A device for nanoliter electrospray ionization of organic inclusions and its application

Abstract

The present invention belongs to the field of chemical analysis, and in particular, relates to a device for nanoliter electrospray ionization of organic inclusions and its application. The device provided by the present invention comprises: a solvent driving device; a solvent circulation pipeline connected to the discharge end of the solvent driving device; a conductive element connected to the discharge end of the solvent circulation pipeline, the conductive element being connected to a power supply; an ionization needle connected to the discharge end of the conductive element, the needle body of the ionization needle being bent into a U-shape or a V-shape, and a sampling port being provided at the lower edge of the bottom end of the bending area; and a sample plate for placing samples to be sampled. The device provided by the present invention can realize the ionization of ng-level trace organic inclusions; on this basis, by combining the device with a mass spectrometer, the molecular composition of organic inclusions can be characterized.

Description

Technical Field

[0001] The invention belongs to the field of chemical analysis, and in particular relates to a device for performing nanoliter electrospray ionization on organic inclusions and an application thereof. Background Art

[0002] Fluid inclusions are inclusions captured during the growth of minerals. They can be oil, water or solid particles. These inclusions are sealed in minerals as they grow. Since there is no addition of foreign matter or overflow of its own matter after the formation of the inclusions, a large amount of geological and geochemical information is recorded, and they can be studied as the original mineralization liquid. Inclusions containing oil and gas components are oil and gas inclusions, also known as organic inclusions and hydrocarbon inclusions. They are direct signs of the migration and accumulation of oil and gas, and are of great significance for determining the evolution and formation stages of oil and gas.

[0003] Since a single inclusion is enclosed in a mineral and the volume of a single inclusion is extremely small (about 10-20 μm in diameter and about picoliter in volume), the current analysis of organic components in inclusions usually requires first breaking the minerals on the surface of the inclusion, collecting the inclusion group, and then analyzing it. Due to the difficulty of sampling trace samples, the current mass spectrometry analysis of inclusions is limited to gas chromatography-mass spectrometry (GC-MS). GC-MS analysis requires a long separation time and has low analysis efficiency. More importantly, due to the limitation of GC-MS sampling, compounds with a boiling point > 300 ° C cannot be vaporized, so the molecular composition information of the sample obtained by this method is very limited. The rich organic molecular composition of oil-bearing inclusions is of great significance to the study of oil and gas accumulation. Unfortunately, due to the constraints of analytical methods, the current understanding of the molecular composition of oil-bearing inclusions is seriously insufficient.

[0004] Before the 21st century, the field of petroleum analysis faced the same dilemma. The emergence of ultra-high resolution mass spectrometry (UHRMS) broke this deadlock. Thanks to the ultra-high resolution and analysis speed of UHRMS, petroleum analysis has entered the era of "petroleumomics". Therefore, UHRMS is currently the most promising method to achieve a comprehensive characterization of the molecular composition of oil-containing inclusions. The biggest challenge in using UHRMS to analyze inclusions is how to achieve effective ionization. UHRMS usually uses electrospray ionization (ESI) to analyze petroleum composition, and the minimum sample amount required is μg level. Even if multiple single inclusions are mixed into inclusion groups, the sample amount is still 10 times less than the sample amount required for mass spectrometry injection. 3 ~10 4 Therefore, commercial ionization sources cannot meet the requirements for ionization of oil-containing inclusions. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a device for nanoliter electrospray ionization of organic inclusions and its application. The device provided by the present invention can realize the ionization of ng-level trace organic inclusions; on this basis, by combining the device with a mass spectrometer, the characterization of the molecular composition of organic inclusions can also be realized.

[0006] The present invention provides a device for performing nanoliter electrospray ionization on organic inclusions, comprising:

[0007] Solvent drive device;

[0008] a solvent circulation pipeline connected to the discharge end of the solvent driving device;

[0009] A conductive element connected to the discharge end of the solvent circulation pipeline, wherein the conductive element is connected to a power source;

[0010] An ionization spray needle connected to the discharge end of the conductive element, wherein the needle body of the ionization spray needle is bent into a U-shape or a V-shape, and a sampling port is provided at the lower edge of the bottom end of the bent area;

[0011] and a sample plate for placing the sample to be sampled.

[0012] Preferably, the inner diameter of the ionization spray needle is 50-200 μm, and the outer diameter is 300-400 μm.

