Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/28—Electrolytic cell components
  • G01N27/401—Salt-bridge leaks; Liquid junctions
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/416—Systems

Definitions

• This disclosure relates to an analytical device.
• Electrochemical measurement is a method for electrochemically measuring the properties of chemical substances.
• flow-type electrochemical measurement devices are designed so that electrodes are in contact with the sample in the flow path.
• the potentiometric method using a flow-type ion-selective electrode allows for quick and easy quantification of the concentration of specific ions in a sample solution, and is therefore used in a wide range of fields, including water quality analysis and medicine.
• the medical field there is a close relationship between metabolic reactions in the body and ion concentration, and quantifying specific ions contained in biological samples such as serum or urine is used to diagnose conditions such as hypertension, kidney disease, and nerve disorders. Because clinical testing requires the continuous analysis of a large number of samples, high-throughput automatic electrolyte analyzers equipped with ion-selective electrodes are routinely used.
• the potentiometric method using an ion-selective electrode consists of an ion-selective electrode equipped with an ion-sensitive membrane and a reference electrode (comparison electrode) that serves as a potential standard.
• the concentration of electrolytes in the test sample can be calculated by measuring the electromotive force generated at the interface between the ion-selective electrode and the test sample, and the electromotive force generated at the interface between the test sample and the reference electrode.
• This reference electrode serves as a potential standard, and its potential must not change over time or due to external factors.
• Reference electrodes generally consist of an ion-sensitive electrode and a reference solution. In order to accurately measure electrolytes in test samples of different concentrations, it is desirable for the reference solution to have similar transport numbers for cations and anions in the liquid.
• Non-Patent Document 1 discloses a configuration in which a reference liquid in a stick-type reference electrode flows out through Vycor glass in the direction of gravity.
• Patent Documents 1 and 2 disclose a configuration in which an internal electrolyte sealed within a reference electrode housing gradually seeps out.
• Patent Document 1 uses porous ceramic as the material that constitutes the liquid junction.
• Patent Document 2 uses hydrophilic porous polyethylene as the material that constitutes the liquid junction.
• Patent Document 1 When a reference liquid is sealed in a housing immersed in a sample, as in the reference electrode described in Non-Patent Document 1, if the electrolyte is allowed to flow out at a certain flow rate, the electrolyte inside the reference electrode must be frequently replenished.
• Patent Documents 1 and 2 a porous material is used in the area that comes into contact with the sample, which suppresses the amount of electrolyte diffusion inside the reference electrode to a certain extent.
• the cylindrical porous member forms the flow path and has a large surface area that comes into contact with the sample, the amount of electrolyte leakage is large, and the electrolyte sealed inside the reference electrode is quickly depleted.
• the leaking electrolyte can invade the joints of nearby ion-selective electrodes, affecting subsequent measurements and causing measurement errors.
• the amount of electrolyte leakage is suppressed too much, the sample and reference liquid cannot form an interface with a sharp concentration change, which could result in an unstable liquid junction potential.
• This disclosure provides technology that can ensure long life and measurement stability for reference electrodes that use porous materials.
• the analytical device disclosed herein comprises a sensor having a detection unit that detects a specific substance in a test sample, a reference electrode that generates a certain electromotive force, and a connection block that connects the sensor and the reference electrode;
• the sensor has a flow path through which the test sample flows, and the detection unit is arranged so as to come into contact with the test sample in the flow path;
• the reference electrode has a porous body and an electrolyte solution sealed therein;
• the connection block has a flow path with at least a first connection port, a second connection port, and a third connection port;
• the first connection port is connected to the outlet of the flow path of the sensor, the second connection port is connected to a flow path for discharging the test sample, the opening surface of the third connection port faces downward, and the porous body of the reference electrode is connected to the third connection port, so that the electrolyte solution inside the reference electrode and the test sample inside the flow path of the connection block come into contact via the porous body.
• FIG. 1 is a schematic diagram for explaining main components of an electrolyte analyzer according to a first embodiment.
• FIG. FIG. 2 is a cross-sectional view showing the structure of a reference electrode.
