Solid phase microextraction combined with dielectric barrier discharge ionization device and application thereof

Abstract

The application discloses a solid phase microextraction combined dielectric barrier discharge ionization device and application thereof. The ionization device comprises a connecting and adapting assembly, a dielectric barrier discharge ionization assembly, a gas conveying pipeline assembly, a high-voltage power supply and a control terminal. The connecting and adapting assembly is used for detachable connection with a mass spectrometer sampling inlet. The dielectric barrier discharge ionization assembly forms a DBDI ionization area around a sample loading channel. The gas conveying pipeline assembly is used for providing carrier gas to the ionization area. The control terminal is used for controlling the carrier gas on-off and discharge time. During detection, an arrow-shaped solid phase microextraction fiber adsorbed with a to-be-detected substance is inserted into the sample loading channel, so that the to-be-detected substance is desorbed, ionized and enters a mass spectrometer for detection under the action of the carrier gas and the DBDI. The ionization device can be used for rapid detection of ricinine, dimethyl methylphosphonate and other small molecules with different characteristics, and has the characteristics of accurate alignment, simple operation and good repeatability.

Description

Technical Field

[0001] This invention belongs to the fields of analytical chemistry, mass spectrometry detection and on-site rapid detection technology, specifically relating to a solid-phase microextraction combined with a dielectric barrier discharge ionization device and its application. Background Technology

[0002] Solid phase microextraction (SPME) is a sample pretreatment technique that integrates sampling, extraction, enrichment, and injection. Its basic principle is to utilize fibers or carriers coated with an extractant phase, allowing the target analyte to partition or adsorb and accumulate between the sample matrix and the extractant phase, thus achieving solvent-free or low-solvent pretreatment of trace analytes. Compared to traditional pretreatment methods such as liquid-liquid extraction and solid phase extraction, SPME offers advantages such as lower sample consumption, fewer operational steps, ease of automation, and suitability for the detection of volatile and semi-volatile small molecules. It has been widely used in fields such as environmental, food safety, pharmaceutical analysis, public safety, and biological sample analysis.

[0003] Traditional SPME fibers are typically based on fine-diameter fused silica or metal supports, resulting in limited coating volume. In complex matrices or ultra-trace analytes analysis, their extraction capacity, mechanical strength, and reusability are easily limited. To improve extraction capacity and operational stability, SPME Arrows have been proposed as improved solid-phase microextraction carriers. SPME Arrows typically have an outer diameter of 1.1 mm or 1.5 mm and can employ a coating of approximately 20 mm. Compared to traditional SPME fibers, they offer a larger adsorbed phase volume and surface area, a more robust mechanical structure, and sensitivity up to 10 times that of traditional SPME fibers, with a lifespan up to 5 times longer. Therefore, SPME Arrows are more suitable for trace detection scenarios requiring high enrichment rates, high repeatability, and strong mechanical robustness.

[0004] Dielectric barrier discharge ionization (DBDI) is a low-temperature plasma ionization technique operating at ambient pressure. This technique generates plasma by applying a high-voltage electric field within a dielectric barrier insulating structure, utilizing electrons, ions, excited-state molecules, and reactive particles within the plasma to achieve desorption and ionization of sample molecules. DBDI ion sources offer advantages such as relatively simple structure, operation at ambient pressure, no need for complex interfaces, and suitability for rapid analysis of solid, liquid, and gas samples. Early studies have reported that DBDI-based ambient-pressure ionization sources can be used for direct mass spectrometry detection of explosives on solid surfaces. Literature reviews indicate that DBDI has been applied in fields such as bioanalysis, food safety, mass spectrometry imaging, forensic identification, and reaction monitoring, featuring low energy consumption, solvent-free or solvent-less operation, and easy miniaturization. Furthermore, DBDI is also used in liquid chromatography / mass spectrometry interfaces and for the detection of various organic pollutants and pesticides.

[0005] It is conceivable that the combination of SPME and cryogenic plasma ionization is a superior rapid analytical detection method. Cryogenic plasma can better facilitate the desorption of analytes on the SPME and apply appropriate energy to ionize them, while complex matrices may have reduced impact on detection due to their weak ionization nature. From the perspective of interface structure, the purpose of combining SPME and cryogenic plasma ionization is not simply to superimpose the two technologies, but rather to utilize SPME to first achieve enrichment and matrix reduction, and then complete rapid desorption, ionization, and short-distance ion transport in the ambient pressure cryogenic plasma region, thereby reducing the impact of complex matrices on mass spectrometry detection and shortening analysis time. From a technological development perspective, the combination of SPME with cryogenic plasma ionization or DBDI-MS already has a certain research foundation. For example, Dumlao et al. combined SPME with low-temperature plasma mass spectrometry to detect organophosphorus toxicant mimics and their hydrolysis products, directly detecting analytes such as DMMP, diethylethylphosphonate (DEEP), and pinacolylmethylphosphonic acid (PinMPA) in water and urine. The detection limits for DMMP, DEEP, and PinMPA were 24.46±0.07, 31.39±0.13, and 68.05±0.14 ppb (water sample) and 55.42±0.08, 27.33±0.38, and 98.89±0.70 ppb (urine sample), respectively. The sampling and data acquisition time for a single sample was less than 2 minutes. This method used a self-made stainless steel needle coated with LTA (Linde Type A) zeolite as the SPME probe. The probe was inserted into a quartz glass capillary as an internal electrode, and a copper electrode was set on the outside. Ambient gas was drawn into the low-temperature plasma chamber through the mass spectrometer inlet. This structure demonstrates that SPME and low-temperature plasma can form a rapid detection process, but its SPME probe also serves as an electrode and relies on a self-made needle-shaped probe, an external positioning platform, and a capillary plasma chamber. It is not compatible with the large outer diameter and arrow-shaped mechanical structure of commercial SPME arrow fibers, nor does it provide a standardized interface that can be detachably nested with the mass spectrometer inlet and maintain coaxial alignment.

