Electrolyte concentration analysis device and electrolyte concentration analysis method

Abstract

The purpose of the present invention is to detect that an unsuitable reagent has been placed in an electrolyte concentration analysis device. This electrolyte concentration analysis device: calculates a first ratio between an electromotive force of a sample having a known concentration and an electromotive force of a reagent, if one type of ion selective electrode is used; calculates a second ratio between electromotive forces of the reagent, if two types of ion selective electrodes are used; and uses the first ratio and the second ratio to determine whether the reagent is normal (see fig. 2).

Description

Electrolyte concentration analyzer, electrolyte concentration analysis method

[0001] The present invention relates to an electrolyte concentration analyzer.

[0002] Automated analyzers are known as devices for analyzing biological samples such as blood and urine. An electrolyte concentration analyzer is installed in the automated analyzer. The electrolyte concentration analyzer is configured to analyze electrolyte components, such as sodium (Na), potassium (K), and chlorine (Cl), in the sample.

[0003] Many of these electrolyte concentration analyzers use a method known as the ion-selective electrode method (ISE method). The ISE method measures the electrolyte concentration in a sample by measuring the potential difference between an ion-selective electrode (ISE) and a reference electrode. The ion-selective electrode has an ion-sensitive membrane that generates a potential difference in response to ionic components.

[0004] This potential varies depending on the electrolyte concentration in the sample. To maintain a reference potential, the reference electrode is configured to be in contact with a solution called a reference electrode solution. For example, a high-concentration KCl solution is used as the reference electrode solution.

[0005] To achieve high throughput, a flow cell type device can be formed as an ion-selective electrode or reference electrode. In this flow cell type device, a flow channel for supplying the sample to be measured is provided inside the housing, and a sensitive membrane is provided in contact with the flow channel.

[0006] In clinical testing, known methods for quantifying the concentrations of electrolytes contained in biological samples (blood, particularly serum, plasma, urine, etc.) include the non-dilution method and the dilution method. In the non-dilution method, the biological sample is measured as a specimen without dilution. In the dilution method, a predetermined amount of biological sample is diluted with a predetermined amount of diluent, and the diluted biological sample is measured by the ISE method or the like. The dilution method requires a small amount of sample liquid, has low concentrations of coexisting substances such as proteins and lipids in the measurement liquid, and is less susceptible to contamination by coexisting substances, making it possible to achieve high stability in the ISE method.

[0007] The current mainstream measurement method for electrolyte concentration analyzers used in biological testing is a combination of the flow cell ISE method and the dilution method. A container called a dilution tank is used to dilute the sample. The diluted biological sample prepared in the dilution tank is sent through piping to a flow cell-type ion-selective electrode for measurement.

[0008] An electrolyte concentration analyzer typically uses multiple reagents, such as (a) a calibrator used for calibration, (b) a cleaning solution for cleaning the ion-selective electrodes, and (c) a maintenance reagent for adjusting the electrodes, flow paths, and sample dispensing mechanism.

[0009] The reagent is manually replenished to a predetermined position in the device. However, this operation is prone to human error. In Patent Document 1, as a method for confirming that the reagent has been properly installed, the ratio of the electromotive force of one electrolyte item between the installed reagent and a liquid with a known electrolyte concentration is compared with a reference range.

[0010] EP2458389

[0011] Human error when placing reagents on the device can lead to improper maintenance such as cleaning, which can result in incorrect data. Specifically, this can include cases where different reagents are mixed by diluting or refilling the reagent, concentrating the reagent by leaving it on the device for a long period of time, or pouring another liquid into the container without cleaning it. The method described in Patent Document 1 may not be able to detect such improper placement of reagents.

[0012] The present invention has been made in view of the above-mentioned problems, and has an object to detect that an inappropriate reagent has been installed in an electrolyte concentration analyzer.

