A solid powder injection liquid chromatography mass spectrometry interface

Abstract

The utility model relates to food detection field, concretely is a kind of solid powder sample introduction liquid chromatography mass spectrometry interface, with waste liquid port, including selection valve, sample introduction valve, on-line filter, container assembly, injection assembly, pre-treatment component and detection component;Selection valve has one public port and eight selection ports;Injection assembly includes high-pressure injection pump and buffer ring, and the public port of high-pressure injection pump, buffer ring and selection valve is sequentially communicated;Sample introduction valve is two-position six-way valve;On-line filter is communicated with the port of sample introduction valve;Pre-treatment component includes metal bath base and sequentially communicated air pump, sample tube, pre-treatment valve and affinity column;Detection component includes column oven, chromatographic column and LED fluorescence detector.The utility model has combined the multiple-step function of sample automatic pre-purification, automatic blow-drying constant volume, automatic sample introduction and automatic chromatography elution and quantification on the same device, can realize mobile work and on-site analysis, can satisfy the requirement of rapid arbitration and on-site arbitration.

Description

Technical Field

[0001] This utility model relates to the field of food testing, and in particular to a liquid chromatography-mass spectrometry interface for solid powder injection. Background Technology

[0002] Aflatoxin is a toxic secondary metabolite derived from fungal strains such as Aspergillus flavus and Aspergillus parasiticus. It has significant carcinogenic effects and high toxicity, and is therefore a mandatory testing item for food safety.

[0003] Currently, aflatoxin detection methods are mainly divided into two categories: precise verification methods and rapid screening methods. Rapid screening methods utilize techniques such as immunoaffinity column-fluorescence detection (IAC-FLD), enzyme-linked immunosorbent assay (ELISA), and colloidal gold immunochromatography. GB5009.24-2016 also clearly stipulates that positive samples detected by ELISA must be retested and confirmed using either method one (isotope dilution liquid chromatography-tandem mass spectrometry) or method two (high-performance liquid chromatography). For high-performance liquid chromatography, the test sample is injected into the liquid chromatography system and eluted with an appropriate proportion of organic solvent. The fluorescence intensity at 430 nm under 360 nm excitation light is measured. The fluorescence is qualitatively compared with that of a standard solution of known concentration under the same conditions, and quantitatively compared with the peak areas. The liquid chromatography system consists of functional modules such as a pump, injector, and detector. After the sample is injected into the chromatographic column, the eluent delivered by the pump washes the different substances from the column inlet to the column outlet. Different compounds are separated according to their different migration velocities and generate fluorescence signals on the detector. The intensity of the fluorescence signals allows for quantitative analysis of the compounds.

[0004] However, conventional liquid chromatographs have the following shortcomings:

[0005] 1. Due to their large size and weight, they are not suitable for mobile measurement. A typical liquid chromatograph consists of 3-6 different modules and weighs tens or even hundreds of kilograms.

[0006] 2. Liquid chromatography (LC) detection requires a large number of professionals to perform multiple steps according to the GB5009.24-2016 standard for the determination of aflatoxin content in food, including immunoaffinity purification, evaporation to dryness and volume adjustment, and chromatographic analysis. This requires operators to have basic chemical experimental training, which inconveniences the measurement process and increases labor costs.

[0007] 3. Currently, positive samples often need to be sent to municipal-level commodity inspection laboratories for high-performance liquid chromatography (HPLC) analysis. For short-shelf-life foods such as milk, dairy products, fresh pork tissue, and starch-based processed foods (pastries, bread, etc.), excessively long arbitration times may cause negative samples that could be sold normally to be discarded due to the extended testing period. Utility Model Content

[0008] The purpose of this invention is to address the problems existing in the background technology by proposing a liquid chromatography-mass spectrometry interface for solid powder injection. It integrates multiple functions such as automatic sample pre-purification, automatic drying and volume adjustment, automatic injection, and automatic chromatographic elution and quantification on the same device. All of these functions are integrated into a small-sized body with a total weight of about 10kg. The device can be easily moved and used for on-site analysis. It can be used by non-chemical professionals to perform the tests, meeting the requirements of rapid arbitration and on-site arbitration, and has low labor costs.