[0013] Preferably, the ionization needle is a fused silica capillary needle with a polyimide outer coating.

[0014] Preferably, the V-shaped bending angle is 100-170°.

[0015] Preferably, the caliber of the sampling port is 50-200 μm.

[0016] The present invention provides a method for performing nanoliter electrospray ionization on organic inclusions, which is performed in the device described in the above technical solution and comprises the following steps:

[0017] The solvent is transported into the solvent flow pipeline by a liquid driving device, the solvent in the pipeline flows through the conductive element and is charged under the voltage applied by the power supply, and then the charged solvent flows into the ionization needle;

[0018] The organic inclusion sample is placed on a sample plate, and then the sample plate is placed close to the sampling port of the ionization needle. The organic inclusion sample on the sample plate enters the ionization needle through the sampling port under the self-absorption of the ionization needle.

[0019] The organic inclusion sample entering the ionization needle is mixed with the charged solvent in the ionization needle, and then reaches the tip of the ionization needle along with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field.

[0020] Preferably, the solvent is a single-component solvent or a mixed solvent that can generate electrospray under the action of an electric field; more preferably, it is a mixture of toluene and methanol, and the volume ratio of toluene to methanol is 1:(2-3).

[0021] The present invention provides a system for characterizing organic inclusions, comprising:

[0022] The device described in the above technical solution;

[0023] and a mass spectrometer for detecting the electrospray ejected from the device.

[0024] Preferably, the mass spectrometer is an ultra-high resolution mass spectrometer.

[0025] The present invention provides a method for characterizing organic inclusions, which is carried out in the system described in the above technical solution and comprises the following steps:

[0026] The solvent is transported into the solvent flow pipeline by a liquid driving device, the solvent in the pipeline flows through the conductive element and is charged under the voltage applied by the power supply, and then the charged solvent flows into the ionization needle;

[0027] The organic inclusion sample is placed on a sample plate, and then the sample plate is placed close to the sampling port of the ionization needle. The organic inclusion sample on the sample plate enters the ionization needle through the sampling port under the self-absorption of the ionization needle.

[0028] The organic inclusion sample entering the ionization needle is mixed with the charged solvent in the ionization needle, and then reaches the tip of the ionization needle along with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field;

[0029] The ejected electrospray enters the mass spectrometer through the mass spectrometer inlet for detection to obtain the detection result.

[0030] Compared with the prior art, the present invention provides a device for performing nanoliter electrospray ionization on organic inclusions and its application. The device provided by the present invention comprises: a solvent driving device; a solvent circulation pipeline connected to the discharge end of the solvent driving device; a conductive element connected to the discharge end of the solvent circulation pipeline, the conductive element being connected to a power source; an ionization spray needle connected to the discharge end of the conductive element, the needle body of the ionization spray needle being bent into a U-shape or a V-shape, and a sampling port being provided at the lower edge of the bottom end of the bending area; and a sample plate for placing the sample to be sampled. The specific operation steps of using the device to ionize organic inclusions are as follows: the solvent is transported to the solvent circulation pipeline through the liquid driving device, the solvent in the pipeline flows through the conductive element and is charged under the voltage applied by the power supply, and then the charged solvent flows into the ionization needle; the organic inclusion sample is placed on the sample plate, and then the sample plate is placed close to the sampling port of the ionization needle, and the organic inclusion sample on the sample plate enters the ionization needle through the sampling port under the self-absorption of the ionization needle; the organic inclusion sample entering the ionization needle is mixed with the charged solvent in the ionization needle, and then reaches the tip of the ionization needle with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field. The device provided by the present invention can realize the ionization of ng-level trace organic inclusions; on this basis, by combining the device with a mass spectrometer, the molecular composition of the organic inclusions can be characterized. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 is a schematic structural diagram of a nanoliter electrospray ionization device provided in an embodiment of the present invention;

[0033] Figure 2 This is a composition distribution diagram of N1 compounds of Xinjiang crude oil provided in Example 1 of the present invention;

[0034] Figure 3 This is a composition distribution diagram of N1O1 compounds in Xinjiang crude oil provided in Example 1 of the present invention;

[0035] Figure 4 This is the composition distribution diagram of N1 compounds of Xinjiang crude oil provided in Comparative Example 1 of the present invention;

[0036] Figure 5 This is the composition distribution diagram of N1O1 compounds in Xinjiang crude oil provided in Comparative Example 1 of the present invention.

