Matrix and associated sample or mixing cup for removing components of a liquid sample

Abstract

An insert for removing a target component of a liquid sample installed in a mixing cup and used by an automated chemical analyzer includes a porous matrix formed of functionalized particles or bearing immobilized functionalized particles having properties that cause the target component of the liquid sample to adhere to the functionalized particles. When the liquid sample is expelled from a disposable tip fitted on an end of a pipette forming a part of the automated chemical analyzer into the mixing cup, the liquid sample is drawn by capillary action into the matrix of the insert, whereby the target component of the liquid sample adheres to the immobilized functionalized particles of the matrix.

Description

[0001] Cross-references to related applications This application relates to and claims priority to U.S. Provisional Patent Application Serial No. 62 / 987,077, filed March 9, 2020, entitled “Matrix And Associated Sample Or Mixing Cup Used For Removing Components Of A Liquid Sample,” the disclosure of which is incorporated herein by reference.

[0002] This application also relates to U.S. Provisional Patent Application Serial No. 62 / 986,988, filed March 9, 2020, entitled “Method for Removing Interfering Components of a Liquid Sample Prior to Dispensing Same on a Chemical Reagent Test Slide”, filed by IDEXX Laboratories, Inc., the disclosure of which is incorporated herein by reference. Background Technology Technical Field

[0004] The present invention generally relates to techniques for removing components from liquid samples, and more specifically, to methods, apparatus and other auxiliary devices for removing components (e.g., proteins, hemoglobin, analytes and other components) from blood samples.

[0005] Description of related technologies The aforementioned U.S. Patent Application Serial No. 62 / 986,988 (hereinafter referred to as the “IDEXX Patent Application”) discloses a novel method and apparatus for removing components from liquid samples, such as whole blood, diluted blood, plasma, serum, etc. (generally referred to herein as “blood samples”), that may interfere with tests or measurements performed by automated chemical analyzers, such as those manufactured and sold by IDEXX Laboratories, Inc. under the trademarks VetTest®, Catalyst Dx®, and Catalyst One®. For example, hemoglobin in a blood sample may affect the accuracy of measurements performed on bile acid assays. The aforementioned IDEXX Patent Application describes a method using porous and non-porous beads (e.g., agarose-based and silica-based beads) held in a mixing cup to which a blood sample is added. Hemoglobin in the blood sample adheres to the beads, and the hemoglobin-adhered beads settle to the bottom of the cup over time by gravity. The blood sample, which is non-hemoglobin-containing and occupies the upper part of the cup, can now be aspirated by a pipette, which is part of the sample metering device that forms part of the chemical analyzer, and placed on the test slide. Summary of the Invention

[0006] The purpose of this invention is to provide a matrix having structural features that cause the target component of a liquid sample to adhere thereto, so as to provide a sample that is free of the target component or has a reduced target component, which can then be added to a test slide or cuvette for determination.

[0007] Another object of the present invention is to provide a matrix that can be formed as part of a sample cup, mixing cup, reagent cup or centrifuge cup, and that can be used to remove or reduce the concentration of components in a liquid sample.

[0008] Another object of the present invention is to provide a matrix / cup combination for use with an automated chemical analyzer to remove impurities or other unwanted components from liquid samples (e.g., “blood samples” as broadly defined herein) before dispensing the sample onto a dry chemical reagent test slide.

[0009] A further object of the present invention is to provide a method for removing components from a liquid sample that may interfere with diagnostic measurements performed on the liquid sample.

[0010] A further object of the present invention is to provide a matrix that can be received, or formed part of, a sample cup or mixing cup used by an automated chemical analyzer, and which carries functionalized particles, wherein components of a liquid sample added to the cup adhere to the functionalized particles to remove the components from the sample prior to testing.

[0011] A further object of the present invention is to provide sample cups, mixing cups, reagent cups, or centrifuge cups for use with automated chemical analyzers and containing a matrix for removing hemoglobin or other components from a “blood sample” as broadly defined herein, which may affect the accuracy of tests performed on the blood sample.

[0012] Another object of the present invention is to provide a liquid sample mixing / dispensing technique that removes unwanted components from liquid samples that may affect the testing performed on the liquid sample and the measurements obtained therefrom.

[0013] Another object of the present invention is to provide a pretreated or filtered liquid sample having a minimum or negligible concentration of a component of the liquid sample, such as hemoglobin in a blood sample, before being dispensed onto a dry chemical reagent test slide (e.g., a bile acid assay test slide).

[0014] A further object of the present invention is to use currently available automated chemical analyzers to analyze reagent test slides, and to use a specially designed mixing cup formed according to the invention, which is used by the analyzer to receive liquid samples, and to adjust the liquid samples together such that the samples have a reduced concentration of interfering components that may further affect the accuracy of fluorescence or absorbance / reflectance measurements obtained from tests performed on the liquid samples.