[0006] Mirabelli et al. proposed a method to detect analytes enriched on SPME fibers via thermal desorption followed by introduction into a dielectric barrier discharge (DBDI) ion source for mass spectrometry. Using small molecules such as cocaine, diazepam, atrazine, and parathion as validation targets, they achieved linear dynamic ranges exceeding three orders of magnitude. The detection limits for cocaine and diazepam were both 0.3 pg / mL, for atrazine 1 pg / mL, and for parathion 3 pg / mL. The key structural element of this device is placing the SPME fiber within a thermal desorption chamber or interface, allowing the analyte to be thermally desorbed from the fiber coating before being transferred by the carrier gas to the DBDI ion source and entering the mass spectrometer inlet. While this method separates the desorption and ionization processes, it also implies the existence of an independent thermal desorption chamber, a transport pathway, and a coupling position between the DBDI source. It does not solve the problem of direct, stable, and reproducible localization of the SPME arrow fiber within the DBDI ionization region. Huba et al. directly coupled an active capillary plasma ionization source with SPME for screening polycyclic aromatic hydrocarbons and polar trace pollutants in water samples, achieving an analysis speed of less than 10 min / sample, a detection limit of 3 pg / mL, an RSD of less than 20%, and a linear dynamic range of no less than two orders of magnitude. Mirabelli et al. also directly interfaced a matrix-compatible SPME phase with DBDI-MS for pesticide detection in grape juice; grape juice, as a complex matrix with a sugar content of approximately 20% w / w and containing pigments, still achieved a detection limit at the ppt level, and intra-day and inter-day precision of less than 30% RSD at spiking levels of 1, 10, and 10 ng / mL. These studies demonstrate the feasibility of SPME-plasma ionization mass spectrometry, but existing structures mainly revolve around ordinary SPME fibers, thermal desorption interfaces, or active capillary ion sources, and have not yet been specifically designed for a detachable, coaxial, and confined interface between the SPME arrow fiber and the mass spectrometer inlet.

[0007] Besides academic papers, publicly available product information also includes direct ionization mass spectrometry (DIMS) ion sources that combine SPME with DBDI. For example, the DBDI-200 solid-phase microextraction (SPME) DIMS ion source is described as a direct ionization ion source that combines dielectric barrier discharge ionization (DPE) with solid-phase microextraction (SPME) to improve detection sensitivity and consistency of results, and to support rapid relative quantitative analysis (Huayiteng DBDI-200 product information). Structurally, such publicly available information typically focuses on the ion source module and the SPME sample introduction function itself, without fully considering structural details such as the detachable nesting method between the fiber sample-carrying end and the mass spectrometer inlet, axial positioning, insertion depth limits, carrier gas state monitoring, and handheld timing control. Ordinary SPME fibers typically have a narrow diameter and limited mechanical strength, making them prone to problems such as fiber bending, coating deviation from the effective discharge zone, and inconsistent distances from the mass spectrometer inlet during manual insertion or external support positioning, leading to fluctuations in desorption / ionization efficiency and ion transport efficiency.

[0008] Replacing ordinary SPME fibers with more robust SPME Arrows would be a more robust option. However, their outer diameter, protective needles, and arrow-shaped adsorption end structure also require interfaces with more defined channel dimensions, insertion limits, and axial positioning. For example, in PAL Systems' automated SPME-SICRIT-MS workflow, the PAL RTC system is used to perform SPME Arrow extraction and thermally desorb the enriched analyte into the SICRIT ion source for real-time mass spectrometry analysis. SICRIT (Soft Ionization by Chemical Reaction In Transfer) is an atmospheric pressure flow-through soft ionization source or a low-temperature plasma soft ionization source. Its structure is typically installed at the front end of the atmospheric pressure inlet of the mass spectrometer, where cold plasma within the source performs soft ionization on molecules drawn into the mass spectrometer inlet. Therefore, this publicly available workflow demonstrates that SPME Arrow has an application basis with plasma-based soft ionization mass spectrometry, but it mainly relies on automated sample introduction platforms and commercial flow-through ion sources. The focus is on automated sample pretreatment and high-throughput detection processes, and it has not been specifically designed for detachable connections, handheld control, gas path monitoring, coaxial alignment of the mass spectrometer inlet, and stable sample loading structures of SPME Arrow in the DBDI ionization region.

