Matrices used to remove components of liquid samples and associated sample or mixing cups

Abstract

An insert, which is attached to a mixing cup and used by an automated chemical analyzer to remove target components of a liquid sample, includes a porous matrix formed of or bearing immobilized functionalized particles, the functionalized particles having properties such that the target components of the liquid sample adhere to the functionalized particles. When a liquid sample is dispensed into the mixing cup from a disposable tip attached to the end of a pipette forming part of the automated chemical analyzer, the liquid sample is drawn into the matrix of the insert by capillary action, and the target components of the liquid sample adhere to the immobilized functionalized particles of the matrix.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application is related to U.S. Provisional Patent Application No. 62 / 987,077, entitled “Matrix And Associated Sample Or Mixing Cup Used For Removing Components Of A Liquid Sample,” filed March 9, 2020, the disclosure of which is incorporated herein by reference, and priority to which is claimed hereby.

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

[0003] (Technical field) The present invention relates generally to techniques for removing components from liquid samples, and more particularly to methods, devices, and other aids used to remove components such as proteins, hemoglobin, analytes, and other constituents from blood samples. [Background technology]

[0004] The above-referenced U.S. patent application Ser. No. 62 / 986,988 (hereinafter referred to as the "IDEXX patent application") discloses novel methods and apparatus that can be used to remove components of a liquid sample, such as whole blood, diluted blood, plasma, serum (herein generally referred to as a "blood sample"), that may interfere with tests performed or measurements obtained by an automated chemistry analyzer, such as the automated chemistry analyzers manufactured and sold by IDEXX Laboratories, Inc. under the trademarks VetTest®, Catalyst Dx®, and Catalyst One®.

[0005] For example, hemoglobin in a blood sample can affect the accuracy of measurements made for bile acid assays. The above-mentioned IDEXX patent application describes a method using porous and non-porous beads, such as agarose-based and silica-based beads, held in a mixing cup to which a blood sample is added. Hemoglobin in the blood sample attaches to the beads, and the beads with attached hemoglobin settle over time to the bottom of the cup due to gravity. The hemoglobin-free blood sample occupying the top of the cup can now be aspirated by a pipette of a sample metering device forming part of the chemical analyzer and placed on a test slide. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide a matrix having structural features to which target components of a liquid sample can be attached, resulting in a target component-free or target component-reduced sample that can be subsequently added to a test slide or cuvette used in the assay.

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

[0008] It is yet another object of the present invention to provide a matrix / cup combination for use with an automated chemistry analyzer to remove impurities or other undesirable components of a liquid sample, such as a "blood sample" as broadly defined herein, prior to application of the sample onto a dry chemistry reagent test slide.

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

[0010] It is yet a further object of the present invention to provide a matrix that is receivable into or forms part of a sample or mixing cup used by an automated chemical analyzer, that adheres components of a liquid sample added to the cup, and that holds functionalized particles that are removed from the sample prior to testing of the sample.

[0011] It is yet a further object of the present invention to provide a sample cup, mixing cup, reagent cup, or centrifuge cup for use with an automated chemical analyzer that contains a matrix that removes hemoglobin or other components of a "blood sample," as broadly defined herein, that 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 / application technique that removes undesirable components of a liquid sample that may affect tests performed on the liquid sample and measurements derived therefrom.

[0013] It is yet another object of the present invention to provide a pretreated or filtered liquid sample in which the concentration of components of the liquid sample, such as hemoglobin in a blood sample, is minimized or reduced to negligible levels prior to application to a dry chemistry reagent test slide, such as a bile acid assay test slide.

[0014] It is a further object of the present invention to use currently available automated chemical analyzers for analyzing reagent test slides, in conjunction with a specially designed mixing cup formed in accordance with the present invention for use with the analyzer to receive a liquid sample, to condition the liquid sample to reduce concentrations of interfering components that may affect the accuracy of fluorescence or absorbance / reflectance measurements derived from tests performed on the liquid sample.

[0015] It is yet a further object of the present invention to provide a method and apparatus for removing components of a liquid sample using conventional chemical analysis equipment and applying the liquid sample to a conventional, unaltered dry chemistry reagent test slide.

[0016] It is yet another object of the present invention to provide a specialized matrix bearing functionalized particles that can be used to precondition a liquid sample by removing or minimizing the presence of interfering or undesirable components of the liquid sample prior to application of the liquid sample onto a conventional reagent test slide. [Means for solving the problem]

[0017] According to one embodiment of the present invention, a matrix is ​​formed from a porous medium through which fluid can flow. In one embodiment, the matrix holds in an immobilized state functionalized particles that remove components of the fluid flowing through the matrix. For example, the porous matrix immobilizes porous or non-porous agarose-based IMAC (immobilized metal affinity chromatography) beads or silica-based IMAC beads or other functionalized particles to which one or more components of the liquid sample passing through the matrix are attached. Thus, such components are removed from the liquid sample or the concentration of such components in the liquid sample is reduced, resulting in a filtered liquid sample that can be applied to a chemical reagent test slide or sample-holding cuvette of an automated chemical analyzer.

[0018] The matrix may be in the form of an insert or plug forming part of a sample 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 attached to the end of a pipette connected to a pump of a sample metering device forming part of the automated chemical analyzer, and transferred to a mixing cup containing the matrix by the pipette expelling the blood sample from the tip into the cup. The blood sample, drawn into the matrix by capillary action or forced into the matrix under the influence of liquid or air pressure from the pipette and a pump connected to the pipette, flows through the matrix located in the mixing cup one or more times as required.

[0019] The target components of the blood sample, e.g., hemoglobin, have an affinity for the functionalized particles, e.g., the aforementioned IMAC beads, immobilized by the matrix, and are attached to such functionalized particles and removed from the blood sample, or at least reduced in concentration in the blood sample. The filtered blood sample filling the matrix is ​​drawn out of the matrix under negative fluid pressure caused by the reverse pumping action of the pipette, flows out through the matrix at the bottom of the mixing cup, is re-aspirated by the pipette, and, if necessary, is reintroduced into the matrix in the mixing cup multiple times until the target components of the filtered blood sample are completely removed or the desired concentration of the components in the filtered blood sample is achieved.