[0015] A further object of the present invention is to provide a method and apparatus for removing components from a liquid sample using a conventional chemical analyzer and dispensing the liquid sample onto a conventional, unmodified dry chemical reagent test slide.

[0016] Another object of the present invention is to provide a dedicated matrix for carrying functionalized particles, which is used to precondition liquid samples by removing or minimizing the presence of interfering or unwanted components before dispensing them onto conventional reagent test slides.

[0017] According to one form of the invention, the matrix is ​​formed of a porous medium through which a fluid can flow. In one form, the matrix holds functionalized particles in a fixed state, the functionalized particles removing components of the fluid flowing through the matrix. For example, the porous matrix immobilizes porous or non-porous agarose-based IMAC (fixed metal affinity chromatography) beads or silica-based IMAC beads or other functionalized particles, to which one or more components of a liquid sample adhere. Thus, such components are removed from the liquid sample, or their concentration therein is reduced, to provide a filtered liquid sample that can be dispensed onto a chemical reagent testing slide or a sample holding cuvette of an automated chemical analyzer.

[0018] The matrix can be in the form of an insert or plug, forming part of a sample cup or mixing cup, reagent cup, or centrifuge cup used by an automated chemical analyzer. For example, a blood sample is aspirated from a sample cup into a disposable tip on the end of a pipette adapted to a pump connected to a sample metering device that forms part of the automated chemical analyzer, and transferred by the pipette to a mixing cup containing the matrix, with the blood sample being expelled from the tip into the cup. Blood samples aspirated into the matrix by capillary action or forced into the matrix under the influence of hydraulic or pneumatic pressure from the pipette and the pump connected thereto flow through the matrix present in the mixing cup once or multiple times as needed.

[0019] The target component of the blood sample (e.g., hemoglobin) has an affinity for and adheres to functionalized particles (e.g., the aforementioned IMAC beads immobilized in the matrix), and is removed from or at least has its concentration reduced in the blood sample. The filtered blood sample, filled with matrix, is drawn from the matrix under negative fluid pressure caused by the reverse pumping action of the pipette and flows out through the matrix at the bottom of the mixing cup, where the filtered blood sample is re-absorbed by the pipette and, if necessary, repeatedly reintroduced into the matrix in the mixing cup until the target component of the filtered blood sample is completely removed or the component in the filtered blood sample reaches the desired concentration.

[0020] These and other objects, features, and advantages of the present invention will become apparent from the following detailed description of its illustrative embodiments, taken in conjunction with the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a bottom perspective view of one form of the matrix of the present invention, which is shaped into an insert or stopper that can be received in a sample cup, reagent cup or mixing cup, and is formed of functionalized particles or carries functionalized particles in a fixed state, wherein the target component of the liquid sample added to the cup adheres to the functionalized particles.

[0022] Figure 2 yes Figure 1 The image shows a top perspective view of the matrix insert or plug of the present invention.

[0023] Figure 3 yes Figure 1 and 2 The diagram shows a top plan view of the matrix insert or plug of the present invention.

[0024] Figure 4 yes Figure 1-3 The diagram shows the bottom plan view of the matrix insert or plug of the present invention.

[0025] Figure 5 yes Figure 1-4 The image shows a side view of the matrix insert or plug of the present invention.

[0026] Figure 6 yes Figure 1-5 The matrix insert or plug of the present invention shown is along... Figure 5 A cross-sectional view of line 6-6, and a cross-sectional view of a mixing cup in which a matrix insert or plug is received.

[0027] Figure 7 This is a top perspective view of another form of the matrix of the present invention, which is shaped into an insert or stopper that can be received in a sample cup, reagent cup or mixing cup, and is formed of functionalized particles or carries functionalized particles in a fixed state, wherein the target component of the liquid sample added to the cup adheres to the functionalized particles.

[0028] Figure 8 yes Figure 7 The image shows a bottom perspective view of the matrix insert or plug of the present invention.

[0029] Figure 9 yes Figure 7 and 8 The diagram shows a top plan view of the matrix insert or plug of the present invention.

[0030] Figure 10 yes Figure 7-9 The diagram shows the bottom plan view of the matrix insert or plug of the present invention.

[0031] Figure 11 yes Figure 7-10 The image shows a side view of the matrix insert or plug of the present invention.

[0032] Figure 12 yes Figure 7-11 The matrix insert or plug of the present invention shown is along... Figure 11 A cross-sectional view of line 12-12, and a cross-sectional view of a mixing cup in which a matrix insert or plug is received.

[0033] Figure 13 yes Figure 6 The diagram shows a cross-sectional view of the matrix insert or plug and the mixing cup, and illustrates the tip of a pipette, which forms part of an automated chemical analyzer, and is inserted into the mixing cup to deliver a liquid sample to the mixing cup.