• FIG. 1 is a side cross-sectional view of a connection block connecting an ion-selective electrode and a reference electrode.
• FIG. 1 is a front cross-sectional view of a connection block that connects an ion-selective electrode and a reference electrode.
• FIG. 10 is a side cross-sectional view showing a state in which a connection block and a reference electrode according to a third embodiment are connected.
• 6B is an enlarged view of the dotted frame in FIG. 6A, showing the vicinity of the surface of the porous body.
• FIG. 10 is a side cross-sectional view showing a structure in which a reference electrode is connected laterally to a connection block.
• FIG. 10 is a front cross-sectional view showing a structure in which a reference electrode is connected to a connection block from the lateral direction.
• FIG. 10 is a schematic diagram of the main components of an immunoassay analyzer according to a fourth embodiment.
• FIG. 1 is a schematic diagram illustrating the main components of an electrolyte analyzer 1 according to a first embodiment.
• the electrolyte analyzer 1 includes a connection block 101, a reference electrode 102, ion-selective electrodes 103, 104, and 105, electromagnetic valves 111, 112, 113, 114, 115, 116, and 117, syringe pumps 121, 122, and 123, a vacuum pump 124, a vacuum bottle 131, a diluent bottle 132, an internal standard bottle 133, a cup 141, a vacuum waste flow path 151, a test sample flow path 152, a diluent injection flow path 153, an internal standard injection flow path 154, a vacuum nozzle 155, and a sample aspiration nozzle 156.
• the connection block 101 is made of, for example, resin.
• the connection block 101 connects the ion-selective electrodes 103-105 and the reference electrode 102.
• the structure of the reference electrode 102 will be described in detail later, but the reference electrode 102 has a porous body 301 (see Figure 2).
• the ion-selective electrode 103 has a sodium ion-sensitive membrane.
• the ion-selective electrode 104 has a potassium ion-sensitive membrane.
• the ion-selective electrode 105 has a chloride ion-sensitive membrane.
• the diluent bottle 132 contains a diluent.
• the internal standard bottle 133 contains an internal standard solution.
• the internal standard solution is an aqueous solution with a constant concentration containing electrolytes such as sodium ions, potassium ions, and chloride ions.
• the ion-selective electrodes 103-105 and the reference electrode 102 are arranged along the test sample flow path 152.
• the test sample is an analyte such as blood, body fluid, or urine.
• the electrolyte analyzer 1 is connected to a control device 2.
• the control device 2 is configured, for example, by one or more arbitrary computer devices.
• the control device 2 includes an input unit 161, a device control unit 162, an output unit 163, a concentration calculation unit 164, and a potential measurement unit 165, whose functions are realized by a processor executing a program or the like loaded in memory.
• the input unit 161 may be configured with input devices such as a mouse, keyboard, touch panel, or microphone.
• the input unit 161 accepts input of various information, such as user instructions.
• the output unit 163 may be configured with output devices such as a display, touch panel, or speaker.
• the output unit 163 outputs the results of processing by the device control unit 162 and the concentration calculation unit 164, as well as an input screen for the user to input various information.
• the potential measurement unit 165 is connected to each of the ion selective electrodes 103-105 and the reference electrode 102, and measures the potential between the ion selective electrodes 103-105 and the reference electrode 102.
• the concentration calculation unit 164 calculates the electrolyte (ion) concentration of the test sample based on the measurement results of the potential measurement unit 165.
• the following describes the procedure for measuring electrolytes in a test sample using the electrolyte analyzer 1. Note that the operation of each component of the electrolyte analyzer 1 is actually controlled by the device control unit 162, but for simplicity's sake, each component will be described as the main operator of the operation.
• the measurement operation of the electrolyte analyzer 1 is carried out when a signal commanding the start of operation is sent from the input unit 161 to the device control unit 162.
• the test sample is placed into cup 141.
• Electromagnetic valve 116 is opened, and the diluent is filled into syringe pump 121 from diluent bottle 132.
• Electromagnetic valve 116 is closed, electromagnetic valve 112 is opened, and syringe pump 121 is operated to inject the diluent into cup 141 via diluent injection flow path 153.