[0009] The technical solution of this utility model is a liquid chromatography-mass spectrometry interface for solid powder injection, which has a waste port and includes a selector valve, an injection valve, an online filter, a container assembly, an injection assembly, a pretreatment assembly, and a detection assembly. The selector valve has one common port and eight selectable ports, one of which is individually connected to the common port. The injection assembly includes a high-pressure injection pump and a buffer ring, which are sequentially connected to the common port of the selector valve. The injection valve is a two-position six-way valve with six ports and two phases, and a built-in metering loop. The online filter is connected to one of the injection valves. The ports are connected; the pretreatment assembly includes a metal bath base and a gas pump, sample tube, pretreatment valve and affinity column connected in sequence, with the sample tube inserted into the metal bath base; the detection assembly includes a column oven, chromatographic column and LED fluorescence detector, with the chromatographic column built into the column oven, and both ends of the chromatographic column connected to the injection valve and LED fluorescence detector respectively; the container assembly includes a standard solution container, container one, container two and sample container; the standard solution container, container one, container two, sample container, injection valve, online filter and affinity column are connected to the seven selection ports of the selection valve, and the remaining selection port is connected to the waste liquid port.

[0010] Preferably, the buffer ring is an inert pipeline with an internal volume consistent with the range of the high-pressure injection pump.

[0011] Preferably, the selector valve includes a first valve body, a first stator located inside the first valve body, and a first rotor rotating around the outer circumference of the first stator. The first rotor has a slot, and a common port and eight selector ports are located on the first valve body. When one of the slots faces a selector port, the selector port is connected to the common port.

[0012] Preferably, the injection valve includes a second valve body, a second stator located within the second valve body, and a second rotor rotating around the outer circumference of the second stator.

[0013] Preferably, both the selector valve and the injection valve are made of stainless steel or polyetheretherketone (PEEK).

[0014] Preferably, the column oven has heating elements for heating and thermocouples for temperature detection.

[0015] Preferably, it also includes a battery for power supply.

[0016] Preferably, the metal bath base has an opening for inserting a sample tube, and the bottom of the opening is connected to a through hole, which is connected to a pretreatment valve via a pipeline.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] This invention simplifies and successfully integrates multiple functions, including automatic sample purification and concentration, automatic sample injection, automatic chromatographic elution, and quantification. All of these functions are integrated into a compact unit weighing approximately 10kg. The device includes a built-in data system and a portable power supply, enabling easy portability and on-site analysis. The entire system operates fully automatically. Measurement results are automatically obtained by comparing them with those from built-in standards. No human intervention is required during the process; operators do not need experimental experience or specialized training to use the device conveniently, thus reducing labor costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model;

[0020] Figure 2 This is a structural diagram of an LED fluorescence detector;

[0021] Figure 3 The chromatogram is for a dairy product sample; the standard addition amount is 1 ng / mL.

[0022] Reference numerals: 1. High-pressure syringe pump; 2. Buffer ring; 3. Selector valve; 4. Air pump; 5. Sample tube; 6. Metal bath base; 7. Pretreatment valve; 8. Affinity column; 9. Standard solution container; 10. In-line filter; 11. Container one; 12. Container two; 13. Sample container; 14. Injection valve; 15. Column oven; 16. Chromatographic column; 17. LED fluorescence detector; 170. LED; 171. Quartz flow cell; 1711. Cell inlet; 1712. Cell outlet; 172. Filter; 173. Focusing lens; 174. Phototube; 18. Battery; 19. Data system. Detailed Implementation

[0023] like Figures 1-3As shown, this embodiment proposes a liquid chromatography-mass spectrometry interface for solid powder injection, which has a waste liquid port and includes a selection valve 3, an injection valve 14, an online filter 10, a container assembly, an injection assembly, a pretreatment assembly, and a detection assembly. It also includes a battery 18 for power supply and an external data system 19 for integrated control. The data system 19 is installed in a personal computer or tablet computer. The battery 18 can be a lithium battery or a 24V adapter to power the entire system, ensuring the system's portability and field operation capability.