[0013] The electrolyte concentration analyzer of the present invention calculates a first ratio between the electromotive force of a sample of known concentration and the electromotive force of a reagent when one type of ion selective electrode is used, and calculates a second ratio between the electromotive forces of the reagents when two types of ion selective electrodes are used, and uses the first ratio and the second ratio to determine whether the reagent is normal.

[0014] The electrolyte concentration analyzer according to the present invention can detect that an inappropriate reagent has been installed. Other objects, configurations, advantages, etc. of the present invention will become apparent from the following description of the embodiments.

[0015] 1 is a schematic diagram showing a general configuration of an electrolyte concentration analyzer 1000 according to embodiment 1. FIG. 2 is a flowchart for detecting that a reagent has been improperly placed in section A1301. FIG. 3 is a flowchart for detecting that a reagent has been improperly placed in section B1302. FIG. 4 shows an example of a determination using the reagent ratio and the flowchart. FIG. 5 is a flowchart for an electrolyte concentration analyzer 1000 according to embodiment 2 to detect that a reagent has been improperly placed in section B1302. FIG. 6 shows an example of a determination using the reagent ratio and the flowchart of FIG.

[0016] 1 is a schematic diagram showing a general configuration of an electrolyte concentration analyzer 1000 according to a first embodiment of the present invention. The electrolyte concentration analyzer 1000 is an electrolyte concentration analyzer equipped with a flow cell type ion selective electrode.

[0017] The measurement control device 1100 (control device) functions as a measurement unit that controls measurements in the electrolyte concentration analyzer 1000 and as a control unit that controls various controls based on the measurement results. The measurement control device 1100 also functions as a display control unit that controls the display of measurement results, etc. on the display unit 1110. The display unit 1110 displays (measurement results, warnings, etc.) based on the received data.

[0018] The dilution tank 1010 is a container to which a diluted specimen liquid, which is a mixture of a specimen and a diluent, or an internal standard liquid is supplied. The diluted specimen liquid and the internal standard liquid are alternately supplied to the dilution tank 1010, whereby measurement of the diluted specimen liquid and measurement of the internal standard liquid are alternately performed.

[0019] The specimen supply unit 1020 supplies specimen containers 1022 mounted on a specimen mounting table 1021 to a specimen dispensing mechanism 1023. The specimen dispensing mechanism 1023 has a function of aspirating specimens from the specimen containers 1022 and dispensing them into the dilution tank 1010. The diluent dispensing mechanism 1030 is a device for dispensing diluent from a diluent tank 1031 to the dilution tank 1010 via a diluent flow path 1032. The internal standard dispensing mechanism 1040 has a function of dispensing an internal standard 1043 from the internal standard tank 1041 to the dilution tank 1010 via the internal standard flow path 1042.

[0020] The liquid delivery mechanism 1050 performs a pumping operation to draw the diluted specimen liquid or internal standard liquid from the dilution tank 1010 toward the ion selective electrodes 1071 to 1073, and also has the function of drawing the ionic solution or reference electrode liquid from the liquid junction 1080 and disposing of it in a waste liquid reservoir 1052. The reference electrode liquid delivery mechanism 1060 is configured to draw the reference electrode liquid from a reference electrode liquid tank 1061 and deliver it to the reference electrode 1090 via a reference electrode liquid flow path 1062.

[0021] The Cl ion selective electrode 1071, the K ion selective electrode 1072, and the Na ion selective electrode 1073 are supplied with diluted analyte solution or internal standard solution from a dilution tank 1010. On the other hand, the reference electrode 1090 is supplied with reference electrode solution from a reference electrode solution delivery mechanism 1060. A liquid junction 1080, which serves as a passage for the diluted analyte solution and reagent in the flow cell system, is provided between the Cl ion selective electrode 1071, the K ion selective electrode 1072, or the Na ion selective electrode 1073 and the reference electrode 1090.

[0022] The waste liquid mechanism 1200 has a function of opening an electromagnetic valve 1201 to discharge the liquid through a waste liquid flow path 1202 when disposing of the liquid in the dilution tank 1010 .

