CA1219797A

CA1219797A - Test strips

Info

Publication number: CA1219797A
Application number: CA000443151A
Authority: CA
Inventors: Anselm Rothe; Wolfgang-Reinhold Knappe; Heinz-Friedrich Trasch
Original assignee: Boehringer Mannheim GmbH
Current assignee: Roche Diagnostics GmbH
Priority date: 1982-12-23
Filing date: 1983-12-13
Publication date: 1987-03-31
Also published as: JPH0782002B2; ATE22996T1; DE3367028D1; US4604264A; EP0113896A1; DE3247608A1; ES8501529A1; EP0113896B1; EP0113896B2; JPS59120958A; ES528322A0; US4820489A

Abstract

ABSTRACT
A test strip comprises a film layer containing reagents and a support or handle member, particularly in the form of a synthetic resin film; the reagent film layer is preponderantly on one side of a multifilar carrier layer such as a fabric or fleece, between the film layer and the support there is preferably employed an additional absorbent layer, the components may be connected together by means of a thin, transparent mesh fixed to the support. A process for the production of such a test strip comprises applying a dispersion or solution of the components forming the reagent film layer in an appropriate solvent, to one side of the carrier layer and drying to form the film layer, whereafter this is connected in per se known manner with the other components of the test strip and, if desired, cut up into appropriate smaller units.

Description

7~7 The present invention is concerned with test strips and with a process for the production thereof.
Test papers, i.e. paper strips impregnated with reagents, have long been used in analytical chemistr~
for the detection of inorganic ions, organic substances and for the determination of pH in liquids and gases. A
further development are test strips or test rods in which the impregnated reagent paper is fixed to a synthetic resin film which serves as a handle. These are of increasing importance in analytical chemistry, such as in product control, in the investigation of water and effluent and especially in clinical chemistry in the investigation of body fluids. Hitherto, the reagents were usually impregnated on to paper. Such test strips permit a rapid but only semi-quantitative visual determination by means of appropriate coloured comparison fields~ The natural non-uniformities of the papers and the non-uniform scattering of light thereby brought about make a quantitative, remission-photometric evaluation difficult.
With the need for quantitative measurement results with the use of test strips, also in the case of blood and serum analysis, the use of reagent films has become increasingly common, the main advantage of which is the high degree of uniformity of the reagent layer. By means of the use of reagent films and of remission-photo-metric evaluation of the colour reaction, it is now possible to achieve with test strips measurement results with the quality of those obtained with wet chemical methods.
Examples of test strips based upon films are described in Federal Republic of Germany Patent Specification "~ ,g~

