A device for regional heat enrichment and its application

Abstract

The present invention provides a device for regional thermal enrichment, the device comprising at least one sample pad and at least two heat conductors, wherein the heat conductors are arranged at intervals in the crawling direction of the sample extract on the sample pad and in contact with the sample pad, and the heat conductors are configured to be heated by a heating element to different temperatures that are sequentially increased in the crawling direction for heating the sample pad. The present invention performs pretreatment on the sample through the device, simplifies the pretreatment process, reduces the loss of the target object, and reduces the amount of reagents and the like. The present invention also provides a method for regional thermal enrichment of the sample extract using the device, a detection sample pad obtained by the method, an immunochromatographic test strip including the detection sample pad, and the use of the device and the detection sample pad in immunochromatographic analysis, mass spectrometry analysis, and surface enhanced Raman testing.

Description

Technical Field

[0001] The present invention relates to the field of biological detection technology, and more specifically, to a device for regional thermal enrichment of a sample, a method for regional thermal enrichment of a sample extract using the device, a detection sample pad obtained by the method, an immunochromatographic test strip including the detection sample pad, and applications of the device and the detection sample pad in immunochromatographic analysis, mass spectrometry analysis, and surface enhanced Raman testing. Background Art

[0002] Hot volatilization of solvents to enrich the target is a common method in food safety testing. Generally, after the target is extracted, the solvent is added to a centrifuge tube or pear-shaped bottle and other consumables for heating, assisted by vacuum or air flow to evaporate the solvent and concentrate / enrich the target. After this process is completed, the re-solution is added. The sample pad of the test strip is then immersed in it for various tests such as immunochromatography.

[0003] In current tests using sample pads, the sample pad only serves as a drainage function. For example, in immunoassays, the usual operation is: after performing a variety of sample pretreatment steps, the test strip sample pad is inserted into the sample solution for drainage and detection. Therefore, the potential of the sample pad as a sample pretreatment tool has not been realized. For another example, in an open mass spectrometer, the treated sample is added to the sample pad only after the sample is treated. In other words, sample pretreatment is still required before being added to the sample pad. In addition, in some studies, electric fields are used to separate targets, but electric field technology is complex, has poor reproducibility and operability, is also dangerous, and cannot simply and effectively enrich and concentrate the target.

[0004] However, it is well known that in detection, the concentration of the target in the sample solution determines the detection sensitivity. For example, in immunochromatography, the concentration of the target in contact with the antibody on the nitrocellulose (NC) membrane determines the detection sensitivity.

[0005] Therefore, based on the problems existing in the prior art, there is an urgent need in the art for a solution that can simply and conveniently concentrate, separate, and purify the target substance in the sample extract to increase its concentration before detection. Summary of the invention

[0006] In view of this, the present invention provides a device for regional thermal enrichment, a method for regional thermal enrichment of a sample extract using the device, a detection sample pad obtained by the method, an immunochromatographic test strip including the detection sample pad, and applications of the device and the detection sample pad in immunochromatographic analysis, mass spectrometry analysis, and surface enhanced Raman testing, thereby solving the technical problems mentioned above.

[0007] According to a first aspect of the present invention, there is provided a device for regional thermal enrichment, the device comprising at least one sample pad and at least two heat-conducting members, wherein the heat-conducting members are arranged at intervals in a crawling direction of a sample extract on the sample pad and are in contact with the sample pad, and the heat-conducting members are configured to be heated by a heating member to different temperatures that sequentially increase in the crawling direction for heating the sample pad.

[0008] According to a second aspect of the present invention, there is provided a method for performing regional thermal enrichment of a sample extract using the device provided by the first aspect of the present invention, the method comprising: 1) adding the sample extract to a sample pad of the device; and 2) heating a heat conductive element of the device using another heating element or a heating element of the device, such that the temperature of the heat conductive element increases sequentially in the creeping direction of the sample extract, thereby heating the sample pad.

[0009] According to a third aspect of the present invention, there is provided a detection sample pad obtained by the method according to the second aspect of the present invention.

[0010] According to a fourth aspect of the present invention, there is provided an immunochromatographic test strip comprising the detection sample pad according to the third aspect of the present invention.

[0011] According to the fifth aspect of the present invention, there is provided the use of the device according to the first aspect of the present invention or the detection sample pad according to the third aspect of the present invention in immunochromatography analysis, mass spectrometry analysis, and surface enhanced Raman testing.