• electromagnetic valve 112 is closed.
• the sample suction nozzle 156 is lowered to near the bottom of cup 141, electromagnetic valve 115 is opened, and the diluted test sample in cup 141 is aspirated by operating syringe pump 123.
• test sample flow path 152 The diluted test sample is then circulated through test sample flow path 152 so as to come into contact with the sensitive membrane (detection unit) of each ion-selective electrode 103-105 (sensor), and then sample suction nozzle 156 is raised, and a certain amount of air is sucked in. Then, electromagnetic valve 115 is closed.
• the potassium chloride concentration changes sharply between the diluted test sample filled near the reference electrode 102 and the porous body 301 of the reference electrode 102, and the potassium chloride diffusion rate is sufficiently fast, so that a potential is instantly generated between the ion-selective electrodes 103, 104, and 105 and the reference electrode 102.
• the generated potentials are acquired by the potential measurement unit 165 and stored in the concentration calculation unit 164 as the diluted test sample potential. After a sufficient amount of time has passed since the diluted test sample was filled, high-concentration potassium chloride remains near the porous body 301 of the reference electrode 102, reducing potassium chloride leaching from the porous body 301.
• the diluted test sample remaining in the cup 141 is sucked and removed by the vacuum pump 124 by lowering the vacuum nozzle 155 to the bottom of the cup 141 and opening the electromagnetic valve 111, and collected in the vacuum bottle 131. The electromagnetic valve 111 is then closed, and the vacuum nozzle 155 is raised.
• the electromagnetic valve 117 is opened, and the internal standard solution is filled into the syringe pump 122 from the internal standard solution bottle 133.
• the electromagnetic valve 117 is closed, the electromagnetic valve 113 is opened, and the syringe pump 122 is operated to inject the internal standard solution into the cup 141 via the internal standard solution injection flow path 154.
• the electromagnetic valve 113 is then closed.
• the sample aspiration nozzle 156 is lowered to near the bottom of the cup 141, the electromagnetic valve 115 is opened, and the internal standard solution in the cup 141 is aspirated by operating the syringe pump 123 and circulated through the flow path so as to come into contact with the sensitive membrane of each ion-selective electrode.
• the sample aspiration nozzle 156 is then raised, and a certain amount of air is sucked in.
• the electromagnetic valve 115 is then closed.
• the potassium chloride concentration changes sharply between the internal standard solution filled near the reference electrode 102 and the porous body 301 of the reference electrode 102, and the diffusion rate of potassium chloride is sufficiently fast, so that a potential is instantly generated between the ion selective electrodes 103, 104, and 105 and the reference electrode 102.
• the generated potentials are acquired by the potential measurement unit 165 and stored in the concentration calculation unit 164 as the internal standard solution potential.
• the concentration calculation unit 164 calculates the electrolyte concentration in the test sample using the stored diluted test sample potential and internal standard solution potential, and outputs the result to the output unit 163.
• ⁇ Example of reference electrode configuration> 2 is a cross-sectional view showing the structure of the reference electrode 102.
• the reference electrode 102 is composed of a porous body 301, a silver-silver chloride electrode 303, and a resin housing 305.
• the housing 305 contains a saturated potassium chloride-silver chloride aqueous solution 302, potassium chloride powder 304, and silver chloride powder 306.
• the silver-silver chloride electrode 303 is attached to the bottom of the housing 305, and its tip is in contact with the saturated potassium chloride-silver chloride aqueous solution 302.
• the opening of the housing 305 is sealed by the porous body 301.
• the porous body 301 can be made of, for example, porous ceramic such as alumina, porous resin, or porous glass.
• porous ceramic such as alumina, porous resin, or porous glass.
• the pore diameter of the porous body 301 is several micrometers.
• the potassium chloride aqueous solution inside the reference electrode 102 is maintained at a saturated concentration, allowing a stable reference electrode potential to be obtained.
• the salt diffuses from the porous body, but water flows in from the flow path, so the liquid inside the reference electrode 102 does not deplete.