[0023] The reagent holder 1300 has a section A 1301 and a section B 1302. A reagent container A 1311 is installed in the section A 1301. The reagent container A 1311 is intended to contain reagent A. A reagent container B 1312 is installed in the section B 1302. The reagent container B 1312 is intended to contain reagent B.

[0024] As another method for supplying the reagent, the reagent may be loaded from the sample supply unit 1020 onto the sample loading stage 1021 and then transported to the sample dispensing mechanism 1023. In this case, the sample loading stage 1021 serves as a compartment where the reagent is placed.

[0025] 2 is a flowchart for detecting that a reagent has been improperly placed in section A 1301. Each step in FIG. 2 will be described below.

[0026] (FIG. 2: Step S210: Part 1) The specimen dispensing mechanism 1023 collects the reagent in the reagent container A1311 installed in the section A1301 and dispenses it into the dilution tank 1010. The electromotive force is measured by the flow cell type ion selective electrodes 1071-1073 through the measurement solution suction nozzle 1051. The measurement control device 1100 calculates the electromotive force Na Ｓ and Na ＩＳ and calculate the ratio (Ratio 1) using Equation 1: Ratio 1 = Na Ｓ / Na ＩＳ ...Formula 1

[0027] (FIG. 2: Step S210: Part 2, S230) The measurement control device 1100 compares Ratio 1 with the reference range for the reagent (reagent A) that should be installed in section A 1301. If it is outside the reference range (S210: NO), it determines that there is an abnormality and outputs a message requesting that reagent A be replaced (S230). If it is within the reference range, proceed to S220.

[0028] (FIG. 2: Step S210: Supplement) The sample with a known electrolyte concentration is, for example, an internal standard solution 1043. The internal standard solution 1043 is supplied to the dilution tank 1010 by the internal standard solution dispensing mechanism 1040, and its electromotive force (Na ＩＳ The reference range is either stored in advance in the measurement control device 1100, or an electrolyte concentration calculated in advance from an electromotive force measured using an appropriate reagent A is used. In the latter case, the reference range is set to a value that can be determined from the electrolyte concentration.

[0029] (FIG. 2: Step S220: Part 1) The measurement control device 1100 measures the electromotive forces of any two electrolyte items in the reagent in the reagent container A1311, and calculates the ratio (ratio 2) using Equation 2. Here, the ratio of two items, Na and K, is calculated as follows: Ratio 2 = Na Ｓ / K Ｓ ...Formula 2

[0030] (FIG. 2: Steps S220: Part 2 to S240) The measurement control device 1100 compares Ratio 2 with the reference range for the reagent (reagent A) that should be installed in section A 1301. If it is outside the reference range (S220: NO), it is determined to be abnormal, and a message requesting that reagent A be replaced is output (S230). If it is within the reference range (S220: YES), it is determined to be normal, and the remaining amount of reagent A is updated (S240).

[0031] (FIG. 2: Step S240: Supplement) The remaining amount of reagent is confirmed, for example, by the liquid level detection function of the sample dispensing mechanism. The liquid level detection function detects the liquid level by detecting electrical characteristics such as capacitance and resistance that change when the sample dispensing probe 1024 at the tip of the sample dispensing mechanism 1023 comes into contact with or approaches the liquid level.

[0032] 3 is a flowchart for detecting that a reagent has been improperly placed in section B 1302. For the reagent in section B 1302, reference ranges for reagent-specific ratios 1 and 2 are also defined, and the same processing as in FIG. 2 is performed.

[0033] Figure 4 shows an example of a determination using the reagent ratios and the above flowchart. A case where a determination is made as normal will be explained. When normal reagent A is placed in section A 1301, both ratio 1 and ratio 2 are within the reference range in the flowchart of Figure 2, and it is determined to be normal. When normal reagent B is placed in section B 1302, both ratio 1 and ratio 2 are within the reference range in the flowchart of Figure 3, and it is determined to be normal.

