Measurement equipment and method

Abstract

To provide a measurement device and a measurement method capable of accurately feeding a plurality of reagents from which bubbles are removed without increasing manufacturing costs.SOLUTION: In a measurement device according to the present invention, a control unit 7 operates a stepping motor 11 so that a first common pipe L12 and a first liquid feed pipe L13 are connected to a first valve V1 and a second common pipe L22 and a second tank pipe L21 are connected to a second valve V2 when a first solution is fed from a first syringe pump unit 16, causing a first required amount of the first solution to be discharged from the first syringe pump unit, and operates the stepping motor so that the first common pipe and a first tank pipe L11 are connected to the first valve and a second common pipe and a second liquid feed pipe L23 are connected to the second valve when a second solution is fed from a second syringe pump unit 17, causing a second required amount of the second solution to be discharged from the second syringe pump unit.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a measurement device and a measurement method. [Background technology]

[0002] Measuring devices are used to measure the water quality (e.g., total nitrogen concentration, total phosphorus concentration, heavy metal concentration, COD (Chemical Oxygen Demand) concentration, etc.) of environmental water (such as industrial wastewater, lakes, rivers, or seawater). In such measuring devices, reagents suitable for the measurement are added to the water to be measured (hereinafter referred to as "sample water") collected using a water sampling pump. Various pumps are used to transport and measure these reagents, and various motors are used to operate the pumps (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-27039 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for liquid-saving measurement devices, primarily for the purpose of cost reduction. Reducing the amount of reagent used to reduce liquid consumption without improving the reagent measurement accuracy inevitably leads to increased measurement errors and failure to meet the specifications of the measurement device. For highly accurate reagent measurement, a pump using a stepping motor, whose rotation amount is controlled by pulses, is suitable. However, stepping motors are relatively expensive. Therefore, using a pump using a stepping motor for each reagent increases the manufacturing cost of the measurement device. Furthermore, air bubbles may be mixed into the reagent drawn into the pump. When the amount of reagent used is reduced, even if the amount of air bubbles is minute, the proportion of air bubbles in the reagent increases. As a result, the impact of air bubbles on the measurement results becomes greater.

[0005] An object of the present invention is to provide a measuring device and a measuring method that are capable of delivering a plurality of reagents from which air bubbles have been removed while measuring them with high accuracy, without increasing manufacturing costs. [Means for solving the problem]

[0006] The measuring device according to the present invention is a measuring device for measuring the quality of sample water, and includes a first syringe pump unit arranged vertically to suck in and discharge a first solution, a second syringe pump unit arranged vertically to suck in and discharge a second solution, a first tank for storing the first solution, a second tank for storing the second solution, a reaction tank to which the sample water, the first solution discharged from the first syringe pump unit, and the second solution discharged from the second syringe pump unit are delivered, a first valve for switching the delivery destination of the first solution, a first tank pipe connected to the first valve and the first tank, a first common pipe connected to the first valve and an upper end of the first syringe pump unit, a first delivery pipe connected to the first valve and the reaction tank, a second valve for switching the delivery destination of the second solution, a second tank pipe connected to the second valve and the second tank, a second common pipe connected to the second valve and an upper end of the second syringe pump unit, and a reaction tank to which the second valve and the reaction tank are delivered. a second liquid transfer pipe connected to a tank; a stepping motor that causes the first syringe pump unit and the second syringe pump unit to perform the same operation simultaneously; and a control unit that controls the operation of the first valve, the second valve, and the stepping motor, wherein the control unit, when a first solution is transferred from the first syringe pump unit to the reaction tank, operates the stepping motor to connect the first common pipe and the first liquid transfer pipe to the first valve and connect the second common pipe and the second tank pipe to the second valve, and operates the stepping motor to discharge a first required amount of the first solution from the first syringe pump unit, and when a second solution is transferred from the second syringe pump unit to the reaction tank, operates the stepping motor to connect the first common pipe and the first tank pipe to the first valve and connect the second common pipe and the second liquid transfer pipe to the second valve, and operates the stepping motor to discharge a second required amount of the second solution from the second syringe pump unit.