No. 15 98 153, , for the de-termination of preferably glucose in blood, and in Federal Republic of Germany Offenlegungsschrift (Published Patent Specification) No. 31 18 331, , in which is described a test strip construction which, for the determination of glucose in urine, also permits the use of such a reagent film even in the case of unmeasured dipping into the sample liquid. Finally, in Federal Republic of Germany Offenlegungsschrift (Published Patent Specification) No. 31 30 749, there are described test strips for the determination of blood parameters which, in addition to the reagent zone, preferably based on a film, have a preceding erythrocyte separation by means of a glass fibre fleece and which permit an analysis directly from whole blood.
In the case of these test strips, the reagent film is either applied directly to the synthetic resin film serving as a handle or is present on an additional carrier film which imparts to it the stability necessary in the case of production and working up.
In the case of reagent films, which, in comparison with most cloth-like and "open" papers, have a smooth surface and only a small portion of hollow spaces, there are, how-ever, to be found certain disadvantages precisely for these reasons.
Thus, in the case of test strips with a relatively closed or compact structure, such as are described in Federal Republic of Germany Offenlegungsschrift ~o.
31 30 749, difficulties can arise with an oxygen-consuming reaction in supplying sufficiently rapidly the oxygen necessary therefor in the required short reaction time.
The reaction layers described therein are not in direct contact with the air but, from the very beginning, are closed off on their upper side by theIr oxygen-impermeable, transparent carrier film and also on their lower side by pressure of the reagent layer on to the blood-separating fleece.
Therefore, in order to ensure a sufficient supply of oxygen, it is necessary, by laborious means in the measuring apparatus, to provide for a temporary lifting off again of the reagent layer from the separating fleece.
In addition, this exerts an unfavourable influence on the ~uality of the measurement values.
Also in the case of the above-mentioned urine test strips according to Federal Republic of Germany Offenlegungsschrift No. 31 18 381, two phenomena arise which are to be attributed to the properties of the reagent films. In the case of these urine test strips for the determination of glucose, the reagent film is fixed to its carrier film over a slow adsorbing paper by means of a thin covering mesh on the handle film. It has been shown that in the case of unskilled handling, an air bubble remains en-closed between the covering mesh and the surface of the reagent film which hinders a colour reaction. On the other hand, it can happen that in the case of the adsorption of comparatively large amounts of excess urine into the slow adsorbing paper, ugly coloured edges arise which lead to incorrect interpretations of the results.
The air bubble formation could only be prevented by an expensive wetting agent treatment of the covering 7~7 mesh but a solving of the coloured edge problem was only possible by a limitation to small test zones.
Surprisingly, we have now found that the fore-going problems can be overcome simply and completely when the reagent film is not coated on to a solid carrier film but on to a carrier layer made of a multifilar fabric or fleece, preferably of polyester or polyamide.
Thus, according to the present invention, there is provided a test strip comprising a film layer containing reagents and a handle member, wherein the reagent film is preponderantly present on one side of a multifilar carrier layer.
Suitably the carrier layer is a multifilar fabric or fleece, and the handle member comprises a synthetic resin film.
In a particular embodiment of the invention there is provided a test strip for evaluation of fluids comprising a reagent assembly supported by a support assembly, said reagent assembly comprising a multifilar substrate and a reagent layer, said reagent layer comprising reagents for the evaluation and being formed as a coating on one side of said substrate without penetration into said substrate.
In yet another aspect of the invention there is provided a process for the production of a test strip compxising applying a liquid composition of reagent com-ponents adapted to form a reagent layer, in a liquid medium to one side of a multifilar carrier layer, drying said composition to form a reagent assembly with said reagent layer as a coating on said one side, and mounting said reagent assembly on a support.

~``` ~æ~s7 For this purpose, a suspension or dispersion, which is as concentrated as possible, of the film-forming synthetic resins, of the necessary reagents, pigments, as well as other filler or adjuvant materials, in an appr~-priate solvent, preferably water, is applied with a rake or nozzle in a thin layer (20 - 500,u, preferably 50 - 200 ~) to the fabric and dried~ There are obtained dry films with a thic~ness of 10 - 200 ~u, preferably of 15 - 100 ~.
It is a characteristic of che present invention that the coating mass remains on the upper side of the fabric whereas, depending upon the amount applied and mass properties, little or no coating mass gets into the interior of the fabric or on to its lower side.
Of course, other carriers or fabrics of other materials can also be used, for example cotton cloth, fleeces, papers and the like, so long as they satisfy the requirements with regard to uniformity, adsorptive ability, permeability and the like.
Monofilar fabrics,the embedding of which into coating masses has been described in Federal Republic of Germany Offenlegungsschrift (Published Patent Specification) No. 28 25 636, are not suitab~e for use according to the present invention. On the one hand, the coating mass penetrates through the fabric during the coating so that an additional carrier film must be used which is subsequently to be discarded. On the other hand, in the case of mono-filar fabrics, the accelerating effect in the case of oxygen-consuming reactions does not occur. Finally, uniform films are only possible with relatively high layer thicknesses and have an unacceptably long reaction time and also do not have the difference between the fabric side and the layer side which is typical of the present invention.

7~

The reagents, film formers and adjuvant materials suitable for the construction of the reagent film are the same as those conventionally used for reagent films such as are described, for example, in the aforementioned Federal Repuhlic of Germany Patent Specification Nos.
15 98 153 and 31 18 381, and Federal Republic of Germany Offenlegungsschrift (Published Patent Specification) No.
29 10 13~.
Suitable film formers are preferably organic synthetic resins, for example, polyvinyl esters, polyvinyl acetate, polyacrylic esters, polymethacrylic esters, polyacrylamides, polyamides, polystyrenes, co-polymers, for example, of butadiene and styrene or of maleic acid esters and vinyl acetate, cellulose and cellulose derivatives or gelatine. Other film-forming, natural and synthetic organic polymers, as well as mixtures thereof, can also be used, preferably in the form of aqueous dispersions. The film formers can also be dissolved in organic solvents, for example, a co-polymer of vinyl chloride and vinyl propionate can be dissolved in ethyl acetate.
The reagents, pigments and other adjuvants necessary for the detection reaction are normally added directly to the dispersion. Eowever, insofar as it is advantageous to do so, the formed film can also be im-pregnated with them. A preimpregnation of the added pig-ments with the reagents is also possible. The process can also be combined in that, for example, certain components are introduced into the dispersion and the others are sub-sequently impregnated on to the film. In this way, a certain spatial separation of the components can be achieved, which can result in more stable or more reactive tests.

