Patent Description:
An electrolyte analysis apparatus is an apparatus that analyzes electrolyte components such as sodium (Na), potassium (K), or chlorine (Cl) in a biological sample such as serum or urine. As an analysis method used in the electrolyte analysis apparatus, for example, an ion selective electrode method (ISE method) is known in which an electrolyte concentration in a specimen is measured by measuring a potential difference between an ion selective electrode (ISE) and a reference electrode that generates a reference potential.

As a technique related to the ISE method, for example, PTL <NUM> discloses an electrolyte analysis apparatus including a dilution tank for diluting and containing a sample, a sample suction mechanism having a sample suction nozzle that suctions the sample diluted and contained in the dilution tank, an electrolyte measurement unit that measures an electrolyte concentration of the sample suctioned by the sample suction mechanism, an outer tube that surrounds the vicinity of a sample suction port of the sample suction nozzle, and a constant temperature water supply mechanism that circulates constant temperature water in the outer tube.

<CIT> discloses an automatic chlorine ion analyzer with the features in the preamble of present claim <NUM>. Other conventional analyzers are described in <CIT>, <CIT>, and <CIT>.

In the electrolyte analysis apparatus using the ISE method, an ion sensitive membrane in which a potential difference is generated in response to an ion component is attached to an ion selective electrode, and a potential that varies depending on an electrolyte concentration in a sample is measured. In order to keep the reference potential constant, the reference electrode is brought into contact with a solution called a reference electrode solution. Then, when the electrolyte concentration is derived, conversion to the electrolyte concentration is performed using the potential difference between the ion selective electrode and the reference electrode and a calibration curve obtained from calibration.

A relationship between the potential difference used in the ISE method and the concentration varies depending on a temperature. Therefore, when a measurement system changes in temperature when calibration is performed and when a concentration of a biological sample is measured, conversion from the obtained potential difference to the electrolyte concentration cannot be appropriately performed, and an error may occur in a measurement result. In particular, when a measurement reagent is switched or the apparatus is started up, a temperature of a measurement reagent to be introduced is likely to change, and thus it is difficult to perform appropriate measurement.

In the related art, in order to keep the temperature of the measurement system constant, constant temperature water whose temperature is managed circulates around the measurement system, and a preheating region is provided in a reagent flow path used for measurement.

However, when a temperature change that may occur is large, it is necessary to further expand the preheating region and to form a more complicated configuration. As a measure related to temperature change, for example, a method of performing dummy measurement for several operations after measurement having a large temperature change is started during intermittent measurement, or providing sufficient time before an apparatus has a uniform temperature when the apparatus is started up, is known. However, there is a problem that throughput is lowered.

The invention has been made in view of the above problems, and an object of the invention is to provide an electrolyte analysis apparatus capable of controlling a temperature of a reagent with a simpler configuration.

The present application, for solving the above problems, provides an electrolyte analysis apparatus with the features defined in claim <NUM>.

According to the invention, the temperature of the reagent can be controlled with a simpler configuration.

Hereinafter, illustrative examples not falling under the claimed scope but useful for understanding the invention and an embodiment of the invention will be described with reference to the drawings. In the present embodiment, an electrolyte analysis apparatus in which a concentrated reagent (also referred to as a reagent stock solution or a concentrated internal standard solution) and pure water are diluted in a dilution and restoration unit and discharged into a dilution tank will be described as an example, but the invention is not limited thereto. For example, the invention can be applied to an electrolyte analysis apparatus in which a concentrated reagent and pure water are discharged into a dilution tank for dilution.

In addition, in the embodiment of the invention, an electrolyte analysis apparatus used alone for measurement will be described as an example, but the invention is not limited thereto. For example, the invention can also be applied to an electrolyte analysis apparatus mounted on an automatic analysis apparatus such as a biochemical automatic analysis apparatus, an immune automatic analysis apparatus, a mass analysis apparatus, or a coagulation analysis apparatus, a combined system thereof, or an automatic analysis system to which these are applied.