• a potassium chloride aqueous solution is used in this embodiment, this is not a limitation; any combination of anions and cations with similar transport numbers will do.
• the porous body 301 is rod-shaped, and only the tip surface comes into contact with the test sample. This has the advantage of reducing the liquid contact area by having the top surface of the cylinder come into contact with the liquid, as opposed to Patent Document 1, in which the inner diameter of the circumferential portion comes into contact with the test sample. Furthermore, in the reference electrode 102, when the porous body 301 is placed on top, the internal liquid is sealed to prevent leakage from the casing 305. This allows the internal liquid to flow out only through the porous body 301.
• the design ensures that at least the lower end of the porous body 301 comes into contact with the saturated potassium chloride/silver chloride aqueous solution 302. This allows the saturated potassium chloride/silver chloride aqueous solution 302 to keep the porous body 301 moist by capillary action, and also allows the electrolyte in the saturated potassium chloride/silver chloride aqueous solution 302 to move upward within the porous body.
• connection block configuration> 3A is a side cross-sectional view of the connection block 101 that connects the ion selective electrodes 103-105 and the reference electrode 102.
• FIG. 3B is a front cross-sectional view of the connection block 101.
• the connection block 101 has a flow path 400 therein.
• the flow path 400 has three flow path ports: an inlet 410, an outlet 411, and a connection port 412.
• the inlet 410 is connected to the test sample flow path 152 that passes through the ion selective electrodes 103-105.
• the test sample that flows in from the inlet 410 fills the connection port 412 and is then discharged from the outlet 411.
• connection port 412 extends vertically downward against the force of gravity.
• the reference electrode 102 is connected to the connection port 412 from directly below the connection block 101, with the porous body 301 facing upward. Connecting the reference electrode 102 facing upward reduces the amount of potassium chloride leaching from the porous body 301 compared to when connected facing downward. Therefore, if the amount of potassium chloride powder 304 in the housing 305 is the same as the lifespan of the reference electrode 102, it is possible to extend its lifespan.
• the saturated potassium chloride and silver chloride aqueous solution 302 when the saturated potassium chloride and silver chloride aqueous solution 302 is leached from the bottom of the flow path 400 using capillary action, the saturated potassium chloride and silver chloride aqueous solution 302 has a higher specific gravity than the test sample and internal standard solution, so it remains in the flow path 400 near the porous body 301, reducing convection within the flow path 400. As a result, the potassium chloride concentration on the surface of the porous body 301 increases, and the concentration gradient between the test sample region and the porous surface becomes smaller, slowing the leaching rate.
• the electrolyte concentration on the surface of the porous body 301 decreases, causing a steeper gradient in the electrolyte concentration inside and outside the reference electrode 102, and the diffusion flux of electrolyte seeping from the porous body 301 into the flow path 400 returns to normal. This reduces the amount of seepage of the saturated potassium chloride/silver chloride aqueous solution 302 while the liquid is stationary. Furthermore, since upward flow due to gravity does not occur, potassium chloride seepage into the test sample proceeds only through capillary action and diffusion.
• the saturated potassium chloride/silver chloride aqueous solution 302 which has wetted the porous body 301 by capillary action, comes into contact with the test sample that contacts the surface of the porous body 301. After coming into contact with the electrolyte solution, potassium chloride diffuses into the test sample due to the diffusion phenomenon.
• the reference liquid In conventional free-flow electrochemical measurement devices, the reference liquid must come into contact with the test sample by gravity, making it impossible to realize the configuration of this embodiment. Furthermore, when a cylindrical porous body is used as the flow path, small air bubbles, if present, tend to adhere to the surface of the porous body, which can cause the measured potential to become unstable.
• a potassium chloride solution of a known concentration was injected into cup 141, sample suction nozzle 156 was lowered, solenoid valve 115 was opened, and syringe pump 123 was operated to perform suction, causing the potassium chloride solution to flow through the flow path. Then, solenoid valve 115 was closed, solenoid valve 114 was opened, syringe pump 123 was operated to perform discharge, and solenoid valve 114 was closed.