[0012] Beneficial effects of the present invention:

[0013] The present invention provides a device for regional heat enrichment, the device comprises at least one sample pad and at least two heat conducting members, and the heat conducting members are used to heat the sample extract flowing through the sample pad to achieve the concentration, separation and purification of the target. Through such a device, the concentration, separation and purification of the target can be completed on the sample pad, simplifying the sample pre-treatment steps, and also achieving the localized concentration of the target, improving the cross-sectional / instantaneous binding concentration of the target, accelerating the volatilization rate of the solvent on the sample pad, so that the target or impurities are captured on the sample pad, and reducing the amount of reagents used, reducing the loss of the target, and achieving the separation of impurities in the sample extract, and also helping to achieve the replacement process between different solvents. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other implementation plans can be obtained based on these drawings without paying creative work.

[0015] Figure 1 is a schematic diagram of a device for regional thermal enrichment including a sample pad and two thermal conductors according to some embodiments of the present invention.

[0016] Figure 2 is a schematic diagram of a device for regional thermal enrichment including a sample pad and four thermal conductors according to some embodiments of the present invention.

[0017] Figure 3 is a schematic diagram of a device for regional heat enrichment including a heating element according to some embodiments of the present invention.

[0018] Figure 4 is a schematic diagram of a device for regional thermal enrichment including two sample pads partially overlapping each other and two thermal conductors according to some embodiments of the present invention.

[0019] Figure 5 Photographs of sample pads after double heating and single heating treatments according to some embodiments of the present invention are shown.

[0020] Figure 6 Photographs of sample pads according to other embodiments of the present invention after no heat treatment, single heat treatment, and double heat treatment are shown.

[0021] Figure 7 Photographs showing test strips with two sample pads superimposed according to some embodiments of the present invention and conventional test strips with only one sample pad.

[0022] Figure 8 and Fig. 9 The mass spectra obtained by detecting carbofuran without heating and with heating the sample pad according to some embodiments of the present invention are shown respectively.

[0023] Fig.10 and Fig.11 Raman spectra of malachite green detected without heating and with heating the sample pad according to some embodiments of the present invention are shown respectively. DETAILED DESCRIPTION

[0024] The present invention will be described clearly and completely below in conjunction with the embodiments and drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments that can be obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0025] In the field of food safety testing and other testing, when testing a target object, it is generally necessary to perform pre-treatment operations such as concentration, separation, and purification on the target object in the sample extract, and then use, for example, a sample pad for further testing. As mentioned above, in the current test using a sample pad, the sample pad only plays a drainage role. The inventors expect that in addition to playing a drainage role, the sample pad can also partially play a role in pre-treating the sample, thereby achieving simple and convenient concentration, separation or purification of the target object. Therefore, the purpose of the present invention is to provide a solution that can achieve concentration, separation or purification of the target object on a sample pad, thereby simplifying the operating process and improving test efficiency and sensitivity.

[0026] Therefore, according to a first aspect of the present invention, a device for regional thermal enrichment is provided, the device comprising at least one sample pad and at least two heat-conducting members, wherein the heat-conducting members are arranged at intervals in the crawling direction of the sample extract on the sample pad and are in contact with the sample pad, and the heat-conducting members are configured to be heated by a heating member to different temperatures that sequentially increase in the crawling direction for heating the sample pad.

[0027] In the present invention, the sample pad refers to a sample pad prepared from a porous material and capable of playing a drainage role. In some embodiments, the sample pad can be a glass fiber sample pad, a non-woven fabric sample pad, a nylon sample pad, a polytetrafluoroethylene sample pad, or a polyethersulfone sample pad. Of course, sample pads of other materials known in the art can also be used, as long as they can play a drainage role, and the present invention does not make further restrictions on this. The sample pad is generally rectangular, and a plurality of heat-conducting parts are arranged at intervals along the length direction of the long and wide surfaces of the sample pad, and fit closely with the sample pad. Preferably, the sample pad and the heat-conducting part are physically closely fitted together. In some embodiments, the sample pad can be brought into contact with the heat-conducting part by a positioning mechanism. However, under the premise that the test results are not affected, it is also possible to consider using chemical methods, such as adhesives, to fit closely together.