[0037] Attached Figure 1 The markings are as follows: 1 is a solvent driving device, 2 is a solvent flow pipeline, 3 is a power supply, 4 is a conductive element, 5 is an ionization needle, 6 is a sampling port, 7 is a sample to be sampled, 8 is a sample plate, and 9 is an inlet of a mass spectrometer. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The present invention provides a device for performing nanoliter electrospray ionization on organic inclusions, comprising:

[0040] Solvent driving device (1);

[0041] A solvent circulation pipeline (2) connected to the discharge end of the solvent driving device (1);

[0042] A conductive element (4) connected to the discharge end of the solvent circulation pipeline (2), wherein the conductive element (4) is connected to a power source (3);

[0043] An ionization spray needle (5) connected to the discharge end of the conductive element (4), wherein the needle body of the ionization spray needle (5) is bent into a U-shape or a V-shape, and a sampling port (6) is provided at the lower edge of the bottom end of the bent area;

[0044] and a sample plate (8) for placing the sample (7) to be sampled.

[0045] The nano-electrospray ionization device provided by the present invention mainly consists of two parts, namely a solvent injection part and a sampling ionization part; wherein the solvent injection part mainly includes a solvent driving device (1), a solvent circulation pipeline (2) and a conductive element (4); and the sampling ionization part mainly includes an ionization spray needle (5) and a sample plate (8).

[0046] In the device provided by the present invention, the solvent driving device (1) is used to automatically inject the solvent, preferably an automatic injection needle driven by a syringe pump. In the present invention, the injected solvent has the function of dissolving and extracting samples, and also serves as an ionization solvent; the solvent can be a mono-organic solvent or a poly-organic solvent, and the proportion of the poly-organic solvent is not limited, but must contain organic solvents such as methanol and acetonitrile that can generate electrospray under the action of an electric field; to ensure that the organic inclusions are fully extracted, dissolved and ionized, the solvent is preferably a mixture of toluene and methanol, and the volume ratio of toluene and methanol is preferably 1: (2-3); the flow rate of the solvent is preferably set to 0.1-0.5 μL / min, specifically 0.1 μL / min, 0.2 μL / min, 0.3 μL / min, 0.4 μL / min or 0.5 μL / min.

[0047] In the device provided by the present invention, the material of the solvent circulation pipeline (2) is preferably a soft material that is resistant to organic solvents, and more preferably fluorinated ethylene propylene copolymer (FEP).

[0048] In the device provided by the present invention, the conductive element (4) is preferably a conductive metal two-way connector, and the conductive element (4) is powered by a power supply (3), and the power supply (3) is preferably a high-voltage power supply. In the present invention, the voltage of the power supply (3) can be a direct current voltage, a pulsed direct current voltage, or an alternating current voltage; the voltage of the power supply (3) is preferably set to +1500 to +3000V, or -3000 to -1500V; when the positive voltage (i.e., positive mode) is used in conjunction with a mass spectrometer, it can be used to detect neutral oxygen-containing compounds containing functional groups such as carbonyl, ester, aldehyde, and ether bonds, as well as compounds such as alkaline nitrides; when the negative voltage (i.e., negative mode) is used in conjunction with a mass spectrometer, it can be used to detect acidic oxygen-containing compounds containing functional groups such as carboxyl and phenolic groups, as well as neutral nitrides, sulfones, sulfoxides, and the like.

[0049] In the device provided by the present invention, the ionization needle (5) is preferably a fused silica capillary needle with a polyimide outer coating; the inner diameter of the ionization needle (5) is preferably 50 to 200 μm, specifically 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm , 170μm, 180μm, 190μm or 200μm; the outer diameter of the ionization spray needle (5) is preferably 300-400μm, specifically 300μm, 310μm, 320μm, 330μm, 340μm, 350μm, 360μm, 365μm, 370μm, 380μm, 390μm or 400μm; the outer diameter of the ionization spray needle (5) is preferably 300-400μm, specifically 300μm, 310μm, 320μm, 330μm, 340μm, 350μm, 360μm, 365μm, 370μm, 380μm, 390μm or 400μm; The length is preferably 8 to 12 cm, specifically 8 cm, 9 cm, 10 cm, 11 cm or 12 cm; the U-shaped or V-shaped bending shape of the ionization needle (5) is preferably formed by heating; the caliber of the sampling port (6) at the bottom edge of the bending area of ​​the ionization needle (5) is preferably 50 to 200 μm, specifically 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm; the sampling port (6) is preferably obtained by sanding the bottom edge of the bending area of ​​the ionization needle (5).