[0020] These and other objects, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof which is to be considered in connection with the accompanying drawings. [Brief description of the drawings]

[0021] [Figure 1]FIG. 1 is a bottom perspective view of one form of the matrix of the present invention shaped as an insert or plug that can be received in a sample, reagent, or mixing cup and formed of or carrying immobilized functionalized particles that adhere to target components of a liquid sample added to the cup. [Diagram 2] FIG. 2 is a top perspective view of the matrix insert or plug of the present invention shown in FIG. 1. [Diagram 3] FIG. 3 is a top view of the matrix insert or plug of the present invention shown in FIGS. 1 and 2. [Figure 4] FIG. 4 is a bottom view of the matrix insert or plug of the present invention shown in FIGS. 1-3. [Diagram 5] FIG. 5 is a side view of the matrix insert or plug of the present invention shown in FIGS. 1-4. [Figure 6] 6 is a cross-sectional view of the matrix insert or plug of the present invention shown in FIGS. 1-5 taken along line 6-6 of FIG. 5, and a cross-sectional view of a mixing cup receiving the matrix insert or plug. [Figure 7] FIG. 1 is a bottom perspective view of another form of the matrix of the present invention molded as an insert or plug that can be received in a sample cup, reagent cup, or mixing cup and formed with or carrying immobilized functionalized particles that adhere to target components of a liquid sample added to the cup. [Figure 8] FIG. 8 is a top perspective view of the matrix insert or plug of the present invention shown in FIG. 7. [Figure 9] FIG. 9 is a top view of the matrix insert or plug of the present invention shown in FIGS. 7 and 8. [Figure 10] FIG. 10 is a bottom view of the matrix insert or plug of the present invention shown in FIGS. 7-9. [Figure 11] FIG. 11 is a side view of the matrix insert or plug of the present invention shown in FIGS. [Figure 12]12 is a cross-sectional view of the matrix insert or plug of the present invention shown in FIGS. 7-11 taken along line 12-12 of FIG. 11, and a cross-sectional view of a mixing cup receiving the matrix insert or plug. [Figure 13] FIG. 7 is a cross-sectional view of the matrix insert or plug and mixing cup shown in FIG. 6, showing a pipette tip of a sample metering device forming part of an automated chemical analyzer being inserted into the mixing cup to provide a liquid sample. [Figure 14] FIG. 14 is a cross-sectional view of the matrix insert or plug, mixing cup, and pipette tip shown in FIG. 13, showing the pipette tip fully received in the central bore formed axially through the matrix insert or plug, prior to ejection of a liquid sample at the pipette tip from the pipette tip. [Figure 15] FIG. 15 is a cross-sectional view of the matrix insert or plug, mixing cup, and pipette tip in the relative positions shown in FIG. 14, illustrating the flow path of the liquid sample into the matrix insert or plug after ejection from the pipette tip. [Figure 16] FIG. 16 is a cross-sectional view of the matrix insert or plug, mixing cup, and pipette tip in the relative positions shown in FIG. 15, illustrating the flow path of the “clean” liquid sample from the matrix insert or plug as the liquid sample is aspirated back into the pipette tip. Detailed Description of the Invention

[0022] 1-12 show various configurations of matrices 2 in mixing or reagent cups 4 formed in accordance with the present invention that are used together with an automated chemical analyzer to remove or reduce the concentration of a target component in a liquid sample 6 prior to testing the liquid sample 6. As previously mentioned, the liquid sample 6 may be a "blood sample," broadly defined herein as, but not limited to, whole blood, diluted blood, plasma, serum, and the like, and the target component may be a component that may interfere with the tests performed and measurements obtained on the liquid sample 6 in the chemical analyzer, such as, but not limited to, the component hemoglobin in a bile acid assay test performed by the automated chemical analyzer on a blood sample as described in the above-referenced IDEXX patent application, or an antigen, antibody, protein, analyte, or any other component of a blood sample. By way of background, the automated chemical analyzer includes a sample metering device or subassembly having a pipette 8 to which a disposable pipette tip 10 is attached, the pipette 8 being connected to a pump (not shown) to allow for the aspirating or dispensing of the liquid sample 6 into the pipette tip 10.

[0023] In the above-mentioned IDEXX patent application, the target components of the liquid sample are attached to IMAC (immobilized metal affinity chromatography) porous beads suspended in the liquid sample in a mixing cup, and the beads, together with the attached components, settle to the bottom of the cup by gravity. The liquid sample, free of the components occupying the top of the cup, is aspirated by a pipette into the tip of the pipette to apply the sample to a test slide. The method and apparatus disclosed in the present application differ from the method and apparatus described in the above-mentioned application in that the IMAC beads or other functionalized particles are immobilized in matrix 2 and do not go into suspension with the liquid, as will be explained in more detail in the following paragraphs.

[0024] As shown in Figures 1-6, the matrix 2 is preferably formed as an insert or plug 12 shaped to closely match the internal shape of the mixing cup, sample cup, reagent cup, or centrifuge cup 4 that receives the matrix 2. For example, the sample cups, reagent cups, and mixing cups 4 used with the above-mentioned Catalyst Dx® and Catalyst One® instruments sold by IDEXX Laboratories, Inc. have a generally frustoconical shape formed with a generally cylindrical upper portion 14, a tapered middle portion 16, and a generally cylindrical lower portion 18 having a diameter smaller than that of the upper portion 14. Thus, in the embodiment shown in Figures 1-6, the matrix insert or plug 12 (hereinafter, "matrix insert") has a similar generally frustoconical shape, with a generally cylindrical or circular upper portion 20 followed by a tapered middle portion 22 of decreasing diameter, which in turn leads to a generally cylindrical lower portion 24 having a diameter smaller than that of the upper portion 20. The overall exterior dimensions of the matrix insert 12 are selected based on the interior dimensions of the cup 4 that receives the matrix insert 12, such that the matrix insert 12 is snugly received by the cup 4 and conforms to the interior shape of the cup 4 such that a side wall 26 of the matrix insert 12 snugly engages at least a portion of a side wall 28 of the cup 4. Such a configuration ensures that a liquid sample 6 added to the cup 4 contacts the matrix insert 12 located within the cup 4 and is drawn into the matrix 2 by capillary action or by liquid or air pressure caused by the pumping action of the pipette 8, rather than through the outside of the matrix insert 12, as will be described in more detail below.