[0034] A case where the determination of ratio 1 results in an abnormality will be described. When normal reagent A is placed in section B1302, ratio 1 is outside the standard range in the flowchart of Figure 3, and it is determined to be abnormal. When reagent B that is 30 times concentrated is placed in section B1302, ratio 1 is outside the standard range in the flowchart of Figure 3, and it is determined to be abnormal. When reagent B that is 10 times diluted is placed in section B1302, ratio 1 is outside the standard range in the flowchart of Figure 3, and it is determined to be abnormal.

[0035] A case will be described where ratio 1 is judged to be normal and ratio 2 is judged to be abnormal. When reagent A is diluted 30 times and placed in section B 1302, in the flowchart of FIG. 3, ratio 1 is within the standard range but ratio 2 is outside the standard range, so it is judged to be abnormal. When reagent B is concentrated 30 times and placed in section A 1301, in the flowchart of FIG. 2, ratio 1 is within the standard range but ratio 2 is outside the standard range, so it is judged to be abnormal. When reagent A is filled into a container in which reagent B has been concentrated and dried and placed in section A 1301, in the flowchart of FIG. 2, ratio 1 is within the standard range but ratio 2 is outside the standard range, so it is judged to be abnormal.

[0036] In the third example from the right in FIG. 4 , reagent A was placed in section B1302, so it would normally be clear that it was an incorrect reagent when determining ratio 1. However, in this example, reagent A was diluted 30 times before being placed in section B1302, which resulted in the determination process corresponding to section B1302 (flowchart in FIG. 3 ) being performed, and determination was made based on the numerical range of reagent B. As a result, ratio 1 accidentally fell within the normal range. As a result, ratio 1 was erroneously determined to be normal, but ratio 2 was abnormal, so it was ultimately possible to detect that an incorrect reagent had been placed. In the second example from the right in FIG. 4 , reagent A (diluted) and reagent B (concentrated) are swapped compared to the third case from the right, but the concept is similar. The measurement control device 1100 may output a determination result indicating that the ratio 1 check was accidentally passed.

[0037] In the first example from the right in Figure 4, reagent A and reagent B are mixed in a container. However, it is reagent A that generates the majority of the electromotive force of Na, and reagent B has only a slight effect on the electromotive force of Na. As a result, ratio 1 was erroneously determined to be normal, but ratio 2 was abnormal, so it was ultimately possible to detect that an incorrect reagent had been installed.

[0038] In this way, determining ratio 1 can detect cases where a normal reagent is installed in the wrong position, or where it is concentrated or diluted. Determining ratio 2 can detect cases where a reagent is added to an inappropriate container, where a concentrated or diluted reagent is installed in the wrong compartment, or where different reagents are mixed. By using both ratio 1 and ratio 2, it is possible to detect all cases of improper installation. In addition to the determination result of whether or not the reagent is normal, the measurement control device 1100 may output a message indicating the possible cause of such an abnormality.

[0039] 5 is a flowchart for an electrolyte concentration analyzer 1000 according to a second embodiment of the present invention to detect that a reagent has been improperly placed in section B1302. The configuration of the electrolyte concentration analyzer 1000 is the same as that of the first embodiment. S510 to S520 are the same as S310 to S320 in FIG. 3, but if the condition is met in S520, S530 is further executed.

[0040] (FIG. 5: Step S530: Part 1) The measurement control device 1100 measures the electromotive forces of any two electrolyte items in the reagent in the reagent container B1312 and calculates the ratio (Ratio 3) using Equation 3. The electrolyte items in this step are different from those in S520. Since the ratio of two items, Na and K, was calculated in S520, the ratio of Cl and K was calculated in this step: Ratio 3 = Cl Ｓ / K Ｓ ...Formula 3

[0041] (FIG. 5: Step S530: Part 2) The measurement control device 1100 compares Ratio 3 with the reference range for the reagent (reagent B) that should be installed in section B 1302. If it is outside the reference range (S530: NO), it is determined to be abnormal and a message requesting that reagent B be replaced is output (S540). If it is within the reference range (S530: YES), it is determined to be normal and the remaining amount of reagent B is updated (S550).