In the following description, a "specimen" is a generic term for analysis targets collected from a living body of a patient, and includes, for example, blood and urine. The "specimen" also includes an analysis target obtained by performing a predetermined pretreatment on these specimens.

A first illustrative example will be described with reference to <FIG> and <FIG>.

<FIG> is a diagram schematically showing the entire configuration of an electrolyte analysis apparatus according to the present example.

In <FIG>, an electrolyte analysis apparatus <NUM> schematically includes a specimen dispensing unit <NUM>, an analysis unit <NUM>, a reagent unit <NUM>, and a mechanism unit <NUM>.

The specimen dispensing unit <NUM> includes a specimen dispensing mechanism <NUM>, a transport unit (not shown), and a specimen vessel <NUM>.

A specimen to be measured is placed in the specimen vessel <NUM> and transported to the vicinity of the specimen dispensing mechanism <NUM> by the transport unit. The specimen dispensing mechanism <NUM> suctions the specimen held in the specimen vessel <NUM>, dispenses the specimen by discharging the specimen into a dilution tank <NUM>, and introduces the specimen into the electrolyte analysis apparatus <NUM>.

The analysis unit <NUM> includes the dilution tank <NUM>, a sipper nozzle <NUM>, a diluent nozzle <NUM>, an internal standard solution nozzle <NUM>, a waste liquid suction nozzle <NUM>, an ion selective electrode (ISE) <NUM>, a reference electrode <NUM>, a pinch valve <NUM>, a voltmeter <NUM>, an amplifier <NUM>, and a computer <NUM>.

The specimen discharged into the dilution tank <NUM> through dispensing of the specimen dispensing unit <NUM> is diluted by a diluent discharged from the diluent nozzle <NUM> to the dilution tank <NUM> and is stirred. The specimen (diluted specimen) diluted and stirred in the dilution tank <NUM> is suctioned by the sipper nozzle <NUM> and fed to the analysis unit <NUM>, and waste liquid remaining in the dilution tank <NUM> is suctioned by the waste liquid suction nozzle <NUM> and discharged into a waste liquid tank.

A reference electrode solution stored in a reference electrode solution bottle <NUM> is fed to the reference electrode <NUM> by an operation of a sipper syringe <NUM> in a state where the pinch valve <NUM> is closed. By opening the pinch valve <NUM> in this state, a diluted specimen solution fed to a flow path of the ion selective electrode <NUM> and the reference electrode solution fed to a flow path of the reference electrode <NUM> come into contact with each other, and the ion selective electrode <NUM> and the reference electrode <NUM> are electrically connected to each other.

The computer <NUM> controls operations of the entire electrolyte analysis apparatus <NUM>, and controls opening and closing operations of solenoid valves <NUM> provided in the specimen dispensing unit <NUM>, the analysis unit <NUM>, the reagent unit <NUM>, and the mechanism unit <NUM>, liquid feeding operations (liquid feeding amounts) of syringes <NUM>, <NUM>, and <NUM>, and the like, and calculates a concentration of an electrolyte of the specimen based on a potential difference generated between the ion selective electrode <NUM> and the reference electrode <NUM> and a calibration curve obtained by calibration performed in advance.

Specifically, an ion sensitive membrane, whose electromotive force changes according to a concentration of a specific ion (for example, sodium ion (Na+), potassium ion (K+), or chlorine ion (Cl)) in the specimen, is attached to the ion selective electrode <NUM>, and the ion selective electrode <NUM> outputs an electromotive force according to each ion concentration corresponding to the specimen. The computer <NUM> acquires an electromotive force between the ion selective electrode <NUM> and the reference electrode <NUM> via the voltmeter <NUM> and the amplifier <NUM>, calculates the ion concentration in the specimen based on the acquired electromotive force, displays the calculated ion concentration on a display device (not shown) and stores the calculated ion concentration in a storage device.

