JPH08233801A - Test piece for measuring specific gravity of urine - Google Patents

Abstract

PURPOSE: To accurately and simply measure the specific gravity of urine by infiltrating an impregnation soln. containing protein, a buffer agent and a pH indicator into a porous matrix and drying the impregnated matrix to produce a test piece. CONSTITUTION: A test piece for measuring the specific gravity of urine is produced by impregnating a porous matrix with an impregnation soln. containing protein, a buffer agent and a pH indicator and drying the impregnated matrix. In this case, protein is pref. selected from albumin, globulin, gelatin, casein and mixture of them. The concns. of protein, the buffer agent and the pH indicator are respectively set to 0.1-3% (w/v), 0.05-2M (mol/l) and 0.1-2M (mol/l). As the porous matrix, filter paper is pref.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry test piece for measuring specific gravity in urine accurately and easily.

[0002]

2. Description of the Related Art A method currently generally used as a method for directly measuring the specific gravity of urine is the use of a device such as a urine specific gravity meter, a pycnometer, and a refractometer. These devices have achieved almost the required accuracy, but in order to maintain the accuracy, these devices require maintenance such as calibrating the scale and maintaining the cleaning management of the equipment, which takes time and effort. , There are many inconveniences.

Further, at the time of measurement, the amount of urine needs to be above a certain level and may be insufficient. Furthermore, it is difficult to read the scale due to bubbles on the liquid surface and the capillary phenomenon. As a solution to these problems, there is a dry test strip / test strip type dry test strip for measuring urine specific gravity, which is being widely used. Dip this test piece in urine,
"Dip and re" which compares the developed color with the colorimetric table
It can be easily measured by the "ad" method, and it can be simultaneously measured by combining it with other urine test items such as glucose, ketone bodies, proteins, hemoglobin, white blood cells, bilirubin, urobilinogen, pH, and ascorbic acid. It is very convenient because you can do it.

The reagent composition loaded on the test piece is as follows:
As disclosed in JP-A-55-101047, a weak electrolytic polymer obtained by partially neutralizing a conventional copolymer of methyl vinyl ether and maleic anhydride with sodium hydroxide is used.
A combination of H indicators was common. When this type is immersed in a test piece and a urine sample, H ^{+ of} a polymer acid group is ion-exchanged with a cation (Na ⁺ ) in urine to be released, resulting in a decrease in pH, which is a pH indicator. It is measured as a color shift.

Recently, as a means for improving the sensitivity and accuracy of color tone movement, a reagent composition and an impregnation test tool therefor have been proposed as disclosed in JP-A-4-315049 and JP-A-6-294790. It was In these methods, the ionic association (bonding) between the strongly electrolytic polymer anion and the dissociative dye cation does not depend on the pH of the test solution, and the salts (N
It is based on the influence of the presence of aCl) and the color shift corresponding to the amount of Na ⁺ .

[0006]

The urine specific gravity measuring test piece is a simple means of the "dip and read" method, and is indispensable in clinical practice as a screening means in the clinical stage. However, in reality, there is always a demand for the development of innovative means that are more excellent in sensitivity and accuracy. As one result of the inventor's earnest research, a novel principle that is completely different from the conventional measurement principle,
We have succeeded in developing a urine specific gravity measuring piece that exhibits excellent measurement performance, and have completed the present invention.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a urine specific gravity measuring test piece prepared by absorbing an impregnating solution containing a protein, a buffering agent and a pH indicator into a porous matrix and drying the solution. In this case, the protein is preferably selected from albumin, globulin, gelatin or casein, or a mixture thereof, and the concentration of the protein, buffer and pH indicator in the impregnating solution is 0.1 to 3 respectively. % (W /
v), 0.05-2 M (mol / l), and 0.1-2
It suggests that M (mol / l) and that filter paper is suitable as the porous matrix.

The present invention makes use of the fact that the "protein error method" generally used as a method for measuring protein in urine is affected by salt concentration. That is, the present invention is a dry test piece for measuring urine specific gravity, which is based on the principle of a competitive reaction between an anion in urine and a pH indicator in the presence of a protein, a buffer and a pH indicator. In the field of urine analysis, methods for measuring proteins using the "protein error method" are already known. It is also known that this "protein error method" is affected by salt concentration, especially anion (especially chloride) concentration. These are described, for example, in “Analytical Chemistry” Vol. 42 (1993) pp. 497-503.

The "protein error method" includes a charge equilibrium state due to a positively charged amino group of a protein and a negatively charged carboxyl group, and a charge equilibrium state due to a dissociation type and a non-dissociation type pH indicator. Coloring is seen due to the binding of. That is, the protein is in a charge-neutral state at an isoelectric point of pH, and is in a state in which the same number of positively charged amino groups and negatively charged carboxyl groups are present. When the pH is equal to or lower than the isoelectric point, the number of positively charged amino groups is increased and the whole is positively charged. On the other hand, when the pH is above the isoelectric point, the negatively charged carboxyl groups increase, and the protein is negatively charged as a whole.
Protein has multiple reaction sites, and dissociative anion pH
The indicator binds to the positively charged amino group. Coexisting anions in urine also bind to this positively charged amino group. That is, the urine anion and the dissociative anion pH indicator competitively react with the positively charged amino group of the protein.