[0009] However, several problems still exist when SPME Arrow is used in conjunction with DBDI-MS: First, the outer diameter and mechanical structure of SPME Arrow differ from traditional SPME fibers, resulting in a larger sample-carrying area. Without a specialized adaptation structure, it is difficult to ensure that the sample-carrying area is within the effective range of the DBDI ionization region during each detection. Second, the DBDI ionization efficiency and ion transport efficiency are highly sensitive to the relative position, axial angle, distance, and gas flow state between the discharge region and the mass spectrometer inlet. Relying on manual placement or external support positioning can easily lead to unstable plasma utilization, fluctuations in ion entry efficiency into the mass spectrometer, and decreased detection repeatability. Third, the analytes enriched on the SPME Arrow need to complete desorption, migration, and ionization under appropriate discharge time, gas flow conditions, and temperature. Without monitoring of gas pressure or carrier gas status, as well as integrated control of discharge time and sample introduction process, problems such as insufficient desorption, sample residue, coating damage, or signal fluctuations can easily occur. Fourth, existing publicly available solutions mostly focus on laboratory automation platforms or the ion source itself, making it difficult to meet the needs of rapid on-site detection for detachable assembly, ease of operation, stable alignment, and standardized control.

[0010] Therefore, it is necessary to provide a solid-phase microextraction combined with a medium barrier discharge ionization device adapted to SPME Arrow. Summary of the Invention

[0011] To address the aforementioned problems in existing technologies, this invention provides a solid-phase microextraction (SPME) combined with a dielectric barrier discharge (DBDI) ionization device and its application. This ionization device enables the SPME arrow fiber to be stably positioned within the DBDI ionization region and maintains stable axial alignment between the DBDI ionization region and the mass spectrometer inlet. Simultaneously, through carrier gas or gas pressure detection, gas path control, discharge control, and manual / automatic sample introduction control, it improves the desorption efficiency of the sample from the SPME arrow surface, the DBDI ionization efficiency, and the transmission stability into the mass spectrometer, thereby reducing human error and improving detection sensitivity, repeatability, and applicability for rapid on-site detection.

[0012] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0013] In a first aspect, the present invention provides a solid-phase microextraction combined with a dielectric barrier discharge ionization device, the ionization device comprising a connection adapter component, a dielectric barrier discharge ionization component, a gas pipeline component, a high-voltage power supply, and a control terminal. The dielectric barrier discharge ionization assembly includes a dielectric barrier tube and a high-voltage conductive component; one end of the dielectric barrier tube is provided with a sample carrying channel for inserting solid-phase microextraction fibers, and the other end forms a low-temperature plasma sample introduction channel; the high-voltage conductive component serves as a discharge electrode covering the outer periphery of the dielectric barrier tube and is connected to the high-voltage power supply to form a DBDI ionization region on the outer periphery of the sample carrying channel. The connection adapter is detachably connected between the mass spectrometer inlet and the medium blocking tube, and is used to control the connection and disconnection between the low-temperature plasma injection channel and the mass spectrometer inlet. The end of the gas pipeline assembly is connected to the medium barrier pipe for supplying carrier gas to the DBDI ionization region; the gas pipeline assembly is provided with a flow detection component for detecting the carrier gas flow rate and a pressure detection component for detecting the carrier gas pressure. The control terminal is used to control the flow rate of the carrier gas in the gas transmission pipeline assembly and the discharge time of the high-voltage conductive component.

[0014] Furthermore, the sample carrying channel, the DBDI ionization region, the low-temperature plasma injection channel, and the mass spectrometer injection port are coaxially arranged; The sample carrying channel is provided with a limiting structure to restrict the insertion depth of the solid-phase microextraction fiber, so that the adsorption end of the solid-phase microextraction fiber is located in the DBDI ionization region.

[0015] Furthermore, the connection adapter assembly includes a hose and a clamp valve for controlling the opening and closing of the hose; The gas pipeline assembly is equipped with a solenoid valve; The control terminal is connected to the pinch valve and the solenoid valve, and is used to control the opening and closing of the pinch valve or the solenoid valve.

[0016] Furthermore, the dielectric barrier tube is made of quartz, glass, or ceramic material; The high-voltage conductive component is a conductive metal mesh.

[0017] Furthermore, the high-voltage power supply is housed within a high-voltage power supply box; the high-voltage power supply box is connected to the high-voltage conductive component and the control terminal, and is used to provide an adjustable high-voltage output to the high-voltage conductive component.

[0018] Furthermore, the control terminal has an automatic sampling mode and a manual sampling mode; in the automatic sampling mode, the control terminal controls the carrier gas injection and the discharge of the high-voltage conductive component according to a preset timing sequence.

[0019] Secondly, the present invention provides an application of the above-mentioned solid-phase microextraction combined with dielectric barrier discharge ionization device, which is used to detect small molecule analytes in a sample to be tested. The small molecule analytes include at least one of organophosphorus compounds, nitrogen-containing heterocyclic compounds, pesticides, veterinary drugs, pharmaceuticals, poisons, explosives or their analogues, and metabolites.

[0020] Furthermore, the small molecule analyte includes ricin and / or dimethyl methylphosphonate.