[0034] Figure 14 yes Figure 13 The diagram shows a cross-sectional view of the matrix insert or stopper, mixing cup, and pipette tip, illustrating that the pipette tip is fully received axially through a central hole formed by the matrix insert or stopper before the liquid sample in the pipette tip is expelled from the matrix insert or stopper.

[0035] Figure 15It is a matrix insert or stopper, mixing cup, and pipette tip in Figure 14 The diagram shows cross-sectional views of their relative positions and illustrates the flow path of the liquid sample into the matrix insert or plug after the liquid sample has been expelled from the pipette tip.

[0036] Figure 16 It is a matrix insert or stopper, mixing cup, and pipette tip in Figure 15 The diagram shows cross-sectional views of their relative positions and illustrates the flow path of the "clean" liquid sample from the matrix insert or plug when the liquid sample is re-aspirated into the pipette tip. Detailed Implementation

[0037] Figure 1-12 Various structures of the matrix 2 in the mixing cup or reagent cup 4 formed according to the present invention are shown, which together are used by an automated chemical analyzer to remove or reduce the concentration of the target component of the liquid sample 6 before testing. As mentioned above, the liquid sample 6 may be, but is not limited to, a “blood sample,” as broadly defined herein as whole blood, diluted blood, plasma, serum, etc., and the target component may be, but is not limited to, a component that may interfere with the testing and measurement performed on the liquid sample 6 on the chemical analyzer, such as the hemoglobin component in a bile acid assay test performed on a blood sample by an automated chemical analyzer, as described in the aforementioned IDEXX patent application, or an antigen, antibody, protein, analyte, or some other component of the blood sample. By background art, automated chemical analyzers include a sample metering device or sub-assembly having a pipette 8 fitted with a disposable pipette tip 10, the pipette 8 being connected to a pump (not shown) so that the liquid sample 6 can be aspirated into or expelled from the pipette tip 10.

[0038] In the aforementioned IDEXX patent application, the target component of the liquid sample adheres to IMAC (Immobilized Metal Affinity Chromatography) porous beads in a suspension containing the liquid sample in a mixing cup, and the beads with the component adhering to them settle to the bottom of the cup by gravity. A certain volume of component-free liquid sample occupying the upper part of the cup is aspirated into its tip by a pipette for dispensing the sample onto a test slide. The method and apparatus disclosed in this application differ from those described in the preceding applications because the IMAC beads or other functionalized particles are immobilized in matrix 2 and do not enter the suspension with the liquid, as will be explained in more detail in subsequent paragraphs.

[0039] As in Figure 1-6As shown, the matrix 2 is preferably formed as an insert or plug 12, shaped to closely conform to the internal shape of the mixing cup, sample cup, reagent cup, or centrifuge cup 4 in which the matrix 2 is received. For example, the sample cup, reagent cup, and mixing cup 4 used with the aforementioned Catalyst Dx® and Catalyst One® instruments sold by IDEXX Laboratories, Inc. have a generally truncated conical shape, formed with a generally cylindrical upper portion 14, a conical middle portion 16, and a generally cylindrical lower portion 18 with a diameter smaller than that of the upper portion 14. Therefore, in Figure 1-6 In the illustrated embodiment, the matrix insert or plug 12 (hereinafter referred to as the "matrix insert") has a similar generally truncated conical shape, having a generally cylindrical or circular upper portion 20, which results in a tapered middle portion 22 with a reduced diameter, which in turn results in a generally cylindrical lower portion 24 with a diameter smaller than that of the upper portion 20. The overall external dimensions of the matrix insert 12 are selected based on the internal dimensions of the cup 4 in which it receives the matrix insert, such that the matrix insert 12 is received tightly by the cup 4 and conforms to the internal shape of the cup 4, wherein the sidewall 26 of the matrix insert 12 tightly engages at least a portion of the sidewall 28 of the cup 4. This structure ensures that the liquid sample 6 added to the cup 4 will come into contact with the matrix insert 12 present therein and will be drawn into the matrix 2 by hydraulic or pneumatic pressure caused by capillary action or by the pumping action of the pipette 8, rather than by the skirt surrounding the outside of the matrix insert 12, as will be described in more detail.

[0040] Or, and as in Figure 7-12 As shown, for sample cups, reagent cups, or mixing cups 4 with a generally cylindrical internal shape, the matrix insert 12 can also be cylindrical. Similarly, with... Figure 1-6 The embodiment shown is similar, in which the size of the cylindrical matrix insert 12 is selected such that its outer wall 26 fits tightly against the inner wall 28 of the cup 4 in which the matrix insert 12 is received.

