Split type membrane filter and microbial limit detection method

Abstract

The invention relates to a split type membrane filter which comprises a filter part and a sample container, a container cavity is formed in the sample container, and a container nozzle is arranged on the sample container and used for allowing sample liquid to enter and exit from the container cavity; a filter cavity is formed in the filter part, a water outlet hole communicated with the filter cavity is formed in the bottom of the filter part, and a filter membrane is arranged in the filter cavity and used for filtering liquid flowing from the filter cavity to the water outlet hole; a connector communicated with the filtering cavity is formed in the filtering piece, and the connector is suitable for being detachably connected with a container nozzle; when the container nozzle is connected with the connector, the sample container and the filter piece are connected into a whole, and the container cavity and the filter cavity are communicated through a channel formed by connecting the container nozzle and the connector. The invention also provides a microbial limit detection method. Sample liquid can be sampled and transferred through the sample container, and popularization of a membrane filtration method is facilitated. The limitation on the size of the filtering piece is reduced, and the manufacturing cost, the storage cost and the transportation cost of the filtering piece can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial limit detection, and in particular to a split membrane filter and a microbial limit detection method. Background Art

[0002] Membrane filtration is suitable for testing microbial limits in sample liquids, such as beverages, pharmaceuticals, biological preparations, biological reagents, hospital water, disinfectants, and other sample liquids. One implementation involves placing the sample liquid in a filter element (such as a filter cup) containing a filter membrane designed to intercept microorganisms. The membrane is compressed and sealed to prevent leakage. Positive or negative pressure is used to drain the liquid from the filter element, trapping the microorganisms on the membrane. The membrane is then placed flat on an agar plate for culture, and the colonies (CFU) growing on the membrane are counted to determine whether the microbial limit has been exceeded.

[0003] Although the use of filter elements to filter sample liquids is widely used, the following technical problems exist: The filter element needs to form a chamber for holding the test sample liquid, which results in a larger filter element, especially a larger dimension in the height direction. On the one hand, more materials are needed to manufacture the filter element, and the material cost is high. On the other hand, the filter element is large in size and will occupy a larger storage space during transportation, resulting in higher logistics costs.

[0004] Due to the high price of filter elements, the entire filter element may be lost during use, especially when used by front-line sampling personnel, there is a risk of entire filter element being lost. The management cost requirements are also high, which limits the application of filter elements and is not conducive to the popularization of membrane filtration.

[0005] The use of filter elements for sampling places high demands on the operator's operation and on the transportation of the filter elements with sample liquid, which limits the application of the filter elements and is not conducive to the popularization of membrane filtration. Summary of the Invention

[0006] The object of the present invention is to provide a split membrane filter and a microbial limit detection method to alleviate or eliminate at least one of the above-mentioned technical problems. The present invention provides a split membrane filter comprising a filter element and a sample container separately disposed relative to the filter element; the sample container has a container cavity formed therein and a container mouth disposed on the sample container for allowing sample liquid to enter and exit the container cavity; The filter element is provided with a filter cavity, a water outlet hole is provided at the bottom of the filter element and is communicated with the filter cavity, a filter membrane is provided in the filter cavity, and the filter membrane is used to filter the liquid flowing from the filter cavity to the water outlet hole; The filter element is provided with an interface communicating with the filter cavity, and the interface is suitable for detachable connection with the container mouth; when the container mouth is connected to the interface, the sample container and the filter element are connected as a whole, and the container cavity and the filter cavity are communicated through a channel formed by the connection between the container mouth and the interface.

[0007] Optionally, the sample container is configured so that the volume of the container cavity can change with changes in the pressure in the container cavity.

[0008] Optionally, the wall of the container cavity is soft, so that the volume of the container cavity can change with the change of the pressure in the container cavity.

[0009] Optionally, the sample container is a sample bag.

[0010] Optionally, the sample bag includes a bag body having a hard bag spout and a bag cover detachably connected to the hard bag spout, and the bag cover is used to open and close the hard bag spout.

[0011] Optionally, the wall of the container cavity is a hard body, and the wall of the container cavity is provided with a vent with an air filter.

[0012] Optionally, the interface is arranged on the top of the filter element.

[0013] Optionally, the height of the filter cavity is 0.1 mm to 100 mm.

[0014] The present invention also provides a microbial limit detection method, using any of the split membrane filters described above, the microbial limit detection method comprising the following steps: collecting a sample, adding the sample to a sample container, forming a sample liquid in the sample container, and sealing the sample container; Connecting the container mouth of the sample container to the interface of the filter element so that the container cavity of the sample container communicates with the filter cavity of the filter element; Performing a filtering operation on the filter element or squeezing the sample container until the sample liquid in the sample container and the filter element is emptied; Open the filter and take out the filter membrane for culture.