[0028] In the present invention, the "heat conducting member" refers to a component made of a material that can conduct heat. The heat conducting member is preferably made of a material with a higher thermal conductivity, such as metals such as silver (thermal conductivity of about 429W / m·k), copper (thermal conductivity of about 400W / m·k), gold (thermal conductivity of about 310W / m·k), aluminum (thermal conductivity of about 240W / m·k), thermally conductive silica gel, graphene, etc., specifically selected according to requirements such as cost, weight, etc. Therefore, in some embodiments, the heat conducting member can be a metal block or a metal sheet. The metal block or metal sheet can be an iron block or an iron sheet, a copper block or a copper sheet, an aluminum block or an aluminum sheet, an aluminum alloy block or an aluminum alloy sheet, a ceramic block or a ceramic sheet, or a glass block or a glass sheet, etc. The present invention does not further limit which material is specifically used to manufacture the heat conducting member, as long as the purpose of the present invention can be achieved, and those skilled in the art can select according to actual needs.

[0029] As described above, the device of the present invention comprises at least two heat conducting members. In the present invention, the number of the heat conducting members may be 2, 3, 4 or 5. Of course, other numbers of heat conducting members may also be provided, and the present invention does not make further limitations on this. Figure 1 A schematic diagram of a device 1 for regional heat enrichment comprising a sample pad 11 and two heat conducting members 12 according to some embodiments of the present invention is shown. Figure 2 2 is a schematic diagram of a device 2 for regional heat enrichment including a sample pad 21 and four heat conductors 22 according to some embodiments of the present invention. The number of heat conductors can be determined according to the volatilization rate of the solvent. For example, if the solvent is difficult to volatilize, the number of heat conductors can be appropriately increased; on the contrary, if the solvent is easy to volatilize, the number of heat conductors can be appropriately reduced.

[0030] As described above, the heat conducting members are arranged at intervals in the crawling direction of the sample extract on the sample pad. In this article, there is no particular restriction on the specific interval between two adjacent heat conducting members, as long as the temperature between the two can be increased in sequence. Specifically, the interval between two adjacent heat conducting members can be 0.3-1 cm, such as 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm.

[0031] As described above, the heat conductor is configured to be heated to different temperatures that are sequentially increased in the crawling direction by the heating element for heating the sample pad. When the heat conductor is heated by the heating element, it is necessary to make the heat conductor have different temperatures or gradient temperatures that are sequentially increased in the crawling direction of the sample extract on the sample pad under the action of the heating element. Since the heat conductor has a gradient temperature under the action of the heating element, the sample pad that is closely attached to the heat conductor also has different temperatures accordingly. As a result, the solvent in the sample extract crawling on the sample pad also has different volatilization rates, specifically, volatilization rates that gradually increase in the crawling direction.

[0032] By configuring the heat-conducting member to have different temperatures that increase sequentially in the crawling direction, when the sample extract crawls on the sample pad, a portion of the solvent therein will first evaporate when passing through a position with a lower temperature on the sample pad, thereby achieving the first concentration; when flowing through a position with a higher temperature on the sample pad, the solvent will further evaporate or even completely evaporate, thereby causing the target object to be enriched at a position with a higher temperature on the sample pad or at a position slightly above the position with a higher temperature, and then obtaining the target object at one end of the sample pad, thereby achieving the concentration, separation and purification of the sample extract.

[0033] The temperature to which the heat conductor is heated can be set according to the boiling point of the solvent. In addition, the temperature sensitivity of the target to be measured needs to be considered, and the heat conductor should be avoided from being heated to a temperature to which the target is sensitive, so as to prevent the decomposition of the target. For example, for thermally unstable targets, solvents with low boiling points, such as acetone, should be selected as much as possible. In addition, the length of the sample pad needs to be considered. If the sample pad is long, the temperature of the heat conductor can be appropriately lowered. If the sample pad is short, the temperature of the heat conductor should be appropriately increased so that the solvent can evaporate as completely as possible when it reaches the end of the sample pad. In addition, the rate at which the liquid is conducted in the sample pad can also be controlled by adjusting the thickness and pore size of the sample pad.

[0034] In the present invention, the last heat-conducting member in the creeping direction of the sample extract is configured to be heated by a heating member to a temperature determined according to the boiling point of the solvent in the sample extract. In one embodiment, the last heat-conducting member is heated to a temperature lower than the boiling point of the solvent to prevent the solvent from boiling violently. Specifically, the temperature of the last heat-conducting member is set to be 5-20°C lower than the boiling point of the solvent, for example, 5°C, 8°C, 10°C, 12°C, 15°C, 18°C ​​or 20°C.

[0035] In one embodiment, two adjacent heat-conducting members are configured to have a temperature difference of 10-30° C., preferably 20-25° C. Of course, other gradients of temperature difference may also be set as required.