[0041] In the above and Figure 1-12 In any embodiment of the matrix insert 12 shown, the matrix insert 12 may be slightly raised from the inner bottom surface 30 of the cup 4 in which it is received, to define a well or chamber 32 of a selected volume together with the bottom surface 30 to receive a liquid sample 6, which is drawn from the matrix insert 12 by gravity or by a pipette 8 forming part of the sample metering subassembly of the chemical analyzer. The well or chamber 32 also provides a volume of space to receive the liquid sample 6 discharged from its tip 10 by the pipette 8. This will also be explained in the following paragraphs.

[0042] exist Figure 1-6In one form of the matrix insert 12 shown, the well or chamber 32 may be formed by one or more supports 34 extending outward and downward from the lower portion 24 of the matrix insert 12. The supports 34 raise the lower portion 24 of the matrix insert 12 to a predetermined distance above the inner bottom surface 30 of the cup 4 to define a chamber or well 32 having a given volume.

[0043] exist Figure 7-12 The cylindrical matrix insert 12 shown may also include one or more supports 34, as in Figure 1-6 As shown, this defines a chamber or well 32. However, it should be noted that if the cylindrical matrix insert 12 is used in a cylindrical cup 4 with a curved bottom, similar to a conventional test tube, rather than having a flat bottom, then the support 34 may not be necessary, because the curvature of the bottom of the cup 4 will keep the matrix insert 12 above the bottom to define the liquid sample receiving well or chamber 32 together with the matrix insert 12.

[0044] Alternatively, if the matrix insert 12 is fixed within the cup 4 at a given distance from the inner bottom surface 30 of the cup 4 to define a liquid sample receiving well or chamber 32 together with the cup 4, then the support 34 is not required in any embodiment of the matrix insert 12.

[0045] Preferably, and as in Figure 1-12As shown, the matrix insert 12 is formed with a central hole 36 extending axially through the thickness of the matrix insert 12, from the top surface 38 to the bottom surface 40. Preferably, the shape, length, and diameter of the hole 36 are sized to conform to and tightly receive the external shape of the disposable tip 10 extending from the end of the pipette 8. Thus, when the pipette tip 10 is received by the central hole 36 formed in the matrix insert 12, it forms a seal with it, allowing the liquid sample 6 carried by the pipette tip 10 to drain from there and enter the liquid sample receiving well or chamber 32 located at the bottom of the cup 4. Furthermore, when the tip 10 is received by the matrix hole 36, it is desirable that the seal formed between the pipette tip 10 and the matrix insert 12 ensures that sufficient reverse hydraulic or pneumatic pressure caused by the aspiration of the pipette 8 draws the componentless liquid sample 6, which fills the matrix material of the insert 12, out of the insert 12. Alternatively, the central aperture 36 of the matrix insert 12 may be formed with an excessively large internal diameter, such that when the pipette tip 10 is received by the aperture 32, a space 42 is defined between the pipette tip 10 and the inner wall 44 of the matrix insert 12 defining the aperture 36. This annular space 42 is provided such that when a liquid sample 6 is dispensed from the pipette tip 10 to the bottom of the cup 4 in which the matrix insert 12 is present, some of the liquid sample 6 will flow upwards along the outer wall of the pipette tip 10 within this space 42 and will contact the inner wall 44 of the matrix insert 12 defining the aperture 36, where it will be drawn into the matrix 2 by capillary action.

[0046] At the top surface 38 of the matrix insert 12, the hole 36 of the matrix insert 12 can be formed as having a funnel-shaped entry opening 46, for example in Figure 1-12 As shown in the diagram, the funnel-shaped inlet opening 46 helps to properly guide the free end of the pipette tip 10 into the orifice 36 of the matrix insert 12.

[0047] Similarly, as in Figure 1-12As shown, the matrix insert 12 may be formed having a single channel, or a plurality of channels 48 periodically spaced from each other, and formed as a recess extending longitudinally around its circumference in the sidewall 26 of the matrix insert 12. The channel 48 is in fluid communication with a liquid sample receiving well or chamber 32 located between the matrix insert 12 and the inner bottom surface 30 of the cup 4. When the liquid sample 6 is discharged from the pipette tip 10 into the well or chamber 32, some of the liquid sample 6 will flow into the channel 48, be contained therein by the inner sidewall 28 of the cup 4, and be guided to the upper portion 20 of the matrix insert 12 or even the top surface 38 of the matrix insert 12, where it will be drawn into the matrix 2 by capillary action. The channel 48 is provided to facilitate the dispensing of the liquid sample 6 into the upper portion 20 of the matrix insert 12 and the matrix 2 therein. The channel 48 may extend along the longitudinal length of the matrix insert 12 to provide the liquid sample 6 to its top surface 38, where the sample 6 will be drawn from the top surface 38 of the insert 12 into the matrix 2, or the channel 48 may terminate before reaching the top surface 38, such that the liquid sample 6 flowing therein will be drawn into the matrix 2 at the sidewall 26 of the insert 12.