In addition, the computer <NUM> discharges an internal standard solution adjusted to a constant concentration into the dilution tank <NUM> from the internal standard solution nozzle <NUM> during a period after specimen measurement and before next specimen measurement, performs measurement in the same manner as the specimen, and uses a measurement result to perform correction of potential fluctuation due to a temperature change or the like, that is, correction of a measurement result of the specimen.

The reagent unit <NUM> supplies a reagent used for measurement or cleaning, and includes a concentrated internal standard solution bottle <NUM>, a diluent bottle <NUM>, a reference electrode solution bottle <NUM>, a degassing mechanism <NUM>, filters <NUM>, and a dilution and restoration unit <NUM>.

The concentrated internal standard solution bottle <NUM> containing the concentrated internal standard solution (concentrated reagent) and the diluent bottle <NUM> containing the diluent are respectively connected to the internal standard solution nozzle <NUM> and the diluent nozzle <NUM> by flow paths via the filters <NUM>. The internal standard solution nozzle <NUM> and the diluent nozzle <NUM> are provided in the dilution tank <NUM> with tip ends introduced therein. The reference electrode solution bottle <NUM> containing a capture electrode solution is connected to the reference electrode <NUM> by a flow path via the filter <NUM>.

The concentrated internal standard solution contained in the concentrated internal standard solution bottle <NUM> is obtained by concentrating the internal standard solution to a known concentration, and the internal standard solution to be used for measurement is generated by diluting and restoring the concentrated internal standard solution to a predetermined concentration with the diluent.

The dilution and restoration unit <NUM> is provided in a flow path from the concentrated internal standard solution bottle <NUM> to the internal standard solution nozzle <NUM>, and is connected to a pure water production device <NUM> via the flow path. The dilution and restoration unit <NUM> dilutes and restores the concentrated internal standard solution with pure water at a predetermined ratio. The pure water referred to herein may be water that does not contain a certain amount or more of impurities, or may be water after being subjected to a deionization treatment. Degassing mechanisms <NUM> are connected to the flow path between the pure water production device <NUM> and the dilution and restoration unit <NUM>, the flow path between the diluent bottle <NUM> and the dilution tank <NUM>, and the flow path between the reference electrode solution bottle <NUM> and the reference electrode <NUM>, and degassed solutions are discharged into the dilution tank <NUM>.

The dilution and restoration unit <NUM> described above is preferably provided in the flow path between the concentrated internal standard solution bottle <NUM> and the dilution tank <NUM>, but the invention is not limited thereto. For example, a pure water nozzle used for supplying pure water may be provided in the dilution tank <NUM>, and dilution and restoration of the concentrated internal standard solution using pure water may be performed in the dilution tank <NUM>.

The mechanism unit <NUM> includes the internal standard solution syringe <NUM>, the diluent syringe <NUM>, the sipper syringe <NUM>, the solenoid valves <NUM>, and the like, and performs various operations such as liquid feeding.

The concentrated internal standard solution and the pure water are introduced into the dilution and restoration unit <NUM> at a constant ratio by operations of the internal standard solution syringe <NUM> and the solenoid valves <NUM>, to obtain the internal standard solution. Accordingly, the concentrated internal standard solution is diluted with pure water and adjusted to a predetermined concentration.

Here, a liquid temperature of the concentrated internal standard solution in the concentrated internal standard solution bottle <NUM> gradually approaches a room temperature with a lapse of time from setting. However, the liquid temperature in the concentrated internal standard solution bottle <NUM> immediately after setting is close to a storage state temperature. In general, a minimum value of the storage state temperature is set to about <NUM>, and a guaranteed use temperature and a supply water temperature of the electrolyte analysis apparatus <NUM> are generally set to about <NUM>. Therefore, a maximum temperature difference of <NUM> or more may be generated between the concentrated internal standard solution and the pure water used for dilution. Therefore, a temperature of the internal standard solution generated by dilution using pure water changes with a change in the liquid temperature in the bottle.