[0036] In some embodiments, the size of the heat conductor is set to at least cover the width of the sample pad. In this way, all sample extracts flowing through the sample pad can be heated to further improve the efficiency of the device. The contact area between the heat conductor and the sample pad, i.e., the heating area, can be determined based on the creeping speed of the solvent, etc. If the creeping speed of the solvent is fast, the contact area between the heat conductor and the sample pad can be appropriately increased, otherwise the contact area between the heat conductor and the sample pad can be appropriately reduced. The height of the heat conductor can be selected according to actual needs, and the present invention does not make further limitations on this.

[0037] In summary, in the present invention, the number of heat-conducting parts, the contact area with the sample pad, and the temperature can be appropriately adjusted according to the boiling point of the solvent and the creeping speed of the solvent on the sample pad. If the solvent is difficult to volatilize, the number of heat-conducting parts can be increased. If the creeping speed is fast, the temperature can be increased or the heating area of ​​the heat-conducting parts can be increased, and vice versa. The creeping speed of the solvent can also be changed by replacing the sample pad with different materials.

[0038] In some embodiments, the device further comprises heating elements having the same number as the heat conducting elements, the heating elements existing independently of each other or existing integrally with each other. Each heating element is used to heat the heat conducting element corresponding thereto in position, thereby achieving heating of the sample pad. Figure 3 is a schematic diagram of a device 3 for regional heat enrichment including a heating element 33 according to some embodiments of the present invention. Figure 3 In the figure, the heating elements 33 exist independently of each other and are used to heat the corresponding heat-conducting element 32. Of course, the heating elements can also be integrated into a single component as part of the device of the present invention (not shown). The heating elements, whether they exist independently of each other or integrally with each other, have no particular restrictions on the area of ​​contact between them and the heat-conducting element, and can be greater than, less than or equal to the contact area of ​​the heat-conducting element, as long as they do not affect the functioning of each other. As understood by those skilled in the art, the heating element can be any heating element known in the art that can be used to heat a heat-conducting element, such as a heating patch.

[0039] Of course, the method of heating the heat conductor is not limited to the heating patch. The heat conductor can also be heated by a heat source from a magnetic field, gas or liquid. As long as the heat conductor can obtain the required heat, the present invention does not make any further limitations thereto.

[0040] In some embodiments, the device includes two sample pads, wherein the two sample pads partially overlap each other. Preferably, the two sample pads overlap each other by 0.2 cm-0.4 cm, such as 0.3 cm. Either of the two sample pads can be arranged on top, but preferably, the latter sample pad in the crawling direction is arranged below the former sample pad, so that the sample extract can be better transferred from the former sample pad to the latter sample pad, thereby more effectively achieving the concentration, separation or purification of the target. In addition, at least one heat conductive member for heating each sample pad is arranged under the sample pad. Figure 4 A schematic diagram of a device 4 for regional thermal enrichment according to some embodiments of the present invention, comprising two sample pads 41 and two heat conductors 42, is shown. It is understood that one heat conductor may be arranged for each of the two sample pads, or more than one (e.g., two or three) heat conductors may be arranged for each of the two sample pads, depending on the specific circumstances, as long as the solvent can be effectively volatilized to achieve concentration, separation or purification of the target.

[0041] In some embodiments, the two sample pads included in the device are made of different materials. The different materials can adsorb different substances, and / or the solvent has different crawling speeds on them, thereby achieving more levels of separation. For example, the sample extract contains solid impurities, substance A dissolved in the solvent, and target substance B dissolved in the solvent. Substance A is more easily adsorbed on the previous sample pad (first sample pad), while substance B is more easily adsorbed on the latter sample pad (second sample pad). Therefore, when the sample extract is added to the first sample pad, the solid impurities are first adsorbed on the first sample pad; and when the first sample pad and the second sample pad are heated, substance A and substance B will move with the crawling of the solvent on the first sample pad, and when the solvent crawls to the overlapping position of the first sample pad and the second sample pad, the remaining solvent will carry substance B to the first end of the second sample pad, and continue to crawl until the second end of the second sample pad. Thus, the separation, purification and concentration of substance B in the sample extract are achieved.