[0048] The matrix 2 is formed of a porous material that allows a liquid sample 6 to flow through it via capillary action, centrifugation, or under the influence of pneumatic or hydraulic pressure. This liquid sample is whole blood, diluted blood, plasma, serum, or other forms of blood samples, or another type of fluid. The porous material from which the matrix 2 is formed preferably has the ability to readily absorb or “wick” liquid samples 6 with a wide or limited viscosity via capillary action, or to carry particles or microparticles of varying sizes, such as red or white blood cells, proteins (e.g., hemoglobin), leukocytes, granulocytes, and other types of particles suspended in the liquid. It also has a porosity that allows the liquid to pass through the matrix insert 12 with little or no “clogging.” Furthermore, the matrix material should have the ability to act as a carrier for reagents, such as functionalized particles 50, such as porous or non-porous beads and nanoparticles, including IMAC agarose-based beads and silica-based beads, as described in the aforementioned IDEXX patent application, and to hold such functionalized particles 50 in a fixed state, preventing their release when wetted by the liquid sample 6.

[0049] Such matrix materials can include, but are not limited to, fibrous materials composed of synthetic or natural fibers (e.g., glass or cellulose-based materials or thermoplastic polymers such as polyethylene, polypropylene, or polyester); sintered structures composed of particulate materials (e.g., glass or various thermoplastic polymers); or cast films composed of nitrocellulose, nylon, polysulfone, etc. (which are generally synthetic in nature). Porous matrix materials can consist of fine particles of sintered polyethylene, commonly referred to as porous polyethylene, such as sintered polyethylene beads; preferably, such materials have a density between 0.35 and 0.55 g / cm³, a pore size between 5 and 40 micrometers, and a void volume between 40 and 60%. Particulate polyethylene composed of cross-linked or ultra-high molecular weight polyethylene is preferred. Flow matrix materials composed of porous polyethylene possess all the desired characteristics listed above, and are also readily manufactured in various sizes and shapes. Particularly preferred materials are 10-15 micrometer porous polyethylene from Chromex Corporation FN#38-244-1 (Brooklyn, New York). Another preferred material is Fusion5™ liquid flow matrix material, available from Whatman, Inc., USA, now Global Life Sciences Solutions USA, ALLC of Pittsburgh, Pennsylvania.

[0050] In one form, the porous matrix 2 may have an open-pore structure with an average pore size of 1-250 micrometers, and in a further aspect, the average pore size is about 3-100 micrometers, or about 10 to about 50 micrometers.

[0051] An example of a potentially suitable porous material, which the inventors consider herein and from which matrix insert 12 can be formed and in which omnidirectional flow occurs, is a high-density or ultra-high molecular weight polyethylene material manufactured by Porex Corporation of Fairburn, Georgia. This material is produced by sintering spherical particles of molten ultra-high molecular weight polyethylene (UHMW-PE). This results in a porous structure with an average pore size of 8-20 micrometers, depending on the particle size (20-60 micrometers, respectively).

[0052] While matrix 2 made of polyethylene is suitable, omnidirectional flow materials formed from other olefins or other thermoplastic materials (such as polyvinyl chloride, polyvinyl acetate, copolymers of vinyl acetate and vinyl chloride, polyamide, polycarbonate, polystyrene, etc.) can also be used. Examples of such materials include Magna Nylon Supported Membrane from GE Osmonics, Inc. (Minnetonka, Minnesota), Novylon Nylon Membrane from CUNO Inc., now 3M Purification Inc. (Meriden, Connecticut), and Durapore® Membrane from Millipore Corporation (Billerica, Massachusetts), now Merck KGaA of Darmstadt, Germany.

[0053] Other porous materials suitable for forming the matrix insert 12 include natural, synthetic, or naturally occurring or synthetically modified materials: cellulose materials (e.g., paper, cellulose and cellulose derivatives (e.g., cellulose acetate and nitrocellulose), fiberglass, glass fiber, fabrics (both naturally occurring (e.g., cotton) and synthetic (e.g., nylon)); porous fibrous matrices; starch-based materials, cross-linked dextran chains; ceramic materials; olefins or thermoplastic materials, including those made of polyvinyl chloride, polyethylene, polyvinyl acetate, polyamide, polycarbonate, polystyrene, copolymers of vinyl acetate and vinyl chloride, and combinations of polyvinyl chloride and silica, etc.) in the form of paper (fibers) or membranes (micropores). This list is representative and not intended to be limiting.

[0054] For example, at least some of the porous materials for fluid flow matrices described in U.S. Patent No. 5,726,010 can be used to form the matrix insert 12 of the present invention, and such disclosure is incorporated herein by reference.

[0055] Alternatively, the porous matrix 2 itself can be formed from functionalized particles 50, such as the aforementioned IMAC beads, which are bonded together in a fixed state.