[0007] The measurement method of the present invention is a method for measuring water quality using the above-mentioned measurement device, and is characterized in that it includes a first solution delivery step in which, after sample water has been delivered to a reaction tank, the control unit controls the operation of the first valve, the second valve, and the stepping motor to deliver a first required amount of first solution to the reaction tank, and a second solution delivery step in which, after the first required amount of first solution has been delivered, the control unit controls the operation of the first valve, the second valve, and the stepping motor to deliver a second required amount of second solution to the reaction tank. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a measuring device and a measuring method that are capable of delivering a plurality of reagents from which air bubbles have been removed while measuring them with high accuracy, without increasing manufacturing costs. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating an embodiment of a measuring device according to the present invention. [Figure 2] 2 is a schematic front view of a first reagent pump provided in the measuring device of FIG. 1. FIG. [Figure 3] 3 is a schematic side view of the first reagent pump in the direction of arrow A in FIG. 2. FIG. [Figure 4] 3 is a partially enlarged cross-sectional view of the first reagent pump taken along line BB in FIG. 2. FIG. [Figure 5] 10 is a flowchart showing an example of a normal measurement process included in the operation of the measurement device of FIG. [Figure 6] 5 is a schematic diagram showing an example of the operation of the first reagent liquid delivery mechanism and the second reagent liquid delivery mechanism provided in the measurement device of FIG. 1 during the normal measurement process of FIG. 5, where (a) to (c) show the oxidation process included in the normal measurement process, and (d) to (e) show the oxidation stop process included in the normal measurement process. [Figure 7] 10 is a flowchart showing an example of a low concentration measurement process included in the operation of the measurement apparatus of FIG. [Figure 8] 10 is a flowchart showing an example of a simple span calibration process included in the operation of the measurement apparatus of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] ●Measuring equipment● Embodiments of a measuring device (hereinafter referred to as "the device") according to the present invention and a measuring method (hereinafter referred to as "the method") according to the present invention will be described below. In the following description, reference will be made to the drawings as appropriate. In the drawings, identical members and elements are given the same reference numerals, and duplicate explanations will be omitted. Furthermore, in the drawings, the shape and size of each member may be intentionally distorted from their actual dimensions in order to clearly and concisely show the configuration of each member.

[0011] The "measuring device" is, for example, a device that calculates (measures) the concentration of a measurement target component contained in a water sample (analyte) after each treatment. In this embodiment, this device is described as a chemical oxygen demand (COD) measuring device that measures the COD concentration.

[0012] "Sample water" is water containing the components to be measured by this device, such as wastewater from a factory or business.

[0013] In the present invention, the sample water is not limited to wastewater, and may be, for example, environmental water such as river water, lake water, or sea water.

[0014] The "component to be measured" is a component contained in the sample water that is the target of measurement by this device, and in this embodiment, is an oxidizable substance.

[0015] In the present invention, the apparatus is not limited to a COD measuring apparatus as long as it requires highly accurate measurement of reagents. For example, the apparatus may be a total nitrogen concentration measuring apparatus or a total phosphorus concentration measuring apparatus.

[0016] In the following explanation, this device is based on JIS K 0102 17. [Oxygen consumption by potassium permanganate at 100℃ (COD MnThe COD concentration is measured using a method similar to that described in the previous section. Specifically, a potassium permanganate solution is added as an oxidizing agent to sample water that has been acidified with sulfuric acid to produce an analytical solution. The analytical solution is then heated for 30 minutes to allow the oxidation reaction of the oxidizable substances in the analytical solution to proceed. Sodium oxalate solution is then added to the analytical solution to stop the oxidation reaction. Finally, titration with the oxidizing agent (potassium permanganate) is performed, and the COD concentration of the sample water is measured based on the amount of oxidizing agent consumed.

[0017] Therefore, in this device, sulfuric acid is used as a reagent to acidify the sample water, potassium permanganate solution is used as an oxidizing agent and titrant, and sodium oxalate solution is used as a reaction reagent (reducing agent) that reacts with the oxidizing agent and titrant, respectively, and as an oxidizable substance. The potassium permanganate solution is an example of a first solution in the present invention, containing potassium permanganate whose concentration is standardized and known (known concentration). The sodium oxalate solution is an example of a second solution in the present invention, containing sodium oxalate of a known concentration.