Furthermore, a separation can be achieved in that on to a ~9797 first film layer there is applied a second film layer ~,~ith a different composition.
Insofar as it is necessary, thickening agents, emulsifiers, dispersion agents, pigments, plasticisers, wetting agents and the like can also be added.
Dispersion agents, emulsifiers and thickening agents serve for the production and stabilisation of the dispersions. Pigments, for example titanium dioxide and silicon dioxide, improve the remission properties of films in that they provide for the smallest possible transparency and increased remission of the filmsO This is especially advantageous when the so-obtained diagnostic test agents are to be evaluated remission photometrically.
The properties of the film coating masses, as well as of the films, can be optimised with plasticisers.
Thus, for example, their stability, their viscosity, their adhesion to the substrate to be coated and the like can be improved r Wetting agents are added in order to achieve a better wetting of the film by the,sample material. At the same time, they can also catalyse reactions or stabilise formulations or make the reaction colours more brilliant or of greater contrast.
The test strips described herein are preferably used for the detection of component materials of body fluids such as urine, serum, faecal juices and saliva, but, with suitable modification, can also be used in other aqueous media, for example drinking water, effluent and the like, and possibly also in organic solvents in which they are insoluble.
In accordance with another aspect of the invention there is provided a method of determining the presence of a material i~ a fluid comprising contacting a sample of the fluid with a test strip of the invention, which contains reagents effective to provide a colour change in the presence of said material, and evaluatiny any colour change in the test strip, as a measure of the presence of said material.
~ he coated fabrics according to the present invention can be advantageously used in all cases where a film coated with a reagen-t film has previously been used. They are preferably used instead of the films in the devices according t~ the aforementioned Federal Republic of Germany Patent Specifications Nos. 31 18 381 and 31 30 749.
In the case of the devices according to Federal Republic of ~ermany Patent Specification No. 31 30 749, by the use of fabrics as substrates, there are, surprisingly, obtained more rapid reactions in the case of oxygen-consuming reactions, possibly because additional oxygen is made available due to the fabric structure. In the case o~ devices according to Federal Republic of Germany Patent Specification No. 31 18 381, a possible liquid supernatant flows off more quickly and without the formation of coloured edges. Also in the case of rapid dipping in or of insuf-ficient wiping off, the contact between the reagent film and the covering mesh is so close that disturbing air bubbles can no longer be formed. The coated fabrics according to the invention can, of course, also be stuck or sealed directly on to synthetic resin films serving as handles but then, as in the case of test strips with con-ventional reagent films on carrier films, re~uire a careful wiping off of e~cess test solution since this otherwise remains behind on the smooth surface as droplets and leads to spotty reactions. Underlaying with a slow adsorbing material does inofar not offer any advantages since the fluid only penetrates very slowly through the synthetic resin layer.
In comparison with test strips with impregnated paper, which are today still preponderantly used, the film-coated fabrics offer the following advantages: due to the components of the coatings (colloidal thickening agents, dispersions) and the relatively low content of solvents in comparison with impregnation solutions, reagents which are incompatible with one another can remain stable in homogeneous solution for several hours in the presence of one another î due to the use of pigmented coating masses, there can be achieved, for remission-photometric evaluation, a background with a degree of whiteness which cannot be achieved by impregnation of a paper, in contradistinction to impregnated papers, in which the inhomogeneity of the paper disturbs a photometric evaluation, the coated fabric is homogeneous since the layer lies substantially on the upper side and has the same homogeneity as a film applied to another film. Shorter reaction times can thus be achieved since a thin film, compared with an adsorbent carrier (paper), is provided with only a fraction of the substrate, and thus reacts quickly and practically the whole of the resultant reaction colour can contribute towards the measurement result. On the other hand, the possibility exists of a preceding reaction in that the fabric is, before the coating, impregnated with an additional reagent or the test solution is applied to the fabric and the reagent film via one or more adsorbent carriers.
~he invention is illustrated in particular and preferred embodiments by reference to the accompanying _ g _ ~9~7 drawings in which:
Figure 1 illustrates schematically a test strip in accorcance with one embodiment of the invention;
Figure 2 illustrates graphically the improvement which may be obtained, in accordance with-this invention, when using a test strip of Figure 1, and Figure 3 illustrates schematically a test strip in accordance with another embodiment of the:;invention.
With further reference to Figure 1, a test strip 10 comp~ises a reagent assembly 12 and a support assembly 14.
Support assembly 14 co~prises a handle member 1 suitably in the form of a carrier film, and an absorbent fleece 2.
Reagent assembly 12 comprises a reagent film 4 on one side of a fabric layer 5 and a protective or covering film 3.
A bonding or fixing means 6 secures the reagent assembly 12 to support assembly 14.
Support assembly 14 extends beyond reagent assembly 12 and reagent assembly 12 can be raised relative to support assembly 1~, as shown in Figure 1.
Handle member 1 extends beyond fleece 2, whereby the test strip 10 can be handled, and contact with reagent assembly 12 can be minimized.
An application zone 2a is defined by fleece 2.
Wlth further reference to Figure 3, a test strip 20 comprises a handle member 21, an adsorbent paper 22, a fleece layer 23 and a reagent ~ilm 24.
A covering mesh 25 is applied over reagent film 24 and the underlying fleece layer 23 and paper 22, and is secured to handle member 21.