As described above, when the liquid temperature used for measurement is changed, concentration conversion from a voltage value generated in the ion selective electrode <NUM> may not be appropriately performed, and the measurement may not be appropriately performed. Therefore, in the present illustrative example, a dilution ratio in the dilution and restoration unit <NUM> is controlled in order to appropriately perform the measurement, that is, to generate the internal standard solution at a constant temperature (more specifically, a temperature which can be easily estimated based on a temperature of an environment in which the electrolyte analysis apparatus <NUM> is provided, and a temperature at which an error that affects the measurement falls within a predetermined acceptable range) by dilution and restoration with pure water regardless of the temperature of the concentrated internal standard solution.

Specifically, the dilution and restoration of the concentrated internal standard solution is performed using pure water, which is used in the electrolyte analysis apparatus <NUM> and is estimated to have a temperature as close as possible to that of the environment in which the electrolyte analysis apparatus <NUM> is provided. That is, in the present illustrative example in which the concentrated internal standard solution is diluted and restored using such pure water, at least the concentrated internal standard solution is diluted with the supplied pure water at a ratio (volume ratio) greater than concentrated internal standard solution: pure water = <NUM>:<NUM> (a concentrated internal standard solution amount < a pure water amount). More preferably, the concentrated internal standard solution is diluted with pure water at a volume ratio such that a difference between the temperature of the internal standard solution generated by dilution and the temperature of pure water (diluent) is <NUM> or less. According to knowledge experimentally obtained by the inventors of the present application, for example, when a minimum temperature (storage temperature or the like) estimated in the concentrated internal standard solution is set to <NUM>, and a maximum temperature (maximum use temperature or the like in a specification of the electrolyte analysis apparatus <NUM>) estimated as the temperature of pure water is set to <NUM>, a difference between the temperature of the internal standard solution generated by dilution and the temperature of pure water (diluent) can be <NUM> or less by diluting the concentrated internal standard solution with the supplied pure water at a ratio (volume ratio) equal to or greater than concentrated internal standard solution: pure water = <NUM>:<NUM> (a ratio at which the volume ratio of the pure water to the concentrated internal standard solution becomes <NUM> times or more). Since the temperature of the pure water is estimated to be a constant temperature close to the temperature of the environment in which the electrolyte analysis apparatus <NUM> is provided, changes in the temperature of the internal standard solution generated by dilution for each measurement is <NUM> or less regardless of the liquid temperature in the concentrated internal standard solution bottle <NUM>. As a result, measurement using the internal standard solution at an appropriate temperature can be performed without depending on the temperature of the concentrated internal standard solution in the concentrated internal standard solution bottle <NUM> provided in the electrolyte analysis apparatus <NUM>, and appropriate measurement can be performed.

<FIG> is a diagram showing a relationship between the temperatures of the concentrated internal standard solution, the pure water, and the internal standard solution diluted and restored with pure water.

As shown in <FIG>, for example, when the concentrated internal standard solution at a temperature T1 is diluted and restored with pure water at a temperature T2, if the concentrated internal standard solution is diluted with the pure water at a ratio greater than concentrated internal standard solution: pure water = <NUM>:<NUM> (a concentrated internal standard solution amount < a pure water amount), the internal standard solution is generated such that an absolute value of a temperature difference TD2 between the internal standard solution (temperature T3) obtained by dilution and restoration and the pure water (temperature T2) is smaller than an absolute value of a temperature difference TD3 between the concentrated internal standard solution (temperature T1) and the internal standard solution (temperature T3).

