JPH08220052A - Method and instrument for measuring ion concentration and automatic chemical analyzer using the instrument - Google Patents

Abstract

PURPOSE: To improve the ion concentration measuring accuracy of a method and instrument for measuring ion concentration even when the ion concentration of a serum sample is abnormally high or abnormally low. CONSTITUTION: In an ion concentration measuring method in which the ion concentration of a sample to be measured composed of an electrolytic solution by using ion selective electrodes 5a, 5b, and 5c, the relation between the electromotive force and ion concentration of a calibrator solution having a known ion concentration is calculated by measuring the electromotive force of the solution and the ion concentration of the sample is corrected by using the correcting value of one of three samples for correction respectively having a known normal ion concentration value, high ion concentration value, and low ion concentration value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion concentration measuring method and apparatus for measuring the ion concentration in a sample to be measured using an ion selective electrode, and an automatic chemical analyzer using this apparatus.

[0002]

2. Description of the Related Art Conventionally, when measuring an ion concentration in an electrolyte solution such as blood or urine of a human body, a flow-through type multi-ion electrode as shown in a sectional view of FIG. 3 and a perspective view of FIG. A device using is used. This multi-ion electrode includes one reference electrode 3 and three ion-selective electrodes 5a, 5a, between the pair of insulating substrates 1a, 1b.
5b and 5c are arranged with the insulating spacers 7a, 7b and 7c interposed therebetween.

The ion-selective electrodes 5a, 5b, 5c are provided with lead wires 13a, which are led out to the outside, on the outer circumferences of ring-shaped conductive terminal plates 11a, 11b, 11c embedded in the electrode bodies 9a, 9b, 9c. 13b, 13c are connected, and ion sensitive layers 15a, 15b, 15c are formed on the inner peripheral sides of the electrode bodies 9a, 9b, 9c to which the inner peripheral sides of the conductive terminal plates 11a, 11b, 11c are connected. There is. Similarly to the ion-selective electrode 5, the reference electrode 3 has an electrode body 17, a conductive terminal plate 19, and a lead wire 21.
And an ion sensitive layer 23, respectively.

The pair of insulating substrates 1a, 1b, insulating spacers 7a, 7b, 7c and ion-sensitive layers 15a, 15
At the centers of b, 15c, and 23, through holes having the same diameter are formed so as to communicate with each other, and these through holes serve as a flow passage 25 to which the electrolyte solution is supplied.

Three ion-selective electrodes 5a, 5b, 5c
Are sensitive to specific ions in the electrolyte solution, such as sodium ions (Na ⁺ ), potassium ions (K ⁺ ), and chloride ions (Cl ⁻ ), respectively, and serve as sensitive materials for the ion sensitive layers 15a, 15b, and 15c. For sodium ion (Na ⁺ ) and potassium ion (K ⁺ ), a polymer film containing a crown ether derivative and valinomycin is known, and for chloride ion (Cl ⁻ ), silver chloride (AgCl) on a silver (Ag) electrode is known. ) It is known that the film is deposited by electric field.

When a serum sample, which is a sample to be measured, is supplied into the flow path 25 of the multi-ion electrode having such a configuration, each ion is independently provided between each ion-selective electrode 5a, 5b, 5c and the reference electrode 3. Electromotive force is generated. Therefore, it becomes possible to measure various ion concentrations by detecting this electromotive force.

The conversion of the electromotive force into the ion concentration is performed based on a calibration curve showing the correlation between the electromotive force and the ion concentration, which is created by measuring the electromotive force of a solution called a calibrator with various known ion concentrations. Be seen. Two types of calibrators, high density and low density, are used.

When the measurement of one sample is completed using the calibration curve as described above, a calibration solution having a known ion concentration similar to that of the normal value serum sample is supplied into the flow passage 25, and the potentials of various ion electrodes ( Voltage) calibration is performed. Here, since each component of the calibrator and the calibration solution is not the same as the serum sample in which various substances are mixed due to problems such as manufacturing cost, when the ion concentration is converted using these solutions, Data divergence (deviation in accuracy) may occur. It is considered that this is because the ion electrode responds by being disturbed by a substance in the serum sample.

Therefore, in order to eliminate this effect, the concentration of a control serum for correction, which is a correction sample having a known ion concentration of about the same level as that of a normal value serum sample, is further measured. The difference is corrected as data to correct the ion concentration of the sample to be measured.

[0010]

However, when the correction is performed using the correction sample having the same ion concentration as that of the normal value serum sample as described above, the serum sample in the vicinity of the normal value concentration is Although there are no particular problems, the correction when measuring serum samples with abnormally high or abnormally low values is not sufficient, and the corrected measurement data shows higher values for samples with abnormally high values and those for samples with abnormally low values. Occasionally, it was empirically seen that lower values were shown, and there was a problem in measurement accuracy. Therefore, it is an object of the present invention to improve the measurement accuracy of the ion concentration even when the sample to be measured has an abnormally high or extremely low ion concentration.