[0042] (Figure 5: Supplement) When calculating ratio 3, the electrolyte concentration calculated from the electromotive force may be used. In this case, the reference range in this step is set to a value that can be determined based on the electrolyte concentration. For reagents in sections other than section B1302, a similar normality determination can be made using ratios 1 to 3 specific to each reagent. In addition to ratio 3, ratio 4 may be calculated and a normality determination may be made based on this. Ratio 4 is calculated for two electrolyte items different from ratios 1 to 3. The measurement control device 1100 may set electrodes to be used in calculating ratios 2 and 3 for each type of reagent in each section. Furthermore, it may be possible to select whether or not to use ratio 3 for each type of reagent in each section.

[0043] 6 shows an example of a determination using the reagent ratios and the above flowchart. A case where a determination is made that the reagent is normal will be described. When normal reagent B is placed in section B1302, in the flowchart of FIG. 5, ratios 1, 2, and 3 are all within the reference range, and the reagent is determined to be normal.

[0044] A case in which an abnormality is determined will be explained. When normal reagent C is placed in section B1302, in the flowchart of Figure 5, although ratio 1 and ratio 2 are within the reference range, ratio 3 is outside the reference range, and therefore it is determined to be abnormal. If reagent C is placed in section B1302 and determination is made using the flowchart of Figure 3 of embodiment 1, since ratio 1 and ratio 2 are within the reference range, it is determined to be normal, and an installation error cannot be detected.

[0045] Specifically, by placing reagent C in section B1302, the judgment criteria corresponding to section B1302 (flowchart in FIG. 5) are implemented, and the normal ranges for ratios 1 and 2 in the judgment criteria coincidentally match the ratios of reagent C. As a result, ratios 1 to 2 are erroneously judged as normal, but ratio 3 is abnormal, so it is ultimately possible to detect that an incorrect reagent has been placed. The measurement control device 1100 may output a judgment result indicating that the checks for ratios 1 to 2 have been passed by chance.

[0046] The reasons why reagent C is abnormal may be any of the following: the wrong reagent was placed in section B1302; the concentration of the reagent placed in section B1302 is incorrect; the wrong reagent was placed in the wrong section; or the correct reagent and the wrong reagent are mixed. In addition to the determination result of whether the reagent is normal or not, the measurement control device 1100 may output a message indicating the possible cause of such abnormality.

[0047] In this way, in the third embodiment, by adding the determination of ratio 3 in addition to ratios 1 and 2, it is possible to detect improper placement of a reagent more accurately than in the first embodiment.

[0048] <Regarding Modifications of the Present Invention> In the above embodiment, an example has been described in which the electromotive force of Na and the electromotive force of K are used to calculate ratio 2. This is because reagents containing large amounts of Na and Cl, such as sodium hypochlorite, are often used as cleaning solutions, and using the ratio of Na and K, which have a large difference in concentration or electromotive force, makes it easier to indicate the characteristics of the reagent to be evaluated.

[0049] In the above embodiment, it has been described that S210 is performed using the Na ion selective electrode 1073, and S220 is performed using the Na ion selective electrode 1073 and the K ion selective electrode 1072. It is not necessary to use a common ion selective electrode between S210 and S220; it is sufficient to use two types of ion selective electrodes in S220. For example, a Cl ion selective electrode 1071 and a K ion selective electrode 1072 may be used. The same applies between S310 and S320, and between S510 and S520.

[0050] In the above embodiment, it has been described that S520 is performed using the Na ion selective electrode 1073 and the K ion selective electrode 1072, and S530 is performed using the Cl ion selective electrode 1071 and the K ion selective electrode 1072. The combination of ion selective electrodes in S520 to S530 is not limited to this, and it is sufficient that the combination of ion selective electrodes used to calculate ratio 2 and the combination of ion selective electrodes used to calculate ratio 3 are different from each other.