[0056] The particles 50 forming the porous matrix insert 12, whether spherical or of another shape, can be bonded together by sintering and / or pressing or by applying heat. For example, the matrix insert 12 can be formed in a sintering mold; more specifically, the matrix 2 is sintered and / or pressed in an offline form or in a mold, and then inserted or pressed into the lower part 18 of the cup 4.

[0057] Alternatively, the matrix insert 12 can be formed in situ, i.e., within the cup 4, by partially filling the cup 4 with particulate media, and then placing a mold forming the upper contour of the matrix insert 12 downwards on top of the particulate media, pressing the particles into the shape of the insert 12. The cup 4, particulate media, and mold can then be heated to bind the particles to themselves and to the inner sidewall 28 of the cup 4, thereby forming the matrix insert 12 and fixing the insert 12 to the cup 4 in the desired position therein. As mentioned earlier, the spherical or other shaped media particles defining the porous matrix insert can have functionalized nanoparticles, IMAC beads, etc., attached thereto in a fixed state, or the media particles themselves can be functionalized such that the target component of the liquid sample 6 in contact with the matrix insert 12 will directly adhere to the functionalized media particles.

[0058] Another approach envisioned for forming matrix 2 is to use a binder or adhesive instead of pressure and heat to form polymer or copolymer bonds or similar particles. Such a bond-forming method can be combined with a reagent coating method for matrix 2 to incorporate reagents or other functionalized particles 50, thereby forming and binding the particles 50 and immobilizing the functionalized reagents to activate the porous matrix 2.

[0059] In yet another method of forming the matrix insert 12, the original liquid particulate medium (e.g., thermoplastic resin) formed by or carrying the functionalized particles 50 can be injected into a mold and cured inside or outside the mold, resulting in a porous matrix insert 12 having a desired shape and allowing fluid to flow through it.

[0060] In a further method of forming the matrix insert 12, the insert 12 can be formed by cutting a porous raw material medium through which fluids can flow into several parts, said parts being machined to have specific shapes and features, such as a support 34, a channel 48, a central hole 36, and a funnel-shaped inlet port 46 leading to the hole 36, as in Figure 1-6 As shown, it can be adapted to sample cups, reagent cups, mixing cups, or centrifuge cups 4 and conforms to their internal shape. For in Figure 7-12 The cylindrical matrix insert 12 shown can cut raw material media in the form of hollow tubes of a given diameter into segment lengths and can also be machined to provide any desired features, such as enlarged holes, funnel-shaped inlet openings 46 that guide pipette tips 10 toward and through the central hole 36 of insert 12.

[0061] If the matrix insert 12 is formed on the outside of the cup 4, the matrix medium can be coated with the desired reagent or other functionalized particles 50 before the completed insert 12 is inserted into the cup 4, either by spraying a coating onto the matrix medium, or by using a dropper in which the coating of functionalized reagent or particles 50 is drawn into the matrix medium by capillary action, or by being forced into the medium by pneumatic or hydraulic pressure, by immersing the matrix medium in a volume of liquid reagent, and then vacuum drying the functionalized reagent or particles 50 on the matrix medium, or by using an ambient or high-temperature drying method, or by freeze-drying. Many (if not all) of these methods can be used to coat the matrix medium with reagent or functionalized particles 50 in situ (i.e., when the matrix medium is already present in the cup 4).

[0062] According to the present invention, a matrix insert 12 formed of or carrying functionalized particles 50 in a fixed state is used to treat, remove, or at least reduce the concentration of components in a liquid sample 6 in the manner described below, and reference should now be made to the accompanying drawings. Figure 13-16 .

[0063] In one example of using the matrix 2 of the present invention to remove blood components, a predetermined volume (e.g., 20 μL) of whole blood or a blood component (e.g., plasma or serum) is aspirated from a sample cup (not shown) into a disposable tip 10 at the end of a pipette 8, which is adapted to form part of the sample metering device of an automated chemical analyzer. Then, a predetermined volume (e.g., 20 μL) of diluent or buffer solution from another cup (not shown) is aspirated into the pipette tip 10. (Alternatively, the blood sample and diluent or buffer solution may be pre-mixed and aspirated from the sample cup into the pipette tip 10.) As in Figure 13 As shown, the pipette tip 10, containing a blood sample and diluent / buffer solution, is lowered into a mixing cup or reagent cup 4 containing a functionalized matrix insert 12 formed according to the invention, until the tip 10 is fully or at least partially received by a central hole 36 formed in the matrix insert 12, as shown in the diagram. Figure 14 As shown in the diagram. In one form of the invention, the pipette tip 10 forms a seal with the insert 12 at its top surface 38 and the inner sidewall 44 of the defining aperture 36. In another form of the invention, no complete seal is formed between the pipette tip 10 and the matrix insert 12, allowing fluid (e.g., blood samples and diluent / buffer solutions) to flow through the annular space 42 between the pipette tip 10 and the matrix insert 12 to the top surface 38 of the insert 12.