In the present illustrative example, the pure water produced by the pure water production device <NUM> is temporarily stored in a supply water tank <NUM>, is pumped by an appropriate pump <NUM> to pass through a degassing unit, and is then supplied into the apparatus. By storing the pure water in the supply water tank <NUM> for a sufficiently long time, the temperature of the pure water supplied to the apparatus becomes equal to the room temperature, and it is easy to manage the temperature of the entire electrolyte analysis apparatus <NUM> including a measurement system with reference to the room temperature. However, a pure water supply system is not limited to the system described above. For example, the supply water tank <NUM> and the degassing unit may be omitted, or the supply of pure water may be controlled using a syringe without providing the pump <NUM>.

Thus, the pure water supplied into the apparatus is fed to the dilution and restoration unit <NUM> by opening and closing of the solenoid valves and the operation of the internal standard solution syringe <NUM>, and mixed with the concentrated internal standard solution in the dilution and restoration unit <NUM> to generate an internal standard solution having a predetermined concentration.

The generated internal standard solution and diluent are fed to the dilution tank <NUM> by the operations of the internal standard solution syringe <NUM>, the diluent syringe <NUM>, and the solenoid valve. In order to avoid an influence of a temperature variation of the diluent on the measurement, the temperature of the diluent is controlled to be within a certain range via a preheating unit <NUM>.

Here, the reagent unit <NUM> and the mechanism unit <NUM> form a reagent generation unit for diluting and restoring a reagent stock solution having a concentration higher than a predetermined ion concentration with pure water to generate a reagent having the predetermined ion concentration. The specimen dispensing unit <NUM>, the dilution tank <NUM> of the analysis unit <NUM>, the reagent unit <NUM>, and the mechanism unit <NUM> form a specimen dilution unit for diluting a specimen to be analyzed with a diluent to generate a diluted specimen.

Operations of the present illustrative example configured as above will be described.

The specimen separated into the specimen vessel <NUM> is transported to the specimen dispensing unit <NUM> by the transport mechanism (not shown). The specimen is dispensed from the specimen vessel <NUM> by the specimen dispensing mechanism <NUM> in the specimen dispensing unit <NUM> and discharged into the dilution tank <NUM>. After the specimen is dispensed into the dilution tank <NUM>, the diluent is discharged from the diluent bottle <NUM> by operations of the diluent syringe <NUM> and the solenoid valve <NUM> via the diluent nozzle to dilute the specimen. In order to prevent bubbles from being generated due to a change in temperature or pressure of the diluent in the flow path, a degassing treatment is performed by the degassing mechanism <NUM> provided in the flow path of diluent. The diluted specimen is suctioned into the ion selective electrode <NUM> by operations of the sipper syringe <NUM> or the solenoid valve <NUM>.

In addition, the reference electrode solution is fed from the reference electrode solution bottle <NUM> to the reference electrode by the pinch valve <NUM> and the sipper syringe <NUM>, and the diluent and the reference electrode solution come into contact with each other, and thereby the ion selective electrode <NUM> and the reference electrode <NUM> are electrically connected to each other. Thus, the electromotive force corresponding to the concentration of the diluent generated by the ion selective electrode is measured using the voltmeter <NUM> and the amplifier <NUM> with reference to the reference electrode <NUM>. Before and after the specimen measurement, the concentrated internal standard solution is diluted to a predetermined concentration with pure water, the generated internal standard solution is discharged into the dilution tank <NUM> by the internal standard solution syringe <NUM>, and the internal standard solution is measured by the same operation as the specimen measurement. Based on the measured potential difference and the result obtained by calibration performed in advance, calculation is performed by the computer <NUM> to calculate an electrolyte concentration in the specimen.

Effects of the present illustrative example configured as above will be described.

A relationship between the potential difference used in an ISE method and the concentration varies depending on a temperature. Therefore, in a case where the measurement system changes in temperature when calibration is performed and when a concentration of a biological sample is measured, conversion from the obtained potential difference to the electrolyte concentration cannot be appropriately performed, and an error may occur in the measurement result. In particular, when a measurement reagent is switched or the apparatus is started up, a temperature of the measurement reagent to be introduced is likely to change, and thus it is difficult to perform appropriate measurement.