[0021] Thirdly, the present invention also provides a method for detecting small molecule analytes using the above-mentioned solid-phase microextraction combined with a dielectric barrier discharge ionization device, the detection method comprising the following steps: The sample to be tested is adsorbed onto the solid-phase microextraction fiber and dried to obtain the solid-phase microextraction fiber carrying the sample to be tested. The solid-phase microextraction fiber carrying the sample to be tested is inserted into the sample carrying channel, so that the adsorption end of the solid-phase microextraction fiber is located in the DBDI ionization region. A carrier gas is introduced into the DBDI ionization region and a high-voltage power supply is controlled to cause the high-voltage conductive component to discharge in the DBDI ionization region, thereby desorbing and ionizing the small molecule analytes adsorbed on the solid-phase microextraction fiber. Mass spectrometry signals are acquired and detected using a mass spectrometer.

[0022] Furthermore, during adsorption or extraction, the adsorption end of the solid-phase microextraction fiber is immersed in the sample to a depth of 1-2 cm. The output power of the high-voltage power supply is 20%-80% of the rated output; The discharge time in the DBDI ionization region is 1s-2s; The carrier gas is nitrogen or helium.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. The ionization device of the present invention, by connecting the adapter component, enables the DBDI ionization region to be stably aligned with the mass spectrometer inlet, thereby improving detection repeatability.

[0024] 2. The ionization device of the present invention limits the adsorption end of the solid-phase microextraction fiber to the DBDI ionization region through a limiting structure, which can improve the desorption and ionization efficiency.

[0025] 3. In the ionization device of the present invention, the flow rate of the carrier gas in the gas pipeline assembly and the discharge time of the high-voltage conductive component are controlled by the control terminal, so that the carrier gas and the discharge sequence are uniformly controlled by the control terminal, reducing the difference in manual operation.

[0026] 4. The ionization device of the present invention does not require a complicated solvent elution step during the detection process, making it suitable for rapid screening of ricin, dimethyl methylphosphonate and other small molecules. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the solid-phase microextraction combined with medium barrier discharge ionization device of the present invention; Figure 2 This is a physical image of the solid-phase microextraction combined with medium barrier discharge ionization device of the present invention; Figure 3 This is a schematic diagram of the physical connection between the solid-phase microextraction combined with the medium barrier discharge ionization device and the mass spectrometer of the present invention. Figure 4 This is a standard curve for ricinine detection under optimized conditions. Figure 5 Mass spectrometry response diagrams of ricinidine detected using the ionization device of the present invention under different discharge voltage intensities; Figure 6 Mass spectrometry response diagrams of ricinidine detected using the ionization device of the present invention under different DBDI discharge time conditions; Figure 7 To detect the mass spectrometry response of ricin using the ionization device of the present invention under different solid-phase microextraction fiber immersion depths; Figure 8 The bar chart shows the effect of extraction temperature on the mass spectrometric response intensity of dimethyl methylphosphonate. Figure 9 The bar chart shows the effect of DBDI discharge time on the mass spectrometric response intensity of dimethyl methylphosphonate. Figure 10 The bar chart shows the effect of extraction time on the mass spectrometric response intensity of dimethyl methylphosphonate. Figure 11This is a response surface plot showing the effect of extraction temperature and extraction time on the mass spectrometry response intensity of dimethyl methylphosphonate.

[0028] Figure label: 1-Connector adapter component, 2-Gas pipeline component, 3-High voltage power supply, 4-Control terminal, 5-Medium barrier tube, 6-High voltage conductive component, 7-Mass spectrometer inlet; 51-Sample loading channel, 52-Low temperature plasma injection channel. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In this embodiment of the invention, the mass spectrometer may be an LTQ Orbitrap Elite linear ion trap-electrostatic orbital trap mass spectrometer. Unless otherwise stated, the reagents, consumables, and instruments used in this embodiment of the invention are all commercially available, and experimental conditions not specified may be performed using conventional conditions in the art or conditions recommended by the instrument manufacturer.

[0031] Example 1 This embodiment provides a solid-phase microextraction combined with a medium barrier discharge ionization device, such as... Figure 1 , Figure 2 and Figure 3 As shown, the ionization device includes a connection adapter assembly 1, a dielectric barrier discharge ionization assembly, a gas pipeline assembly 2, a high-voltage power supply 3, and a control terminal 4; wherein: The dielectric barrier discharge ionization assembly includes a dielectric barrier tube 5 and a high-voltage conductive component 6. The dielectric barrier tube 5 is made of quartz, glass, or ceramic. As a dielectric barrier layer, the dielectric barrier tube 5 has a sample carrying channel 51 at one end for inserting solid-phase microextraction (SPME) fibers. The sample carrying channel 51 contains a limiting structure to restrict the insertion depth of the SPME fibers, ensuring that the adsorption end of the SPME fibers is located within the DBDI ionization region. A low-temperature plasma injection channel 52 is formed at the other end of the dielectric barrier tube 5. The high-voltage conductive component 6 is a conductive metal mesh. The high-voltage conductive component 6 is connected to a high-voltage power supply 3 and serves as a discharge electrode. The high-voltage conductive component 6 covers the outer periphery of the middle part of the dielectric barrier tube 5, forming a DBDI ionization region on the outer periphery of the sample carrying channel 51. The high-voltage power supply 3 is housed within a high-voltage power supply box. The high-voltage power supply box is connected to the high-voltage conductive component 6 and a control terminal 4, providing an adjustable high-voltage output to the high-voltage conductive component 6.

[0032] The adapter component 1 is detachably connected between the mass spectrometer inlet 7 and the dielectric barrier tube 5 to control the connection and disconnection between the low-temperature plasma injection channel 52 and the mass spectrometer inlet 7. The adapter component 1 allows the DBDI ionization region to be repeatedly positioned at the front end of the mass spectrometer inlet 7.

