CS273781B1 - Diagnostic strips for azocouplable substances determination - Google Patents

Abstract

The diagnostic strip for determination of azo-coupling substances, especially urobilinogen and bilirubin in body fluids with the content of an agent that is capable of entering into coupling reaction in acid medium with the determined substance. As a sizing agent, the strips also contain hydrophilic water-soluble modified cellulose in the amount of 1 to 10 percent by weight in relation to the total weight of all solid substances that are applied on paper in impregnation. Hydrophilic cellulose substantially increases coherence of cellulose fibres and hence mechanical strength in highly acid medium.

Description

Among the diagnostic devices used in clinical biochemistry to detect various functional disorders in patients, diagnostic strips have recently gained prominent place. The reason is not only the extraordinary simplicity and speed of use, but also the high reliability of the findings that these strips show due to tremendous progress. achieved in their formulation and production method in the last two decades.

In spite of this progress, however, it is still not possible to say that the production of diagnostic strips was without any problems. One of the unresolved problems is the properties of the absorbent carrier generally used today, on which all the chemicals and reagents required for the color reaction of the diagnostic strips are deposited.

Although the patent literature provides a rich list of various absorbent materials useful for this purpose, currently practically exclusively non-sized filter paper is used. Although this material surpasses all other proposed materials by its properties, the fact that its mechanical properties are strongly influenced by some of the chemicals necessary for the function of the strips remains a drawback. In particular, the acidic environment, which is required, for example, for the determination of certain azo-coupling substances, such as urobilinogen or bilirubin, has a negative effect on the cohesion of the paper fibers. This undesirable effect is very unfavorable in the further processing of the paper, such as cutting, in which the paper is broken and stratified.

The West German patent 2,007,013 has already been addressed to overcome this deficiency, according to which the paper for bilirubin diagnostic strips has been replaced by a synthetic fiber fleece such as polypropylene. However, this solution did not work because the prepared strips had perfect mechanical strength, but they gave such a weak coloration with bilirubin that they were not useful for determining lower concentrations of this bile dye. Indeed, it has been shown that a substantial difference between cellulose fiber paper and synthetic fiber web is that, when the paper is impregnated, a portion of the reagents also penetrate into the hollow cellulose fibers, whereas in the case of synthetic fibers the reagents are only retained on the fiber surface.

A similar recent West German patent 2,158,124, which recommends the use of a non-woven or nonwoven consisting entirely or predominantly of polyamide fibers, has also failed to provide a satisfactory solution, since the polyamide fiber carrier reactions are somewhat more intense than polypropylene, polyester or polyvinyl chloride fibers. far below the intensity and color brilliance of the reaction on a pad of normal filter paper.

The present invention is directed to diagnostic strips for the determination of azocopulable substances, such as urobilinogen and bilirubin in body fluids, comprising an agent capable of entering the azocopulation reaction in an acidic environment with the substance to be examined, further comprising a hydrophilic sizing agent in water soluble modified cellulose such as ethylhydroxymethylcellulose or methylhydroxypropylcellulose or methylcellulose or methylcarboxymethylcellulose in an amount of 1 to 10% by weight, based on the total weight of all solids which are applied to the paper when impregnated.

This hydrophilic, water-soluble, modified cellulose increases perfectly the cohesion of the cellulosic fibers of the paper and hence its mechanical strength and in a strongly acidic environment, as is necessary, for example, for the bile dye strips, the urobilino gene and especially bilirubin. In doing so, these polymers not only do not reduce the intensity of the dyes produced by the reaction with said azo-copulators, but, on the contrary, the development of the dyes τ

• Ά

CS 273781 Bl 2 supports and increases its brilliance.

The sizing of the paper with the hydrophilic, water-soluble, modified cellulose according to the invention may be carried out already in the paper making process in a manner known per se; however, it is far more advantageous and economical to apply said sizing agent to an already finished, non-sized paper upon impregnation, whereby the components of the reagent stripe reaction system are applied to the paper, i.e. if the sizing agent is added to the so-called impregnating solutions only during the strip manufacture.

A very small amount of sizing agent in the range of 1 to 10% by weight, preferably 2 to 3% by weight, based on the total weight of all solids which are applied to the paper during impregnation, is sufficient for a perfect effect.

Examples

Diagnostic strips for the determination of urobilinogen in urine

Impregnation solution A:

Distilled water 185 ml

Citric acid 40 g

1,5-Naphthalenedisulfonic acid disodium salt 28 g

Hydroxypropylmethylcellulose, acetone solution (4 g / 100 ml) 45 ml sodium dodecyl sulfate, aqueous solution (1 g / 100 ml) 5 ml

Impregnation solution B:

Ethyl acetate 200 ml

N- (4-benzyloxybenzenazo) morpholine 1.44 g

The filter paper, having a basis weight of 180 g / m @ 2, is gradually impregnated with the above solutions A and B until saturation, so that after each impregnation the paper is completely dried by a stream of air at 50 ° C. The paper thus impregnated is then cut into 6x6 mm squares which are adhered, for example with a double-sided adhesive tape, to the end of the 6 x 80 mm plastic film.

The paper impregnated with the above solutions contains hydrophilic, water-soluble methylhydroxypropylcellulose and is perfectly cohesive in cutting and other mechanical processing and handling, while paper impregnated with the same solutions but without modified cellulose breaks and stratifies under the slightest mechanical stress.