[0024] Selector valve 3 has one common port and eight selectable ports (numbered A, B, C, D, E, F, G, and H) for selecting different liquid pathways. One of the eight selectable ports is individually connected to the common port. Selector valve 3 is a typical configuration conforming to standard GB5009.24-2016. Selector valve 3 includes a first valve body, a first stator located inside the first valve body, and a first rotor rotating around the outer circumference of the first stator. The first rotor has slots. The common port and eight selectable ports are all located on the first valve body. When one slot faces a selectable port, that selectable port is connected to the common port. As the first rotor rotates, when the slot connects the common port and a selected port with a specific number, that pathway is connected to the common port; that is, when one slot faces a selectable port, that selectable port is connected to the common port. Selector valve 3 is made of stainless steel or polyetheretherketone (PEEK), an inert material that does not react with the analyte or the reagents used.

[0025] The injection assembly includes a high-pressure injection pump 1 and a buffer ring 2. The common port of the high-pressure injection pump 1, buffer ring 2, and selector valve 3 is connected sequentially. The injection pump and its matching buffer ring are configured according to the required reagent volume. A typical configuration conforming to standard GB5009.24-2016 is a 10mL injection pump with an infusion volume step of 0.01mL and a 10mL volume for buffer ring 2. Smaller or larger injection pumps can be used as needed. Buffer ring 2 is an inert tubing with an internal volume matching the flow rate of high-pressure injection pump 1, ensuring that when the injection pump draws a specific amount of liquid, the drawn liquid only enters buffer ring 2 and does not enter the injection pump, thus preventing pump contamination.

[0026] The injection valve 14 is a two-position six-way valve with an internal volume of 10 μL, as typically configured according to standard GB5009.24-2016. The injection valve 14 has six ports and two selectable phases: port 1, port 2, port 3, port 4, port 5, and port 6. The injection valve 14 has a built-in metering loop that can accommodate the sample according to its internal volume and introduce it into the high-pressure liquid chromatography flow path. In one phase, ports 1-2, 3-4, and 5-6 are connected in pairs; in the other phase, ports 1-6, 2-3, and 4-5 are connected in pairs. Port 2 is connected to the metering loop inlet, port 4 is connected to an open tubing as a waste outlet, port 5 is connected to the metering loop outlet, and port 6 is connected to the column inlet. The injection valve 14 includes a second valve body, a second stator located within the second valve body, and a second rotor rotating around the outer circumference of the second stator. The injection valve 14 is made of stainless steel or polyetheretherketone, which is an inert material that does not react with the analyte or the reagents used.

[0027] The online filter 10 is connected to port 3 of the injection valve 14 and is used to filter out small amounts of particulate matter that may be present in the sample, preventing system clogging. The online filter 10 generally uses a sieve plate or filter element with micropores as the filter material. The filter element and corresponding sleeve are made of inert materials that do not react with the analyte and the reagents used, such as sintered stainless steel sieve plates.