[0042] The device for regional heat enrichment provided by the present invention has the following beneficial effects:

[0043] (1) Increase the cross-sectional / instantaneous binding concentration of the target to be detected. By allowing the solvent in the sample extract to gradually evaporate during the crawling process on the sample pad, the target contained therein can eventually be concentrated in a relatively narrow three-dimensional space. When a detection liquid such as a chromatography liquid is subsequently added, the concentration of the target on the cross section can be effectively increased, thereby improving the test efficiency and sensitivity.

[0044] (2) The localized concentration of the target object is achieved. By setting different temperature points that rise in sequence, and combining the heating area and the number of heating points (i.e., the number of heat-conducting parts), the speed and amount of solvent evaporation can be controlled, so that the sample liquid evaporates at a certain position, thereby achieving the localized concentration of the target object, making the subsequent detection process, such as the chromatography process, shorter.

[0045] (3) Accelerate the evaporation rate of the solvent. In traditional sample tube heating, the surface in contact with the air is small, and the same volume of liquid evaporates slowly at the same temperature; however, the sample pad has a porous structure, so it can effectively increase the evaporation rate of the solvent.

[0046] (4) Reduce the amount of reagents used, increase the amount of effective solvents used and the concentration of the target. When the solvent is heated and evaporated and redissolved in the sample tube, in order to ensure the subsequent process such as chromatography, the redissolved solution usually needs to be added several times the amount required for the chromatography solution, which invisibly dilutes the target. After the target is enriched on the sample pad, the required chromatography solution is directly dripped onto the sample pad. All solvents are effectively used in the chromatography process, and the chromatography process is achieved with less solvent, which also increases the concentration of the target.

[0047] (5) Realize the replacement of different solvents. If the solvent used in the target extraction process has an impact on the detection process results, the volatilization on the sample pad can achieve the replacement of different solvents, so that a solvent different from the extraction solvent is subsequently applied to the sample pad.

[0048] (6) Reduce the loss of the target. In the traditional method, the solvent is evaporated, redissolved, and transferred in different containers, which inevitably causes the loss of the target, resulting in a decrease in the concentration of the target. In this method, the evaporation and redissolution are both on the sample pad, which is efficient, loss-free, and more environmentally friendly.

[0049] (7) Reduce the use of consumables. It reduces the use of consumables and utensils, which is more environmentally friendly and convenient.

[0050] (8) The separation of some impurities is achieved. After some impurities (such as pigments) are heated and volatilized, their ability to adhere to the sample pad can be enhanced. Then, when the test strips are assembled and the chromatography liquid is dripped in, the impurities cannot climb onto the nitrocellulose membrane, thereby achieving the separation of the target and the impurities, making the results more accurate.

[0051] (9) Simplified sample pretreatment process. The device for regional thermal enrichment provided by the present invention enables the separation, purification and concentration of the target to be completed on the sample pad, thereby reducing the sample pretreatment steps and simplifying the sample pretreatment process.

[0052] The device provided by the present invention heats the volatile solvent in different regions by differentially heating different regions on the sample pad, thereby achieving gradient concentration of the target on the sample pad, so that the sample can be enriched at a specified end of the sample pad, thereby improving the "unit volume concentration" of the target during the sample chromatography process, and even achieving the effect of removing impurities. Applying the regional thermal enrichment of the sample extract to the sample pretreatment process can greatly improve the detection efficiency.

[0053] Therefore, according to the second aspect of the present invention, there is provided a method for performing regional thermal enrichment of a sample extract using the device according to the first aspect of the present invention, the method comprising:

[0054] 1) adding a sample extract to a sample pad of the device; and

[0055] 2) Using another heating element or the heating element of the device to heat the heat-conducting element of the device, so that the temperature of the heat-conducting element is sequentially increased in the creeping direction of the sample extract, thereby heating the sample pad.

[0056] Those skilled in the art will appreciate that the above descriptions related to the device for regional heat enrichment of the first aspect of the present invention are all applicable to the second aspect of the present invention, and therefore will not be repeated here.

[0057] According to a third aspect of the present invention, there is provided a detection sample pad obtained by the method according to the second aspect of the present invention.

[0058] According to a fourth aspect of the present invention, there is provided an immunochromatographic test strip comprising the detection sample pad according to the third aspect of the present invention.

[0059] It should be pointed out that when combined with other parts of the immunochromatographic test paper to form a complete test strip, the low-temperature end or the high-temperature end of the detection sample pad can be combined with other parts of the immunochromatographic test paper, but preferably, the low-temperature end of the detection sample pad is combined with other parts of the immunochromatographic test paper, so that impurities that are concentrated simultaneously with the target object are kept away from the NC membrane, reducing the impact on the detection process.