[0051] In the above embodiment, the numerator and denominator when calculating ratios 1 to 3 are not limited to those described above, and the numerator and denominator may be reversed. For example, ratio 1 = Na ＩＳ / Na Ｓ , ratio 2=K Ｓ / Na Ｓ may be.

[0052] In the above embodiment, Na Ｓ and Na in S220 Ｓ The value of ion selective electrode may be common to all steps, or may be measured again for each step. The same applies when a common ion selective electrode is used for other steps.

[0053] In the above embodiments, the measurement control device 1100 can be configured by hardware such as a circuit device that implements its functions, or by software that implements its functions being executed by an arithmetic device such as a CPU (Central Processing Unit).

[0054] In the above embodiments, the section A1301, the section B1302, and the sample mounting table 1021 all serve as mounting sections for placing reagent containers. When reagent containers are placed on the sample mounting table 1021, the sample mounting table 1021 may also be divided into sections for each type of reagent, similar to the reagent holder 1300. Therefore, there is also a possibility that a reagent container may be placed in the wrong section on the sample mounting table 1021. The procedures for detecting installation errors in the section A1301 and the section B1302 in the above embodiments can be applied to installation errors in similar sections of the sample mounting table 1021.

[0055] 1000: Electrolyte concentration analyzer 1010: Dilution tank 1020: Sample supply unit 1021: Sample mounting table 1022: Sample container 1023: Sample dispensing mechanism 1024: Sample dispensing probe 1030: Dilution liquid dispensing mechanism 1031: Dilution liquid tank 1032: Dilution liquid flow path 1040: Internal standard liquid dispensing mechanism 1041: Internal standard liquid tank 1042: Internal standard liquid flow path 1043: Internal standard liquid 1050: Liquid delivery mechanism 1051: Measurement solution suction nozzle 1052: Waste liquid reservoir 1060: Reference electrode liquid delivery mechanism 1061: Reference electrode liquid tank 1062: Reference electrode liquid flow path 1071: Cl ion selective electrode 1072: K ion selective electrode 1073: Na ion selective electrode 1080: Liquid junction 1090: Reference electrode 1100: Measurement control device 1110: Display unit 1200: Waste liquid mechanism 1201: Solenoid valve 1202: Waste liquid flow path 1300: Reagent holder 1301: Compartment A 1302: Compartment B 1311: Reagent container A 1312: Reagent container B

Claims

1. An electrolyte concentration analyzer for measuring the ion concentration contained in a sample using an ion-selective electrode, comprising: two or more types of ion-selective electrodes including a first ion-selective electrode that selectively reacts with a first ion and a second ion-selective electrode that selectively reacts with a second ion; a control device that measures the ion concentration in the sample using the electromotive force of the ion-selective electrode. The control device obtains a first electromotive force of a sample with a known ion concentration measured using any one of the two or more types of ion-selective electrodes and a second electromotive force of a reagent. The control device calculates a first ratio between the first electromotive force and the second electromotive force. The control device obtains a third electromotive force and a fourth electromotive force of the reagent measured using any two of the two or more types of ion-selective electrodes respectively. The control device calculates a second ratio between the third electromotive force and the fourth electromotive force. The control device determines whether the reagent is normal using the first ratio and the second ratio. An electrolyte concentration analyzer characterized by the above.

2. The electrolyte concentration analyzer according to claim 1, wherein when the first ratio is outside a first range, the control device determines that the reagent is abnormal.

3. The electrolyte concentration analyzer according to claim 2, wherein when the first ratio is within the first range, the control device further calculates the second ratio. When the second ratio is within a second range, the control device determines that the reagent is normal, and when the second ratio is outside the second range, the control device determines that the reagent is abnormal.