[0015] The present invention can collect and transport sample liquid through the sample container, which is conducive to the popularization of membrane filtration. The present invention also reduces the limitation on the size of the filter element, which helps to reduce the manufacturing cost, storage cost and transportation cost of the filter element. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the split membrane filter described in some embodiments; Figure 2is a partially enlarged schematic diagram of the filter element described in some embodiments; Figure 3 Schematic diagram of the operation of the microbial limit detection method described in some embodiments.

[0017] In the figure: 1 - filter element; 2 - sample bag; 3 - sample liquid; 11 - cup holder; 12 - side wall; 13 - top wall; 14 - filter chamber; 15 - interface; 16 - filter membrane; 17 - water outlet; 18 - connecting tube; 21—Bag body; 22—Bag cover. DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] The following describes the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art will readily appreciate the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the various details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are intended only to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0020] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. The illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0021] like Figure 1 The split membrane filter shown includes a filter element 1 and a sample container separately arranged relative to the filter element 1; a container cavity is formed in the sample container, and a container mouth is provided on the sample container, which is used to supply sample liquid 3 into and out of the container cavity; a filter cavity 14 is provided in the filter element 1, and a water outlet 17 communicating with the filter cavity is provided at the bottom of the filter element 1, and a filter membrane 16 is provided in the filter cavity 14, and the filter membrane 16 is used to filter the liquid flowing from the filter cavity 14 to the water outlet 17; the filter element 1 is provided with an interface 15 communicating with its filter cavity 14, and the interface 15 is suitable for detachable connection with the container mouth; when the container mouth is connected to the interface 15, the sample container and the filter element 1 are connected as a whole, and the container cavity and the filter cavity 14 are communicated through a channel formed by the connection between the container mouth and the interface 15.

[0022] Using the above technical solution, a sample container can be used to collect samples and hold sample liquid 3 at the sampling site. At the testing site, the sample container containing sample liquid 3 is connected to the filter element 1 to filter the sample liquid 3. The filter membrane 16 is used to intercept microorganisms in the sample liquid 3, and the water outlet 17 is used to drain water from the sample liquid 3.

[0023] By using the above-mentioned split membrane filter, sample containers can be used for sampling and transporting samples. There is no need to bring the filter element 1 to the sampling site, which reduces the possibility of losing the filter element 1. Moreover, the cost of the sample container is usually much lower than that of the filter element 1, which reduces the limitations on the application of the filter element 1. Since the high-cost sample does not leave the laboratory, only the low-cost sample container leaves the laboratory and is distributed to various clinical departments, the loss cost is reduced, which is conducive to the collection, transportation and popularization of the membrane filtration method.

[0024] With the aforementioned split membrane filter, since the sample container provides a chamber for holding the sample liquid 3, the volume requirement for the sample cup filter chamber 14 is smaller, allowing the filter element 1 to be made smaller. This reduces the material used in the filter element 1 and thus material costs. Furthermore, the smaller filter element 1 requires less storage space, helping to reduce storage and transportation costs.

[0025] In practice, the use of the aforementioned split membrane filter significantly reduces restrictions on the height of the filter cavity 14 of the filter element 1. The height of the filter cavity 14 can be set to a range of 0.1 mm to 100 mm. For example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, ..., 1 mm, 2 mm, 3 mm, ..., 100 mm. In practice, the height of the filter cavity 14 can be set to any desired height between 0.1 mm and 100 mm.

[0026] In some embodiments, the sample container is configured such that the volume of the container cavity changes with changes in the pressure within the container cavity. With this solution, when the sample container containing the sample liquid 3 is placed on the filter element 1 for filtration, the container cavity, which changes in volume with pressure, allows the sample liquid 3 in the sample container to be smoothly transferred from the container cavity to the filter cavity 14 of the filter element 1 under the action of negative pressure. Furthermore, this type of sample container can typically be shrunk to reduce storage space requirements, thereby reducing storage and transportation costs.

[0027] In the prior art, to ensure smooth filtration, it is usually necessary to provide a vent hole in the cup lid of the filter element 1, and to place an air filter at the vent hole to filter the air. By providing a container cavity whose volume changes with pressure, the vent hole in the cup lid of the filter element 1 can be eliminated, simplifying the structure of the filter element 1 and reducing the cost of the filter element 1.

[0028] In some embodiments, the wall of the container cavity is flexible, allowing the volume of the container cavity to change with changes in the pressure within the container cavity. In a specific implementation, the wall of the container cavity can be configured as a flexible, deformable container, thereby forming a container cavity whose volume can change with changes in the pressure within the cavity. In a specific implementation, the flexible container can be made of a flexible material, or it can be formed by combining a flexible material with a deformable structure. The deformable structure can be, but is not limited to, a corrugated structure or a thin-walled structure, and the flexible material can be, but is not limited to, plastic or rubber.