• Sample suction nozzle 156 was raised, solenoid valve 111 was opened, and vacuum nozzle 155 was lowered, causing the remaining test sample to be sucked in. Then, vacuum nozzle 155 was raised and solenoid valve 111 was closed.
• a potassium chloride solution of a known concentration was again injected into cup 141, sample suction nozzle 156 was lowered, solenoid valve 115 was opened, and syringe pump 123 was operated to perform suction. Then, electromagnetic valve 115 was closed, electromagnetic valve 114 was opened, and syringe pump 123 was operated to discharge the liquid waste, which was then collected and its conductivity was measured to calculate the potassium chloride concentration. This operation was performed 15 times each for when porous body 301 was connected facing upward and when it was connected facing downward, and the average amount of potassium chloride that flowed out was calculated.
• Figure 4 shows the experimental results showing the difference in potassium chloride outflow depending on the orientation of the reference electrode.
• the amount of potassium chloride outflow was 1.52 ⁇ g/time.
• the amount of potassium chloride outflow was 0.98 ⁇ g/time.
• the amount of potassium chloride outflow when the reference electrode 102 was connected facing upward was 30% less than when the reference electrode 102 was connected facing downward.
• the potassium chloride aqueous solution which has a higher specific gravity than the test sample and internal standard solution, remains near the porous body 301 at the tip of the reference electrode 102.
• the amount of potassium chloride leaching from the interface between the test sample and the surface of the porous body 301, where the concentration gradient is small is small.
• the potassium chloride aqueous solution which has a higher specific gravity than the test sample and internal standard solution, continues to leach downward from the tip of the reference electrode 102 without remaining there. Therefore, when the reference electrode 102 is facing upward, the amount of potassium chloride leaching decreases. For this reason, by facing the reference electrode 102 upward, it is possible to achieve a lifespan that is approximately 1.5 times longer.
• the measurement flow path formed by the ion-selective electrodes 103, 104, and 105 and the reference electrode 102 is not an ideal cylindrical shape, and a structure exists in which stagnation of the liquid flow occurs in the flow path, between each electrode, between the electrode and the device, and other gaps.
• potassium chloride filled inside the reference electrode diffuses into the test sample and internal standard solution filled in the flow path.
• the reference electrode 102 is connected facing upward, which reduces the amount of potassium chloride that leaks out, and therefore reduces the amount of potassium chloride that gets mixed into the gap between the electrodes. This effect suppresses fluctuations in the measured potential, enabling accurate measurements. Furthermore, depending on the type of sensor, the performance of the sensor may deteriorate if exposed to potassium chloride for a long period of time. This embodiment can reduce these adverse effects.
• the electrolyte analyzer 1 includes ion-selective electrodes 103-105 (sensors) each having a sensitive membrane (detection unit) for detecting a specific substance in a test sample, a reference electrode 102 that generates a constant electromotive force, and a connection block 101 that connects the ion-selective electrodes 103-105 to the reference electrode 102.
• the ion-selective electrodes 103-105 each have a test sample flow path 152 through which the test sample flows, and the sensitive membrane is disposed so as to contact the test sample in the test sample flow path 152.
• the reference electrode 102 includes a porous body 301, and a saturated potassium chloride/silver chloride aqueous solution 302 (electrolyte solution) is sealed therein.
• the connection block 101 includes a flow path 400 having an inlet 410 (first connection port), an outlet 411 (second connection port), and a connection port 412 (third connection port).
• the inlet 410 is connected to the outlet of the test sample flow path 152 of the ion selective electrodes 103-105.
• the outlet 411 is connected to a flow path for discharging the test sample.
• the opening of the connection port 412 faces downward, and the porous body 301 of the reference electrode 102 is connected to the connection port 412.
• the saturated potassium chloride/silver chloride aqueous solution 302 inside the reference electrode 102 comes into contact with the test sample inside the flow path 400 of the connection block 101 via the porous body 301.
• the technology of this embodiment makes it possible to suppress the amount of reference liquid seeping out of the porous reference electrode 102, thereby extending the life of the reference electrode 102 and reducing invasive phenomena to the ion-selective electrodes 103-105.