[0064] Now, and as in Figure 15As shown, the pumping action of pipette 8 is reversed to dispense 40 μL of blood sample and diluent / buffer solution from pipette tip 10 to the bottom of cup 4 (i.e., into liquid sample receiving well or chamber 32, if such a receiving well or chamber is provided), such that the blood sample and diluent / buffer solution will come into contact with matrix insert 12. The blood sample and diluent / buffer solution will be drawn into the matrix 2 of insert 12 by capillary action or by the force of hydraulic or pneumatic pressure caused by the pumping action of pipette 8, wherein the blood sample and diluent / buffer solution will be exposed to the functionalized particles 50 carried by or forming the matrix 2 of insert 12.

[0065] It should be noted that the blood and diluent / buffer solution contact the matrix 2 not only at the bottom surface 40 of the insert 12, but also on its side surfaces 26, inner pore walls 44, and top surface 38 as it flows counter-currently upward through the side channels 48 and pore spaces 42 of the insert 12. The blood sample and diluent / buffer solution will flow into and through the porous matrix insert 12, where the target components of the sample (i.e., hemoglobin or some other protein or cell type) will adhere to the immobilized functionalized particles 50 of the matrix 2 and similarly immobilize within the matrix insert 12. It should be further noted that if the blood sample is not premixed with the diluent / buffer solution before being added to the matrix insert 12, the flow of the blood sample and diluent / buffer solution through the matrix 2 will cause mixing of the blood sample and diluent / buffer solution. More specifically, the matrix 2, due to its porosity, simultaneously causes turbulent mixing of the blood sample and diluent / buffer solution and induces a reaction between the blood sample and the functionalized particles 50.

[0066] Now, and as in Figure 16 As shown, with the pipette tip 10 still in the proper position within the orifice 36 of the insert 12, the pumping action of the pipette 8 is reversed, causing a mixture of blood and diluent / buffer solution containing no target component or with a reduced concentration of the target component to be drawn from the matrix 2 of the insert 12, and most likely re-drawn into the tip 10 along with some air or possible air bubbles. Since the preferred diluent / buffer solution contains an antifoaming component that dissipates air bubbles, aspirating air bubbles should not be a problem; furthermore, air helps to mix the blood sample and the diluent / buffer solution together.

[0067] It should be recognized that the matrix 2 of the insert 12 can support or be formed from high concentrations of fixed functionalized particles 50, especially when using functionalized particles in solution, as disclosed in the aforementioned IDEXX patent application, which teaches a method for removing interfering components from a liquid sample. Therefore, by using the matrix 2 of the present invention with fixed functionalized particles 50, most (if not all) of the target components of the liquid sample 6 can be removed in a single pass through the matrix 2. Another advantage of using the functionalized matrix 2 of the present invention is that the time required for the component-adhering particles to settle in the liquid sample 6 by gravity, a step performed in the method disclosed in the aforementioned IDEXX patent application, is not required.

[0068] In any case, if necessary, the blood or liquid sample 6 can be passed through the matrix 2 of the insert 12 several times, by expelling the liquid sample 6 and any air aspirated from the pipette tip 10 to the bottom of the cup 4 and re-aspirating the liquid sample 6 drawn from the matrix insert 12 back into the tip 10, until substantially all the target component is removed from the liquid sample 6 by its adhering to the functionalized particles 50 of the matrix 2. The final aspiration step in this process will remove as much liquid sample 6 as possible from the matrix 2, but it is conceivable, within the scope of the invention, to apply a centripetal force (i.e., centrifugation) to the cup 4 with the insert 12 to help pull the liquid sample 6, which does not contain the target component, out of the gaps in the matrix 2. The “clean” liquid sample 6 can now be placed on a chemical reagent testing slide or a sample holding cuvette for testing by an automated chemical analyzer.

[0069] Therefore, the matrix 2 of the present invention, in the form of insert 12, essentially functions as a filter or bidirectional flow column to remove target components from the liquid sample 6. The matrix 2 itself can be formed from functionalized beads or particles 50, or alternatively, from microbeads used to immobilize functionalized nanobeads. The matrix 2 is porous and allows the liquid sample 6 to flow through it.

[0070] In another form of the invention, the insert 12 may be formed by a stack of annular layers of a matrix impregnated with functionalized particles 50, with the annular holes aligned to define a central hole 36 through the insert 12.

[0071] In yet another embodiment of the invention, the matrix 2 of the insert 12 may be made thicker in the overall region above the liquid sample receiving chamber 32 defined by the support 34, between the bottom of the central hole 36 and the bottom surface 40 of the insert 12. It is believed that with the above configuration, the insert 12 can generate better fluid flow through the matrix 2.