[0025] Alternatively, as shown in Figures 7-12, the matrix insert 12 can be cylindrically shaped for a sample cup, reagent cup, or mixing cup 4 having a generally cylindrical interior shape. Again, similar to the embodiment shown in Figures 1-6, the dimensions of the cylindrically shaped matrix insert 12 are selected so that its outer sidewall 26 closely engages the inner sidewall 28 of the cup 4 into which it is to be received.

[0026] In any of the embodiments of the matrix insert 12 described above and shown in Figures 1-12, the matrix insert 12 is slightly above the interior bottom surface 30 of the cup 4 receiving the matrix insert 12 and can cooperate with the bottom surface 30 to define a well or chamber 32 of a selected volume for receiving a liquid sample 6 that passes through the matrix insert 12 by the action of gravity or is drawn by suction from the matrix insert 12 by a pipette 8 that forms part of a sample metering subassembly of a chemical analyzer. Additionally, the well or chamber 32 also provides a space for receiving a liquid sample 6 that is dispensed from the pipette tip 10 by the pipette 8, as will also be described in the following paragraphs.

[0027] 1-6, a well or chamber 32 may be formed by one or more standoffs 34 that are a portion of the matrix insert 12 that extend outwardly and downwardly from the lower portion 24 of the matrix insert 12. The standoffs 34 elevate the lower portion 24 of the matrix insert 12 a predetermined distance above the interior bottom surface 30 of the cup 4, defining a chamber or well 32 having a given volume.

[0028] The cylindrical matrix insert 12 shown in Figures 7-12 may also include one or more standoffs 34, as shown in Figures 1-6, to define a chamber or well 32. It should be noted, however, that if the cylindrical matrix insert 12 is used in a cylindrical cup 4 that does not have a flat bottom, but rather has a curved bottom similar to a traditional test tube, the standoffs 34 may not be necessary because the curvature of the bottom of the cup 4 will keep the matrix insert 12 above the bottom and together with the matrix insert 12 define a well or chamber 32 for receiving a liquid sample.

[0029] Alternatively, standoffs 34 are not required in any embodiment of matrix insert 12 where matrix insert 12 is fixed in a predetermined position within cup 4 a given distance away from the inner bottom surface 30 of cup 4 and cooperates with cup 4 to define a well or chamber 32 for receiving a liquid sample.

[0030] Preferably, as shown in Figures 1-12, the matrix insert 12 is formed with a central bore 36 that extends axially through the thickness of the matrix insert 12 from a top surface 38 to a bottom surface 40 of the matrix insert 12. The bore 36 preferably corresponds in shape, length, and diameter to the contour of a disposable tip 10 extending from the end of a pipette 8 and is dimensioned to snugly receive the disposable tip 10. Thus, when the pipette tip 10 is received in the central bore 36 formed in the matrix insert 12, the pipette tip 10 forms a seal with the central bore 36 such that a liquid sample 6 carried by the pipette tip 10 is expelled from the pipette tip 10 into a liquid sample-receiving well or chamber 32 located at the bottom of the cup 4. Additionally, the seal formed between the pipette tip 10 and the matrix insert 12 when the tip 10 is received in the bore 36 of the matrix desirably ensures that there is sufficient reverse liquid or air pressure caused by suction by the pipette 8 to draw the liquid sample 6 from the insert 12 without the components that fill the matrix material of the insert 12. Alternatively, the central bore 36 of the matrix insert 12 may be formed with an oversized inner diameter such that when the pipette tip 10 is received in the bore 32, a space 42 is defined between the pipette tip 10 and an inner wall 44 of the matrix insert 12 that defines the bore 36. This annular space 42 is provided such that as the liquid sample 6 is expelled from the pipette tip 10 to the bottom of the cup 4 in which the matrix insert 12 is located, a portion of the liquid sample 6 will flow up the outer sidewall of the pipette tip 10 within this space 42 and come into contact with the inner wall 44 of the matrix insert 12 that defines the bore 36, where it will be drawn into the matrix 2 by capillary action.

[0031] The bore 36 of the matrix insert 12 may be formed with an inlet opening 46 having a funnel-like shape in the upper surface 38 of the matrix insert 12, as shown in FIGS. 1-12.

[0032] The funnel-shaped entrance opening 46 helps to properly guide the free end of the pipette tip 10 into the bore 36 of the matrix insert 12 .

[0033] As also shown in FIGS. 1-12, the matrix insert 12 may be formed with a channel formed as a longitudinally extending recess in the sidewall 26 of the matrix insert 12, or a plurality of channels 48 periodically spaced from one another around the circumference of the matrix insert 12. The channel 48 fluidly connects to a liquid sample receiving well or chamber 32 located between the matrix insert 12 and the interior bottom surface 30 of the cup 4. As the liquid sample 6 is dispensed from the pipette tip 10 into the well or chamber 32, a portion of the liquid sample 6 flows into the channel 48, is confined therein by the interior sidewall 28 of the cup 4, and is directed to the top 20 of the matrix insert 12 or to the top surface 38 of the matrix insert 12 where it is drawn into the matrix 2 by capillary action. The channel 48 is provided to aid in the distribution of the liquid sample 6 to the top 20 of the matrix insert 12 and the matrix 2 present therein. The channel 48 may extend completely along the longitudinal length of the matrix insert 12 to bring the liquid sample 6 to the top surface 38 of the matrix insert 12 so that the sample 6 is drawn from the top surface 38 of the insert 12 into the matrix 2, or the channel 48 may terminate short of the top surface 38 so that the liquid sample 6 flowing through the channel 48 is drawn into the matrix 2 at the side wall 26 of the insert 12.