[0033] The end of the gas delivery pipeline assembly 2 is connected to the medium barrier tube 5 to provide carrier gas to the DBDI ionization region. During detection, the carrier gas enters the DBDI ionization region through the gas delivery pipeline assembly 2, carrying the desorbed and ionized analyte into the mass spectrometer inlet 7. The carrier gas is nitrogen or helium. The gas delivery pipeline assembly 2 is equipped with a flow detection component for detecting the carrier gas flow rate and a pressure detection component for detecting the carrier gas pressure; the flow detection component can be a gas flow meter; the pressure detection component can be a pressure sensor.

[0034] The control terminal 4 is used to control the flow rate of the carrier gas in the gas pipeline assembly 2 and the discharge time of the high-voltage conductive component 6. The control terminal 4 has an automatic injection mode and a manual injection mode; in the automatic injection mode, the control terminal 4 controls the carrier gas introduction and the discharge of the high-voltage conductive component 6 according to a preset timing sequence.

[0035] The sample carrying channel 51, the DBDI ionization region, the low-temperature plasma sample introduction channel 52, and the mass spectrometer inlet 7 are coaxially arranged to reduce manual alignment errors.

[0036] The connection adapter component 1 includes a flexible tube and a clamp valve for controlling the opening and closing of the flexible tube; the flexible tube can be made of silicone tubing; the clamp valve can be a normally closed solenoid clamp valve. The gas delivery pipeline component 2 includes a solenoid valve in the gas delivery pipeline; the solenoid valve controls the flow of carrier gas in the pipeline, and can be a miniature solenoid valve or a three-way reversing solenoid valve; the gas delivery pipeline can be made of silicone tubing. The control terminal 4 is connected to the clamp valve and the solenoid valve, and is used to control the opening and closing of the clamp valve or the solenoid valve. The control terminal 4 can be a handheld control terminal. The handheld control terminal is connected to the high-voltage power supply box, the clamp valve, and the solenoid valve, and can control the carrier gas introduction, discharge time, and detection sequence according to a preset program; it can also be used in manual sample injection mode where the operator controls the carrier gas and discharge process separately.

[0037] Example 2 This embodiment provides an application of the solid-phase microextraction combined with dielectric barrier discharge ionization device in Embodiment 1 above. The ionization device is used to detect small molecule analytes in the sample to be tested. The small molecule analytes include at least one of organophosphorus compounds, nitrogen-containing heterocyclic compounds, pesticides, veterinary drugs, pharmaceuticals, poisons, explosives or their analogues, and metabolites. Preferably, the small molecule analytes are ricinine and / or dimethyl methylphosphonate.

[0038] Example 3 This embodiment provides a method for detecting small molecule analytes using the solid-phase microextraction combined with a dielectric barrier discharge ionization device as described in Embodiment 1 above. The detection method includes the following steps: The first step involves adsorbing the sample to be tested onto a solid-phase microextraction fiber and drying it to obtain a solid-phase microextraction fiber carrying the sample to be tested. During adsorption or extraction, the adsorption end of the solid-phase microextraction fiber is immersed in the sample to a depth of 1cm-2cm, preferably 1.5cm-2cm, with 2cm being the optimal choice.

[0039] The second step is to insert the solid-phase microextraction fiber carrying the sample into the sample carrying channel 51, so that the adsorption end of the solid-phase microextraction fiber is located in the DBDI ionization region. The third step involves introducing a carrier gas into the DBDI ionization region and controlling the high-voltage power supply 3 to discharge the high-voltage conductive component 6 in the DBDI ionization region, thereby desorbing and ionizing the small molecule analytes adsorbed on the solid-phase microextraction fiber. The output intensity of the high-voltage power supply 3 is 20%-80% of the rated output, preferably 20%-60%, and most preferably 60%. The discharge time in the DBDI ionization region is 1s-2s, preferably 1.5s-2s, and most preferably 2s. The carrier gas is nitrogen or helium.

[0040] The fourth step is to acquire and detect the mass spectrometry signal using a mass spectrometer.

[0041] Example 4: Ricin Sample Enrichment and Injection Detection Procedure This embodiment illustrates the sample enrichment, fiber loading, and mass spectrometry injection process when using the ionization device described in Embodiment 1 above to detect ricin.

[0042] Take 3 mL of ricin aqueous solution with a concentration of 1 μg / mL as the test sample. Fix the SPME Arrow fiber on the sample adsorption device and immerse its adsorption end in the test sample. Stir at 800 rpm for 30 min at room temperature. After adsorption is complete, remove the SPME Arrow fiber and dry the surface residual droplets with a clean airflow or let it air dry naturally to obtain SPME Arrow fiber loaded with ricin.

[0043] A SPME arrow fiber carrying ricin is inserted into the sample carrying channel 51 of the medium barrier tube 5, with its adsorption end located within the DBDI ionization region. Subsequently, the adapter assembly 1 is connected to the mass spectrometer inlet 7, ensuring that the sample carrying channel 51, the DBDI ionization region, and the mass spectrometer inlet 7 are arranged coaxially or substantially coaxially along the sample introduction direction. The temperature of the mass spectrometer inlet 7 is set to 300°C, carrier gas is introduced, and DBDI discharge is initiated to collect the mass spectrometric response of ricin.