[0060] According to the fifth aspect of the present invention, there is provided the use of the device according to the first aspect of the present invention or the detection sample pad according to the third aspect of the present invention in immunochromatography analysis, mass spectrometry analysis, and surface enhanced Raman testing.

[0061] As understood by those skilled in the art, immunochromatography analysis uses strip-shaped fiber chromatography materials as the solid phase, and causes the sample solution to swim / crawl on the chromatography material through capillary action, while simultaneously causing the analyte labeled with a marker in the sample to react with a reaction reagent (such as an antigen or antibody) coated in the chromatography material against the analyte to undergo a highly specific and high-affinity immune reaction. During the chromatography process, the immune complex is enriched or retained in a certain area (detection zone) of the chromatography material, and intuitive experimental phenomena (such as color development) are obtained through enzyme reactions or direct use of visually observable markers (such as colloidal gold, colored latex, etc.).

[0062] In combination with the present invention, the detection sample pad provided in the third aspect of the present invention is assembled with other parts of the immunochromatographic test strip to perform immunochromatographic analysis. In this process, when the chromatographic fluid brings the target to the NC membrane, its cross-sectional concentration is greatly improved compared with conventional methods, thereby improving the sensitivity of immunochromatography.

[0063] As understood by those skilled in the art, mass spectrometry detection and analysis is generally a technology that performs qualitative, quantitative, and structural analysis on target objects. It has the characteristics of high resolution, high sensitivity, and strong anti-interference ability. It has been widely used in food and drug safety testing fields such as pesticide residues, plasticizers, polycyclic aromatic hydrocarbons, and genotoxic substances.

[0064] In combination with the present invention, the detection sample pad provided in the third aspect is directly used for mass spectrometry analysis, which can further improve the efficiency of mass spectrometry detection and analysis.

[0065] As those skilled in the art understand, Raman spectroscopy is a molecular structure characterization technology based on the Raman effect. Its spectral line position (displacement value), number of spectral lines, and spectral band intensity directly reflect the vibration mode information based on the extension and bending of chemical molecular bonds, so the composition and conformation information of the molecule can be understood. Surface enhanced Raman detection has the advantages of rapidity, accuracy, sensitivity, good reproducibility, short detection time, low detection cost, small and portable system, and relatively simple equipment operation. It is very suitable for on-site and rapid detection of trace illegal additives in food safety.

[0066] In combination with the present invention, using the detection sample pad provided in the third aspect for surface enhanced Raman testing can further shorten the detection time and improve the detection efficiency.

[0067] The present invention is described in more detail below in conjunction with the examples. It should be noted that the methods / experimental steps not explicitly described in the present invention can be performed by conventional methods / experimental steps in the art, and reference can be made to corresponding experimental reference books.

[0068] Example 1: Application in immunochromatographic analysis

[0069] Detection of pesticide chlorpyrifos residues in tea: Cut a 0.6×3.5cm glass fiber sample pad and place it on two 0.7×1×5cm iron blocks, with a distance of 0.5cm between the two iron blocks. The iron blocks are heated with a heating patch, and the temperatures are 50℃ and 75℃ respectively (i.e. double heating). 100μL (chlorpyrifos concentration is 0.3ppm) acetonitrile tea pesticide residue extract is dripped five times at one end of the glass fiber sample pad (the end close to the iron block with lower temperature) and evaporated. Then, the sample pad (containing pesticide residues) obtained in this way is assembled with the chlorpyrifos test strip, in which the end of the sample pad heated at 50℃ is close to the nitrocellulose (NC) membrane. Subsequently, the test strip obtained by this assembly is inserted into a gold cup with 250μL of 0.1M Tris-HCl (pH8.0) dissolved for chromatography.

[0070] For comparison, the same experiment was conducted with the glass fiber sample mat being heated (ie, single heating) and not being heated (ie, untreated) by a piece of iron.

[0071] Figure 5 A group of photos of sample pads after double heating and single heating are shown. It can be seen from the figure that in the case of double heating of the sample pad, the brown area is larger, which indicates that the solvent evaporates faster in the sample pad; while in the case of single heating of the sample pad, the brown area is smaller, which indicates that the solvent evaporates slower in the crawling pad.

[0072] In addition, experiments have shown that heating the sample pad dries the sample pad faster than without heating. Furthermore, when the sample pad is double heated, the sample pad dries faster, with a drying time of 17 minutes, while when it is single heated, the drying time is 28 minutes.