[0028] The sample pretreatment assembly includes a metal bath base 6 and, in sequence, an air pump 4, a sample tube 5, a pretreatment valve 7, and an affinity column 8. The immunoaffinity column 8 is the core component for sample pretreatment purification, filled with powdered packing material to provide separation capability. The outlet of the immunoaffinity column 8 is connected to the COM port of the pretreatment valve 7. The pretreatment valve 7, located after the immunoaffinity column 8, is a two-position three-way solenoid valve used to switch between the eluent and waste liquid during pretreatment, ensuring automatic execution of the pretreatment process. The NO port of the pretreatment valve 7 serves as the waste liquid outlet, and the NC port of the pretreatment valve 7 connects to the interface at the bottom of the metal bath base 6. The sample tube 5 is inserted into the metal bath base 6, which is made of an inert material, such as stainless steel, that does not react with the analyte or reagents. A PT100 thermocouple provides temperature feedback, and a PTC ceramic heating element heats the sample tube, providing a constant temperature function. An opening for inserting the sample tube 5 is located on the top of the metal bath base 6, and a through-hole connects to the pretreatment valve 7 via a pipeline. When it is necessary to draw liquid from or inject liquid into sample tube 5, the liquid is drawn or injected from the bottom of sample tube 5 through the selection port E of selection valve 3. Sample tube 5 is a polypropylene syringe, which is an inert material that does not react with the analyte and the reagents used. The connection between sample tube 5 and metal bath base 6 uses a Luer interface, and a disposable plastic syringe with the piston removed is inserted into the metal bath base as a sample tube. In order to dry the immunoaffinity chromatography eluent to remove solvent as required in section 5.2 of standard GB5009.24-2016, the device has an independent air pump 4 that provides compressed air to sample tube 5 to dry the eluent. Specifically, the air blown out by air pump 4 is introduced into the top of sample tube 5 through a line to dry the pretreatment eluent.

[0029] The detection assembly includes a column oven 15, a chromatographic column 16, and an LED fluorescence detector 17. The column oven 15 has a heating element for heating and a thermocouple for temperature detection. The chromatographic column 16 is built into the column oven 15, and its two ends are connected to the injection valve 14 and the LED fluorescence detector 17, respectively. The chromatographic column 16 is the core component for separation, and its stainless steel shell is filled with powdered packing material to provide separation capability. The chromatographic column 16 is selected as a C18 packed column. The column oven 15 is a heating container with temperature feedback control, which can maintain the chromatographic column 16 placed inside at a stable separation temperature according to the method requirements, set at 40°C according to section 12.3 of standard GB5009.24-2016. In the column oven 15, a PT100 thermocouple is used for temperature feedback, and a PTC ceramic heating element is used to heat the column oven 15. The LED fluorescence detector 17 includes an LED 170, a quartz flow cell 171, a filter 172, a focusing lens 173, and a phototube 174. The quartz flow cell 171 has an inlet 1711 and an outlet 1712. An existing LED fluorescence detector 17 is used. The LED fluorescence detector 17 is used to measure the real-time fluorescence emission of the effluent from the chromatographic column 16. It uses a 360nm emitting LED as the light source and a dedicated fluorescence detector with a 430nm filter is installed before the photocell used for detection. After the chromatographic effluent is introduced into the quartz flow cell 171, the absorption of the effluent by the LED light source is measured using a photocell to quantify the amount of aflatoxin effluent. The outlet of the LED fluorescence detector 17 is connected to an open pipe as a waste outlet.

[0030] The container assembly includes a standard solution container 9, container one 11, container two 12, and sample container 13. Standard solution container 9 contains aflatoxin standard solution, container one 11 contains water, container two 12 contains a 1:1 methanol-acetonitrile solution, and sample container 13 contains the sample. The measurement method requires the use of water and an organic solvent (a mixture containing 50% methanol and 50% acetonitrile), and the equipment calibration requires the use of standards containing aflatoxin of known concentration. All reagents are contained in appropriate containers. All connecting lines to the apparatus are inert lines suitable for liquid chromatography systems, such as 1 / 16-inch outer diameter stainless steel or polyetheretherketone (PEEK) tubing.

[0031] Standard solution container 9, container one 11, container two 12, sample container 13, injection valve 14, online filter 10, and affinity column 8 are connected to the seven selection ports of selection valve 3. Specifically, container one 11 is connected to selection port C, container two 12 is connected to selection port B, sample container 13 is connected to selection port A, standard solution container 9 is connected to selection port D, port 1 of injection valve 14 is connected to selection port H (selection port H is the mobile phase output port), online filter 10 is connected to selection port G, and affinity column 8 is connected to selection port E. Selection port F is connected to the waste liquid port. For the waste liquid port, it can be used as an air inlet when the high-pressure injection pump 1 draws in air and as a waste liquid outlet when it exits.