[0018] In the following description, the "upstream side" of a pipe refers to the upstream side in the flow of liquid in that pipe, and the "downstream side" refers to the downstream side in the flow of liquid in that pipe. That is, for example, the "downstream side" refers to the syringe pump side in the flow from each tank to the syringe pump, and the reaction tank side in the flow from the syringe pump to the reaction tank. In other words, the reaction tank side in the flow including the sample water toward the reaction tank is the "downstream side," and the waste tank is the most downstream side in the flow of waste liquid from the reaction tank toward the waste tank.

[0019] Measurement device configuration FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present device.

[0020] This device 1 measures the water quality (COD concentration) of sample water. The device 1 includes a reaction tank 2, a heating tank 3, a heater 4, a thermometer 5, an electrode 6, a control unit 7, a first reagent tank T1, a second reagent tank T2, a third reagent tank T3, a fourth reagent tank T4, a pure water tank T5, a water receiving tank T6, a waste liquid tank T7, a first reagent pipe L1, a second reagent pipe L2, a third reagent pipe L3, a fourth reagent pipe L4, a pure water pipe L5, a sample water pipe L6, an air pipe L7, a waste liquid pipe L8, a first reagent pump P1, a third reagent pump P2, a fourth reagent pump P3, a pure water pump P4, a sample water pump P5, an air pump P6, a waste liquid pump P7, a first valve V1, a second valve V2, a third valve V3, and a fourth valve V4.

[0021] Here, the first reagent tank T1, the first reagent pump P1, the first reagent piping L1, and the first valve V1 constitute a first reagent liquid delivery mechanism M1. The second reagent tank T2, the first reagent pump P1, the second reagent piping L2, and the second valve V2 constitute a second reagent liquid delivery mechanism M2. The third reagent tank T3, the third reagent pump P2, and the third reagent piping L3 constitute a third reagent liquid delivery mechanism M3. The fourth reagent tank T4, the fourth reagent pump P3, and the fourth reagent piping L4 constitute a fourth reagent liquid delivery mechanism M4. The pure water tank T5, the pure water pump P4, the pure water piping L5, and the third valve V3 constitute a pure water liquid delivery mechanism M5. The water receiving tank T6, the sample water pump P5, and the sample water piping L6 constitute a sample water liquid delivery mechanism M6.

[0022] The configuration of the device 1 is the same as that of known COD measurement devices except for the first reagent liquid delivery mechanism M1 and the second reagent liquid delivery mechanism M2. Therefore, in the following description, detailed description of the configuration other than the first reagent liquid delivery mechanism M1 and the second reagent liquid delivery mechanism M2 will be omitted.

[0023] The reaction tank 2 is a tank that temporarily stores the delivered sample water and each reagent and causes a chemical reaction. The lower part of the reaction tank 2 is immersed in the bath of the heating tank 3. The heating tank 3 heats the lower part of the reaction tank 2, thereby heating the analysis solution in the reaction tank 2. The heating tank 3 is, for example, an oil bath or a boiling water bath. The heater 4 heats the heating tank 3. The thermometer 5 measures the temperature of the heating tank 3.

[0024] The electrode 6 is, for example, a platinum electrode, and is inserted into the reaction vessel 2 to detect the end point of the titration.

[0025] The control unit 7 controls the overall operation of the device 1. The control unit 7 is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory) that functions as a work area for the CPU, and a ROM (Read Only Memory) that stores various information such as measurement programs.

[0026] A measurement program runs in the control unit 7, and the measurement program cooperates with the hardware resources of the device 1 to realize the measurement method described below. Furthermore, by having a processor (CPU) constituting the control unit 7 execute the measurement program, the measurement program can cause the processor to function as the control unit 7 and execute the measurement method. Similarly, by having a computer execute the measurement program, the measurement program can cause the computer to function as the control unit 7.

[0027] In the present invention, the measurement program may be stored in a storage medium (not shown) such as a flash memory. Alternatively, the measurement program may be stored in an installable file format or an executable file format on a non-transitory storage medium (e.g., a CD (Compact Disc), a DVD (Digital Versatile Disc), a USB (Universal Serial Bus) memory, etc.) and provided to the device 1 via a dedicated read-out medium.