[0034] Matrix 2 is formed from a porous material that allows the flow of liquid sample 6, which may be whole blood, diluted blood, plasma, serum, or other form of blood sample, or another type of fluid, through it by capillary action, centrifugation, or the influence of air or liquid pressure. The porous material forming matrix 2 is preferably of wide or finite viscosity, has the ability to readily absorb or "wick up" by capillary action liquid sample 6 carrying particles or particulates of various sizes, such as red or white blood cells, proteins (e.g., hemoglobin), white blood cells, granulocytes, and other types of particles suspended in the liquid, and has a porosity that allows the liquid to traverse the width and length of matrix insert 12 with little or no "clogging." Additionally, the matrix material should be capable of acting 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 applications, and of retaining such functionalized particles 50 in an immobilized state such that the particles 50 are not released when wetted by the liquid sample 6.

[0035] Such matrix materials may include, but are not limited to, fibrous materials composed of synthetic or natural fibers (e.g., glass or cellulosic 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 membrane films composed of nitrocellulose, nylon, polysulfone, and the like (generally synthetic in nature). The porous matrix material may be composed of sintered fine particles of polyethylene, commonly known as porous polyethylene, such as sintered polyethylene beads, preferably such materials have a density of 0.35-0.55 grams per cubic centimeter, a pore size of 5-40 microns, and a void volume of 40-60%. Particulate polyethylene composed of crosslinked or ultra-high molecular weight polyethylene is preferred. Flow flow matrices composed of porous polyethylene have all of the desirable characteristics described above, and furthermore are easily manufactured into a variety of sizes and shapes. A particularly preferred material is 10-15 micron porous polyethylene from Chromex Corporation FN#38-244-1 (Brooklyn, NY). Another preferred material is Fusion 5™ liquid flow matrix material available from Whatman, Inc., now Global Life Sciences Solutions USA LLC, Pittsburgh, PA, USA.

[0036] In one form, the porous matrix 2 can have an open pore structure with an average pore size of from 1 to 250 micrometers, and in further embodiments from about 3 to 100 micrometers, or alternatively from about 10 to about 50 micrometers.

[0037] An example of a possible suitable porous material contemplated by the inventors herein that may form the matrix insert 12 and provide omnidirectional flow is a high density or ultra-high molecular weight polyethylene material manufactured by Porex Corporation of Fairburn, Georgia. This material is fabricated by fusing spherical particles of ultra-high molecular weight polyethylene (UHMW-PE) together by sintering. This produces a porous structure with an average pore size of 8-20 microns depending on the size of the particles (20-60 microns, respectively).

[0038] A polyethylene matrix 2 may be suitably used, although omni-flow materials made of other olefins or other thermoplastic materials, such as polyvinyl chloride, polyvinyl acetate, copolymers of vinyl acetate and vinyl chloride, polyamides, polycarbonates, polystyrene, etc. 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, Darmstadt, Germany.

[0039] Other porous materials that may be suitably used to form the matrix insert 12 include natural, synthetic, or naturally occurring or synthetically modified materials, i.e., papers (fibrous) or membranes (microporous) of cellulosic materials such as paper, cellulose, and cellulose derivatives such as cellulose acetate and nitrocellulose, glass fibers, glass fibres, 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 such as polyvinyl chloride, polyethylene, polyvinyl acetate, polyamides, polycarbonates, polystyrene, copolymers of vinyl acetate and vinyl chloride, and polyvinyl chloride-silica combinations, etc. This list is representative and not intended to be limiting.

[0040] For example, at least some of the porous materials for a fluid-permeable matrix described in US Pat. No. 5,726,010 can be used to form the matrix insert 12 of the present invention, the disclosure of which is incorporated herein by reference.

[0041] Alternatively, the porous matrix 2 may itself be formed of functionalized particles 50, such as the aforementioned IMAC beads, which are bound to one another in an immobilized manner.

[0042] 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 the application of heat. For example, the matrix insert 12 can be formed in a sintering die, or more specifically, the matrix 2 is sintered and / or pressed in an off-line form or mold and then inserted or pressed into the lower portion 18 of the cup 4.

[0043] Alternatively, the matrix insert 12 can be formed in situ, i.e., within the cup 4, by partially filling the cup 4 with particle media, and then a die forming the top contour of the matrix insert 12 is lowered onto the top of the particle media to press the particles into the shape of the insert 12. The cup 4, particle media, and die can then be heated to bond the particles to each other and to the interior sidewall 28 of the cup 4 to form the matrix insert 12 and secure the insert 12 to the cup 4 at a desired location within the cup 4. As previously mentioned, the media particles defining the porous matrix insert, whether spherical or of some other shape, can have functionalized nanoparticles, IMAC beads, etc. attached to them in an immobilized state, or the media particles themselves can be functionalized such that target components of the liquid sample 6 contacting the matrix insert 12 are attached directly to these functionalized media particles.

[0044] Another method contemplated for use in forming the matrix 2 is the use of a binder or adhesive to form polymer or copolymer bonds, etc., of the particles instead of pressure and heat. Such bond forming processes can be combined with a reagent coating process of the matrix 2 to add reagents or other functionalized particles 50 to form and bond the particles 50 and immobilize the functionalized reagents to activate the porous matrix 2.

[0045] In yet another method of forming the matrix insert 12, a raw liquid particle medium, such as a thermoplastic resin formed with or carrying immobilized functionalized particles 50, can be poured into a mold and cured, either in or outside the mold, to provide a porous matrix insert 12 having a desired shape and capable of passing fluid flow therethrough.

[0046] In yet a further method of forming the matrix insert 12, the insert 12 can be formed by cutting raw media stock, which is porous and capable of passing fluid flow, into sections that are machined to have specific shapes and specific features, such as standoffs 34, channels 48, central hole 36, and funnel-shaped inlet port 46 leading to hole 36, as shown in Figures 1-6, to fit into and conform to the internal shape of a sample cup, reagent cup, mixing cup, or centrifuge cup 4. In the case of the cylindrical matrix insert 12 shown in Figures 7-12, raw media stock in the form of a hollow tube of a given diameter can be cut into sections of a predetermined length and again machined to provide any desired features, such as a sunken funnel-shaped inlet opening 46 that guides the pipette tip 10 into and through the central hole 36 of the insert 12.

