WO2011137172A1

WO2011137172A1 - Method of forming a reagent card

Info

Publication number: WO2011137172A1
Application number: PCT/US2011/034146
Authority: WO
Inventors: James A. Profitt; Michael J. Pugia; Kenneth Galano
Original assignee: Siemens Healthcare Diagnostics Inc.
Priority date: 2010-04-29
Filing date: 2011-04-27
Publication date: 2011-11-03

Abstract

A method of forming a reagent card includes applying a reagent containing sheet of material to a substrate. The reagent containing sheet of material is cut to define a plurality of spaced apart reagent containing areas and a waste matrix extending about the reagent containing areas. The waste matrix is separated from the substrate such that the reagent containing areas remain on the substrate so as to define a plurality of spaced apart reagent pads.

Description

METHOD OF FORMING A REAGENT CARD

BACKGROUND OF THE PRESENTLY DISCLOSED AND/OR CLAIMED INVENTIVE CONCEPTS

1 . Field of the Presently Disclosed and/or Claimed Inventive Concepts.

[0001 ] The inventive concepts disclosed and claimed herein relate to reagent cards for conducting immunochemical, diagnostic or serological tests, and more particularly, but not by way of limitation, to a method of forming reagent cards.

2. Brief Description of Related Art.

[0002] Many instruments have been developed to measure the quantity of analytes in various biological samples, for example urine, blood, salvia, or extracts of mucus or tissue. Typically, a sample liquid is applied to a reagent that reacts with the analyte. The reagent produces a detectable response that is measured and related to the amount of the analyte. Both dry and wet reagents are employed in chemical analysis. Dry reagents are generally chemicals and biochemicals deposited into an absorbent paper using a solvent. After the solvent dries, the chemical remains impregnated on and/or within the paper.

[0003] To allow multiple tests of analytes to be conducted in an automated process, substrates have been used to support multiple reagents. The reagent areas are typically secured to a plastic substrate with the reagent areas spaced from one another so as to prevent cross contamination. The plastic substrate may be formed in the shape of a strip where the substrate supports one row of reagent areas, or the plastic substrate may be in the shape of a card where the substrate supports multiple rows of reagent areas. [0004] One process for manufacturing reagent cards involves adhering reagent ribbons to a plastic carrier sheet. Lateral cuts are then made through the ribbons and the carrier sheet to form separate strips containing multiple reagents. These strips are then secured to a second plastic carrier in a spaced relationship. The securing of the strips to the second carrier can be expensive because the adhesive used to secure the reagent ribbons to the first carrier sheet has a tendency to clog punch and place mechanisms which are needed for high speed manufacturing.

[0005] Due to heat generated by a punch, adhesive tends to migrate from the strips to the punch. Once the strips are separated, the strips must be held in position until they can be bonded to the second strip carrier. If the strips are held in the punch, the ability to make a bond is limited. Heat cannot be generated and additional adhesives cannot be applied inside the punch. The time during which the strips are held in the punch is short, thereby also making the step of bonding the strips to the second carrier difficult. Separation of the punch area from the bonding area is an approach to prevent adhesive clogs. While such methods can be effective, they are slower than high speed, web based processes.

[0006] To this end, a need exists for an improved method of forming reagent cards which is amenable to automated, high speed manufacturing processes. It is to such a method that the inventive concepts disclosed and claimed herein are directed. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a top plan view of a reagent card constructed in accordance with the inventive concepts disclosed and claimed herein.

[0008] FIG. 1 A is a fragmented, perspective view of a portion of the reagent card of FIG. 1 .

[0009] FIG. 2 is a perspective view of a reagent ribbon.

[0010] FIG. 2A is a cross sectional view taken along line 2A-2A of FIG. 2

[0011 ] FIG. 3 is fragmented, top plan view of an absorbent sheet of material with a plurality of reagent areas.

[0012] FIG. 3A is a cross sectional view taken along line 3A-3A of FIG. 3.

[0013] FIG. 4 is a schematic representation of a reagent card forming apparatus constructed in accordance with the present invention.

[0014] FIG. 5 is a side elevational view of a rotary cutting die.

[0015] FIG. 5A is a cross sectional view taken along line 5A-5A of FIG. 5.