[0028] The first reagent tank T1 stores the first reagent (potassium permanganate solution). The second reagent tank T2 stores the second reagent (sodium oxalate solution). The third reagent tank T3 stores the third reagent (sulfuric acid). The fourth reagent tank T4 stores the fourth reagent (silver nitrate). The pure water tank T5 stores pure water. The water receiving tank T6 receives sample water delivered by a water sampling pump (not shown). The first reagent tank T1 is an example of the first tank in the present invention, and the second reagent tank T2 is an example of the second tank in the present invention.

[0029] The first reagent pump P1 operates under the control of the control unit 7 to deliver the first reagent and the second reagent to the reaction vessel 2. The configuration of the first reagent pump P1 will be described in detail later.

[0030] The third reagent pump P2 delivers the third reagent to the reaction tank 2, and the fourth reagent pump P3 delivers the fourth reagent to the reaction tank 2. The third reagent pump P2 and the fourth reagent pump P3 are each a known syringe pump operated by, for example, an AC motor (not shown).

[0031] The pure water pump P4 delivers pure water to the reaction vessel 2. The pure water pump P4 is, for example, a known syringe pump operated by a stepping motor (not shown).

[0032] The sample water pump P5 sends the sample water to the reaction vessel 2. The sample water pump P5 is, for example, a known roller pump operated by an AC motor (not shown).

[0033] The air pump P6 pumps air under pressure into each of the pipes L1 to L5. The air pump P6 is a known air pump that is operated by, for example, an AC motor (not shown).

[0034] The operation of each of the pumps P1 to P7 is controlled by a control unit .

[0035] The first reagent pipe L1 is a path through which the first reagent stored in the first reagent tank T1 is delivered to the reaction vessel 2. A first valve V1 is connected to the first reagent pipe L1. The first reagent pipe L1 includes a first tank pipe L11, a first common pipe L12, and a first liquid delivery pipe L13.

[0036] One end (upstream end) of the first tank pipe L11 is connected to the first reagent tank T1, and the other end (downstream end) of the first tank pipe L11 is connected to the first valve V1. One end of the first common pipe L12 is connected to the first reagent pump P1 (first pipe mounting hole 18c described below: see FIG. 4), and the other end of the first common pipe L12 is connected to the first valve V1. One end (upstream end) of the first liquid supply pipe L13 is connected to the first valve V1, and the other end (downstream end) of the first liquid supply pipe L13 is connected to the reaction tank 2.

[0037] In this embodiment, the volume "V12" of the first common pipe L12 is smaller than the volume "V11" of the first tank pipe L11 and the volume "V13" of the first liquid supply pipe L13. The volume "V11" of the first tank pipe L11 is larger than the volume "V13" of the first liquid supply pipe L13.

[0038] The second reagent pipe L2 is a path through which the second reagent stored in the second reagent tank T2 is delivered to the reaction vessel 2. A second valve V2 is connected to the second reagent pipe L2. The second reagent pipe L2 includes a second tank pipe L21, a second common pipe L22, and a second liquid delivery pipe L23.

[0039] One end (upstream end) of the second tank pipe L21 is connected to the second reagent tank T2, and the other end (downstream end) of the second tank pipe L21 is connected to the second valve V2. One end of the second common pipe L22 is connected to the first reagent pump P1 (second pipe mounting hole 18d described below: see FIG. 4), and the other end of the second common pipe L22 is connected to the second valve V2. One end (upstream end) of the second liquid supply pipe L23 is connected to the second valve V2, and the other end (downstream end) of the second liquid supply pipe L23 is connected to the reaction tank 2.

[0040] In this embodiment, the volume "V22" of the second common pipe L22 is smaller than the volume "V21" of the second tank pipe L21 and the volume "V23" of the second liquid feed pipe L23. The volume "V21" of the second tank pipe L21 is larger than the volume "V23" of the second liquid feed pipe L23. The volume "V21" of the second tank pipe L21 is the same as the volume "V11" of the first tank pipe L11, the volume "V22" of the second common pipe L22 is the same as the volume "V12" of the first common pipe L12, and the volume "V23" of the second liquid feed pipe L23 is the same as the volume "V13" of the first liquid feed pipe L13.