• the structure of this embodiment which defies gravity and utilizes capillary action to seep the electrolyte from the porous body 301 out the bottom of the flow path 400, can reduce convection within the flow path 400 that occurs due to changes in the specific gravity of the liquid within the flow path 400 caused by the seeped electrolyte. This reduces the amount of electrolyte that leaks out while the liquid is stationary.
• This structure of this embodiment has not been considered for conventional stick-type electrodes.
• the electrolyte concentration on the surface of the porous body 301 decreases, causing the electrolyte concentration gradient inside and outside the reference electrode 102 to become steeper, and the diffusion flux of electrolyte seeping from the porous body 301 into the flow path 400 to return to normal.
• the amount of electrolyte seeping from the porous body while the liquid is stationary is reduced, reducing the risk of the ion-selective electrodes 103-105 (sensor unit) being invaded by high-concentration electrolytes. This allows the sensor unit and reference electrode 102 to be closer together, allowing for a more compact device design.
• the reference electrode 102 is connected to the connection block 101 from directly below.
• the connection direction of the reference electrode 102 may be inclined with respect to the vertical direction.
• Figure 5 is a front cross-sectional view showing the state in which the connection block 500 and reference electrode 102 according to the second embodiment are connected.
• the structure of the reference electrode 102 is the same as in the first embodiment.
• the connection port 412 of the flow path 400 faces diagonally downward. This allows the reference electrode 102 to be connected to the connection block 500 from diagonally downward.
• a characteristic of this embodiment is that the liquid surface 502 of the saturated potassium chloride/silver chloride aqueous solution 302 in the reference electrode 102 is positioned below the bottom surface 501 of the flow path 400.
• Potassium chloride seeping out of porous body 301 accumulates near porous body 301.
• the potassium chloride seepage rate decreases. In other words, the concentration gradient becomes smaller, resulting in a smaller diffusion flux.
• the potassium chloride seeping out of porous body 301 increases the specific gravity of the solution, and the solution with a higher specific gravity continuously flows downward due to gravity.
• a liquid with a lower concentration flows into the vicinity of the porous surface, and the concentration gradient inside and outside the reference electrode 102 remains unchanged, so potassium chloride continues to seep into the test sample while maintaining its diffusion flux. This phenomenon is also seen in the cylindrical design of Patent Document 1 and when connected horizontally.
• the second embodiment can also improve the stability of measurements. Furthermore, a configuration in which the reference electrode 102 is connected from an obliquely downward direction makes it easier for the operator to attach and detach the reference electrode 102.
• connection block 400 in the connection block is horizontal and the connection port 412 connecting the flow channel 400 and the reference electrode 102 faces downward.
• a connection block structure for suppressing the occurrence of a portion in the flow channel that is not filled with the test sample will be described.
• FIG. 6A is a side cross-sectional view showing the connection between a connection block 600 and a reference electrode 102 according to the third embodiment.
• the connection block 600 has a flow path 401 with a V-shaped cross section. The bottom of this V-shaped flow path 401 is open.
• the connection block 600 has a flow path 401 in which the inlet 410 and outlet 411 for the test sample are each directly connected to the surface of the porous body 301 of the reference electrode 102.
• Figure 6B is an enlarged view of the dotted frame in Figure 6A, showing the vicinity of the surface of the porous body 301.
• the angles ⁇ 1 and ⁇ 2 formed by the wall surface 701 of the inlet 410 and the wall surface 702 of the outlet 411 with respect to the surface 703 of the porous body 301 are each between 90 degrees or greater and less than 180 degrees.
• Figure 7 is a side cross-sectional view showing a comparative example structure in which the reference electrode 102 is connected laterally to the connection block 101.
• the flow path 400 is parallel to the vertical direction, and the flow path 400 is shown filled with the test sample 801.
• segmented air is present, which means that there is a certain probability that a test sample unfilled portion 802, i.e., an air bubble, will occur at the connection port 412 with the reference electrode 102.
• a test sample unfilled portion 802 occurs, the electrical connection between the reference electrode 102 and electrodes 103, 104, and 105 is lost, making it impossible to obtain the potential formed with the test sample.
