JP3810534B2 - Hematocrit value measuring element and method for measuring hematocrit value - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an element for measuring a hematocrit value, and a method for measuring a hematocrit value using the element.
[0002]
[Prior art]
The hematocrit value in whole blood is called the red blood cell volume ratio and is used to diagnose anemia or polycythemia. At present, the hematocrit value is measured by injecting blood into a glass tube, centrifuging at 12,000 revolutions per minute for 4 to 5 minutes, and measuring the relative ratio of the separated blood cell parts.
It is also possible to calculate from the hemoglobin concentration determined using an apparatus that automatically measures the number of red blood cells or a reagent that quantifies the hemoglobin concentration.
[0003]
[Problems to be solved by the invention]
According to the conventional method for measuring the hematocrit value, a high-speed centrifuge is required, and it has not been possible to easily measure anywhere regardless of location.
Accordingly, an object of the present invention is to provide an element for quickly and easily measuring a hematocrit value in blood and a measuring method using the element.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the hematocrit value measuring element of the present invention includes an electrically insulating substrate, an electrode system including at least two electrodes formed on the substrate, and a reagent layer, and the reagent layer includes: It is characterized by containing an acid dissociation index pK of 2 to 11 and solid acid at normal temperature in an amount of 10 to 100 mM when dissolved in about 1 drop of a sample to be measured.
In order to measure the hematocrit value using this measuring element, the step of adding a blood sample to the reagent layer and the electrical conductivity or electrical resistance between the two electrodes are measured.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a plan view showing a schematic configuration of a hematocrit value measuring element of the present invention. Reference numeral 1 denotes an electrically insulating substrate made of polyethylene terephthalate. A conductive paste is printed on the substrate 1 by screen printing to form lead portions 2 and 3 and two electrode portions 4 and 5. Further, an electric insulating paste 6 is printed by screen printing so as to partially cover the leads to form the electric insulating layer 6, and the areas of the exposed portions of the electrodes 4 and 5 are made constant.
A reagent layer 7 is preferably formed on this substrate so as to cover the electrodes 4 and 5.
[0006]
When the blood sample is supplied to the reagent layer 7 on the substrate, the acid in the reagent layer is dissolved, and the hydrogen ion concentration in the sample solution increases. However, due to the strong buffering action of the imidazole group present in the hemoglobin molecule in blood cells, some hydrogen ions are trapped on the nitrogen atom of the imidazole ring. Since the electrical conductivity of the blood sample is governed by the dissolved ion concentration rather than the blood cell volume, the electrical conductivity of the blood sample is reduced by the buffering action.
On the other hand, since the buffering action becomes stronger as the blood cell volume, that is, the hematocrit value increases, the hematocrit value can be obtained based on the measurement of conductivity.
[0007]
As the acid used here, an acid dissociation index of 2 to 11 defined by pK = −log K when the equilibrium constant is K and a solid acid at normal temperature is suitable. In addition, the amount of acid contained in the reagent layer is an amount that dissolves in about one drop of the sample supplied to the reagent layer, usually blood, to a concentration of 10 to 100 mM.
Examples of the acid used in the element for measuring hemagrit according to the present invention include gluconic acid, citric acid, 2- (N-morpholino) ethanesulfonic acid, and sodium dihydrogen phosphate shown in the following examples, as well as malic acid and oxalic acid. An aliphatic carboxylic acid such as tartaric acid or an aromatic carboxylic acid such as benzoic acid can be used.
[0008]
The reagent layer can contain a hydrophilic polymer. The hydrophilic polymer promotes dissolution of the reagent layer and serves as an acid carrier. Suitable hydrophilic polymers include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxyethyl methyl cellulose, polyvinyl pyrrolidone, polyvinyl alcohol, gelatin and derivatives thereof, acrylic acid and its salts, methacrylic acid and its polymers, starch And one or more selected from polymers of maleic anhydride and salts thereof.
[0009]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
After forming the lead portions 2 and 3, the electrode portions 4 and 5, and the electrical insulating layer 6 on the electrically insulating substrate 1 made of polyethylene terephthalate as shown in FIG. 1, so as to cover the electrode portions 4 and 5, 5 microliters of the solution which melt | dissolved 20 micromol of gluconic acids in 1 milliliter of water was dripped, and it was made to dry for 10 minutes in a 50 degreeC warm air dryer, and the reagent layer 7 was formed.
Blood was supplied to the reagent layer 7 of the hematocrit value measuring element having such a configuration. The hematocrit value of the blood used here is 25%, 35%, 45%, or 55%. When the electrical conductivity between the electrodes 4 and 5 was measured 10 seconds after the blood supply, there was a correlation as shown in FIG. 2 between the hematocrit value and the resistance value between the electrodes.
[0010]
Example 2
To the electrode part formed in the same manner as in Example 1, 5 microliters of a solution in which 30 micromoles of citric acid was dissolved in 1 milliliter of water was dropped, and dried in a hot air dryer at 50 ° C. for 10 minutes to form the reagent layer 7 Formed.
FIG. 2 shows the relationship between the resistance value measured in the same manner as in Example 1 and the hematocrit value.
[0011]
Example 3
To the electrode portion formed in the same manner as in Example 1, 5 microliters of a solution of 10 micromol of 2- (N-morpholino) ethanesulfonic acid dissolved in 1 milliliter of water was dropped, and in a hot air dryer at 50 ° C. The reagent layer 7 was formed by drying for 10 minutes. FIG. 2 shows the relationship between the resistance value measured in the same manner as in Example 1 and the hematocrit value.
[0012]
Example 4
5 microliters of the solution which melt | dissolved 30 micromoles sodium dihydrogenphosphate in 1 milliliter of water was dripped at the electrode part formed like Example 1, and it was made to dry for 10 minutes in a 50 degreeC warm air dryer. Reagent layer 7 was formed.
FIG. 2 shows the relationship between the resistance value measured in the same manner as in Example 1 and the hematocrit value.
[0013]
【The invention's effect】
As described above, according to the present invention, the hematocrit value in blood can be measured easily and rapidly.
[Brief description of the drawings]
FIG. 1 is a plan view showing a schematic configuration of a hematocrit value measuring element according to an embodiment of the present invention.
FIG. 2 is a diagram showing a relationship between a resistance value and a hematocrit value measured in Examples.
[Explanation of symbols]
1 Electrically Insulating Substrate 2, 3 Lead 4, 5 Electrode 6 Electrical Insulating Layer 7 Reagent Layer

Claims (2)

An electrical insulating substrate, an electrode system including at least two electrodes formed on the substrate, and a reagent layer are provided, and the reagent layer is supplied with an acid dissociation index pK of 2 to 11 and a solid acid at room temperature. An element for measuring a hematocrit value, which is contained in an amount of 10 to 100 mM when dissolved in a sample to be measured. Using a hematocrit value measuring element comprising an electrically insulating substrate, an electrode system including at least two electrodes formed on the substrate, and a reagent layer containing a solid acid at room temperature, a blood sample is added to the reagent layer A method of measuring a hematocrit value, comprising: dissolving the acid in a blood sample at a concentration of 10 to 100 mM; and measuring the conductivity or electrical resistance between the two electrodes.

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