[0029] The wall of the container cavity is preferably soft, but can also be hard if necessary. When the wall of the container cavity is hard, a vent with an air filter is provided on the wall of the container cavity to balance the air pressure and allow the sample liquid 3 in the container cavity to flow smoothly into the filter cavity 14 of the filter element 1.

[0030] As a specific example, the sample container is a sample bag 2. Sample bag 2 can be a commercially available product. Sample bag 2 is easy to manufacture, low-cost, and readily available. Sample bag 2 also satisfies the requirement that the volume of the container cavity can vary with changes in the pressure within the cavity.

[0031] In practice, the sample bag 2 typically comprises a bag body 21, a spout connected to the bag body 21, and a lid 22 for opening and closing the spout. The inner cavity of the bag body 21 serves as the container cavity. Compared to a sample cup, the sample bag 2 requires less operator control and less transportation, facilitating the widespread use of membrane filtration.

[0032] In some embodiments, the sample bag 2 includes a bag body 21 having a rigid spout and a bag cover 22 detachably connected to the rigid spout. The bag cover 22 is used to open and close the rigid spout. The rigid spout facilitates direct connection between the bag spout and the interface 15. In a specific embodiment, the rigid spout is provided with external threads, and the bag cover 22 is provided with internal threads that mate with the external threads. The bag cover 22 and the rigid spout are detachably connected via a threaded connection.

[0033] In some embodiments, a detachable connection structure is provided between the interface 15 and the container mouth. This detachable connection structure is suitable for directly connecting the interface 15 and the container mouth. With the container mouth and interface 15 directly connected, the sample liquid 3 can enter the filter cavity 14 of the sample cup through the container mouth and interface 15. This eliminates the need for piping to connect the sample container and the filter element 1, helping to reduce testing costs and allowing more sample liquid 3 in the sample container to enter the filter element 1. In specific implementations, the detachable connection structure may employ, but is not limited to, a threaded connection, a snap-fit ​​connection, or a quick-connect connector.

[0034] In practice, in order to better connect the container mouth, a connector for detachable connection with the container mouth is provided at the interface 15. The connector can be formed on the top wall 13 of the cup body in an integral manner with the cup body of the filter element 1.

[0035] In practice, since the filter element 1 and the sample container are designed to be separated, the filter element 1 can be packaged independently. This means that a sealing member is not required at the interface 15 of the filter element 1. For example, the filter element 1 can be packaged in a separate packaging bag, which can be opened and removed for immediate use. Obviously, a removable sealing member can also be installed at the interface 15 of the filter element 1, if desired.

[0036] In some embodiments, the bottom of the filter element 1 is provided with a water outlet 17 that communicates with the filter cavity 14. A filter membrane 16 is disposed within the filter cavity 14. The filter membrane 16 is configured to filter liquid flowing from the filter cavity 14 to the water outlet 17. The filter membrane 16 is configured to intercept microorganisms in the sample liquid 3, and the water outlet 17 is configured to drain water from the sample liquid 3.

[0037] In a specific embodiment, the filter element 1 includes a cup body and a cup base 11. The cup body has a top wall 13 and side walls 12, which enclose a space with an open bottom. The cup body and the cup base 11 form a filter chamber 14. A water outlet 17 is provided on the cup base 11. A filter membrane 16 is clamped between the cup body and the cup base 11. An interface 15 is provided on the top wall 13 of the cup body. The above-described technical solution clamps the filter membrane 16 between the cup body and the cup base 11, preventing leak detection and facilitating easy installation and removal of the filter membrane 16. A membrane pressing ring is provided within the cup body, which compresses and seals the periphery of the filter membrane 16 downward to prevent leak detection.

[0038] In some embodiments, the interface 15 is disposed on the top of the filter element 1 . The interface 15 is disposed on the top wall 13 of the cup body to facilitate the sample liquid 3 in the sample container to flow downward into the filter cavity 14 of the filter element 1 .

[0039] In specific implementation, the cup body, the cup seat 11, the connection structure therebetween, and the sealing structure therebetween can be implemented with reference to the filter element 1 or the suction cup in the prior art.

[0040] In specific implementation, the cup body of the present application can adopt an integrally formed structure, such as an integrally formed transparent plastic cup body.

[0041] In some embodiments, the cup holder 11 is provided with a structure for detachably connecting to a filtration device. Using the filtration device for filtration is easy to operate. The cup holder 11 is provided with a downwardly extending connecting tube 18, which is connected to the water outlet 17 and sealed to the filtration device. The filtration device can be an existing product, such as the fully automatic membrane filtration machine described in Chinese patent application number CN201720853552.6.