• such a test sample unfilled portion 802 can occur because there are areas in the flow path that are shadowed by the flux.
• FIG. 8 is a front cross-sectional view showing a comparative example in which the reference electrode 102 is connected laterally to the connection block 101.
• the liquid level 502 of the saturated potassium chloride/silver chloride aqueous solution 302 in the reference electrode 102 is positioned above the bottom surface 501 of the flow path 400.
• the service life cannot be extended for the following reasons.
• the high-concentration potassium chloride which has a high specific gravity, seeps through the porous body 301 and droops down along the flow path 400 in the direction of gravity.
• liquid convection occurs, which increases the concentration gradient between the surface of the porous body 301 and the test sample, thereby increasing the diffusion flux.
• the high-concentration potassium chloride continues to droop along the flow path 400, and the potassium chloride continues to seep into the test sample while maintaining its diffusion flux. Therefore, the service life cannot be extended.
• FIG. 9 is a schematic diagram of the main components of an immunoassay device 3 according to the fourth embodiment.
• the immunoassay device 3 generates an optically detectable signal by applying a potential to a test sample.
• the immunoassay device 3 includes a measurement cell 200, a power supply (not shown) for applying a potential to the measurement cell 200, and a detector (not shown) for detecting radiation from the sample solution in the measurement cell 200.
• the measurement cell 200 has a connection block 101, a reference electrode 102, an upper member 201, a bottom member 208, a working electrode 202, a counter electrode 203, and a magnet 206.
• the upper member 201 and the bottom member 208 are both approximately L-shaped, and an approximately L-shaped flow path 204 is defined between them.
• Sample liquid is introduced through an inlet 207 of the flow path 204.
• An opening 209 of the flow path 204 is connected to an inlet 410 of a flow path 400 in the connection block 101.
• the working electrode 202 is disposed on the upper surface of the bottom member 208 of the measurement cell 200.
• the counter electrode 203 is disposed on the bottom surface of the upper member 201 of the measurement cell 200, facing the working electrode 202.
• the working electrode 202 is connected to a first electrode of a power supply, and the counter electrode 203 is connected to a second electrode of the power supply.
• the upper member 201 of the measurement cell 200 functions as an optical window.
• the test sample contains an ECL labeling substance, and when a potential is applied, it emits electromagnetic radiation as a result of chemical and electrochemical reactions.
• a detector detects the radiation emerging from the optical window.
• the magnet 206 can be moved toward or away from the measurement cell 200 by a driving device (not shown).
• the test sample flows in through the inlet 207, fills the flow path 204, and comes into contact with the reference electrode 102 via the connection port 412.
• the test sample is discharged from the outlet 411 of the connection block 101.
• measurement stability can be ensured by connecting the reference electrode 102 upward to the connection block 101.
• the present disclosure is not limited to the above-described embodiments and includes various modifications.
• the above-described embodiments have been described in detail to clearly explain the present disclosure, and it is not necessary to include all of the described configurations.
• a part of one embodiment can be replaced with a configuration of another embodiment.
• a configuration of another embodiment can be added to a configuration of one embodiment.
• a part of the configuration of each embodiment can be added to, deleted from, or substituted for a part of the configuration of another embodiment.
• Electrolyte analyzer 2 Control device 3: Immunoanalyzer 101, 500, 600: Connection block 102: Reference electrodes 103, 104, 105: Ion-selective electrodes (sensors) 111, 112, 113, 114, 115, 116, 117: electromagnetic valves 121, 122, 123: syringe pump 124: vacuum pump 131: vacuum bottle 132: diluent bottle 133: internal standard bottle 141: cup 151: vacuum waste flow path 152: test sample flow path 153: diluent injection path 154: internal standard injection flow path 161: input unit 162: device control unit 163: output unit 164: concentration calculation unit 165: potential measurement unit 200: measurement cell (sensor) 301: Porous body 302: Saturated potassium chloride and silver chloride aqueous solution 303: Silver and silver chloride electrode 304: Potassium chloride powder 305: Housing 400: Flow path 410: Inlet 411: Outlet 412: Connection port

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