[0016] FIG. 6 is a sectional view showing the cutting die having penetrated the absorbent sheet of material at the perimeter of a reagent area.

[0017] FIG. 6A is a sectional view showing the cutting die having penetrated the absorbent sheet of material a distance outward from the perimeter of the reagent area.

[0018] FIG. 7 is a fragmented perspective view showing a waste matrix being removed from a substrate. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0019] Before explaining at least one embodiment of the presently disclosed and claimed inventive concept(s) in detail, it is to be understood that the presently disclosed and claimed inventive concept(s) is not limited in its application to the details of construction, experiments, exemplary data, and/or the arrangement of the components set forth in the following description or illustrated in the drawings. The presently disclosed and claimed inventive concept(s) is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for purpose of description and should not be regarded as limiting.

[0020] Referring now to the drawings, FIGS. 1 and 1 A illustrate a reagent card 10 including a substrate 1 2 with a plurality of reagent pads 14 secured thereto. The reagent card 10 is used in automated equipment because a card can quickly and conveniently be presented for running multiple tests. Due to its configuration, the reagent card 10 can be pre-loaded into a canister or other holding device and fed automatically into an automated photometric apparatus for determining reflectance characteristics of the reagent pads 14. If desired, the reagent card 10 may incorporate suitable indexing features, such as punched holes (not shown) in its edges to facilitate the alignment, presentation, and sequencing of the reagent card 10 through automated instrumentation. Once the reagent card 10 is aligned in the equipment, the reagent card 10 permits simultaneous or sequential analysis of analyte at all or a portion of the reagent pads 14 present on the reagent card 10.

[0021 ] The substrate 12 can be formed of any suitable material which is rigid or semi-rigid and which is non-reactive with the reagents present in the reagent pads 12 and the sample to be tested. The thickness of the substrate may vary, but preferably is in a range of from about .005 inches to about .012 inches. In addition, it is preferred that the substrate 12 have hydrophobic properties and lay flat after processing. The substrate 1 2 may be formed of a single layer of material or multiple layers of material, the substrate 12 may be molded or embossed cartridges which may be in the form of micro-fluidic devices. Examples of suitable materials for use in forming the substrate 12 include polyethylene terephthalate, polysytrene, polyester, polyethylene polypropylene, nylon, polyvinylidene chloride, polyvinyl chloride, multi-resin, and ethylene vinyl alcohol.

[0022] In the embodiment illustrated in FIG. 1 , the substrate 1 2 is formed to have a rectangular shape and is sized to have the dimensions of about 3.8 inches by about 5.0 inches. However, the size and the shape of the substrate may be varied, as desired. For example, the substrate 12 may be formed in the shape of a narrow strip where the substrate 12 supports only one row of reagent pads 14.

[0023] The reagent pads 14 are formed of an absorbent sheet material incorporated with a selected reagent. The reagent pads 14 are shown to be circular in shape. However, it will be appreciated that the shape, as well as the size, of the reagent pads 14 may be varied. That is, the reagent pads 14 may be formed to have any geometric, non-geometric, asymmetrical, or fanciful design. For example, the reagent pads 14 may include any geometric form, for example, squares, triangles, rectangles, octagons, and rings, or other shapes, such as stars, hearts, slogans, logos, and/or any series of letters and/or numbers, and the like (not shown).

[0024] The absorbent sheet material used to form the reagent pads 14 is capable of rapidly absorbing water at greater than 10 mg/cm² and more preferably in a range of from about 20 mg/cm² to about 65 mg/cm². The thickness of the absorbent material may be varied, but preferably is in a range from about 50 micrometers to about 1000 micrometers with the mean pore sis varying from about 2 micrometers to about 50 micrometers. The absorbent sheet material can be a variety of porous, non-woven materials comprised of polymer fibers, such as cellulose (cotton, wood, notrocellulose, rayon, and the like), proteins, glass, polyamide (nylon), polyurethanes, polyethers (polyethene such as TYVEK®, polypropylenes), acrylic fibers, polyolefin (teslin), polyurethan (MAKROFOL®), aromatic polyamides, and polyesters. These materials can be treated with surfactant (e.g., anionic, non-anionic, cationic, and zwitterions types) and binders (e.g., kymene, polyvinyl alcohol, and latex).