[0042] The present invention also provides a method for detecting microbial limits, using any of the split membrane filters described above, the method comprising the following steps: Collecting a sample, adding the sample to a sample container, forming a sample liquid 3 in the sample container, and sealing the sample container; transporting the sample container containing the sample liquid 3 to a testing site; Connect the container mouth of the sample container to the interface 15 of the filter element 1 so that the container cavity of the sample container communicates with the filter cavity 14 of the filter element 1; Perform a suction filtration operation on the filter element 1 or squeeze the sample container, and the sample liquid 3 in the sample container gradually transfers to the filter cavity 14 of the filter element 1. The sample liquid 3 in the filter cavity 14 of the filter element 1 is filtered until the sample liquid 3 in the sample container and the sample liquid 3 in the filter element 1 are completely filtered out. Open filter element 1 and take out the filter membrane for culture.

[0043] It should be noted that when the sample does not contain liquid or contains less liquid, liquid can be added to the sample container to form the sample liquid 3 .

[0044] During specific implementation, the filtration operation on the filter element 1 can be performed using a filtration device that matches the filter element 1 .

[0045] The sample container can be a sample bag 2. By squeezing the sample bag 2, the sample liquid 3 in the sample container gradually transfers to the filtration cavity 14 of the filter element 1, where the sample liquid 3 in the filtration cavity 14 of the filter element 1 is filtered. This method of squeezing the sample bag 2 is easy to implement, requires minimal effort, and is low-cost.

[0046] The characteristics of the above-mentioned microbial limit detection method have been described in the introduction to the split membrane filter. Please refer to the introduction to the split membrane filter and will not be described in detail here.

[0047] The present invention separates the two functional areas of the conventional filter cup widely used in the prior art, which is convenient for reducing costs and facilitating use. The present invention designs the container function part and the filtration function part to be separable from each other, so that the sample collection, transportation and filtration operations can be separated from each other, making the division of labor clear, and the two working stages separated. The main cost is on the filtration function part, and only the container part is involved in the collection and transportation of the sample, and the loss cost during circulation is greatly reduced. It avoids the greater loss of conventional filter parts during circulation. The risk is reduced to the low-cost container function part of the circulation. It is conducive to the collection and centralized transportation of samples after collection, such as sample collection by third-party inspection companies and sample collection and centralized transportation during epidemic outbreaks.

[0048] The above embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the scope of protection of the present invention. In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. mean that the specific features, structures, materials or characteristics of the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0049] In the description of the present invention, it should be understood that the terms "upper", "lower" and the like indicate directions based on the attached drawings. Figure 1 The orientations represented by the coordinate system are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

Claims

1. A split membrane filter, characterized in that: The invention comprises a filter element and a sample container which is separately arranged relative to the filter element; a container cavity is formed in the sample container, and a container mouth is provided on the sample container, and the container mouth is used for allowing the sample liquid to enter and exit the container cavity; The filter element is provided with a filter cavity, a water outlet hole is provided at the bottom of the filter element and is communicated with the filter cavity, a filter membrane is provided in the filter cavity, and the filter membrane is used to filter the liquid flowing from the filter cavity to the water outlet hole; The filter element is provided with an interface communicating with the filter cavity, and the interface is suitable for detachable connection with the container mouth; when the container mouth is connected to the interface, the sample container and the filter element are connected as a whole, and the container cavity and the filter cavity are communicated through a channel formed by the connection between the container mouth and the interface.

2. The split membrane filter according to claim 1, characterized in that: The sample container is configured such that the volume of the container cavity can change with changes in the pressure in the container cavity.

3. The split membrane filter according to claim 2, characterized in that: The wall of the container cavity is soft, so that the volume of the container cavity can change with the change of the pressure in the container cavity.

4. The split membrane filter according to claim 3, characterized in that: The sample container is a sample bag.

5. The split membrane filter according to claim 4, characterized in that: The sample bag comprises a bag body with a hard bag spout and a bag cover detachably connected to the hard bag spout, wherein the bag cover is used for opening and closing the hard bag spout.

6. The split membrane filter according to claim 1, characterized in that: The wall of the container cavity is a hard body, and the wall of the container cavity is provided with a vent with an air filter.

7. The split membrane filter according to claim 1, characterized in that: The interface is arranged on the top of the filter element.

8. The split membrane filter according to claim 1, characterized in that: The height of the filter cavity is 0.1 mm to 100 mm.

9. A method for detecting microbial limits, characterized in that: Using the split membrane filter according to any one of claims 1 to 8, the microbial limit detection method comprises the following steps: collecting a sample, adding the sample to a sample container, forming a sample liquid in the sample container, and sealing the sample container; Connecting the container mouth of the sample container to the interface of the filter element so that the container cavity of the sample container communicates with the filter cavity of the filter element; Performing a filtering operation on the filter element or squeezing the sample container until the sample liquid in the sample container and the filter element is emptied; Open the filter and take out the filter membrane for culture.

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