[0050] In the device provided by the present invention, the ionization needle (5) on the left side of the sampling port (6) is connected to the solvent flow pipeline (2) through the conductive element (4), and the ionization needle (5) on the right side of the sampling port (6) is the tip of the ionization needle (also called the ionization end), which can be formed by drawing by heating. In the present invention, if the bending is U-shaped, when the device is used in conjunction with a mass spectrometer, the ionization end of the ionization needle (5) needs to be perpendicular to the mass spectrometer inlet (9). In order to allow the solution electrospray to more fully enter the mass spectrometer inlet, it is necessary to bend a 90° angle in the middle of the ionization end so that the ionization end and the mass spectrometer inlet (9) are at the same level. Therefore, the ionization end of the U-shaped bent ionization needle (5) needs to retain a relatively long length of about 4 cm. If the bending is V-shaped, when the device is used in conjunction with a mass spectrometer, the ionization end of the ionization needle (5) forms a certain angle with the mass spectrometer inlet (9), and the spray can directly enter the mass spectrometer. Therefore, the ionization end of the V-shaped bent ionization needle (5) does not need to be bent, and the length of the ionization end is about 1 cm. Therefore, in the present invention, the bending shape of the needle body of the ionization needle (5) is preferably V-shaped, so as to reduce the length of the ionization end of the ionization needle (5) and reduce the dilution of organic inclusions in the pipeline; the bending angle of the V-shape is preferably 100-170°, specifically 100°, 110°, 120°, 130°, 140°, 150°, 160° or 170°.

[0051] In the device provided by the present invention, the sample plate (8) is used to place the sample (7) to be sampled. The sample (7) to be sampled (i.e., the organic inclusion sample) is preferably an inclusion group, which can be collected by mechanically rupturing or thermally rupturing the mineral sample containing the inclusions. In the present invention, the material of the sample plate (8) must be resistant to organic solvents to avoid generating too many mass spectrometry background signals; and the sample plate (8) must be a hydrophobic material to facilitate the transfer of the organic inclusion sample to the sample plate (8).

[0052] The present invention also provides a method for performing nanoliter electrospray ionization on organic inclusions using the above device, comprising the following steps:

[0053] The solvent is transported to the solvent circulation pipeline (2) through the liquid driving device (1), the solvent in the pipeline flows through the conductive element (4) and is charged under the action of the voltage applied by the power supply (3), and then the charged solvent flows into the ionization spray needle (5);

[0054] The organic inclusion sample (i.e., the sample to be sampled (7)) is placed on a sample plate (8), and then the sample plate (8) is placed close to the bottom of the sampling port (6) of the ionization spray needle (5). The organic inclusion sample on the sample plate (8) enters the ionization spray needle (5) through the sampling port (6) under the self-absorption action of the ionization spray needle (5);

[0055] The organic inclusion sample entering the ionization needle (5) is mixed with the charged solvent in the ionization needle (5), and then reaches the tip of the ionization needle (5) along with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field.

[0056] In the nano-electrospray ionization method provided by the present invention, the solvent can be a mono-organic solvent or a poly-organic solvent, and the ratio of the poly-organic solvent is not limited, but it must contain organic solvents such as methanol and acetonitrile that can produce electrospray under the action of an electric field; to ensure sufficient extraction, dissolution and ionization of organic inclusions, the solvent is preferably a mixture of toluene and methanol, and the volume ratio of toluene and methanol is preferably 1:(2-3); the flow rate of the solvent is preferably set to 0.1-0.5 μL / min, specifically 0.1 μL / min, 0.2 μL / min, 0.3 μL / min, 0.4 μL / min or 0.5 μL / min.