t The following Examples are given for the pur-pose of illustrating the present invention:
Example 1 Production of a test strip for the detection of glucose in blood.
A test reagent composition i9 formed of:
35 KU glucose oxidase 200 KU peroxidase 15 ml. 0.5M phosphate buffer, p~ 5 0.3 g. sodium alginate 25 g. polyvinyl propionate dispersion in the form of a 50% dispersion in water 0.5 g. 3,3',5,5'-tetramethylbenzidine 0.2 g. phenyl semicarbazide 1 g. dioctyl sodium sulphosuccinate 6 ml. methoxyethanol 20 g. titanium dioxide, and 35 ml. water The composition is worked up to give a homogeneous mass and coated with a thickness of 0.1 mm. on to a 150 thick multifilar polyamide fabric 5 (181 F 892* Schweizer Seidengaze-Fabrik) and dried to form a reagent film 4, as shown in Figure 1. The fabric 5 with film 4 on one side, so obtained, is thereafter attached to a transparent covering film 3 so that the coYering film 3 lies on the reagent film 4.
Subsequently, a 1 cm. wide strip of the resulting reagent assembly 12 is fixed, with the fabric side below, in the manner illustrated in Figure 1 of the accompanying drawings, on to a plastics strip 1 on to which a 15 mm. wide glass fibre fleece 2 with a thickness of 1.5 mm. and a fibre thick-ness of about 2~u has been applied so that the free end of *supplier's designation ~97~7 the reagent assemblY still extends 6 mm. over the fleece.
This is then cut up into 6 mm. wide test strips 10.
When 15 ~1. of whole blood are now applied to the sample application zone 2a (see Figure 1), then, within 30 to 60 seconds, the plasma componert penetrates through the whole of the glass fibre fleece 2, also below the transparent film 3, whereas the erythrocytes are held in zone 2a. By applying pressure to the covering film 3, the reagent film 4 now comes into contact with the separated plasma via the fabric layer 5, and is uniformly moistened throughout. The glucose contained in the plasma reacts within 1 to 2 minutes, depending upon its concentration, with the development of a more or less deep blue coloration.
The photometric measurement is preferably carried out in a remission photometer, the measurement head of which only descends on to the test field after a definite incubation time (plasma separation) and, with the pressure produced therewith, establishes the contact between the separation fleece 2 and the rear side of the fabric layer 5.
In the case of a reaction time of 60 seconds and a mPasure-ment wavelength of 630 nm, there is obtained the measure-ment curve 1 shown in Figure 2 of the accompanying drawings.
Curve 2 of Figure 2 shows the measurement values obtained when the reagent film is applied directly to the covering film 3 as carrier layer and not to a fabric layer 5.
The difference between curve~l and curve 2 clearly shows that graduations to the highest glucose concentrations first become possible by the construction according to the present invention. The stronger reaction which thereby takes place, possibly due to the supply of oxygen from the interior of the fabric layer 5, was completely unexpected 7~
since a simple calculation shows that the oxygen ori~inally present in the hollow spaces of the fabric layer 5 does not suffice to meet the oxygen requirement of the reaction.
Furthermore, the construction according to the present invention resulted in a marked reduction of the:reaction time.
In contradistinction to the device described in the aforementioned Federal Republic of Germany Patent Specification ~o. 31 30 749, the transparent covering film 3 can be omitted since the reagent film 4 is sufficiently stabilised by the underlying fabric layer 5, but it can, for reasons of safety, be additionally present in order to prevent a touching or damaging of the reagent-film 4.
Example 2 Production of a test strip for the detection of glucose in urine.
A test reagent composition is formed of:
20 KU glucose oxidase 80 KU peroxidase 5 ml. lM citrate buffer, pH 5 0.13 g. sodium alginate 13 g. 50% polyvinyl propionate dlspersion in water 0.375 gO 3,3',5,5'-tetramethylbenzidine 0.1 g. l-phenylsemicarbaz~de 1 g. dioctyl sodium sulphosuccinate 5 ml. methoxyethanol 10 g. silica gel, and 12 ml. water The composition is worked up to give a homogeneous mass and coated with a thickness of 0.1 mm. on a 350 ~
thick polyester fleece 23 (Dupont/Remey* 2033) and dried to form a reagent film 24, as shown in Figure 3. The fleece * trademark 23 with reagent film 24, so obtained, is, as described in Federal Republic of Gerln~ny Patent Specification No.
31 18 381, fixed over a slow-absorbing paper 22 on to a synthetic resin film serving as a handle 21 with the use of a thin fabric covering mesh 25 which has been treated with a wetting agent and worked up to give test strips 20 of the type illustrated in Figure 3.
When the strips are dipped into glucose-containing urine samples then, even in the case of careless handling, there are obtained reaction colours which are free from spots and of edge colorations.
Example 3 Production of a test strip for the detection of cholesterol in blood.