In the related art, in order to keep the temperature of the measurement system constant, constant temperature water whose temperature is managed circulates around the measurement system, and a preheating region is provided in a reagent flow path used for measurement. However, when a temperature change that may occur is large, it is necessary to further expand the preheating region and to form a more complicated configuration. As a measure related to temperature change, for example, a method of performing dummy measurement for several operations after measurement having a large temperature change is started during intermittent measurement, or providing sufficient time before an apparatus has a uniform temperature when the apparatus is started up, is known. However, there is a problem that throughput is lowered.

On the other hand, in the present illustrative example, the electrolyte analysis apparatus <NUM> measures a concentration of a specific ion in the specimen based on a result of measuring a reagent having a predetermined ion concentration with the ion selective electrode <NUM>, and includes a reagent generation unit (for example, the reagent unit <NUM> and the mechanism unit <NUM>) for diluting and restoring a reagent stock solution (concentrated internal standard solution) having a concentration higher than a predetermined ion concentration with pure water to generate a reagent having the predetermined ion concentration, and the reagent generation unit generates the reagent such that the absolute value of the temperature
difference between the reagent obtained by the dilution and restoration, and the pure water is smaller than the absolute value of the temperature difference between the reagent obtained by the dilution and restoration, and the reagent stock solution, so that the temperature of the reagent can be controlled with a simpler configuration.

A second illustrative example will be described with reference to <FIG>.

In the present illustrative example, a diluted specimen is generated by diluting a specimen with pure water instead of a diluent in the first illustrative example.

<FIG> is a diagram schematically showing the entire configuration of an electrolyte analysis apparatus according to the present illustrative example. In the drawing, the same members as those of the first illustrative example are denoted by the same reference numerals, and descriptions thereof will be omitted.

In <FIG>, the electrolyte analysis apparatus <NUM> has a configuration in which pure water supplied from the pure water production device <NUM> is held in a supply tank, and then a supply flow path for supplying the pure water to the device using the pump <NUM> branches to the diluent syringe <NUM> in addition to the internal standard solution syringe <NUM>. A method of supplying pure water to the diluent syringe is preferably the system described above, but is not limited thereto. For example, a configuration of supplying pure water to the internal standard solution syringe <NUM> and a configuration of supplying pure water to the diluent syringe <NUM> may be independently provided.

When a specimen is diluted with pure water, a temperature difference between the original pure water and specimen dilution water after dilution is required to be sufficiently small. Specifically, it is necessary to control a temperature change to <NUM> or less. In view of a fact that a management temperature of the specimen is about the same as a temperature of a concentrated internal standard solution, for example, when a diluted specimen is generated by dilution at a ratio of specimen: pure water = <NUM>:<NUM> or more (a ratio at which a volume ratio of the pure water to the specimen becomes <NUM> times or more), the diluted specimen is generated such that an absolute value of a temperature difference between the diluted specimen and the pure water is smaller than an absolute value of a temperature difference between the diluted specimen and the specimen, and the temperature change is <NUM> or less.

Other configurations are the same as those of the first illustrative example.

In the present illustrative example configured as above, the same effect as those of the first illustrative example can also be obtained.

In addition, not only a liquid temperature of an internal standard solution but also a liquid temperature used for diluting the specimen becomes a temperature of the pure water, and thus the preheating unit <NUM> for temperature adjustment can be omitted. The same effect can also be obtained by providing the dilution and restoration unit <NUM> in a dilution water flow path and using a concentrated diluent concentrated to a concentration corresponding to a dilution ratio.

A third illustrative example of the invention will be described with reference to <FIG>.

In the present illustrative example, a circulation path for circulating pure water is provided in the electrolyte analysis apparatus in the second illustrative example, and dilution of a concentrated internal standard solution (concentrated reagent) is performed with the pure water introduced from the circulation path.