[0011]

In order to achieve the above-mentioned object, the present invention uses an ion-selective electrode which generates an electromotive force corresponding to an ion concentration when a sample to be measured is brought into contact with the sample to be measured. In the ion concentration measuring method for measuring the ion concentration, the electromotive force of a solution having a known ion concentration is obtained by the ion-selective electrode, and the correlation between the electromotive force and the ion concentration is calculated in advance, and this is calculated. Based on the correlation, the ion concentration in the sample to be measured is obtained from the electromotive force of the sample to be measured measured by the ion selective electrode, and a plurality of different known ion concentrations for correcting the obtained ion concentration are corrected. The electromotive force of the sample is measured by the ion-selective electrode, and the ion concentration of each is calculated from the measured electromotive force based on the calculated correlation. The difference between each of the calculated ion concentrations of the correction sample and each known concentration is calculated as a correction value, and the ion concentration in the measured sample obtained using any one of the correction values is calculated. This is a method for measuring the ion concentration to be corrected.

[0012]

According to such an ion concentration measuring method, according to the ion concentration in the sample to be measured obtained based on the relationship between the electromotive force and the ion concentration, each correction value by the correction sample having a plurality of different known ion concentrations is obtained. By correcting the ion concentration data in the sample to be measured using any of the above, the corrected measurement data becomes accurate even if the ion concentration has an abnormally high value or an abnormally low value.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the overall configuration of an ion concentration measuring apparatus to which an ion concentration measuring method showing an embodiment of the present invention is applied. This concentration measuring device includes a multi-ion electrode 27 having a structure similar to that shown in FIG. Tubes 29 and 31 are connected to the openings of the flow paths 25 in the insulating substrates 1a and 1b at both ends of the multi-ion electrode 27, and a sample to be measured, for example, serum circulates in the direction of arrow A.

Each lead wire 13a, 13b, 13c led out from the ion selective electrodes 5a, 5b, 5c is connected to one input terminal of each of the three amplifiers 33a, 33b, 33c, and each amplifier 33a, 33b, The lead wire 21 led out from the comparison electrode 3 is connected to the other input terminal of each of 33c. Each of the amplifiers 33a, 33b, 33c amplifies the difference between the electromotive force output from the comparison electrode 3 and the electromotive force output from each of the ion selective electrodes 5a, 5b, 5c.

The operation unit 35 includes amplifiers 33a, 33b,
In response to the input of the output signal of 33c, sodium ion (N
a ⁺ ), potassium ion (K ⁺ ) and chlorine ion (C
Each of the concentrations of l ⁻ ) is calculated, and the display unit 37 displays the calculated various ion concentrations.

Using the ion concentration measuring device having such a configuration, the ion concentration in the sample to be measured is measured by the following procedure. First, two kinds of calibrator solutions with known various ion concentrations (low concentration and high concentration) are applied to the multi-ion electrode 27.
And the electromotive force is measured a plurality of times. Every time one measurement is performed, a calibration solution having a known ion concentration approximately the same as the concentration of the normal value serum sample is supplied into the flow passage 25 to calibrate the potentials of various ion electrodes. A calibration curve is created from the relationship between the electromotive force of each calibrator whose potential has been calibrated using the calibration liquid and the known ion concentration.

Next, a medium-concentration control serum having an ion concentration almost equal to that of a normal-value serum sample, a high-concentration control serum having an ion concentration in an abnormally high value region, and a low-concentration control serum having an ion concentration in an abnormally low value region. Three types of correction samples with serum are supplied into the flow passage 25, the electromotive forces of these three types of correction samples are measured, and the ion concentration of each correction sample is obtained from the calibration curve. The differences between the obtained ion concentrations of the three types of correction samples and the known concentrations are respectively calculated, and these differences are used as the normal value concentration correction value P _M , the high concentration correction value P _H, and the low concentration The correction value P _L is stored in each of the memories built in the calculation unit 35.

The measurement of the serum sample is started only after the above operation is completed. When the serum sample is supplied into the flow passage 25 of the multi-ion electrode 27, electromotive force corresponding to various ion concentrations in serum is generated, and various ion concentrations are obtained from the calibration curve created by the calibrator measurement.

Among the various ion concentrations thus obtained, some items, for example, the concentration of sodium ion (Na ⁺ ) shows an abnormally high value, and other items, for example, potassium ion (K ⁺ ).
⁺⁾ And chlorine ions (Cl ^-) if showed normal values for Na ⁺ performs correction of the data by using the high density correction value P _H calculated from the control sera abnormally high area density, other For the item, the data is corrected using the normal value concentration correction value P _M calculated from the normal value control serum. Further, for ions showing an abnormally low value concentration, the data is corrected using the low concentration correction value P _L calculated from the control serum having an abnormally low value region concentration.

As described above, by correcting the measurement data using the correction value of the control serum having the concentration closest to the measured value concentration of each item of the serum sample, not only for the serum sample having the normal value concentration, The accuracy of measurement data is also improved for serum samples with abnormally high and extremely low values.