[0025] Referring to FIGS. 2 and 2A, a reagent is incorporated into the absorbent sheet material using methods well known in the prior art. For example, reagent may be incorporated into the absorbent sheet material by drawing a web or strip of the absorbent material 15 through a solution or suspension of a selected reagent, together with an appropriate solvent, such as water, methanol, benzene, or cyclohexane. After drying, the web or strip of absorbent material 15 is in the form of a reagent containing strip or ribbon 16 (FIGS. 2 and 2A). The reagent containing ribbon 1 6 may be provided with an adhesive layer 18 so that the reagent containing ribbon 16 is ready to be applied to the substrate 12. Any suitable adhesive may be used, such as an adhesive coating or a double-faced adhesive tape known as DOUBLE STICK®, available from the 3M Company. Typically, a release liner 20 is applied to the adhesive to protect the adhesive until it is desired to apply the reagent containing ribbon 16 to the substrate 12.

[0026] Alternatively, with reference to FIGS. 3 and 3A, a reagent containing material 22 may be formed by injecting an absorbent sheet material 24 (FIG. 3) with a solution of a reagent and an appropriate solvent, such as water, methanol, benzene, or cyclohexane, so as to incorporate the reagent into the absorbent sheet material 24 at selected locations to define reagent containing areas 26 while leaving other areas of the web of absorbent sheet material 24 untreated. After drying, the reagent containing material 22 may be provided with an adhesive layer 28 so that the reagent containing material 22 is ready to be applied to the substrate 12. Any suitable adhesive may be used, such as an adhesive coating or a double-faced adhesive tape known as DOUBLE STICK®, available from the 3M Company. Typically, a release liner 29 is applied to the adhesive to protect the adhesive until it is desired to apply the reagent containing material 22 to the substrate 1 2.

[0027] Referring now to FIG. 4, a reagent card forming apparatus 30 is schematically represented. The reagent card forming apparatus 30 is adapted to automatically form multiple reagent cards, such as the reagent card 1 0. The process of forming the reagent cards 1 0 includes applying a reagent containing sheet material, such as the reagent containing material 16 (FIG. 2) or 22 (FIG. 3) to a substrate material 32. The web of reagent containing sheet material 16 or 22 is then cut to define a plurality of spaced apart reagent containing areas 34 (FIG. 7) and a waste matrix 36 extending about the reagent containing areas 34. The waste matrix 36 is then removed from the substrate material 32 such that the reagent containing areas 34 remain on the substrate material 32 so as to define a plurality of spaced apart reagent pads 14 (FIGS. 1 and 1 A). The substrate material 32 is then cut to form reagent cards 10 (FIG. 1 ) of a selected length.

[0028] In one embodiment, the reagent card forming apparatus 30 includes a reagent material delivery assembly 42, a liner take-up assembly 44, a substrate delivery assembly 46, a cutter assembly 48, a waste take-up assembly 50, and a card cutting assembly 52. The reagent card forming apparatus 30 is illustrated herein using a web of the reagent containing material 22 as described above in reference to FIGS. 3 and 3A, and thus the reagent material delivery assembly 42 is shown to include a single roll 53 for rotatably supporting a roll of reagent containing material 54 which provides the web of reagent containing material 22. However, it will be appreciated that the reagent card forming apparatus 30 may be used to form reagent cards from reagent ribbons, such as the reagent containing ribbon 16 described above in reference to FIG. 2 and 2A. In this case, the reagent material delivery assembly 42 would include a plurality of rolls of reagent ribbon and a guide mechanism (not shown) for guiding each of the reagent ribbons on the web of plastic sheet material 32.

[0029] The web of reagent containing material 22 passes to the liner take-up assembly 44 for the purpose of removing and collecting the release liner 29. The liner take-up assembly 44 is shown in FIG. 4 to include a roller 55, a guide tube 56, and a collection receptacle 57. It should also be appreciated that it may be desirable to apply an adhesive to the web of reagent containing material 22 during the process of forming the reagent cards 10, rather than during the process of forming the reagent containing material. In this case, the liner take-up assembly 44 may be substituted for an adhesive applicator assembly (not shown).