[0032] This device can perform the following functions: self-cleaning liquid aspiration and infusion, automatic immunoaffinity purification of samples for pretreatment, column rinsing and elution, and liquid chromatography sample filtration, injection and tubing self-cleaning.

[0033] Function 1: Self-cleaning fluid aspiration and infusion.

[0034] If a liquid of volume V needs to be drawn from port M and discharged to port N, followed by cleaning of the pipeline, and the ports M and N are arbitrarily set according to application requirements, then the specific process is as follows:

[0035] Selector valve 3 switches to selector port F, discharging all remaining liquid and bringing the piston to its furthest point. Then, full-capacity air is drawn in from selector port E and the syringe is emptied several times to ensure that the flow from the common port to the outlet at selector port F is emptied.

[0036] Selector valve 3 is switched to port A, and the syringe draws 1 mL of a 1:1 methanol-acetonitrile mixture. Then, selector valve 3 is switched to port E, and 0.1-0.2 mL of air is drawn in. Afterward, the syringe is switched to the designated aspiration port M, and volume V is drawn in at the specified rate. The drawn-in air acts as a separator between the 1 mL of methanol and a portion of volume V, preventing the two zones from mixing.

[0037] The syringe is then switched to port N, the desired output port, and the piston is pushed out at a specified speed, increasing the volume by V. A volume V of liquid is drawn from port M into buffer ring 2 and expelled to port N. After the infusion is complete, selector valve 3 is switched to port F, expelling the remaining air and 1 mL of methanol. The expelled methanol flushes away any remaining liquid from port M within buffer ring 2, achieving self-cleaning of the tubing.

[0038] Function 2: Automated immunoaffinity purification pretreatment of samples:

[0039] After the system is equipped with the immunoaffinity column 8 and sample tube 5, if it is necessary to perform automatic sample pretreatment in accordance with section 5.2 of standard GB5009.24-2016, the following procedure can be followed;

[0040] Insert the empty sample tube 5, which has a Luer interface at the bottom and an open top, into the metal bath base 6. The volume of the sample tube 5 should be 10 mL. Use a 10 mL polypropylene syringe with the piston removed as the sample tube.

[0041] S1. Load the sample solution awaiting immunoaffinity purification into sample container 13 connected to port A. Switch selector valve 3 to select port A, and draw up the sample solution with the syringe. Then switch to select port E, and push the sample to be purified onto the affinity column at a flow rate of 2 mL / min according to the flow rate requirements in section 5.2 of standard GB5009.24-2016, until all the sample solution has been drawn up and injected into the affinity column 8. At this time, the NO port of pretreatment valve 7 opens, and the effluent is discharged to the waste port;

[0042] S2. After loading all samples, switch the selection valve 3 to selection port C, draw 10 mL of water, and then switch to selection port E to push 10 mL of water to affinity column 8 at a flow rate of 2 mL / min as required in section 5.2 of standard GB5009.24-2016, to clean affinity column 8 and remove interfering substances. At this time, the NO port of pretreatment valve 7 is opened, and the effluent is discharged to the waste liquid port.

[0043] S3. The syringe draws air from the selection port F, then switches to the selection port E to dry the affinity column 8 with air. At this time, the NO port of the pretreatment valve 7 is opened, and the effluent is discharged to the waste liquid.

[0044] S4. Starting from this step, the NC port of pretreatment valve 7 is opened, and the effluent is delivered to sample tube 5. The syringe draws 2 mL of a 1:1 methanol-acetonitrile mixture from selection port B, then switches to selection port E, and pushes the mixture onto the affinity column 8 at a rate of 2 mL / min. Next, the syringe draws air from selection port F, then switches to selection port E to purge the liquid from the affinity column 8 with air. The syringe again draws 2 mL of the 1:1 methanol-acetonitrile mixture from selection port B, then switches to selection port E, and pushes the mixture onto the affinity column 8 at a rate of 2 mL / min. Then, selection valve 3 switches to selection port F, the syringe draws air from selection port F, then switches to selection port E to purge the liquid from the affinity column 8 with air. This allows the immunoaffinity column 8 to be washed twice with 2 mL of methanol / acetonitrile according to the requirements of GB5009.24-2016, and the eluent is transferred to an intermediate container to await drying and volume adjustment.