[0057] In the nano-electrospray ionization method provided by the present invention, the voltage can be a direct current voltage, a pulsed direct current voltage or an alternating current voltage; the voltage is preferably set to +1500 to +3000 V, or -3000 to -1500 V; wherein, when the voltage is positive (i.e., positive mode), it can be used in conjunction with a mass spectrometer to detect neutral oxygen-containing compounds containing functional groups such as carbonyl, ester, aldehyde, and ether bonds, as well as compounds such as alkaline nitrides; when the voltage is negative (i.e., negative mode), it can be used in conjunction with a mass spectrometer to detect acidic oxygen-containing compounds containing functional groups such as carboxyl and phenolic groups, as well as compounds such as neutral nitrides, sulfones, and sulfoxides.

[0058] In the nano-electrospray ionization method provided by the present invention, the organic inclusion samples include but are not limited to single-phase hydrocarbon inclusions (pure liquid phase), gas-liquid two-phase hydrocarbon inclusions (gas phase is natural gas, liquid phase is petroleum) or water-containing hydrocarbon inclusions.

[0059] In the nano-electrospray ionization method provided by the present invention, the organic inclusion sample can be an inclusion group, and the inclusion group can be collected by mechanically fracturing, thermally fracturing, etc. the mineral sample containing the inclusions; the organic inclusion sample can also be a single inclusion, and the single inclusion is preferably obtained by: fracturing the surface mineral of the single inclusion by laser irradiation to expose the single inclusion.

[0060] The present invention also provides a system for characterizing organic inclusions, comprising:

[0061] The device described in the above technical solution;

[0062] and a mass spectrometer for detecting the electrospray ejected from the device.

[0063] In the characterization system provided by the present invention, the mass spectrometer includes but is not limited to a low-resolution mass spectrometer, a high-resolution mass spectrometer or an ultra-high-resolution mass spectrometer, preferably an ultra-high-resolution mass spectrometer.

[0064] In the characterization system provided by the present invention, the distance between the needle tip of the ionization needle (5) and the mass spectrometer inlet (9) is preferably 5 to 10 mm, specifically 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm or 10 mm.

[0065] The present invention also provides a method for characterizing organic inclusions, which is carried out in the system described in the above technical solution and comprises the following steps:

[0066] The solvent is transported to the solvent circulation pipeline (2) through the liquid driving device (1), the solvent in the pipeline flows through the conductive element (4) and is charged under the action of the voltage applied by the power supply (3), and then the charged solvent flows into the ionization spray needle (5);

[0067] The organic inclusion sample (i.e., the sample to be sampled (7)) is placed on a sample plate (8), and then the sample plate (8) is placed close to the bottom of the sampling port (6) of the ionization spray needle (5). The organic inclusion sample on the sample plate (8) enters the ionization spray needle (5) through the sampling port (6) under the self-absorption action of the ionization spray needle (5);

[0068] The organic inclusion sample entering the ionization needle (5) is mixed with the charged solvent in the ionization needle (5), and then reaches the tip of the ionization needle (5) along with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field;

[0069] The ejected electrospray enters the mass spectrometer through the mass spectrometer inlet (9) for detection to obtain the detection result.

[0070] In the characterization method provided by the present invention, the type of solvent, the flow rate of the solvent, the voltage setting method, the relevant information of the organic inclusion sample, etc. have been introduced above and will not be repeated here.

[0071] The technical solution provided by the present invention has the following advantages:

[0072] 1) Compared with the GC-MS method, the GC-MS method cannot obtain more detailed information on the molecular composition of inclusions. The device provided by the present invention, when used in conjunction with a high-resolution mass spectrometer, can achieve a comprehensive characterization of the molecular composition of organic inclusions, providing data support for geological exploration such as oil and gas accumulation; in addition, compared with the GC-MS method, the technology of the present invention greatly shortens the analysis time and improves the analysis efficiency.

[0073] 2) Compared with the ESI ionization method which is currently the most widely used for direct mass spectrometry ionization of crude oil, ESI cannot ionize trace samples, while the present invention can technically realize the ionization of ng-level trace oil-containing inclusions.

[0074] For the sake of clarity, the following examples and comparative examples are used to explain in detail. Since the amount of organic inclusions collected from minerals is difficult to meet the sample volume requirement of ESI ionization, in order to compare the results of the ionization method of the present invention with those of ESI ionization, in the following examples and comparative examples of the present invention, crude oil whose composition is highly similar to that of organic inclusions is directly selected as the test sample.