[0044] This embodiment illustrates that, through the sample carrying channel 51 and the connecting adapter component 1, the SPME Arrow fiber adsorption end can be stably placed in the DBDI ionization region and can maintain a repeatable alignment with the mass spectrometer inlet 7.

[0045] Example 5: Establishment of the ricinine standard curve This embodiment illustrates the process of establishing a ricinine standard curve using the ionization device described in Example 1.

[0046] Following the procedure in Example 4, ricinine standard solutions of different concentrations were subjected to SPME Arrow fiber adsorption, drying, loading, DBDI desorption ionization, and mass spectrometry acquisition. A standard curve was established with the ricinine mass spectrometry response intensity as the ordinate and the ricinine standard solution concentration as the abscissa. The results are shown in [Figure 4]. Figure 4 .

[0047] Depend on Figure 4 As can be seen, within the investigated concentration range, the mass spectrometric response of ricin increases with increasing concentration, indicating that the ionization device of the present invention can be used for quantitative or semi-quantitative detection of ricin samples.

[0048] Example 6: Effect of discharge voltage intensity on the mass spectrometric response of ricin. This example illustrates the effect of DBDI discharge voltage intensity on the mass spectrometry response of ricin.

[0049] SPME arrow fibers loaded with ricin were prepared according to the procedure in Example 4 and inserted into the DBDI ionization region of the ionization device of the present invention. Using the rated output of the high-voltage power supply 3 as a reference, different output intensities were set for testing, and the results are shown below. Figure 5 .

[0050] The results showed that a ricinine response was obtained when the output intensity reached 20%; as the output intensity increased, the mass spectrometry signal strengthened, reaching a high level around 60%; when the output intensity further increased to 80%, the signal decreased. Therefore, in the detection of ricinine, the output intensity of the high-voltage power supply 3 is preferably 20%-80%, more preferably 20% to 60%, and even more preferably 60%.

[0051] Example 7: Effect of DBDI discharge time on ricin mass spectrometry response This example illustrates the effect of DBDI discharge time on the mass spectrometry response of ricin.

[0052] SPME arrow fibers loaded with ricin were prepared according to the procedure in Example 4. Under the same carrier gas and mass spectrometry conditions, different DBDI discharge times were set for detection. The results are shown in [Figure 4]. Figure 6 .

[0053] The results showed that the ricin response was weak when the discharge time was short; the mass spectrometry response increased with the extension of the discharge time, reaching a high level at about 2 seconds. Considering that excessively long discharge times may increase the risk of damage to the fiber coating, the DBDI discharge time is preferably 1-2 seconds, more preferably 1.5-2 seconds, and even more preferably 2 seconds in the detection of ricin.

[0054] Example 8: Effect of SPME Arrow fiber immersion depth on ricin alkaloid enrichment. This example illustrates the effect of the depth of the SPME Arrow fiber adsorption end immersed in the sample on the enrichment and detection response of ricinine.

[0055] Samples of ricin E (ironic acid) of the same concentration were taken and adsorbed at different SPMEArrow fiber immersion depths under the same stirring conditions and at room temperature. After adsorption, DBDI-MS analysis was performed according to the procedure in Example 4. The results are shown in [Figure 4]. Figure 7 .

[0056] The results showed that ricinine signal could be detected at an immersion depth of 1 cm; the mass spectrometry response increased with increasing immersion depth, reaching a high level at 2 cm. Therefore, the preferred immersion depth of the SPME Arrow fiber adsorption end during sample adsorption is 1 cm-2 cm, more preferably 1.5 cm to 2 cm, and even more preferably 2 cm.

[0057] Example 9: Suitability Study of Carrier Gas Type and Flow Rate This embodiment is used to illustrate the applicability of the ionization device of the present invention to different carrier gas types and carrier gas flow rates.

[0058] Based on the ionization device and detection process in Example 4, nitrogen and helium were used as carrier gases, and the carrier gas flow rate was adjusted within the range that the mass spectrometer could withstand to investigate the mass spectrometry response of ricin and the operational stability of the mass spectrometer.

[0059] Experimental results show that, within the carrier gas flow rate range that the mass spectrometer can withstand, both nitrogen and helium can be used as carrier gases in the ionization device of this invention. Considering the convenience of gas source, cost, and detection stability, nitrogen is the preferred carrier gas.

[0060] Example 10: Validation of the precision and accuracy of ricin alkaloid detection This embodiment is used to illustrate the repeatability and accuracy of the ionization device and detection method of the present invention when used for ricinine detection.

[0061] According to the conditions determined in Examples 4 to 9, ricinine samples at three concentration levels (low, medium, and high) were tested, and the inter-day precision, intra-day precision, and accuracy were calculated respectively. The results are shown in Table 1.

[0062] Table 1. Precision and accuracy results of ricinine (n=3)

[0063] As shown in Table 1, at low, medium, and high concentration levels, the inter-day precision RSD for ricinine detection is 1.12%-1.55%, the intra-day precision RSD is 0.74%-1.37%, and the accuracy is 88.75%-90.24%. These results demonstrate that the ionization device and detection method of the present invention exhibit good repeatability and accuracy when used for ricinine detection.