[0045] S5. After the previous step is completed, sample tube 5 will contain 4 mL of immunoaffinity-treated eluent. The system will, according to GB5009.24-2016, section 5.2, maintain the metal bath temperature at 50°C and turn on air pump 4 to blow air into sample tube 5, causing the eluent to evaporate completely. After the programmed evaporation time, selector valve 3 will switch to port C, draw 0.7 mL of water, then switch to port B, draw 0.3 mL of a 1:1 methanol-acetonitrile mixture. Next, selector valve 3 will switch to port E to expel all the drawn-in solvent. Then, selector valve 3 will switch to port F, and the syringe will draw air from port F. Selector valve 3 will then switch to port E, blowing the gas into sample tube 5. Bubbling from below will allow the purified and dried sample to be reconstituted and thoroughly mixed with the aforementioned 1 mL of solvent.

[0046] S6. After completing the above steps, prepare a 1 mL sample and store it in a sample tube.

[0047] Function 3: Column washing and elution:

[0048] According to standard GB5009.24-2016, to achieve elution with 70% water and 30% 1:1 methanol-acetonitrile, selector valve 3 is switched to selector port C, 0.7 mL of water is drawn, then switched to selector port B, 0.3 mL of the 1:1 methanol-acetonitrile mixture is drawn, and this process is repeated 20 times. The liquids are then allowed to mix spontaneously to obtain 20 mL of the required eluent, which is used for elution. The eluent is pushed into selector port H at a specified rate, allowing the washing solvent to enter the column head. During elution, column oven 15 is used to maintain column 16 at the separation temperature specified by the method, which is set to 40°C.

[0049] During rinsing and elution, injection valve 14 is in a phase where ports 1-2, 3-4, and 5-6 are connected in pairs. Liquid injected into port 1 flows through the flow path 1→2→quantitative loop→5→6→column into column 16. Ports 3 and 4 are not in the flow path.

[0050] Function 4: Liquid chromatography sample filtration, injection, and tubing self-cleaning.

[0051] After the aforementioned sample purification steps are completed, the sample to be tested, retained in the sample tube, is filtered and injected into column 16. The specific method for achieving self-cleaning of the sample flow through the pipeline is as follows:

[0052] Selector valve 3 is switched to selector port A, and 20 mL of eluent is drawn into the syringe. Then, selector valve 3 is switched to selector port E, and 0.1-0.2 mL of air is drawn in. Afterward, selector valve 3 is switched back to selector port E, and a volume of Vs of sample is drawn from the bottom of sample tube 5. The drawn-in air acts as a separator, preventing the two zones from mixing. The volume of the quantitative loop is Vloop, and the sample volume Vs > Vloop.

[0053] Next, switch selector valve 3 to selector port G, and simultaneously connect injection valve 14 to each of the three sets of ports 1-6, 2-3, and 4-5 in pairs. Push the syringe out a volume slightly more than Vloop, but not exceeding Vs. The previously aspirated sample zone will first be filtered through online filter 10, then injected into port 3, and flow through the sequence 3→2→quantitative loop→5→4 into the quantitative loop. The original liquid in the quantitative loop, along with the extra injected sample, will be discharged through port 4.

[0054] Next, switch the injection valve 14 to the phase where ports 1-2, 3-4, and 5-6 are connected in pairs. The liquid injected into port 1 will flow through the flow path 1→2→quantitative loop→5→6→column into column 16. Ports 3 and 4 are not in the flow path. Expel all remaining liquid from the syringe through selection port G. The previously drawn 20 mL of elution solvent will clean the online filter 10 and the injection line, and then be discharged through port 4. At this point, the quantitative loop is filled with the purified sample. After the syringe pump draws 20 mL of elution solvent again according to the steps in function three, it can be discharged from selection port H at the required flow rate of 1 mL / min for chromatographic elution.