2.5 KU cholesterol oxidase 1.5 KU cholesterol esterase 50 KU peroxidase 10 mg. gallic acid 0.5 g. 3,3',5,5'-tetramethylbenzidine 20~ 0.3 g. dioctyl sodium sulphosuccinate 1.5 ml. acetone 6.5 g. 50% polyvinyl propionate dispersion in water 5 g. titanium dioxide 10 g. cellulose 15 ml. phosphate buffer 0.5M, pH7 20 ml. water are worked up 'o give a homogeneous mass and coated with a strip width of 0.15 mm. on to a 200,u thick multi-filar polyester fabric (2 F 777* Schweizer Seidengaze-Fabrik) and dried.
The coated carrier so obtained is, as described in Example 1, worked up to give test strips.

*supplier's designation ~Z1~97 The reaction with cholesterol-containing blood took place as in Example 1 and, after a reaction time of 100 seconds, gave an excellent graduation over the whole relevant concentration range.
Example 4 Production of a test strip for the detection of trigly-cerides in blood.

.
50 KU peroxidase 20 KU cholesterol esterase 50 KU glycerol kinase 10 KU glycerophosphate oxidase 20 g. 50% polyvinyl propionate dispersion in water 20 g. cellulose 0.2 g. sodium alginate 10 g. titanium dioxide 0.68 g. 3,3',5,5'-tetramethylbenzidine 0.30 g. dioctyl sodium sulphosuccinate 1.5 ml. acetone 25 ml. 0.2M phosphate buffer, pH 7.8 10 ml. water 0.2 g. adenosine triphosphate are worked up to give a homogeneous mass and coated with a strip width of 0.2 mm. on a 210 ~ thick cotton fabric and dried. The so obtained coated carrier is, as described in Example 1, worked up to give test strips.
The reaction with triglyceride-containing blood took place as in Example 1 and gave, after a reaction time of 120 seconds, an excellent graduation over the whole relevant concentration range.

ExamPle 5 Production of a test strip for the_detection of uric acid in blood.