[0047] If the matrix insert 12 is formed outside of the cup 4, the matrix medium can be coated with the desired reagent or other functionalized particles 50 prior to inserting the completed insert 12 into the cup 4 by spraying the coating onto the matrix medium or using a dropper, the coating of functionalized reagent or particles 50 being drawn into the matrix medium by capillary action or forced into the medium by air or liquid pressure, immersion of the matrix medium in the liquid reagent, and the functionalized reagent or particles 50 on the matrix medium is then vacuum dried or dried using an ambient or elevated temperature drying process, or by freeze drying. Many, if not all, of these processes can be used to coat the matrix medium with the reagent or functionalized particles 50 in situ, i.e., when the matrix medium is already present within the cup 4.

[0048] Matrix inserts 12 formed in accordance with the present invention from functionalized particles 50 or carrying functionalized particles 50 in an immobilized state are used to treat, remove or at least reduce the concentration of components of a liquid sample 6 in a manner described below, reference should now be made to Figures 13-16 of the drawings.

[0049] In one example of using matrix 2 of the present invention to remove blood components, a predetermined volume (e.g., 20 microliters) 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 attached to the end of a pipette 8 that forms part of the sample metering device of an automated chemical analyzer. A predetermined volume (e.g., 20 microliters) of diluent or buffer is then aspirated from a separate cup (not shown) into the pipette tip 10 (alternatively, the blood sample and diluent or buffer may be premixed and aspirated from the sample cup into the pipette tip 10).

[0050] As shown in Figure 13, a pipette tip 10 containing a blood sample and diluent / buffer is lowered into a mixing or reagent cup 4 containing a functionalized matrix insert 12 formed in accordance with the present 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 Figure 14. In one form of the invention, the pipette tip 10 forms a seal with the insert 12 at the top surface 38 and the inner sidewall 44 that defines the hole 36. In another form of the invention, a complete seal is not formed between the pipette tip 10 and the matrix insert 12, such that fluid (e.g., blood sample and diluent / buffer) can 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.

[0051] 15, the pumping action of pipette 8 is reversed and 40 microliters of blood sample and diluent / buffer are expelled from pipette tip 10 into the bottom of cup 4 (i.e., into a well or chamber 32 for receiving a liquid sample, if such well or chamber is provided) where the blood sample and diluent / buffer contact matrix insert 12. The blood sample and diluent / buffer are drawn into matrix 2 of insert 12 by capillary action or the force of liquid or air pressure caused by the pumping action of pipette 8, and the blood sample and diluent / buffer are carried by or exposed to functionalized particles 50 forming matrix 2 of insert 12.

[0052] It is noted that the blood and diluent / buffer not only contact matrix 2 at the bottom surface 40 of insert 12, but also at its sides 26, inner pore walls 44, and top surface 38 as they flow back up the side channels 48 and pore spaces 42 of insert 12. The blood sample and diluent / buffer flow into and through porous matrix insert 12, and the target components of the sample, be they hemoglobin or some other protein or cell type, attach to the immobilized functionalized particles 50 of matrix 2 and are also immobilized within the confines of matrix insert 12. It is further noted that if the blood sample is not premixed with the diluent / buffer before being added to matrix insert 12, mixing of the blood sample and diluent / buffer will occur as the blood sample and diluent / buffer flow into and through matrix 2. More specifically, the matrix 2 , due to its porosity, induces turbulent mixing of the blood sample with the diluent / buffer while also inducing reaction of the blood sample with the functionalized particles 50 .

[0053] 16, with the pipette tip 10 still in place within the bore 36 of the insert 12, the pumping action of the pipette 8 is reversed, so that a mixed blood and diluent / buffer solution without or with a reduced concentration of the target component is drawn out of the matrix 2 of the insert 12 and aspirated back into the tip 10, possibly with some air and possibly air bubbles. Aspiration of air bubbles is not an issue since preferred diluents / buffers contain anti-foam components that dissipate bubbles, and furthermore the air helps the blood sample and diluent / buffer mix with each other.

[0054] It should be appreciated that the matrix 2 of the insert 12 can carry or be formed with a high concentration of immobilized functionalized particles 50, particularly when using functionalized particles in solution as disclosed in the aforementioned IDEXX patent application teaching a method for removing interfering components of a liquid sample. Thus, by using the matrix 2 of the present invention having immobilized functionalized particles 50, it is possible to remove most or all of the target components of the liquid sample 6 by passing the liquid sample 6 through the matrix 2 only once. Another advantage of using the functionalized matrix 2 of the present invention is that it is not necessary to allow the particles with attached components to settle by gravity within the liquid sample 6, a step performed in the method disclosed in the aforementioned IDEXX patent application.

[0055] In any event, the blood or liquid sample 6 can be passed as many times as necessary through the matrix 2 of the insert 12 by successively expelling the liquid sample 6 and aspirated air from the pipette tip 10 into the bottom of the cup 4 and re-aspirating the liquid sample 6 withdrawn from the matrix insert 12 into the tip 10 until substantially all of the target components have been removed from the liquid sample 6 by adhering to the functionalized particles 50 of the matrix 2. The final aspirating step in this process withdraws as much of the liquid sample 6 as possible from the matrix 2, although it is considered within the scope of the invention to apply a centripetal force (i.e., centrifugation) to the cup 4 with the insert 12 to aid in withdrawing the target component-free liquid sample 6 from the interstices of the matrix 2. The now "clean" liquid sample 6 can be brought onto a chemical reagent test slide or sample holding cuvette for testing by an automated chemical analyzer.

[0056] Thus, the matrix 2 of the present invention, in the form of the insert 12 , essentially acts as a filter or bidirectional flow column to remove target components of the liquid sample 6 .

[0057] The matrix 2 may itself be formed of functionalized beads or particles 50, or in the alternative may be formed from microbeads that are used to immobilize functionalized nanobeads. The matrix 2 is porous, allowing the liquid sample 6 to flow through it.