[0055] The quantitative loop has a volume of 10 μL. During injection, 20 mL of eluent is first drawn, followed by 0.2 mL of air, and then 0.5 mL of sample. After ejecting 0.5 mL of sample to fill the quantitative loop, the injection valve 14 is switched, and the remaining liquid is ejected to clean the injection tubing. Then, 20 mL of eluent is drawn and ejected from the selector port H at a flow rate of 1 mL / min for chromatographic elution. The chromatographic effluent passes through an LED fluorescence detector 17 and is excited by 360 nm ultraviolet light. The 430 nm fluorescence emitted by aflatoxin-like compounds is filtered by a filter 172 to remove interference from other wavelengths and then focused onto a phototube 174. The resulting signal intensity is proportional to the effluent concentration of aflatoxin.

[0056] The following is a detailed procedure for achieving fully automated purification and separation determination equivalent to manually operated affinity extraction as described in GB5009.24-2016 and chromatographic elution performed on conventional chromatography:

[0057] Method setup: The apparatus is equipped with a 20mL syringe, a 10mL buffer loop, a 10μL metering loop, a 360nm LED excitation source, and a fluorescence detector with a 430nm emission filter. Column temperature setting: 40℃. Pretreatment gas drying rate: 8L / min; Pretreatment evaporation temperature: 50℃; Container 1: Water; Container 2: 1:1 methanol-acetonitrile; Standard solution container 9: 5ng / mL aflatoxin standard sample.

[0058] Test steps:

[0059] A1. Remove the piston from the disposable syringe with the Luer connector at the lower end, leaving only the outer tube as the sample tube, and insert it into the metal bath base 6;

[0060] A2. Add the filtered food sample dilution to the sample container 13 connected to the selection port A channel;

[0061] A3. The system purifies the sample solution according to the steps in Function 2 above. After purification, there is 1 mL of purified sample to be tested in sample tube 5.

[0062] A4. Following the steps in Function 4 above, the system draws the sample from sample tube 5 through selection port E and pushes it out to selection port G into the metering loop. The volume is 10 μL of the metering loop volume. Excess sample is discharged through the waste liquid port. Then, the sample injection line is cleaned.

[0063] A5. Following the steps in Function 3 above, wash column 16 with 70-30 water-1:1 methanol / acetonitrile eluent at a flow rate of 1 mL / min for a total elution time of 10 min. Record the fluorescence signal. The data system automatically integrates the peak area of ​​the sample to obtain the peak area As of the sample.

[0064] A6. Following the steps in Function 3 above, use 5 mL of 1:1 methanol / acetonitrile and 5 mL of eluent sequentially to rinse the column at a flow rate of 1 mL / min to clean and equilibrate the column.

[0065] A7. Following the steps in Function 4 above, use 5 mL of 1:1 methanol / acetonitrile to clean the tubing from Select Port D to the sample base twice, and then blow it dry with output air.

[0066] After the above steps, the system automatically completes the sample pretreatment and determination.

[0067] As a quantitative basis, the following steps are taken to determine the standard sample:

[0068] B1. Following the steps in Function 4 above, the system draws in 5 ng / mL aflatoxin standard solution through selector port D and pushes it out through selector port G into the quantitative loop with a volume of 10 μL. Excess sample is discharged through the waste outlet, and then the injection line is cleaned.

[0069] B2. Following the steps in Function 3 above, wash column 16 with 70-30 water-1:1 methanol / acetonitrile eluent at a flow rate of 1 mL / min for a total elution time of 10 min, and record the fluorescence signal. The data system automatically integrates the peak areas of the sample. Obtain the peak area Astd of the sample.

[0070] B3. Following the steps in Function 3 above, flush the column with 5 mL of 1:1 methanol / acetonitrile and 5 mL of eluent at a flow rate of 1 mL / min to clean and equilibrate column 16.