[0075] Example 1

[0076] 1) A nanoliter electrospray ionization device, the structure of which is as follows Figure 1 As shown, including:

[0077] The connection and position relationship of the solvent driving device (1), the solvent circulation pipeline (2), the power supply (3), the conductive element (4), the ionization needle (5), the sampling port (6) and the sample plate (8) are shown in the figure. Figure 1 As shown, no further details are given here; wherein the solvent driving device (1) is specifically an automatic injection needle driven by a syringe pump; the solvent circulation pipeline (2) is specifically selected from a FEP tube with a relatively soft material and resistance to organic solvents; the power supply (3) is a high voltage power supply; the conductive element (4) is specifically selected from a conductive metal two-way connector; the ionization needle (5) is made of a fused silica capillary with a polyimide outer coating, with an inner diameter of 100 μm, an outer diameter of 365 μm, and a length of 10 cm. The capillary is bent into a V shape (with a bending angle of 130°) by heating, and an opening with a diameter of about 100 μm is ground with sandpaper at the bottom of the V-shape, which is the sampling port (6). The capillary on the right side of the sampling port (6) is drawn out with a tip by heating, and the capillary on the right side of the sampling port (6) serves as the ionization end of the ionization needle (5), and the length of the ionization end is about 1 cm; the sample plate (8) is a plate that is resistant to organic solvents and hydrophobic.

[0078] 2) A method for characterizing organic inclusions, combining the above-mentioned nano-electrospray ionization device with an ultra-high resolution mass spectrometer, the specific process comprising:

[0079] The solvent is transported to the solvent circulation pipeline (2) through the liquid driving device (1), and the solvent in the pipeline flows through the conductive element (4) and is charged under the voltage applied by the power supply (3), and then the charged solvent flows into the ionization needle (5); the organic inclusion sample (i.e., the sample to be sampled (7)) is placed on the sample plate (8), and then the sample plate (8) is placed close to the bottom of the sampling port (6) of the ionization needle (5), and the organic inclusion sample on the sample plate (8) is placed under the sampling port (6) of the ionization needle (5). 5) enters the ionization needle (5) through the sampling port (6) under the self-absorption action; the organic inclusion sample entering the ionization needle (5) is mixed with the charged solvent in the ionization needle (5), and then reaches the tip of the ionization needle (5) along with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field; the ejected electrospray enters the mass spectrometer through the mass spectrometer inlet (9) for detection, and the distance between the needle tip of the ionization needle (5) and the mass spectrometer inlet (9) is 5 mm;

[0080] The operating conditions of the nano-electrospray ionization device are as follows: sample: 10 nL, 20 mg / mL toluene-methanol 1:3 (v / v) solution of Xinjiang crude oil, solvent: mixed solvent of toluene and methanol (1:3, v / v), solvent flow rate: 0.5 μL / min, voltage: +2000 V;

[0081] The mass spectrometer conditions were: mass spectrometer model: Thermo Fisher Scientific Orbitrap FusionMS, ion transfer tube temperature: 300 °C, detector type: Orbitrap, RF Lens: 80%, automatic gain control target: 5.0e5, maximum injection time: 100 ms, micro scan: 1.

[0082] The characterization results are as follows Figures 2-3 As shown, Figure 2 is the composition distribution diagram of N1 compounds of Xinjiang crude oil provided in Example 1 of the present invention, Figure 3 This is the composition distribution diagram of N1O1 compounds in Xinjiang crude oil provided in Example 1 of the present invention.

[0083] Comparative Example 1

[0084] A characterization method for organic inclusions combines conventional electrospray ionization (ESI) with ultra-high resolution mass spectrometry. The specific test conditions are as follows:

[0085] ESI ionization conditions: sample: 100 μL, 0.2 mg / mL Xinjiang crude oil toluene methanol 1:1 (v / v) solution, ionization solvent: mixed solvent of toluene and methanol (1:1, v / v), solvent flow rate: 0.5 μL / min, ion spray voltage: +3000 V, sheath gas: 5 arbitrary units, auxiliary gas: 2 arbitrary units, backflush gas: 0.1 arbitrary units;

[0086] The mass spectrometer conditions were: mass spectrometer model: Thermo Fisher Scientific Orbitrap FusionMS, ion transfer tube temperature: 300 °C, detector type: Orbitrap, RF Lens: 80%, automatic gain control target: 5.0e5, maximum injection time: 100 ms, micro scan: 1.