[0058] In another form of the invention, the insert 12 may be formed from a stack of donut-shaped layers of matrix impregnated with functionalized particles 50, the holes of the donut being aligned to define a central hole 36 through the insert 12.

[0059] In yet another aspect of the invention, the matrix 2 of the insert 12 can be made thicker in the general area between the bottom of the central hole 36 and the bottom surface 40 of the insert 12 above the liquid sample receiving chamber 32 defined by the standoffs 34. It is believed that the above-described structure enables the insert 12 to generate better fluid flow through the matrix 2.

[0060] Although the insert 12 has been primarily described herein as being placed in a mixing cup 4 used by an automated chemical analyzer, it should be understood that the insert 12 may also 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 a target component from a liquid sample 6 or reduce the concentration of a target component in a liquid sample 6, and the term "mixing cup" 4 as used herein and in the claims should be interpreted to include any of the cups and containers described above.

[0061] Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and various other changes and modifications can be made by those skilled in the art without departing from the scope or spirit of the invention.

Claims

1. 1. An insert for use by an automated chemical analyzer for removing a target component from a liquid sample, the automated chemical analyzer including a sample metering device having a pipette with a disposable pipette tip attached thereto, and a pump operatively connected to the pipette for aspirating the liquid sample into the pipette tip and expelling the liquid sample from the pipette tip, the insert comprising: a porous matrix formed of or carrying immobilized functionalized particles having properties such that the target components of the liquid sample adhere to the matrix, the porous matrix having a predetermined porosity that allows the liquid sample to flow therethrough; Equipped with the insert has one or more side walls, a top wall, and a bottom wall opposite the top wall, the one or more side walls extending between the top wall and the bottom wall; one or more liquid flow channels formed in the one or more sidewalls of the insert, the one or more liquid flow channels extending longitudinally along at least a portion of the one or more sidewalls, the one or more channels fluidly connecting to the matrix of the insert; as the liquid sample is expelled from the pipette tip, the liquid sample is drawn into the matrix of the insert by capillary action or forced into the matrix by positive liquid or air pressure exerted by the pump of the sample metering device, whereupon the target components of the liquid sample attach to the immobilized functionalized particles of the matrix; Under negative liquid or air pressure exerted on the liquid sample within the matrix by the pump of the sample metering device, a liquid sample that does not contain the target component or has a reduced concentration of the target component is drawn from the matrix of the insert and aspirated into the pipette tip for subsequent testing by the automated chemical analysis device.

2. An insert as described in claim 1, wherein a central hole is formed axially in the insert, the central hole passing through the insert from the top wall to the bottom wall, and the central hole is dimensioned to at least partially receive the pipette tip of the sample metering device.

3. The insert of claim 2 , wherein the top wall of the insert defines a funnel-shaped inlet port, the funnel-shaped inlet port being aligned with and fluidly connected to the central bore.

4. An insert as described in claim 1, wherein the insert includes at least one standoff extending outwardly from the bottom wall of the insert a predetermined distance, and wherein the at least one standoff serves to define a chamber between the bottom wall of the insert and the mixing cup for receiving the liquid sample when the insert is received in the mixing cup.

5. The insert described in claim 1, wherein the insert is formed with a shape generally similar to that of a truncated cone, the insert including a generally circular upper portion having a first diameter and located at or near the top wall, a tapered intermediate portion extending from the upper portion and decreasing in diameter, and a generally cylindrical lower portion extending from the intermediate portion and located at or near the bottom wall, the lower portion having a second diameter smaller than the first diameter of the upper portion.

6. The insert described in claim 1, wherein the insert is formed to have a generally cylindrical shape.

7. the mixing cup defines an interior cavity for receiving the liquid sample and includes an interior bottom surface; 2. The insert of claim 1, wherein the insert is received in the mixing cup and positioned within the internal cavity of the mixing cup such that the bottom wall of the insert is positioned away from the internal bottom surface of the mixing cup to cooperate with the internal bottom surface of the mixing cup to define a chamber for receiving the liquid sample.

8. The insert of claim 1 , wherein the matrix of the insert is formed of a medium that holds the functionalized particles in an immobilized state.

9. The insert of claim 8 , wherein the functionalized particles are immobilized metal affinity chromatography (IMAC) beads.

10. 10. The insert of claim 9, wherein the IMAC beads are at least one of agarose-based beads and silica-based beads.

11. The insert of claim 8 , wherein the functionalized particles are nanobeads.

12. The insert of claim 1 , wherein the matrix of the insert is formed of the functionalized particles.

13. The insert of claim 12 , wherein the functionalized particles are immobilized metal affinity chromatography (IMAC) beads.

14. The insert of claim 13 , wherein the IMAC beads are at least one of agarose-based beads and silica-based beads.

15. The insert of claim 12 , wherein the functionalized particles are nanobeads.

16. The insert of claim 1 , wherein the matrix is ​​formed from a fiberglass-based material with a plastic binder.

17. 10. The insert of claim 1, wherein the matrix is ​​formed from a porous material selected from the group consisting of natural, synthetic, or naturally occurring or synthetically modified materials, fibrous materials, paper, cellulose and cellulose derivatives such as cellulose acetate and nitrocellulose, membranes of cellulosic materials including fiberglass, glass fiber, natural fabrics such as cotton and synthetic fabrics such as nylon, porous gels such as silica gel, agarose, dextran, and gelatin, porous fibrous matrices, starch-based materials, cross-linked dextran chains, ceramic materials, olefins and thermoplastic materials including films of polyvinyl chloride, polyethylene, polyvinyl acetate, polyamides, polycarbonates, polystyrene, copolymers of vinyl acetate and vinyl chloride, and polyvinyl chloride-silica combinations.

18. 10. The insert of claim 1, wherein the matrix is ​​selected from the group of materials consisting of sintered polyethylene beads, nitrocellulose, fiberglass, and paper.

