, which have multiple physiological functions such as antioxidant, anti-inflammatory and anti-cancer. Understanding their distribution in pepper fruits is helpful to study the specific functions of these ingredients and their mechanisms of action. Analyzing the distribution of capsanthin and capsanthorubin metabolites in pepper fruits can help breeders to cultivate new varieties rich in these beneficial ingredients in specific parts through genetic engineering or traditional breeding methods. In the processing of peppers, understanding the distribution of capsanthin and capsanthorubin can help optimize the processing technology. For example, when extracting these pigments, the epidermis and placenta of peppers can be treated in a targeted manner to improve the extraction efficiency and pigment purity. In short, the information provided by DESI mass spectrometry imaging analysis technology has important guiding significance for scientific research, agricultural production and food processing of peppers.

[0099] This application obtains the spatial metabolome differences and tissue specificity of different carotenoid metabolites by analyzing the response values ​​of the imaging distribution map of the distribution of carotenoid metabolites, analyzes the differences in active metabolites between different tissues, and provides a valuable reference for extracting carotenoid metabolites in plants.

[0100] The above is a further detailed description of the present invention, which should not be regarded as a limitation on the specific implementation of the present invention. For ordinary technicians in the technical field to which the present invention belongs, simple deduction or replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A spray solvent for a carotenoid spatial metabolome analysis method, characterized in that: The spray solvent is a spray solvent used in an ionization source in desorption electrospray ionization mass spectrometry imaging (DESI-MSI), and the spray solvent is an acetonitrile:isopropanol:water:formic acid solution with a volume ratio of (40-60):(30-50):10:0.

1.

2. The spray solvent according to claim 1, characterized in that The spray solvent is an acetonitrile:isopropanol:water:formic acid solution in a volume ratio of (45-55):(35-45):10:0.

1.

3. The spray solvent according to claim 1, characterized in that The carotenoids include at least one of capsanthin, capsanthin, zeaxanthin and lutein.

4. A method for detecting and analyzing the spatial metabolome of carotenoids, characterized in that: The method comprises the following steps: The sample to be tested is placed on a glass slide, dried, and then subjected to spatial metabolome analysis using a mass spectrometer equipped with a DESI ion source, wherein the spray solvent used is as described in any one of claims 1-3.

5. The detection and analysis method according to claim 4, characterized in that: The mass spectrometer includes a tandem quadrupole mass spectrometer and a high-resolution mass spectrometer.

6. The detection and analysis method according to claim 5, characterized in that: When the sample to be tested is a solution, take 1-2 μl of the solution to be tested and place it on a glass slide.

7. The detection and analysis method according to claim 5, characterized in that: The samples to be tested are corn kernels or pepper fruits.

8. The detection and analysis method according to claim 7, characterized in that: When the sample to be tested is pepper fruit, the pepper fruit is pre-treated, and the pre-treatment method includes cutting the pepper into small segments of 0.8-1.2 cm; embedding with a gelatin solution with a mass percentage of 10-15%, and then freezing at or below -80°C for a freezing time of not less than 12 hours; and cutting the frozen and embedded pepper segments into 15-25um flakes.

9. The detection and analysis method according to claim 7, characterized in that: When the sample to be tested is corn kernels, the corn kernels are pre-treated, and the pre-treatment method includes embedding the corn kernels with a gelatin solution with a mass percentage of 10-15%, and then freezing them at or below -80°C for a freezing time of not less than 12 hours; and cutting the frozen and embedded corn kernels into 15-25um flakes.

10. The detection and analysis method according to claim 5, characterized in that: When using a high-resolution mass spectrometer for detection, the flow rate is set to 2-3ul / min, the ion source temperature is 140-160°C, and the mass spectrometry data is collected in positive ion scanning mode.

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