[0030] With the adhesive applied to the web of reagent containing material 22, the substrate delivery assembly 46 supplies the substrate 32 and guides the web of reagent containing material 22 onto the substrate 32. The substrate delivery assembly 46 includes an arbor 58 for rotatably supporting a roll of substrate material 59 which provides a web of substrate material 32. The substrate delivery assembly 46 further includes a guide assembly 60 which serves to position the web of the reagent containing material 22 on, or in alignment with, the web of substrate material 32 so that the web of reagent containing material 22 is adhesively adhered to the web of the substrate 32, or prepared to be adhesively adhered to the web of substrate 32.

[0031] The web of reagent containing material 22 and the web of substrate 32 are guided through the cutter assembly 48 to adhere the web of reagent containing material 22 to the web of substrate material 32 and to cut the web of reagent containing material 22 to define the plurality of spaced apart reagent containing areas 34 and the waste matrix 36 which extends about the reagent containing areas 34. More specifically, the web of reagent containing material 22 is cut in a manner (commonly referred to as a "kiss cut") that the web of substrate 32 is not cut so as to maintain the integrity of the web of substrate 32.

[0032] FIGS. 2, 5, and 5A show the cutting assembly 48 to include a rotary die cutter 62 and an anvil 64 positioned in a complimentary cutting relationship with the rotary die cutter 62. As best shown in FIGS. 5 and 5A, the rotary cutting die 62 includes a plurality of spaced apart cutting elements 66 extending from a drum 68. The cutting elements 66 extend outwardly from the drum 68 and include a cutting edge 70. The cutting edge 70 of the cutting elements 66 is shown to define a closed loop structure corresponding to the desired shape and size of the reagent pads 14. The cutting elements 66 have an interior 72 and an exterior 74 such that when one of the cutting elements 66 is employed to cut the web of reagent containing material 22, the web of reagent containing material 22 is delineated between the reagent containing areas 34 and the waste matrix 36 with the reagent containing areas 34 being defined by the interior 72 of the cutting elements 66. It should be appreciated that the cutting edge 70 may be broken into multiple segments so that the cutting elements 66 define the reagent containing areas 34 by creating a line of perforations through the web of reagent containing material 22. The interior 72 of the cutting elements 66 is provided with a depth sufficient to receive the reagent containing material 22 upon the cutting element 66 penetrating through the web of reagent containing material 22 such that the resulting reagent pad 14 is not significantly crushed or otherwise damaged during the cutting process. In addition, the cutting elements 66 are spaced apart such that the resulting reagent pads 14 are spaced apart from one another a sufficient distance to prevent cross contamination when the reagent card 10 is in use. It will be further appreciated that the spacing between the reagent pads 14, as well as the size of the reagent pads 14, may be varied.

[0033] The rotary cutting die 62 and the anvil 64 are spaced relative to one another to cause the cutting elements 66 to penetrate the web of reagent containing material 22 and the adhesive layer 28 without penetrating the web of substrate material 32. Tension of the web of reagent containing material 22 and the web of substrate material 32 may be controlled by any conventional devices and methods, such as magnetic clutches (not shown).

[0034] While a rotary cutting die and anvil combination have been described and illustrated for cutting the web of reagent containing material 22, it should be appreciated that any conventional device and method may be employed to cut the web of reagent containing material 22 to form the reagent containing areas 34 and the waste matrix web 36. Examples of such other conventional devices and methods which may be employed to cut the web of reagent containing material 22 are reciprocating knives or punches, laser cutting, water jet cutting, air jet cutting, and the like.

[0035] One of the disadvantages of using punch-in-place manufacturing processes with the reagent containing ribbons 1 6 described above, is that the punching or cutting process results in the waste of reagents that are contained in the portion of the reagent containing ribbon 16 that becomes the waste matrix. Accordingly, product costs increase due to increased amounts of chemicals or reagents being used and due to increased cost associated with disposal of the waste product. Additionally, while some dry reagents and absorbent sheet materials can be cut or punched, the integrity of the absorbent sheet material can be altered by the application of certain reagents. Also, certain reagents may be damaged during the cutting process which in turn may lead to incorrect analysis.