2. Diagnostic strips for the determination of bilirubin in urine

Impregnation solution A:

Water distilled 100 ml metaphosphoric acid 10 g

Citric acid 4 g

2,6-Dichlorobenzenediazonium tetrafluoroborate 0.1 g

Methylcellulose, aqueous solution (4 g / 100 ml) 18 ml /

Impregnation solution B:

Ethyl acetate 50 ml

Ethyl alcohol 20 ml

Water distilled 10 ml

CS 2737-1 Bl

3,9-Diethyl-6-tridecanol hydrogen sulphate sodium,

25% aqueous solution 0.5 ml

The diagnostic strips are prepared as described in Example 1. The paper thus prepared is substantially more mechanically resistant than the paper prepared by impregnating solutions in the absence of methylcellulose.

3. Diagnostic strips for the determination of bilirubin in urine

Impregnation solution A:

Water Distilled 100 ml

Metaphosphoric acid 10 g

Citric acid A g

2, E-Dichlorobenzenediazonium tetrafluoroborate 0.1 g

Ethyl hydroxymethylcellulose, aqueous solution (2.4 g / 100 ml) 18 ml

Impregnation solution B:

Ethyl acetate 50 ml

Ethyl alcohol 20 ml

Water distilled 10 ml

3,9-Diethyl-6-tridecanol hydrogen sulphate sodium salt, aqueous solution (25 g / 100 ml) 0.5 ml

The diagnostic strips are prepared in the same manner as in Example 1. The paper thus prepared is mechanically more resistant to processing than paper prepared by impregnating a solution in the absence of ethylhydroxymethylcellulose.

4. Diagnostic strips for determination of urinary toxin

Impregnation solution A:

Water distilled 100 ml

Citric acid monohydrate 20 g

1,5-Naphthalenedisulfonic acid disodium salt 14 g

Methylcarboxymethylcellulose, aqueous solution (4 g / 100 ml) 27 ml

Sodium dodecyl sulfate, aqueous solution (1 g / 100 ml) 2.5 ml

Impregnation solution B:

Ethyl acetate 200 ml

4-Benzyloxybenzenediazonium tetrafluoroborate 1.44 g

The diagnostic strips are prepared in the same manner as in Example 1. The methyl carboxymethylcellulose present in the impregnation solution substantially improves the mechanical properties of the impregnated paper, which is then perfectly cohesive and does not break during cutting or other mechanical processing. In the absence of methylcarboxymethylcellulose, the paper is brittle and easily stratified.

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5. Diagnostic strips for the determination of bilirubin in blood serum

Impregnating solution:

Water distilled 100 ml

1,5-Naphthalenedisulfonic acid disodium salt 2.15 g

Theophylline 1.39 g

Methylcarboxymethylcellulose, aqueous solution (3 g / 100 ml) 32.5 ml

Metaphosphoric acid 7.14 g

2,4-Dichlorobenzenediazonium tetrafluoroborate 0.29 g

The filter paper, weighing 120 g / m @ 2, is impregnated with the above solution until saturation and dried thoroughly with a 50 [deg.] C. air stream. The paper thus impregnated is then cut into 6x6 mm squares which are glued, for example by means of double-sided self-adhesive tape, to the end of a 6 x 80 mm plastic film.

The impregnated paper containing methylcarboxymethylcellulose shows a better cohesiveness in mechanical processing and handling than paper impregnated with the same solutions, but without modified cellulose, which breaks and stratifies in mechanical processing.

6. Diagnostic strips for urobilinogen in urine

Impregnation solution A:

Distilled water 130 ml

Citric acid monohydrate 28.1 g

1,5-Naphthalenedisulfonic acid disodium salt 19.7 g

Hydroxypropylcellulose, aqueous solution (3 g / 100 ml) 42.2 ml

Sodium dodecyl sulfate, aqueous solution (1 g / 100 ml) 3.5 ml

Impregnation solution B:

Ethyl acetate 100 ml

N- (4-Benzyloxybenzenazo) morpholine 0.72 g

The diagnostic strips were prepared in the same manner as in Example 1. The presence of hydroxypropylcellulose causes the paper to be perfectly cohesive in mechanical processing, whereas in the absence of modified cellulose the paper is stratified and broken under mechanical stress.

7. Diagnostic strips for the determination of bilirubin in urine

Impregnation solution A:

Water distilled 120 ml

Metaphosphoric acid 12 g

Citric acid monohydrate 4.8 g

2,6-Dichlorobenzenazomorpholine 0.1 g

Impregnation solution B:

Ethyl acetate 45 ml

Ethyl alcohol · 18 ml

3,9-Diethyl-6-tridecanol hydrogen sulfate sodium salt, 25% aqueous solution

0.45 ml

CS 273781 01

Hydroxypropyl methylcellulose naphthalate, aqueous solution (4 g / 100 ml) 12 ml

The diagnostic strips are prepared as described in Example 1. The paper impregnated with the above solutions contains hydrophilic, water-soluble, water-soluble hydroxypropyl methylcellulose phthalate and is perfectly cohesive in mechanical processing, while paper impregnated with the same solutions but without modified cellulose breaks and stratifies.

Claims (1)

SUBJECT OF THE INVENTION Diagnostic strips for the determination of azocopulable substances, in particular urobilinogen and bilirubin in body fluids, containing an agent capable of entering into the azocopulation reaction in an acidic environment with the substance to be examined, characterized in that they contain hydrophilic, water-soluble modified cellulose such as ethylhydroxymethylcellulose; or methylhydroxypropylcellulose or methylcellulose or methylcarboxymethylcellulose, in an amount of 1 to 10% by weight, based on the total weight of all solids which are applied to the paper upon impregnation.