[0072] Although this document primarily describes the placement of insert 12 in a mixing cup 4 used by an automated chemical analyzer, it is contemplated that insert 12 may be placed in a sample cup, reagent cup, centrifuge cup, or any other type of cup or liquid holding container that can be used to remove the target component of liquid sample 6 or reduce its concentration in liquid sample 6, and it should be understood that the term "mixing cup" 4 as used herein and in the claims should be interpreted to include all of the aforementioned cups and containers.

[0073] Although illustrative embodiments of the invention have been described herein with reference to the accompanying drawings, it should be understood that the invention is not limited to these precise embodiments, and various other changes and modifications can be made therein by those skilled in the art without departing from the scope or spirit of the invention.

Claims

1. A method for removing a target component from a liquid sample using an automated chemical analyzer, the automated chemical analyzer comprising a sample cup and a sample metering device having a pipette adapted with a disposable pipette tip and a pump operatively connected to the pipette, the pump being used to aspirate the liquid sample into and from the pipette tip, the method comprising the following steps: A certain volume of the liquid sample contained in the sample cup is aspirated into the tip of the pipette; The pipette tip containing the volume of the liquid sample is positioned above a mixing cup, the mixing cup defining an internal cavity for receiving the liquid sample and having an internal bottom surface, the mixing cup further having an insert mounted within its internal cavity, wherein the insert comprises a porous matrix formed of or carrying functionalized particles in a fixed state, the functionalized particles having properties that cause the target component of the liquid sample to adhere to the functionalized particles, the porous matrix having a predetermined porosity that allows the liquid sample to flow through it, the insert further having a top wall, a bottom wall disposed opposite to the top wall, and one or more side walls extending between the top wall and the bottom wall, the insert having a central hole axially formed therein, the central hole extending through the insert from the top wall to the bottom wall of the insert, wherein the size of the hole is determined to at least partially receive the pipette tip of the sample metering device; The pipette tip is lowered into the mixing cup such that the pipette tip is received at least partially by the central hole of the insert disposed within the mixing cup; The volume of liquid sample is dispensed from the pipette tip into the insert, wherein the liquid sample dispensed from the pipette tip is drawn into the porous matrix of the insert by capillary action, or is forced into the porous matrix by positive hydraulic or pneumatic pressure applied thereto by the pump of the sample metering device, thereby causing the target component of the liquid sample to adhere to the fixed functionalized particles in the porous matrix; and Using the pipette tip at at least a partially receiving position within the central hole of the insert, negative hydraulic or pneumatic pressure is applied to the liquid sample within the porous matrix by the pump of the sample metering device, thereby extracting and aspirating a component-free liquid sample, containing no target component or with a reduced concentration of the target component, from the porous matrix of the insert into the pipette tip for subsequent testing by the automated chemical analyzer.

2. The method as defined in claim 1, further comprising the following steps: The liquid sample that is drawn from the porous matrix of the insert and aspirated into the pipette tip is discharged from the pipette tip into the insert at least a second time, thereby the discharged liquid sample flows into the porous matrix of the insert at least a second time; and Using the pipette tip at at least a partially receiving position within the central hole of the insert, negative hydraulic or pneumatic pressure is applied to the liquid sample within the porous matrix at least a second time by the pump of the sample metering device, thereby drawing the component-free liquid sample, which contains no target component or has a reduced concentration of target component, from the porous matrix of the insert at least a second time and drawing it back into the pipette tip.

3. The method as defined in claim 1, wherein the insert forms one or more liquid flow channels in the one or more sidewalls, wherein the one or more liquid flow channels extend longitudinally along at least a portion of the one or more sidewalls, and wherein the one or more channels are in fluid communication with the porous matrix of the insert; and The step of dispensing the volume of liquid sample from the pipette tip into the insert includes a sub-step of forcing the liquid sample dispensed from the pipette tip into the one or more liquid flow channels.

4. The method as defined in claim 1, wherein the insert is positioned within the internal cavity of the mixing cup such that the bottom wall of the insert is spaced apart from the internal bottom surface of the mixing cup to together define a chamber for receiving the liquid sample; and The step of dispensing the volume of liquid sample from the pipette tip into the insert includes a sub-step of forcing the liquid sample dispensed from the pipette tip into the liquid sample receiving chamber.

5. The method as defined in claim 1, wherein the step of lowering the pipette tip into the mixing cup such that the pipette tip is at least partially received by the central aperture of the insert comprises a sub-step of forming a substantially liquid-tight seal between the pipette tip and the inner wall of the insert defining the central aperture of the insert.

6. The method as defined in claim 1, wherein the size of the central aperture of the insert is determined to provide an annular space between at least a portion of the inner wall of the insert defining the central aperture and at least a portion of the pipette tip, the annular space being in fluid communication with the porous matrix of the insert, when the pipette tip is at least partially received by the central aperture of the insert; and The step of dispensing the volume of liquid sample from the pipette into the insert includes a sub-step of forcing the liquid sample dispensed from the tip of the pipette into the annular space.

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