[0036] Consequently, the tensile strength of the reagent containing material can be a limiting factor in whether cutting of the reagent containing material will be lead to a useable product. By way of example, an absorbent sheet material may have a dry tensile strength above 2000 g/1 .5 cm. However, upon depositing a reagent into the absorbent sheet material, the tensile strength of the absorbent sheet material may have a tensile strength as low as 300 g/1 .5 cm. To this end, it is necessary that the tensile strength of the reagent containing material be greater than the forces acting on the reagent containing material during the cutting process by the cutting element 66 and the adhesive layer 28 as the cutting element 66 moves away from the reagent containing material. One method of accomplishing this is to use absorbent material having a higher tensile strength such that the resulting reagent containing material maintains a tensile strength greater than opposing forces acting on the cutting elements 66 and the adhesive. A downside of this method is that limiting the process to materials having higher tensile strengths limits the types of absorbent materials that can be used in the process.

[0037] FIGS. 6 and 6A illustrate other solutions to the tensile strength issue. FIG. 6 shows a portion of the web of reagent containing material 22 attached to the web of substrate material 32 after having been cut by the cutting elements 66 of the rotary cutting die 62. More specifically, FIG. 6 shows the web of reagent containing material 22 having been cut along the perimeter of the reagent containing area 34. Similarly, FIG. 6A shows the web of reagent containing material 22 having been cut a distance outward from the perimeter of the reagent containing area 34. In each case, the cutting element 66 penetrates the web of reagent containing material 22 at a location that does not contain reagent. As such, the integrity of the reagent containing material 22 remains unaltered at the location where the penetration is made. Some of the advantages of cutting the web of reagent containing material 22 at locations that are free of reagent is that little or no reagent is wasted during the manufacturing process and the integrity of the waste matrix is maintained so that breakage of the waste matrix while removing the waste matrix from the web of substrate 32 is alleviated.

[0038] Returning to FIG. 4, the cut web of material is passed through a diverter 80 to separate the waste matrix web 36 from the reagent containing areas 34 and the web of substrate material 32. The waste matrix web 36 is collected on a roll 82 in a manner well know in the art.

[0039] With the waste matrix 36 removed from the web of substrate material 32, the substrate material 32 together with the reagent pads 14 are passed to the card cutting assembly 42 where the web of substrate material 32 is cut to form reagent cards of a predetermined length. It will be appreciated that any well known cutting device may be used as the card cutter. Examples of such devices which can be employed as the card cutter and methods which can be employed to cut the web of plastic sheet material to form the reagent cards 1 0 are rotary knives, reciprocating knives, die cutting, laser cutting, water jet cutting, air jet cutting, and the like. [0040] From the above description, it is clear that the inventive concepts disclosed and claimed herein are well adapted to carry out the objects and to attain the advantages mentioned herein, as well as those inherent in the invention. While presently preferred embodiments of the inventive concepts have been described for purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the inventive concepts disclosed and/or as defined in the appended claims.

Claims

What is claimed is:

1 . A method of forming a reagent card, comprising:

applying an absorbent sheet of material to a substrate, the absorbent sheet of material containing at least one reagent;

cutting the absorbent sheet of material to define a plurality of spaced apart reagent containing areas and a waste matrix extending about the reagent containing areas; and

removing the waste matrix from the substrate such that the reagent containing areas remain on the substrate so as to define a plurality of spaced apart reagent pads.

2. The method of claim 1 wherein the waste matrix has a width greater than the diameter of the reagent containing areas.

3. The method of claim 2 wherein the ratio of the width of the waste matrix to the diameter of the reagent containing areas is at least about 5 to 3.

4. The method of claim 1 wherein the absorbent sheet of material is applied to the substrate with an adhesive and wherein the absorbent sheet of material is cut to define the reagent containing areas with a cutting tool, and wherein each of the reagent containing areas of the absorbent sheet of material has a tensile strength greater than opposing forces of the cutting tool and the adhesive so as to prevent the reagent containing areas from splitting during the cutting step.

5. The method of claim 4 wherein the absorbent sheet of material is a reagent ribbon impregnated with the reagent.

6. The method of claim 5 wherein the step of applying the absorbent sheet of material further comprises applying a plurality of reagent ribbons to the substrate in a parallel relationship to one another.

7. The method of claim 1 wherein the reagent is provided on the absorbent sheet of material in a plurality of spaced apart reagent areas, and wherein the step of cutting the absorbent sheet of material to define the plurality of spaced apart reagent containing areas further comprises cutting the absorbent sheet of material along the perimeter of the spaced apart reagent areas.