[0087] The characterization results are as follows Figures 4-5 As shown, Figure 4 This is the composition distribution diagram of N1 compounds in Xinjiang crude oil provided in Comparative Example 1 of the present invention. Figure 5 This is the composition distribution diagram of N1O1 compounds in Xinjiang crude oil provided in Comparative Example 1 of the present invention.

[0088] By comparison Figure 2 and Figure 4 It can be seen that the composition distribution of the N1 compounds obtained in Example 1 and Comparative Example 1 is basically the same, with a distribution range of carbon number 15-40 and DBE 5-15. Figure 3 and Figure 5 It can be seen that the composition distribution of N1O1 compounds obtained in Example 1 and Comparative Example 1 is basically the same, and the distribution range is carbon number 15-40, DBE 5-17; it can be seen that the method provided in Example 1 can realize the accurate detection and analysis of trace crude oil molecular composition.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for performing nano-electrospray ionization on organic inclusions, which is performed in a device for performing nano-electrospray ionization on organic inclusions, wherein the device include: Solvent drive device; a solvent circulation pipeline connected to the discharge end of the solvent driving device; A conductive element connected to the discharge end of the solvent circulation pipeline, wherein the conductive element is connected to a power source; An ionization spray needle connected to the discharge end of the conductive element, wherein the needle body of the ionization spray needle is bent into a U-shape or a V-shape, and a sampling port is provided at the lower edge of the bottom end of the bent area; and a sample plate for placing the sample to be sampled; The method comprises the following steps: The solvent is transported into the solvent flow pipeline by the solvent driving device, the solvent in the pipeline flows through the conductive element and is charged under the voltage applied by the power supply, and then the charged solvent flows into the ionization spray needle; The organic inclusion sample is placed on a sample plate, and then the sample plate is placed close to the sampling port of the ionization needle. The organic inclusion sample on the sample plate enters the ionization needle through the sampling port under the self-absorption of the ionization needle. The organic inclusion sample entering the ionization needle is mixed with the charged solvent in the ionization needle, and then reaches the tip of the ionization needle along with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field.

2. The method according to claim 1, It is characterized in that The inner diameter of the needle body of the ionization spray needle is 50-200 μm, and the outer diameter is 300-400 μm.

3. The method according to claim 1, It is characterized in that The ionization needle is a fused silica capillary needle with a polyimide outer coating.

4. The method according to claim 1, It is characterized in that The bending angle of the V-shape is 100-170°.

5. The method according to claim 1, It is characterized in that The caliber of the sampling port is 50-200 μm.

6. The method according to claim 1, It is characterized in that The solvent is a single-component solvent or a mixed solvent that can generate electrospray under the action of an electric field.

7. A method for characterizing an organic inclusion, performed in a system for characterizing an organic inclusion, wherein the system include: Solvent drive device; a solvent circulation pipeline connected to the discharge end of the solvent driving device; A conductive element connected to the discharge end of the solvent circulation pipeline, wherein the conductive element is connected to a power source; An ionization spray needle connected to the discharge end of the conductive element, wherein the needle body of the ionization spray needle is bent into a U-shape or a V-shape, and a sampling port is provided at the lower edge of the bottom end of the bent area; A sample plate for placing samples to be sampled; and a mass spectrometer, the mass spectrometer being used to detect the electrospray ejected from the ionization needle; The method comprises the following steps: The solvent is transported into the solvent flow pipeline by the solvent driving device, the solvent in the pipeline flows through the conductive element and is charged under the voltage applied by the power supply, and then the charged solvent flows into the ionization spray needle; The organic inclusion sample is placed on a sample plate, and then the sample plate is placed close to the sampling port of the ionization needle. The organic inclusion sample on the sample plate enters the ionization needle through the sampling port under the self-absorption of the ionization needle. The organic inclusion sample entering the ionization needle is mixed with the charged solvent in the ionization needle, and then reaches the tip of the ionization needle along with the flow of the charged solvent, and is ejected in the form of electrospray under the action of the electric field; The ejected electrospray enters the mass spectrometer through the mass spectrometer inlet for detection to obtain the detection result.

8. The method according to claim 7, It is characterized in that The mass spectrometer is an ultra-high resolution mass spectrometer.

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