[0064] Example 11: Sample preparation and DBDI-MS detection procedure for dimethyl methylphosphonate This example illustrates the applicability of the ionization device described in Example 1 to small organophosphorus molecule mimics such as dimethyl methylphosphonate (DMMP).

[0065] Accurately weigh an appropriate amount of DMMP standard, and serially dilute it with 20% NaCl aqueous solution to prepare a DMMP standard solution with a concentration of 1 μg / mL. Store the solution at 4 ℃ in a dark, sealed container for later use. Place 10 mL of the above DMMP standard solution into a 15 mL headspace vial, add a magnetic stir bar, and immerse the SPME Arrow fiber in the sample solution for immersion extraction. After extraction, remove the SPME Arrow fiber and gently dry any remaining droplets on the surface with high-purity nitrogen gas to obtain DMMP-loaded SPME Arrow fiber.

[0066] A SPME arrow fiber carrying DMMP is inserted into the DBDI ionization region of the ionization device of this invention. It is then connected to the mass spectrometer inlet 7 via the adapter component 1, ensuring that the low-temperature plasma injection channel 52 is axially aligned with the mass spectrometer inlet 7. The temperature of the mass spectrometer inlet 7 is set to 300 °C, a preset discharge voltage is applied, and the discharge time is controlled via a handheld control terminal 4. The DMMP mass spectrometry signal is acquired, and the response intensity at a mass-to-charge ratio of m / z 125 is used as the evaluation index.

[0067] Example 12: Single-factor condition investigation for rapid DMMP detection This example illustrates a key single factor affecting the response intensity of DMMP mass spectrometry.

[0068] Following the procedure in Example 11, the effects of extraction temperature, DBDI discharge time, and extraction time on the DMMP mass spectrometry response intensity were investigated. The results regarding the effect of extraction temperature are shown below. Figure 8 The results of the effect of DBDI discharge time are shown in Figure 9 The effect of extraction time is shown in the results. Figure 10 .

[0069] Single-factor experiments showed that extraction temperature, extraction time, and DBDI discharge time all affect the DMMP mass spectrometry response intensity.

[0070] Therefore, the subsequent response surface optimization selected extraction temperature (A), extraction time (B), and DBDI discharge time (C) as the factors to be considered.

[0071] Example 13: DMMP Response Surface Experimental Design and Regression Model Establishment This example illustrates the response surface methodology and regression model establishment for DMMP detection parameters.

[0072] Based on the single-factor experimental results of Example 12, a Box-Behnken three-factor, three-level response surface design was used for the experiment, and the factor levels are shown in Table 2. Regression analysis was performed using the mass spectrometry response intensity of DMMP at m / z 125 as the response value, and a central replicate experiment was set up to evaluate the experimental random error.

[0073] Table 2. Response Surface Experimental Factors and Levels

[0074] Multiple regression was performed on the experimental data to establish a quadratic polynomial regression model between the mass spectrometry response intensity Y and each factor: Y = 1.29 × 10 5 +1.97×10 4 A-6.41×10 3 B + 8.33C - 4.98 × 10 4 A 2 -3.83×10 4 B 2 -3.14×10 4 C 2 + 6.63×10 3 AB +3.26×10 3 AC-8.73×10 3 BC.

[0075] An analysis of variance was performed on the model, and the results are shown in Table 3.

[0076] Table 3. Analysis of variance and significance test of response surface

[0077] Table 3 shows that the model's F-value is 6.87, and P=0.0029, indicating that the established model is significant. The lack-of-fit term has a P=0.9402, indicating that the lack of fit is not significant, suggesting that the model has a good fit to the experimental data and can be used for DMMP detection parameter prediction and optimization. In the linear term, the extraction temperature (A) has a significant impact on the response intensity. 2 B2 and C 2 The quadratic terms are significant, and the interaction of various factors has no significant effect on the response intensity.

[0078] Example 14: DMMP Response Surface Analysis and Optimal Parameter Verification This embodiment is used to illustrate the analysis of DMMP response surface methodology and the confirmation of optimal process parameters.

[0079] Response surface plots can visually reflect the impact of changes in factors on the response intensity of DMMP mass spectrometry. Figure 11 The effect of extraction temperature and extraction time on the response intensity is shown. Figure 11 As can be seen, the response surface exhibits a downward-opening curved shape, indicating that within the experimental range, the response intensity first increases and then decreases with increasing extraction temperature and extraction time, and there exists an optimal value range. Combined with the analysis of variance results, the interaction between extraction temperature, extraction time, and DBDI discharge time is not significant, and the detection sensitivity is mainly determined by the single-factor and quadratic effects of each factor.

[0080] The regression model was solved using a comprehensive optimizer, yielding the optimal process parameters for DMMP detection: extraction temperature 61.9℃, extraction time 24.6 min, and DBDI discharge time 1.5 s. Under these conditions, the model predicted a mass spectrometry response intensity of approximately 1.31 × 10⁻⁶. 5 .

[0081] To verify the accuracy of the model predictions and the repeatability of the method, five parallel confirmatory experiments were conducted under the aforementioned optimal parameters. The average mass spectrometry response intensity of DMMP was 1.34 × 10⁻⁶. 5 The relative deviation from the model prediction was 2.29%, and the relative standard deviation (RSD) of the method was 5.41%. These results indicate that the response surface model prediction is reliable, and the device of this invention exhibits good repeatability for DMMP detection.