8. The method of claim 1 wherein the reagent is provided on the absorbent sheet of material in a plurality of spaced apart reagent areas, and wherein the step of cutting the absorbent sheet of material to define the plurality of spaced apart reagent containing areas further comprises cutting the absorbent sheet of material a distance outward from the perimeter of the reagent areas.

9. The method of claim 6 wherein the absorbent sheet of material is provided with a plurality of rows and a plurality of columns of spaced apart reagent areas.

1 0. A method, comprising:

applying a web of an absorbent sheet of material to a web of a substrate material, the web of the absorbent sheet of material containing at least one reagent;

cutting the web of the absorbent sheet of material to define a plurality of spaced apart reagent containing areas and a waste matrix extending about the reagent containing areas;

removing the waste matrix from the web of the substrate material such that the reagent containing areas remain on the web of the substrate material so as to define a plurality of spaced apart reagent pads; and cutting the web of the substrate material to form a reagent card having a predetermined length.

1 1 . The method of claim 10 wherein the waste matrix has a width greater than the diameter of the reagent containing areas.

1 2. The method of claim 1 1 wherein the ratio of the width of the waste matrix to the diameter of the reagent containing areas is at least about 5 to 3.

13. The method of claim 10 wherein the web of the absorbent sheet of material is applied to the web of the substrate material with an adhesive and wherein the web of the absorbent sheet of material is cut to define the reagent containing areas with a cutting tool, and wherein each of the reagent containing areas of the web of the absorbent sheet of material has a tensile strength greater than opposing forces acting on the reagent containing areas so as to prevent the reagent containing areas from splitting during the cutting step.

14. The method of claim 1 3 wherein the web of the absorbent sheet of material is a reagent ribbon impregnated with the reagent.

15. The method of claim 14 wherein the step of applying the web of the absorbent sheet of material further comprises applying a plurality of reagent ribbons to the web of the substrate material in a parallel relationship to one another.

16. The method of claim 10 wherein the reagent is provided on the web of the absorbent sheet of material in a plurality of spaced apart reagent areas, and wherein the step of cutting the web of the absorbent sheet of material to define the plurality of spaced apart reagent containing areas further comprises cutting the web of the absorbent sheet of material along the perimeter of the spaced apart reagent areas.

17. The method of claim 10 wherein the reagent is provided on the web of the absorbent sheet of material in a plurality of spaced apart reagent areas, and wherein the step of cutting the web of the absorbent sheet of material to define the plurality of spaced apart reagent containing areas further comprises cutting the web of the absorbent sheet of material a distance outward from the perimeter of the reagent areas.

1 8. The method of claim 1 7 wherein the web of the absorbent sheet of material is provided with a plurality of rows and a plurality of columns of spaced apart reagent areas.

19. An apparatus, comprising:

a web of a substrate material, and

a web of an absorbent sheet of material applied to the web of the substrate material, the web of the absorbent sheet of material containing at least one reagent, the web of the absorbent sheet of material having a plurality of spaced apart reagent containing areas and a waste matrix extending about the reagent containing areas such that the reagent containing areas remain on the web of the substrate material so as to define a plurality of spaced apart reagent pads upon removal of the waste matrix from the substrate.

20. The apparatus of claim 19 wherein the waste matrix has a width greater than the diameter of the reagent containing areas.

21 . The apparatus of claim 20 wherein the ratio of the width of the waste matrix to the diameter of the reagent containing areas is at least about 5 to 3.

22. The apparatus of claim 1 9 wherein the web of the absorbent sheet of material is a reagent ribbon impregnated with the reagent.

23. The apparatus of claim 22 wherein the web of the absorbent sheet of material comprises a plurality of reagent ribbons applied to the web of the substrate material in a parallel relationship to one another.

24. The apparatus of claim 19 wherein the reagent is provided on the web of the absorbent sheet of material in a plurality of spaced apart reagent areas, and wherein the web of the absorbent sheet of material is cut to define the plurality of spaced apart reagent containing areas along the perimeter of the spaced apart reagent areas.

25. The apparatus of claim 19 wherein the reagent is provided on the web of the absorbent sheet of material in a plurality of spaced apart reagent areas, and wherein the web of the absorbent sheet of material is cut to define the plurality of spaced apart reagent containing areas a distance outward from the perimeter of the reagent areas.