In the above embodiment, the correction values P _M , P _H and P _L for normal density, high density and low density are used.
Although the data is corrected by using, the correction calibration curve showing the relationship between each of these correction values P _M , P _H and P _L and the known concentration value of the control serum was prepared, and the serum sample was measured. The correction may be performed using the correction value obtained by comparing the various ion concentrations calculated in step 1 with this correction calibration curve.

In the above examples, three types of correction control sera were used.
The type may be different, and the correction serum concentration value is not particularly limited.

FIG. 2 is a perspective view showing the outline of an automatic chemical analyzer equipped with the ion concentration measuring device as described above. This automatic chemical analyzer is for analyzing serum collected from a human body, and includes a sample section 41 having a plurality of sample containers 39 containing a sample to be measured such as serum and a reagent corresponding to a test item. It is provided with a reagent section 45 having a reagent tube 43 inserted for each type, and a reaction section 49 having a plurality of reaction tubes 47 for reacting the sample to be measured by mixing the sample to be measured and the reagent.

The sample section 41 is provided with a sample dispensing section 51 for supplying the sample solution in the sample container 39 to the reaction tube 47, and the reagent section 45 is provided with the reagent contained in the reagent tube 43. A reagent dispensing unit 53 that supplies the reagent to the unit 47 is provided. The reaction unit 49 includes a stirring unit 55 for stirring the sample to be measured and the reagent contained in the reaction tube 47, and the ion concentration measuring device shown in FIG. 1 for measuring the ion concentration of the sample to be stirred. An ion concentration measuring unit 57 having the above and a cleaning tank 59 for cleaning the reaction tube 47 are provided.

The ion concentration measuring section 57 has a suction nozzle 57.
a is provided, the sample to be measured including serum is sucked from the reaction tube 47 by the suction nozzle 57a, the sample is circulated through the flow hole 25 of the multi-ion electrode 27 incorporated in the ion concentration measuring device, and the ion concentration is measured. It

[0026]

As described above, according to the present invention, a plurality of different known ion concentration correcting samples are prepared according to the ion concentration in the sample to be measured, which is obtained based on the relationship between the electromotive force and the ion concentration. Since the ion concentration data in the sample to be measured is corrected using any of the correction values of the above, even if the sample to be measured has an abnormally high or abnormally low ion concentration, the corrected measured data will be accurate. Can be one.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the overall configuration of an ion concentration measuring apparatus to which an ion concentration measuring method according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view showing an outline of an automatic chemical analysis device equipped with the ion concentration measuring device of FIG.

FIG. 3 is a cross-sectional view of a multi-ion electrode in an ion concentration measuring device.

FIG. 4 is a perspective view of the multi-ion electrode of FIG.

[Explanation of symbols]

 5a, 5b, 5c Ion-selective electrode 27 Multi-ion electrode 35 Operation unit

Claims (5)

[Claims] 1. An ion concentration measuring method for measuring an ion concentration in a sample to be measured using an ion-selective electrode that generates an electromotive force corresponding to the ion concentration when the sample to be measured is brought into contact with the sample. The electromotive force of the resulting solution is calculated by the ion-selective electrode, and the correlation between the electromotive force and the ion concentration is calculated in advance. Based on the calculated correlation, the measurement target measured by the ion-selective electrode Obtaining the ion concentration in the sample to be measured from the electromotive force of the sample, the electromotive force of the correction sample of a plurality of different known ion concentration for correcting the obtained ion concentration is measured by the ion-selective electrode, Each ion concentration is calculated based on the calculated correlation from each measured electromotive force, and each ion concentration and each known concentration of the calculated correction sample Is calculated as a correction value, and the ion concentration in the sample to be measured thus obtained is corrected using any one of the correction values. 2. A plurality of correction samples with different known ion concentrations have three types of high, medium, and low ion concentrations, and the correction values obtained by these three types of correction samples are used as the high ion concentration of the sample to be measured. The method for measuring ion concentration according to claim 1, wherein the method is used in correspondence with medium and low. 3. A calibration curve showing the relationship between each correction value by three types of correction samples having high, medium, and low ion concentrations and each known ion concentration value of the three types of correction samples is prepared, The ion concentration measuring method according to claim 2, wherein the ion concentration in the sample to be measured is corrected based on the created calibration curve. 4. An ion selective electrode for generating an electromotive force corresponding to an ion concentration when a sample to be measured is brought into contact, and an arithmetic unit for calculating an ion concentration corresponding to an electromotive force generated at this ion selective electrode. Then, this calculation unit corrects the ion concentration in the sample to be measured, which is obtained based on the relationship between the electromotive force and the ion concentration of the solution whose ion concentration is known in advance, by each of the correction samples of different known ion concentrations. An ion concentration measuring device, characterized in that the correction is performed using any of the values. 5. A sample part having a plurality of sample containers containing a sample to be measured, a reagent part having a reagent tube containing a reagent corresponding to a test item for each type, and the sample to be measured and the reagent. 5. An automatic chemical analyzer comprising: a reaction part having a plurality of reaction tubes for mixing and reacting a sample to be measured, wherein the ion concentration measuring device according to claim 4 is used in the reaction part. Automatic chemical analyzer.