<FIG> is a diagram schematically showing the entire configuration of an electrolyte analysis apparatus according to the present illustrative example. In the drawing, the same members
as those of the second illustrative example are denoted by the same reference numerals, and descriptions thereof will be omitted.

In <FIG>, the electrolyte analysis apparatus <NUM> includes a pure water circulation path <NUM> that is provided on a flow path from the pump <NUM> to the internal standard solution syringe <NUM> and the diluent syringe <NUM> and through which the pure water sent from the pump <NUM> circulates in the electrolyte analysis apparatus <NUM>, a pump <NUM> that circulates the pure water in the pure water circulation path <NUM>, and a solenoid valve <NUM> provided on the flow path from the pump <NUM> to the pure water circulation path <NUM>.

In the present illustrative example, the pure water used for diluting the concentrated internal standard solution is introduced from the pure water circulation path <NUM>. The pure water produced by the pure water production device <NUM> is held in the supply water tank <NUM>, and is supplied to the pure water circulation path <NUM> by the pump <NUM> after passing a degassing device. In the pure water circulation path <NUM>, the pure water in the path is efficiently circulated by the pump <NUM>. As a result, a temperature of the pure water in the pure water circulation path <NUM> is made uniform, and even if the temperature of the pure water supplied from the pure water production device <NUM> changes, a temperature change in the system can be reduced. In view of a fact that the temperature of the pure water is controlled to be constant depending on a room temperature by circulation in the pure water circulation path <NUM>, the supply water tank <NUM> may be omitted. A pure water equivalent amount used for diluting the concentrated internal standard solution is newly supplied to the pure water circulation path <NUM> by opening and closing of the solenoid valve <NUM> provided in an introduction portion of the pure water circulation path <NUM> and an operation of the pump <NUM>.

Other configurations are the same as those of the second illustrative example.

In the present illustrative example configured as above, the same effect as those of the second embodiment can also be obtained.

A fourth illustrative example of the invention will be described with reference to <FIG>.

In the present illustrative example, a temperature control device for controlling a temperature of pure water is provided in the pure water circulation path in the third illustrative example.

<FIG> is a diagram schematically showing the entire configuration of an electrolyte analysis apparatus according to the present illustrative example. In the drawing, the same members as those of the third illustrative example are denoted by the same reference numerals, and descriptions thereof will be omitted.

In <FIG>, the electrolyte analysis apparatus <NUM> includes a temperature control device <NUM> that controls the temperature of the pure water circulating in the pure water circulation path <NUM> to be constant. For example, the temperature control device <NUM> may monitor the temperature of circulating water with a thermocouple and control output of a heater based on the obtained temperature, and an embodiment of the temperature control device <NUM> is not limited. By providing the temperature control device <NUM> in the pure water circulation path <NUM>, the temperature of the circulating pure water is controlled to be constant regardless of a room temperature or a temperature of supply water. That is, a temperature of an internal standard solution generated by diluting a concentrated internal standard solution with the pure water introduced from the pure water circulation path <NUM> is also controlled to be constant regardless of an environmental temperature. Accordingly, stable measurement with high robustness against environmental changes can be performed.

Other configurations are the same as those of the third illustrative example.

In the present illustrative example configured as above, the same effect as those of the third illustrative example can also be obtained.

A fifth illustrative example will be described with reference to <FIG>.

In the present illustrative example, a sterilizer for sterilizing pure water is provided in the pure water circulation path in the third illustrative example.