19. a mixing cup defining an interior cavity for receiving a liquid sample; an insert mounted within the interior cavity of the mixing cup; A combination of the mixing cup and the insert are used by an automated chemical analyzer to remove a target component from the liquid sample received in the mixing cup, the automated chemical analyzer including a sample metering device having a pipette with a disposable pipette tip attached thereto and a pump for aspirating the liquid sample into the pipette tip and expelling the liquid sample from the pipette tip; the insert is formed of functionalized particles having properties such that the target components of the liquid sample adhere to it, or comprises a porous matrix carrying the functionalized particles in an immobilized state, the porous matrix having a predetermined porosity that allows the liquid sample to flow therethrough; the insert has one or more side walls, a top wall, and a bottom wall opposite the top wall, the one or more side walls extending between the top wall and the bottom wall; the mixing cup includes an interior bottom surface; the insert includes at least one standoff, the at least one standoff extending a predetermined distance outwardly from the bottom wall of the insert to engage the inner bottom surface of the mixing cup, the at least one standoff serving to define a chamber between the bottom wall of the insert and the inner bottom surface of the mixing cup for receiving the liquid sample; as the liquid sample is expelled from the pipette tip, the liquid sample is drawn into the matrix of the insert by capillary action or forced into the matrix by positive liquid or air pressure exerted by the pump of the sample metering device, whereupon the target components of the liquid sample attach to the immobilized functionalized particles of the matrix; Under negative liquid or air pressure exerted on the liquid sample within the matrix by the pump of the sample metering device, a liquid sample free of the target component or with a reduced concentration of the target component is drawn from the matrix of the insert and aspirated into the pipette tip for subsequent testing by the automated chemical analyzer.

20. The combination described in claim 19, wherein one or more liquid flow channels are formed in the one or more side walls of the insert, the one or more liquid flow channels extending longitudinally along at least a portion of the one or more side walls, and the one or more channels are fluidly connected to the matrix of the insert.

21. The combination described in claim 19, wherein a central hole is formed axially in the insert, the central hole passing through the insert from the top wall to the bottom wall, and the central hole is dimensioned to at least partially receive the pipette tip of the sample metering device.

22. 22. The combination of claim 21, wherein said top wall of said insert defines a funnel-shaped inlet port, said funnel-shaped inlet port aligned with and communicating with said central aperture.

23. The combination of claim 19, wherein the insert is formed with a generally frustum shape, the insert including a generally circular upper portion having a first diameter and located at or near the top wall, a tapered intermediate portion extending from the upper portion and decreasing in diameter, and a generally cylindrical lower portion extending from the intermediate portion and located at or near the bottom wall, the lower portion having a second diameter smaller than the first diameter of the upper portion.

24. The combination described in claim 19, wherein the insert is formed to have a generally cylindrical shape.

25. 20. The combination of claim 19, wherein the matrix of the insert is formed of a medium that holds the functionalized particles in an immobilized state.

26. 26. The combination of claim 25, wherein the functionalized particles are immobilized metal affinity chromatography (IMAC) beads.

27. 27. The combination of claim 26, wherein the IMAC beads are at least one of agarose-based beads and silica-based beads.

28. 26. The combination of claim 25, wherein the functionalized particles are nanobeads.

29. The combination of claim 19 , wherein the matrix of the insert is formed of the functionalized particles.

30. 30. The combination of claim 29, wherein the functionalized particles are immobilized metal affinity chromatography (IMAC) beads.

31. 31. The combination of claim 30, wherein the IMAC beads are at least one of agarose-based beads and silica-based beads.

32. 30. The combination of claim 29, wherein the functionalized particles are nanobeads.

33. 20. The combination of claim 19, wherein the matrix is ​​formed from a fiberglass-based material with a plastic binder.

34. 20. The combination of claim 19, wherein the matrix is ​​formed from a porous material selected from the group consisting of natural, synthetic, or naturally occurring or synthetically modified materials, fibrous materials, paper, cellulose and cellulose derivatives such as cellulose acetate and nitrocellulose, membranes of cellulosic materials including fiberglass, glass fibre, natural fabrics such as cotton and synthetic fabrics such as nylon, porous gels such as silica gel, agarose, dextran, and gelatin, porous fibrous matrices, starch-based materials, cross-linked dextran chains, ceramic materials, olefins and thermoplastic materials including films of polyvinyl chloride, polyethylene, polyvinyl acetate, polyamides, polycarbonates, polystyrene, copolymers of vinyl acetate and vinyl chloride, and polyvinyl chloride-silica combinations.

35. 20. The combination of claim 19, wherein the matrix is ​​selected from the group of materials consisting of sintered polyethylene beads, nitrocellulose, fiberglass, and paper.

36. 1. A method for removing a target component from a liquid sample using an automated chemical analyzer, the automated chemical analyzer including a sample cup and a sample metering device having a pipette with a disposable pipette tip attached thereto, and a pump operatively connected to the pipette for aspirating the liquid sample into the pipette tip and expelling the liquid sample from the pipette tip, the method comprising: aspirating the liquid sample contained in the sample cup into the pipette tip; positioning the pipette tip containing the liquid sample over 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 comprising an insert mounted within the internal cavity, the insert being formed of functionalized particles having properties such that the target components of the liquid sample adhere to them or comprising a porous matrix carrying the functionalized particles in an immobilized state, the porous matrix having a predetermined porosity that allows the liquid sample to flow through the porous matrix, the insert further comprising one or more side walls, a top wall and a bottom wall opposite the top wall, the one or more side walls extending between the top wall and the bottom wall, a central hole formed axially in the insert, the central hole passing through the insert from the top wall to the bottom wall of the insert, the central hole being dimensioned to at least partially receive the pipette tip of the sample metering device; lowering the pipette tip into the mixing cup such that the pipette tip is at least partially received in the central bore of the insert disposed within the mixing cup; Dispensing the liquid sample from the pipette tip into the insert, where the liquid sample dispensed from the pipette tip is drawn into the matrix of the insert by capillary action or forced into the matrix by positive liquid or air pressure exerted by the pump of the sample metering device, whereupon the target components of the liquid sample attach to the immobilized functionalized particles of the matrix; applying a negative liquid or air pressure to the liquid sample in the matrix by the pump of the sample metering device with the pipette tip in the at least partially received position within the central bore of the insert to draw a liquid sample free of the target component or having a reduced concentration of the target component from the matrix of the insert and aspirate it into the pipette tip for subsequent testing by the automated chemical analyzer; The method includes:

37. dispensing the liquid sample drawn from the matrix of the insert from the tip of the pipette into the insert at least a second time and aspirating the dispensed liquid sample into the matrix of the insert at least a second time; using the pipette tip in the at least partially received position within the central bore of the insert to apply a negative liquid or air pressure to the liquid sample within the matrix with the pump of the sample metering device at least a second time to draw a liquid sample that is free of the target component or has a reduced concentration of the target component from the matrix of the insert and re-aspirate it into the pipette tip; 37. The method of claim 36, further comprising:

38. one or more liquid flow channels formed in the one or more sidewalls of the insert, the one or more liquid flow channels extending longitudinally along at least a portion of the one or more sidewalls, the one or more channels fluidly connecting to the matrix of the insert; 37. The method of claim 36, wherein ejecting the liquid sample from the pipette tip into the insert comprises the substep of forcing the liquid sample ejected from the pipette tip into the one or more liquid flow channels.

39. the insert is disposed within the interior cavity of the mixing cup such that the bottom wall of the insert is spaced from the interior bottom surface of the mixing cup to cooperate with the interior bottom surface of the mixing cup to define a chamber for receiving the liquid sample; 37. The method of claim 36, wherein the step of expelling the liquid sample from the pipette tip into the insert comprises the substep of forcing the liquid sample expelled from the pipette tip into a chamber that receives the liquid sample.

40. The central hole is defined by an inner wall of the insert, 37. The method of claim 36, wherein lowering the pipette tip into the mixing cup such that the pipette tip is at least partially received in the central bore of the insert includes the substep of forming a substantially liquid-tight seal between the pipette tip and the interior wall of the insert that defines the central bore.

41. The central hole is defined by an inner wall of the insert and is dimensioned to provide an annular space between at least a portion of the inner wall of the insert defining the central hole and at least a portion of the pipette tip when the pipette tip is at least partially received in the central hole of the insert, the annular space being fluidly connected to the matrix of the insert; 37. The method of claim 36, wherein expelling the liquid sample from the pipette into the insert comprises the substep of forcing the liquid sample expelled from the pipette tip into the annular space.

42. The insert of claim 1, wherein the insert has a hole formed therein, the hole being dimensioned to at least partially receive the pipette tip of the sample metering device.

43. An insert as described in claim 42, wherein a funnel-shaped inlet port is formed in the upper wall of the insert, the funnel-shaped inlet port being aligned with and fluidly connected to the hole.

44. The combination described in claim 19, wherein the insert has a hole formed therein, the hole being dimensioned to at least partially receive the pipette tip of the sample metering device.

45. The combination described in claim 44, wherein a funnel-shaped inlet port is formed in the upper wall of the insert, the funnel-shaped inlet port being aligned with and fluidly connected to the hole.

46. ​​A method for removing a target component from a liquid sample using an automated chemical analyzer, the automated chemical analyzer including a sample cup and a sample metering device having a pipette having a disposable pipette tip attached thereto, and a pump operatively connected to the pipette for aspirating the liquid sample into the pipette tip and expelling the liquid sample from the pipette tip, the method comprising: aspirating the liquid sample contained in the sample cup into the pipette tip; positioning the pipette tip containing the liquid sample over 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 comprising an insert mounted within the internal cavity, the insert being formed of functionalized particles having properties such that the target components of the liquid sample adhere to them or comprising a porous matrix carrying the functionalized particles in an immobilized state, the porous matrix having a predetermined porosity that allows the liquid sample to flow through the porous matrix, the insert further comprising one or more side walls, a top wall and a bottom wall opposite the top wall, the one or more side walls extending between the top wall and the bottom wall, a hole formed in the insert, the hole being sized to at least partially receive the pipette tip of the sample metering device; lowering the pipette tip into the mixing cup such that the pipette tip is at least partially received in the hole of the insert disposed within the mixing cup; Dispensing the liquid sample from the pipette tip into the insert, where the liquid sample dispensed from the pipette tip is drawn into the matrix of the insert by capillary action or forced into the matrix by positive liquid or air pressure exerted by the pump of the sample metering device, whereupon the target components of the liquid sample attach to the immobilized functionalized particles of the matrix; applying a negative liquid or air pressure to the liquid sample in the matrix by the pump of the sample metering device with the pipette tip in the at least partially received position within the bore of the insert to draw a liquid sample free of the target component or having a reduced concentration of the target component from the matrix of the insert and aspirate it into the pipette tip for subsequent testing by the automated chemical analyzer; The method includes:

47. A step of discharging the liquid sample drawn from the matrix of the insert from the tip of the pipette into the insert at least a second time and then aspirating the discharged liquid sample into the matrix of the insert at least a second time; using the pipette tip in the at least partially received position within the bore of the insert to draw a liquid sample free of the target component or having a reduced concentration of the target component from the matrix of the insert and re-aspirate it into the pipette tip at least a second time by applying a negative liquid or air pressure to the liquid sample in the matrix with the pump of the sample metering device at least a second time; 47. The method of claim 46, further comprising:

48. The hole is defined by an inner wall of the insert, 47. The method of claim 46, wherein lowering the pipette tip into the mixing cup such that the pipette tip is at least partially received in the hole of the insert includes the substep of forming a substantially liquid-tight seal between the pipette tip and the interior wall of the insert that defines the hole.

49. The hole is defined by an inner wall of the insert and is dimensioned to provide an annular space between at least a portion of the inner wall of the insert defining the hole and at least a portion of the pipette tip when the pipette tip is at least partially received in the hole of the insert, the annular space being fluidly connected to the matrix of the insert; 47. The method of claim 46, wherein the step of expelling the liquid sample from the pipette into the insert comprises the substep of forcing the liquid sample expelled from the pipette tip into the annular space.

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