[0082] This embodiment illustrates that the solid-phase microextraction combined with dielectric barrier discharge ionization device of the present invention can be used for the rapid detection of organophosphorus small molecule mimics and can realize an integrated process of "enrichment-desorption / ionization-mass spectrometry detection".

[0083] The above embodiments are merely illustrative examples of the present invention. Any equivalent substitutions or conventional adjustments made by those skilled in the art to the device structure, connection method, carrier gas type, detection object, and mass spectrometry conditions without departing from the concept of the present invention should fall within the protection scope of the present invention.

Claims

1. A solid-phase microextraction combined with a dielectric barrier discharge ionization device, characterized in that, This includes connection adapter components, dielectric barrier discharge ionization components, gas pipeline components, high-voltage power supply, and control terminal. The dielectric barrier discharge ionization assembly includes a dielectric barrier tube and a high-voltage conductive component; one end of the dielectric barrier tube is provided with a sample carrying channel for inserting solid-phase microextraction fibers, and the other end forms a low-temperature plasma sample introduction channel; the high-voltage conductive component serves as a discharge electrode covering the outer periphery of the dielectric barrier tube and is connected to the high-voltage power supply to form a DBDI ionization region on the outer periphery of the sample carrying channel. The connection adapter is detachably connected between the mass spectrometer inlet and the medium blocking tube, and is used to control the connection and disconnection between the low-temperature plasma injection channel and the mass spectrometer inlet. The end of the gas pipeline assembly is connected to the medium barrier pipe for supplying carrier gas to the DBDI ionization region; the gas pipeline assembly is provided with a flow detection component for detecting the carrier gas flow rate and a pressure detection component for detecting the carrier gas pressure. The control terminal is used to control the flow rate of the carrier gas in the gas transmission pipeline assembly and the discharge time of the high-voltage conductive component.

2. The solid-phase microextraction combined with dielectric barrier discharge ionization device as described in claim 1, characterized in that, The sample carrying channel, the DBDI ionization region, the low-temperature plasma injection channel, and the mass spectrometer injection port are coaxially arranged. The sample carrying channel is provided with a limiting structure to restrict the insertion depth of the solid-phase microextraction fiber, so that the adsorption end of the solid-phase microextraction fiber is located in the DBDI ionization region.

3. The solid-phase microextraction combined with dielectric barrier discharge ionization device as described in claim 1, characterized in that, The connection adapter assembly includes a hose and a clamp valve for controlling the opening and closing of the hose; The gas pipeline assembly is equipped with a solenoid valve; The control terminal is connected to the pinch valve and the solenoid valve, and is used to control the opening and closing of the pinch valve or the solenoid valve.

4. The solid-phase microextraction combined with dielectric barrier discharge ionization device as described in claim 1, characterized in that, The dielectric barrier tube is made of quartz, glass, or ceramic material; The high-voltage conductive component is a conductive metal mesh.

5. The solid-phase microextraction combined with dielectric barrier discharge ionization device as described in claim 1, characterized in that, The high-voltage power supply is housed within a high-voltage power supply box; the high-voltage power supply box is connected to the high-voltage conductive component and the control terminal, and is used to provide an adjustable high-voltage output to the high-voltage conductive component.

6. The solid-phase microextraction combined with dielectric barrier discharge ionization device as described in any one of claims 1-5, characterized in that, The control terminal has an automatic sampling mode and a manual sampling mode; in the automatic sampling mode, the control terminal controls the carrier gas injection and the discharge of the high-voltage conductive component according to a preset timing sequence.

7. An application of the solid-phase microextraction combined with dielectric barrier discharge ionization device as described in any one of claims 1-6, characterized in that, Used to detect small molecule analytes in test samples; The small molecule analytes include at least one of organophosphorus compounds, nitrogen-containing heterocyclic compounds, pesticides, veterinary drugs, pharmaceuticals, poisons, explosives or their analogues, and metabolites.

8. The application as described in claim 7, characterized in that, The small molecule analytes include ricin and / or dimethyl methylphosphonate.

9. A method for detecting small molecule analytes using a solid-phase microextraction combined with a dielectric barrier discharge ionization device as described in any one of claims 1-6, characterized in that, Includes the following steps: The sample to be tested is adsorbed onto the solid-phase microextraction fiber and dried to obtain the solid-phase microextraction fiber carrying the sample to be tested. The solid-phase microextraction fiber carrying the sample to be tested is inserted into the sample carrying channel, so that the adsorption end of the solid-phase microextraction fiber is located in the DBDI ionization region. A carrier gas is introduced into the DBDI ionization region and a high-voltage power supply is controlled to cause the high-voltage conductive component to discharge in the DBDI ionization region, thereby desorbing and ionizing the small molecule analytes adsorbed on the solid-phase microextraction fiber. Mass spectrometry signals are acquired and detected using a mass spectrometer.

10. The method as described in claim 9, characterized in that, During adsorption or extraction, the adsorption end of the solid-phase microextraction fiber is immersed in the sample to a depth of 1-2 cm. The output power of the high-voltage power supply is 20%-80% of the rated output; The discharge time in the DBDI ionization region is 1s-2s; The carrier gas is nitrogen or helium.

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