In <FIG>, the electrolyte analysis apparatus <NUM> includes a sterilizer <NUM> that sterilizes pure water circulating in the pure water circulation path <NUM>. In the pure water present in the pure water circulation path <NUM>, proliferation of bacteria or the like may occur when the electrolyte analysis apparatus <NUM> is in a system off state and stagnation of the pure water occurs or when circulation continues for a long period of time. When properties of the pure water change due to the proliferation of bacteria, an ion concentration of a target specimen may not be appropriately obtained. In addition, a film may be generated in the flow path, which may also cause clogging of the flow path. Therefore, in the present illustrative example, the sterilizer <NUM> is provided in the pure water circulation path <NUM> in order
to prevent an influence of the proliferation of bacteria. The sterilizer <NUM> sterilizes the pure water in the flow path in a contactless manner using, for example, ultraviolet rays. When the sterilizer <NUM> using a generally used liquid is used, it is necessary to select the sterilizer <NUM> based on an ion concentration and a chemical reaction contained in the liquid for sterilization. By applying the sterilizer <NUM> that sterilizes the pure water to the pure water circulation path <NUM>, stable measurement can be performed even in long-term use.

An embodiment of the invention will be described with reference to <FIG>.

In the present embodiment, the pure water circulation path in the third illustrative example is provided so as to pass through the analysis unit <NUM> that measures a reagent by an ion selective electrode, the dilution tank <NUM> for diluting a specimen to be measured with pure water, and the preheating unit <NUM> that heats the reagent generated by the reagent generation unit (the reagent unit <NUM> and the mechanism unit <NUM>).

<FIG> is a diagram schematically showing the entire configuration of an electrolyte analysis apparatus according to the present embodiment. In the drawing, the same members as those of the third illustrative example are denoted by the same reference numerals, and descriptions thereof will be omitted.

In <FIG>, the pure water circulation path <NUM> of the electrolyte analysis apparatus <NUM> is configured to pass through the ion selective electrode <NUM>, the dilution tank <NUM>, and preheating units <NUM> provided for an internal standard solution portion and a diluent portion, and to keep these parts constant at a temperature of circulating water. However, the pure water circulation path <NUM> may be configured to pass through only a part of these parts, that is, to keep temperatures of only a part of these parts constant. In addition, the pure water circulation path <NUM> may pass through another path. When the pure water circulation path <NUM> is configured such that the entire system related to measurement is kept constant at the temperature of the circulating water as in the present embodiment, stable measurement can be performed with less temperature changes. A temperature of an internal standard solution produced by using the pure water introduced from the circulating water is substantially equal to a temperature of the pure water used for dilution. Therefore, even when the preheating unit <NUM> is provided, it is advantageous in space reduction of the unit and configuration simplification as compared with a system in which a concentrated reagent is diluted with pure water.

In the present embodiment configured as above, the same effect as those of the third illustrative example can also be obtained.

Claim 1:
An electrolyte analysis apparatus (<NUM>) configured to measure the concentration of a specific ion in a specimen based on the result of measuring a reagent having a predetermined ion concentration with an ion selective electrode (<NUM>) and the result of measuring the specimen with the ion selective electrode (<NUM>), comprising:
an analysis unit (<NUM>) including an ion selective electrode (<NUM>) for measuring the reagent,
a dilution tank (<NUM>) for diluting the specimen to be measured with pure water,
a pump (<NUM>),
a reagent generation unit (<NUM>, <NUM>) for diluting and restoring a reagent stock solution having a concentration higher than a predetermined ion concentration with pure water to generate a reagent having the predetermined ion concentration,
wherein
the reagent generation unit (<NUM>, <NUM>) is configured to generate the reagent by mixing the reagent stock solution and the pure water passing through a circulation path (<NUM>) in a volume ratio such that the absolute value of the temperature difference between the reagent obtained by the dilution and restoration, and the pure water is smaller than the absolute value of the temperature difference between the reagent obtained by the dilution and restoration, and the reagent stock solution,
the electrolyte analysis apparatus (<NUM>) being characterized in that a reagent preheating region (<NUM>) for heating the reagent generated by the reagent generation unit (<NUM>, <NUM>) is present, and the circulation path (<NUM>) is configured to circulate, by the
pump (<NUM>), the pure water used for the dilution of the reagent stock solution to pass through the analysis unit (<NUM>), the dilution tank (<NUM>) and said reagent preheating region (<NUM>).