40 I~U peroxidase 1 KU uricase 18 g. 50% polyvinyl propionate dispersion-in water 0.25 g. sodium alginate 0.5 gO non-ionic wetting agent 0.5 g. disodium ethylenediamine-tetraacetic acid 20 g. kieselguhr 20 ml. 0.2M phosphate buffer, p~ 7 0~4 g. primaquine diphosphate 18 ml. water are worked up to give a homogeneous mass and coated with a thickness of 0.2 mm. on to a 200 ~ thick multi-filar polyester fabric (2 F 777* Schweizer Seideng~ze-Fabrik) and drIed.
A thin filter paper (597 NF-Ind.*, Schleicher &
Schull) is impregnated with 0.2 g. 4-aminoantipyrine and 0.2 g. non-ionic wetting agent in 50 ml. water and dried.
Test strips are produced as described in Example 1 which, between the separation fleece and the lower side of the reagent fabric, contained a layer of aminoantipyrine paper.
The reaction with uric acid-containing blood took place as in Example 1 and, after a reaction time of 120 seconds, gave an excellent graduation over the whole relevant concentration range.
Example 6 Production of a test strip for the detection of y-glutamyl transferase in blood.

. . _. _ ~

1.0 g. N'méthylanthranilic acid 2.5 g. glycylglycine *supplier's designation g7 0.85 g. disodium ethylenediamine-tetraacetic acid 0.2 g. glutamyl-p-phenylenediamine-3-carboxylic acid 20 g. 50% polyvinyl propionate dispersion in water 0.2 g. sodium alginate 0.35 g. dioctyl sodium sulphosuccinate 1.0 ml. methanol 5 g. titanium dioxide 8 g~ cellulose 15 ml. tris buffer, pH 7.6 15 ml. water are worked up to give a homogeneous mass and coated with a thickness of 0.15 mm. on a 250~um. thick multifilar polyamide fabric (1093* Verseidag-Industrie-Textilien GmbH) and dried.
A teabag paper of the firm Scholler & Hosch with a weight per unit surface`area of 12 g,/m2 is impregnated with an aqueous solution containing 250 mmole/litre of potassium ferricyanide and dried for 5 minutes at -30C. Test strips are produced as described in ~igure 1 of the accompanying drawings which, between the separation fleece and the lower side of the reagent fabric, additionally contained a layer of the oxidation paper.
The reaction with y-glutamyl transferase-containing blood took place as in Example 1 and, after a reaction time of 120 seconds, gave an excellent graduation over the whole relevant concentration range.
Examp e 7 Production of a test strip ~or the detection of bilirubin in blood.
0 0.2 g. 2-methoxy-4-nitrobenzenediazonium tetrafluoro-borate *supplier's designation 1.5 g. metaphosphoric acid 1.5 g. diphenylphosphoric acid 0.2 g. dioctyl sodium sulphosuccinate 5 g. silica gel 1 g. cellulose 7.5 g. 40% polyvinylidene chloride dispersion (Diofan*
217 D, BASF) in water 15 g. 2.5% swelling agent (Bentone* EW, ~ational Lead) in water are worked up to give a homogeneous mass and coated with a strip width of 0.2 mm. on a 200 ~m. thick multifilar poly-ester fabric (2 F 777** Schweizer Seidengaze-Fabrik) and dried.
The so obtained coated carrier is worked up to give test strips as described in Example 1. The reaction with bilirubin-containing blood took place as in Example 1 and, after a reaction time of 60 seconds, gave an excellent graduation- over the- whole relevant concentration range.
Example 8 Production of a test strip for the detection of uric aci_ in blood.
8~4 g. gelatine 40 ml. phosphate buffer (0.5 M, pH 7.0) 0~28 g. polyoxyet~ylensorbitanoleate (Tween* 20) 5 ml. enzyme suspension (0,5 KU uricase, 50 KU peroxidase in 5 ml. water) 0.15 g. indicator (2(4`hydroxy-3,5-dimethoxy-phenyl)-4, 5-bis-(p-dimethylamino-phenyl)-imidazole-hydro-choride) 0.3 ml. isopropanol *trademark **supplier1s designation t 7~7 are worked up to a homogeneous mass at 37C and applied over a 300~um nozzle in a curtain coating method, usual in gelatine film technology, onto a multifilar polyamide fabric (Schwe.izer Seidengazefabrik 2F/131*) and dried.
The reagent film so obtained is worked up according to Example 1 to form test strips according to Figure 1.
On application of 30Jul blood at 37C to the area 2a and pressing on of the fabric layer 5 to the transporta-tion fleece 2, a blue coloration was obtained after 1 minute proportional to the uric acid concentration which could be read offafter another 1 to 2 minutes. With a re-mission photometer the values set forth in Table 1 are read off at a wavelength of 680 nm.