Considering that the "protein error method", which is a method for measuring urine protein, is affected by salt concentration, it was examined whether it could be applied as a method for measuring urine specific gravity.
Surprisingly very good results were obtained. The present invention intends to produce a test piece for measuring urine specific gravity by utilizing the influence of salt concentration in the "protein error method". In the measurement of the specific gravity, it is preferable to set a condition in which the positively charged amino group of the protein and the dissociative anion pH indicator are easily bound to each other and easily released. For that purpose, the pH, the isoelectric point / amount / structure / charge of the substituent / molecular size of the protein, and the amount / structure / charge of the substituent / molecular size of the pH indicator are optimized.

The method of preparing the impregnating liquid, the method of impregnating the impregnating liquid, the selection of the porous matrix for the impregnation, and the like may be conventional methods. That is, water or / and alcohols such as methanol, ethanol, and isopropanol can be used as a solvent or a dispersion medium (hereinafter abbreviated as a solvent for impregnating liquid) of the reagent composition. As the porous matrix, any material can be used as long as it is a material that is physiologically inert to the solvent liquid for the impregnating liquid and has a large surface area per weight and reagent-carrying performance. Examples of these include various types such as natural and synthetic paper states, cloth states, open cells, granules, and granules, and filter paper is particularly preferable from the viewpoint of ease of handling, strength, and purity. .

The types of proteins that can be used include albumin, α-globulin, β-globulin, γ-globulin, gelatin and casein.
-Globulin is preferred. The protein concentration is preferably 0.1 to 3% (w / v) in the impregnating liquid state. Citric acid and phosphoric acid are suitable as the type of buffer solution that can be used, and the concentration is 0.05 to 2 M (mol / mol in the impregnating solution state).
1) is preferred. Further, the pH of the buffer solution may be equal to or lower than the isoelectric point of the protein. For example, when albumin is used as the protein, the isoelectric point is 4.9, so that the pH is 3 to
4.5 is preferred.

Any pH indicator can be used as long as it has a color change range below the isoelectric point of protein, such as bromphenol blue, bromcresol green, bromcresol purple, congo red and tetrabromophenol blue. , Bromxylenol blue, tetrabromophenolphthalein, methyl orange, etc., and the concentration is 0.1-2M in the impregnating liquid state.
(Mole / 1) is preferable.

In the dry test piece of the present invention, the first discoloration occurs when the protein, the buffer and the pH indicator are impregnated in the matrix layer and dried. At a constant pH, the negative charge or radical present in the pH indicator approaches the positive charge of the protein, and the dissociative pH indicator is generated, which
It is thought that this is because the indicator binds to the protein. And
Save in this state.

When reacting with salt-containing urine, a second discoloration occurs due to competition between the pH indicator bound to the protein and anion (especially chloride ion in the case of urine). This is probably because the pH indicator is released from the protein as a non-dissociative type when the anion concentration is high.
And this discoloration is measured. Examples will be shown below, but the present invention is not limited thereto.

[0016]

【Example】

Preparation of Impregnation Solution (Prescription) Bromcresol Green 20 mg Ethanol 15 ml 0.1 M Citrate Buffer (pH 3.5) 85 ml Bovine Serum Albumin 100 mg After preparing the impregnation solution with the above mixture, 15 × 15 c
m filter paper (manufactured by Whatman: 3MMchr)
Dry at 50 ° C. for 30 minutes. This was cut into 5 × 5 mm and attached to the tip of a 5 × 60 mm white polyethylene terephthalate plate using a double-sided tape to give a test piece. In order to show the usefulness of the test piece for measuring urine specific gravity of the present invention, a test was conducted using the test piece prepared as described above. Test method Specific gravity 1.000, 1.010, 1.020, 1.03
A sodium chloride aqueous solution adjusted to each level of 0 was prepared and used as a sample. The test piece previously prepared was immersed in this for 2 seconds, and the color of the pulled-up test piece was visually observed, and at the same time, it was measured with a color difference meter (Nippon Denshoku Industries Co., Ltd., Σ-90) at 620 nm
The reflectance at was measured. Test results The test results are shown in Table 1.

[0017]

[Table 1] Table 2 shows the relationship between the specific gravity value in Table 1 and the reflectance measured by a color difference meter. It can be seen that the specific gravity and reflectance of the test aqueous solution have a good proportional relationship.

[0018]

[Table 2]

[0019]

The present invention is based on a principle completely different from the conventional principle, and according to the present invention, a new urine specific gravity measuring test paper showing a good measurement result can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehiro Yamaguchi 57, Higashikujo Nishi-Ameracho, Minami-ku, Kyoto City Stock Company Kyoto Daiichi Kagaku

Claims (3)

[Claims] 1. A test piece for measuring urine specific gravity, which is produced by allowing an impregnating solution containing a protein, a buffer and a pH indicator to be absorbed in a porous matrix and then dried. 2. The test piece for measuring urine specific gravity according to claim 1, wherein the protein is selected from albumin, globulin, gelatin, and casein, or a mixture thereof. 3. The concentration of protein, buffer and pH indicator in the impregnating solution is 0.1 to 3% (w / v) and 0.0, respectively.
5-2M (mol / l), and 0.1-2M (mol / l)
The test piece for urine specific gravity measurement according to claim 1 or 2.