[0073] Figure 6 Another group of photos of sample pads without heating treatment, single heating treatment and double heating treatment are shown (there are two sample pads for each treatment method, one of which has 500 μL of acetonitrile solvent added as a control, and the other has 500 μL of the above-mentioned acetonitrile tea pesticide residue extract added). From the photos and the test strip readings in Table 1, it can be seen that compared with the case of no heating (untreated), the detection limits of double heating and single heating are lower. In addition, compared with single heating, the sample pad treated with double heating is cleaner, in other words, more impurities can be filtered out. In short, double heating treatment will allow the solvent in the sample pad to evaporate faster, can remove more impurities at the same time, and when used in conjunction with the test strip, it will make the detection limit of the test strip lower and the sensitivity higher.

[0074] Table 1

[0075]

[0076] Example 2: Application in immunochromatographic analysis

[0077] Detection of pesticide chlorpyrifos residues in tea :Two non-woven sample pads of 0.6×1.5cm and 0.6×1cm were placed on two iron blocks of 0.7×1×5cm, with a distance of 0.5cm between the two iron blocks and an overlap of 0.3cm. The iron blocks were heated with a heating patch at 50℃ and 75℃, respectively. 100μL of acetonitrile tea pesticide residue extract was dripped five times on one end of the non-woven sample pad (the end close to the iron block with lower temperature) and evaporated. Then, the sample pad heated at 75℃ (0.6×1.5cm, containing pesticide residues) was taken and assembled with the chlorpyrifos test strip, in which the non-overlapping end of the sample pad heated at 50℃ was close to the nitrocellulose (NC) membrane. Subsequently, 100μL of 0.1M Tris-HCl (pH8.0) was dripped on the sample pad of the test strip obtained by this assembly for chromatography.

[0078] For comparison, the same experiment was also conducted on a normal test strip with only a non-woven sample pad, and a test strip with a non-woven sample pad and a water filter membrane (nitrocellulose membrane) superimposed on the sample pad. The results are as follows: Figure 7 As shown. Figure 7 It can be seen that the crawling of the acetonitrile tea pesticide residue extract on the sample pads stacked with two non-woven fabrics is similar to that on a single non-woven fabric sample pad, but the filtering effect of the sample pads stacked with two non-woven fabrics on impurity particles is significantly enhanced. In addition, by comparing the stacking of two sample pads of the same material with the stacking of two sample pads of different materials, it can be seen that when two sample pads of different materials are used, the second sample pad in the crawling direction is very clean, which indicates that the particulate impurities in the acetonitrile tea pesticide residue extract are basically removed.

[0079] In addition, a series of experimental results show that by properly selecting different materials to prepare stacked sample pads, a good complementary effect can be obtained in terms of impurity removal, thereby achieving the removal of more types of impurities.

[0080] Example 3: Application in open mass spectrometry

[0081] The pesticide residue of carbofuran in food Detection: Cut a 0.6×3cm non-woven sample pad, cut its end into a triangular tip, and place it on two 0.7×1×5cm iron blocks, with a distance of 0.5cm between the two metal sheets. The iron blocks are heated with a heating patch, and the temperatures are 50°C and 70°C respectively, of which the temperature close to the triangular tip is 70°C. 100μL (carbofuran concentration is 100ppb) of anhydrous ethanol extract of food is dripped five times at the end of the sample pad away from the triangular tip, and evaporated. Then, the tip of the sample pad is close to the injection port of the open mass spectrometer, 100μL of anhydrous ethanol is dripped to the tip, and mass spectrometry analysis is started.

[0082] Figure 8 and Fig. 9 The mass spectra obtained by detecting carbofuran without heating and with heating of the sample pad are shown respectively. Figure 8 and Fig. 9 Comparison shows that the peak after heating is stronger. It can be seen that the sample treated with this method has a higher concentration than the sample without previous treatment (no heating).

[0083] Example 4: Application in surface enhanced Raman testing

[0084] Detection of Malachite Green :Cut a 0.8×1cm glass fiber sample pad and place it on two 0.7×1×5cm iron blocks, with a distance of 0.5cm between the two iron blocks. The iron blocks are heated with a heating patch at 50°C and 70°C respectively. 100μL of malachite green (100ppb) acetonitrile solution is dripped five times at one end of the glass fiber sample pad (the end close to the iron block with lower temperature) and wait for evaporation. Then, 50μL of nanosilver is dripped at the evaporation position, followed by 50μL of enhancement reagent. Place it under the Raman probe and align the light spot with the evaporation position for detection.