[0071] The final aflatoxin content in the sample was C = 5As / Astd ng / mL. The method had a linear range of 0.1-5 ng / mL, and reproducibility was based on a 1 ng / mL sample, with an RSD < 5%.

[0072] This invention adopts a similar structure to liquid chromatography, simplifying the device and successfully integrating multiple functions such as automatic sample purification and concentration, automatic sample injection, automatic chromatographic elution, and quantification. All of these functions are integrated into a compact unit weighing approximately 10kg. The device includes a built-in data system and a portable power supply, enabling easy portability and on-site analysis. The entire system operates fully automatically. After the filtrate of the food sample to be tested is added to the sample tube, the system automatically performs all pretreatment, analysis, and self-cleaning steps. The measured results are automatically obtained by comparing them with the results of the built-in standard. No human intervention is required during the process; operators do not need experimental experience or specialized training to use the system conveniently, reducing labor costs. This allows for its adoption by grassroots commodity inspection units and larger food trading markets, enabling non-chemical professionals to perform testing, thus meeting the requirements for rapid and on-site arbitration.

[0073] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A liquid chromatography-mass spectrometry interface for solid powder injection, characterized in that, It has a waste liquid outlet, including: Selector valve (3) has one common port and eight selector ports, one of which is individually connected to the common port; The injection assembly includes a high-pressure injection pump (1) and a buffer ring (2), and the common port of the high-pressure injection pump (1), the buffer ring (2) and the selector valve (3) are connected in sequence; The injection valve (14) is a two-position six-way valve with six ports and two phases, and has a built-in quantitative loop; An online filter (10) is connected to one port of the injection valve (14); The pretreatment assembly includes a metal bath base (6) and an air pump (4), a sample tube (5), a pretreatment valve (7) and an affinity column (8) connected in sequence. The sample tube (5) is inserted into the metal bath base (6). The detection assembly includes a column oven (15), a chromatographic column (16) and an LED fluorescence detector (17). The chromatographic column (16) is built into the column oven (15), and the two ends of the chromatographic column (16) are connected to the injection valve (14) and the LED fluorescence detector (17) respectively. The container assembly includes a standard solution container (9), a first container (11), a second container (12), and a sample container (13); The standard solution container (9), container one (11), container two (12), sample container (13), injection valve (14), online filter (10) and affinity column (8) are respectively connected to the seven selection ports of the selection valve (3), and the remaining selection port is connected to the waste liquid port.

2. The liquid chromatography-mass spectrometry interface for solid powder injection according to claim 1, characterized in that, The buffer ring (2) is an inert pipeline with an internal volume that matches the range of the high-pressure injection pump (1).

3. The liquid chromatography-mass spectrometry interface for solid powder injection according to claim 2, characterized in that, The selector valve (3) includes a first valve body, a first stator located inside the first valve body, and a first rotor rotating on the outer circumference of the first stator. The first rotor has a slot, and a common port and eight selector ports are located on the first valve body. When the slot is oriented towards a selector port, the selector port is connected to the common port.

4. The liquid chromatography-mass spectrometry interface for solid powder injection according to claim 3, characterized in that, The injection valve (14) includes a second valve body, a second stator located inside the second valve body, and a second rotor rotating around the outer circumference of the second stator.

5. A liquid chromatography-mass spectrometry interface for solid powder injection according to claim 4, characterized in that, The selector valve (3) and the injection valve (14) are both made of stainless steel or polyether ether ketone.

6. The liquid chromatography-mass spectrometry interface for solid powder injection according to claim 1, characterized in that, The column oven (15) has heating elements for heating and thermocouples for temperature detection.

7. The liquid chromatography-mass spectrometry interface for solid powder injection according to claim 1, characterized in that, It also includes a battery (18) for power supply.

8. The liquid chromatography-mass spectrometry interface for solid powder injection according to claim 1, characterized in that, The metal bath base (6) has an opening above it for inserting a sample tube (5), and the bottom of the opening is connected to a through hole, which is connected to a pretreatment valve (7) via a pipeline.

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