4. The electrolyte concentration analyzer further comprises a placement part for placing a reagent container for containing the reagent. When the first ratio is outside the first range, the control device outputs a determination result indicating that the reagent is abnormal due to either an incorrect reagent being installed on the placement part or an incorrect concentration of the reagent. The electrolyte concentration analyzer according to claim 2 is characterized by the above.

5. The electrolyte concentration analyzer further includes a placement unit for placing a reagent container that houses the reagent. When the second ratio is outside the second range, the control device determines that: an incorrect reagent has been added to the reagent container; the concentration of the component measured by the ion-selective electrode used to calculate the first ratio among the components of the reagent is correct, but the type of the reagent is incorrect; or the correct reagent and the incorrect reagent are mixed. The electrolyte concentration analyzer according to claim 3 is characterized in that the control device outputs a determination result indicating that the reagent is abnormal due to any of the above cases.

6. The electrolyte concentration analyzer further includes a placement unit for placing a reagent container that houses the reagent, provided for each type of the reagent. The control device sets the first range for each type of the reagent or for each placement unit. When the first ratio is within the first range and the second ratio is outside the second range, the control device outputs a determination result indicating that it has been erroneously determined that the first ratio is normal because the first range corresponding to the incorrect placement unit is set to regard the reagent as normal although the reagent is placed in the incorrect placement unit. The electrolyte concentration analyzer according to claim 3 is characterized by the above.

7. The two or more types of ion-selective electrodes further include a third ion-selective electrode that selectively responds to a third ion. The control device measures a fifth electromotive force of the reagent using the third ion-selective electrode. The control device calculates a third ratio between the third electromotive force and the fifth electromotive force, or between the fourth electromotive force and the fifth electromotive force. The electrolyte concentration analyzer according to claim 1 is characterized in that the control device determines whether the reagent is normal using the first ratio, the second ratio, and the third ratio.

8. When the first ratio is within the first range, the control device further calculates the second ratio. When the second ratio is within the second range, the control device further calculates the third ratio. The electrolyte concentration analyzer according to claim 7 is characterized in that when the third ratio is outside the third range, the control device determines that the reagent is abnormal, and when the third ratio is within the third range, the control device determines that the reagent is normal.

9. The electrolyte concentration analyzer further includes a placement unit for placing a reagent container that houses the reagent. When the third ratio is outside the third range, the control device determines that: the wrong reagent is placed on the placement unit; the concentration of the reagent is incorrect; the wrong reagent is placed on the placement unit at the wrong concentration; or the correct reagent and the wrong reagent are mixed. The electrolyte concentration analyzer according to claim 8 is characterized in that the control device outputs a determination result indicating that the reagent is abnormal due to any one of the above.

10. Among the two or more ion-selective electrodes, any one type is a sodium ion-selective electrode that selectively responds to sodium ions, and any one type is a potassium ion-selective electrode that selectively responds to potassium ions. The electrolyte concentration analyzer according to claim 1 is characterized by this.

11. When the reagent is a cleaning liquid, the control device measures the first electromotive force and the second electromotive force using the sodium ion-selective electrode, and measures the third electromotive force using the sodium ion-selective electrode and measures the fourth electromotive force using the potassium ion-selective electrode. The electrolyte concentration analyzer according to claim 10 is characterized by this.

12. An electrolyte concentration analysis method for measuring the ion concentration contained in a sample using an ion-selective electrode, comprising: obtaining the first electromotive force of a sample with a known ion concentration and the second electromotive force of a reagent, each measured using any one of two or more ion-selective electrodes, including a first ion-selective electrode that selectively reacts to a first ion and a second ion-selective electrode that selectively reacts to a second ion; calculating a first ratio between the first electromotive force and the second electromotive force; obtaining the third electromotive force of the reagent and the fourth electromotive force of the reagent, each measured using any two of the two or more ion-selective electrodes; calculating a second ratio between the third electromotive force and the fourth electromotive force; and determining whether the reagent is normal using the first ratio and the second ratio. The electrolyte concentration analysis method is characterized by having these steps.

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