Table 1 Uric acid %
mg/100 ml remission 0 66.4 46.7 33.4 * supplier's designation

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A test strip comprising a film layer containing test reagents, a handle member and a multifilar carrier layer, said film layer being preponderantly on one side of said carrier layer.

2. A test strip according to claim 1, wherein the carrier layer is a fabric or fleece consisting of poly-ester, polyamide, cotton or cellulose.

3. A test strip according to claim 1 or 2 wherein the film layer has a thickness of 10 to 200 µ.

4. A test strip according to claim 1 or 2 wherein the film layer has a thickness of 15 to 100 µ.

5. A test strip according to claim 1 further including an absorbent layer present between the handle member and the film layer.

6. A test strip according to claim 5 wherein the handle member, the absorbent layer, the carrier layer and the film layer are assembled together by means of a thin mesh which is fixed to the handle member.

7. A test strip according to claim 5, wherein the handle member and the absorbent layer are connected to-gether and the carrier layer upon which the film layer is present is connected to the handle member adjacent the absorbent layer at one edge so that the carrier layer at least partly loosely covers the absorbent layer.

8. A test strip according to claim 7 further including a covering layer over the film layer.

9. A test strip according to claim 8 wherein the covering layer is transparent and is connected to the film layer.

10. A test strip according to claim 1, 5 or 8 wherein said multifilar layer comprises a multifilar fabric or fleece.

11. A test strip according to claim 1, 5 or 8 wherein said multifilar layer comprises a multifilar fabric or fleece and said handle member comprises a synthetic resin film.

12. A test strip for evaluation of fluids comprising:
a reagent assembly supported by a support assembly, said reagent assembly comprising a multifilar substrate and a reagent layer, said reagent layer comprising reagents for the evaluation and being formed as a coating on one side of said substrate without penetration into said substrate.

13. A test strip according to claim 12 wherein said support assembly comprises a support and an absorbent layer, said reagent layer being disposed on a side of said sub-strate remote from said absorbent layer.

14. A test strip according to claim 13 wherein said multifilar substrate comprises a fabric or fleece, and said coating has a dry thickness of 10 - 200 µ.

15. A test strip according to claim 14 wherein different reagent components of the reagent layer are spatially separated in said coating.

16. A process for the production of a test strip comprising:
applying a liquid composition of reagent components adapted to form a reagent layer in a liquid medium to one side of a multifilar carrier layer, drying said composition to form a reagent assembly with said reagent layer as a coating on said one side, and mounting said reagent assembly on a support.

17. A process according to claim 16 comprising impregnating a part of the reagent components into a dried coating.

18. A process according to claim 16 wherein after mounting said reagent assembly on said support, the resulting combination is divided up into smaller units.

19. A process according to claim 16 wherein said multifilar carrier layer is a fabric.

20. A process according to claim 16 wherein said multifilar carrier layer is a fleece.

21. A process according to claim 16, 19 or 20 wherein said liquid composition is applied to said one side of said carrier layer in a wet thickness of 20 - 500 µ and is dried to a thickness of 10 - 200 µ.

22. A process according to claim 16, 19 or 20 wherein said liquid composition comprises a solution of said reagent components in a solvent.

23. A process according to claim 16, 19 or 20 wherein said liquid composition comprises a dispersion of said reagent components in said liquid medium.

24. In a test strip for evaluation of body fluids comprising a reagent film and a support, the improvement wherein said reagent film is formed as a coating on one side of a multifilar substrate, said one side being remote from said support.

25. A test strip according to claim 24,further including an absorbent layer disposed between said support and said multifilar substrate.

26. A test strip according to claim 25 wherein said absorbent layer defines a zone for application of a body fluid sample for evaluation.

27. A method of determining the presence of a material in a fluid comprising contacting a sample of said fluid with a test strip as defined in claim 1, 12 or 13, wherein said reagent layer contains reagents effective to provide a colour change in the presence of said material, and evaluating any colour change in the test strip, as a measure of the presence of said material.

28. A method of determining the presence of a material in a fluid comprising contacting a sample of the fluid with a test strip as defined in claim 24 or 25 which contains reagents effective to provide a colour change in the presence of said material, and evaluating any colour change in the test strip, as a measure of the presence of said material.