[0085] Fig.10 and Fig.11 The Raman spectra of malachite green obtained by detecting the sample pad without heating and heating are shown respectively. It is known that there are three groups of characteristic peaks for judging whether malachite green exists: 1000-1200cm -1 、1350-1400cm -1 , 1600-1700cm -1 There are 3-5 peaks around. Fig.10 The spectrum obtained by detecting malachite green without heating the sample pad is shown, in which only three peaks are detected, and there is only one characteristic peak 1368. However, judging from the peak shape, it should be interfered by impurities (the peak is too broad), so the presence of malachite green cannot be determined based on this. Fig.11The spectrum obtained by detecting malachite green in the case of heating the sample pad is shown, in which, in addition to the same large package peak, three characteristic peaks of 1611, 1387, and 1165 also appear, so the presence of malachite green can be clearly determined. It should be noted that due to the appearance of other characteristic peaks, the instrument automatically eliminates the interference of the large package peak, which is also the advantage of the method for heating the sample pad provided by the present invention, which improves the accuracy of the judgment of the detection result.

[0086] In summary, the samples treated with this method have higher concentrations than the samples that have not been treated before (not heated).

[0087] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for regional heat enrichment, It is characterized in that The device includes at least one sample pad and at least two heat-conducting members, wherein the heat-conducting members are arranged at intervals in the crawling direction of the sample extract on the sample pad and are in contact with the sample pad, and the heat-conducting members are configured to be heated to different temperatures that are sequentially increased in the crawling direction by a heating member for heating the sample pad, so as to volatilize the solvent in the sample extract and accelerate the volatilization speed of the solvent, thereby obtaining a target object at one end of the sample pad.

2. The device according to claim 1, It is characterized in that The last heat-conducting member in the creeping direction of the sample extract is configured to be heated by a heating member to a temperature determined according to a boiling point of a solvent in the sample extract.

3. The device according to claim 2, It is characterized in that The temperature difference between two adjacent heat-conducting members is 15-30°C.

4. The device according to claim 3, It is characterized in that The temperature difference between two adjacent heat-conducting members is 20-25°C.

5. The device according to any one of claims 1 to 4, It is characterized in that The thermal conductor is dimensioned to cover at least the width of the sample pad.

6. The device according to any one of claims 1 to 4, It is characterized in that The number of the heat conducting members is 2, 3, 4 or 5.

7. The device according to any one of claims 1 to 4, It is characterized in that The heat conducting member is a metal block or a metal sheet.

8. The device according to claim 7, It is characterized in that The heat conducting member is an iron block or sheet, a copper block or sheet, an aluminum block or sheet, an aluminum alloy block or sheet, a ceramic block or sheet, or a glass block or sheet.

9. The device according to any one of claims 1 to 4, It is characterized in that The device further includes heating elements having the same number as the heat conducting elements, and the heating elements exist independently of each other or exist integrally with each other.

10. The device according to any one of claims 1 to 4, It is characterized in that The sample pad is a glass fiber sample pad, a non-woven fabric sample pad, a nylon sample pad, a polytetrafluoroethylene sample pad or a polyethersulfone sample pad.

11. The device according to any one of claims 1 to 4, It is characterized in that The device includes two sample pads, wherein the two sample pads partially overlap each other.

12. The device according to any one of claims 1 to 4, It is characterized in that The two sample pads overlapped each other by 0.2 cm to 0.4 cm.

13. The device according to any one of claims 1 to 4, It is characterized in that The two sample pads have different materials.

14. A method for performing regional thermal enrichment of a sample extract using the device according to any one of claims 1 to 13, It is characterized in that The method comprises: 1) adding a sample extract to a sample pad of the device; and 2) using another heating element or the heating element of the device to heat the heat-conducting element of the device, so that the temperature of the heat-conducting element is sequentially increased in the creeping direction of the sample extract, thereby heating the sample pad to volatilize the solvent in the sample extract and accelerate the volatilization speed of the solvent, Thereby, the target object is obtained at one end of the sample pad.

15. A sample pad for detection obtained by the method according to claim 14.

16. An immunochromatographic test strip, It is characterized in that The detection sample pad comprises the detection sample pad according to claim 15.

17. Use of the device according to any one of claims 1 to 13 or the detection sample pad according to claim 15 in immunochromatography analysis, mass spectrometry analysis, and surface enhanced Raman testing.

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