[0041] The third reagent pipe L3 is a path through which the third reagent stored in the third reagent tank T3 is sent to the reaction tank 2. One end (upstream end) of the third reagent pipe L3 is connected to the third reagent tank T3, and the other end (downstream end) of the third reagent pipe L3 is connected to the reaction tank 2. A third reagent pump P2 is connected to the third reagent pipe L3.

[0042] The fourth reagent pipe L4 is a path through which the fourth reagent stored in the fourth reagent tank T4 is sent to the reaction tank 2. One end (upstream end) of the fourth reagent pipe L4 is connected to the fourth reagent tank T4, and the other end (downstream end) of the fourth reagent pipe L4 is connected to the reaction tank 2. A fourth reagent pump P3 is connected to the fourth reagent pipe L4.

[0043] The pure water pipe L5 is a path through which pure water stored in a pure water tank T5 is sent to the reaction tank 2. A third valve V3 is connected to the pure water pipe L5. The pure water pipe L5 includes a tank pipe L51, a common pipe L52, and a liquid sending pipe L53.

[0044] One end (upstream end) of the tank pipe L51 is connected to the pure water tank T5, and the other end (downstream end) of the tank pipe L51 is connected to the third valve V3. One end of the common pipe L52 is connected to the pure water pump P4, and the other end of the common pipe L52 is connected to the third valve V3. One end (upstream end) of the liquid supply pipe L53 is connected to the third valve V3, and the other end (downstream end) of the liquid supply pipe L53 is connected to the reaction tank 2.

[0045] The sample water pipe L6 is a path through which the sample water stored in the water receiving tank T6 is sent to the reaction tank 2. A sample water pump P5 is connected to the sample water pipe L6. One end (upstream end) of the sample water pipe L6 is connected to the water receiving tank T6, and the other end (downstream end) of the sample water pipe L6 is connected to the reaction tank 2.

[0046] The air pipe L7 is a path through which air from the air pump P6 is blown to each of the pipes L1 to L5. One end (upstream end) of the air pipe L7 is connected to the air pump P6. The other end (downstream end) of the air pipe L7 branches into multiple parts and is connected to a first liquid supply pipe L13, a second liquid supply pipe L23, a third reagent pipe L3, a fourth reagent pipe L4, and a liquid supply pipe L53.

[0047] The first valve V1 to the fourth valve V4 are, for example, solenoid valves whose operations are controlled by the control unit 7. The first valve V1 to the third valve V3 are three-way valves, and the fourth valve V4 is a normally closed valve.

[0048] As described above, the first valve V1 is connected to the first tank pipe L11, the first common pipe L12, and the first liquid feed pipe L13, and connects the first tank pipe L11 to the first common pipe L12 or the first common pipe L12 to the first liquid feed pipe L13 under the control of the control unit 7. Similarly, the second valve V2 connects the second tank pipe L21 to the second common pipe L22 or the second common pipe L22 to the second liquid feed pipe L23 under the control of the control unit 7. Similarly, the third valve V3 connects the tank pipe L51 to the common pipe L52 or the common pipe L52 to the liquid feed pipe L53 under the control of the control unit 7.

[0049] FIG. 2 is a schematic front view of the first reagent pump P1. FIG. 3 is a schematic side view of the first reagent pump P1 as viewed from the arrow A in FIG. FIG. 4 is a partially enlarged cross-sectional view of the first reagent pump P1 taken along line BB in FIG.

[0050] In the following description of the first reagent pump P1 and in FIGS. 2 to 4, unless otherwise specified, when three mutually orthogonal axes in space are defined as the X-axis, Y-axis, and Z-axis, the "X-axis direction" is the direction along the X-axis and is the left-right direction. The "Y-axis direction" is the direction along the Y-axis and is the front-to-back direction. The "Z-axis direction" is the direction along the Z-axis and is the up-to-down direction. Furthermore, the "+X direction" is the left, the "-X direction" is the right, the "+Y direction" is the front, the "-Y direction" is the rear, the "+Z direction" is the up, and the "-Z direction" is the down. In the following description, FIG. 1 will be referenced as appropriate.

[0051] The first reagent pump P1 comprises a substrate 10, a motor 11, a coupling 12, a shaft 13, a slider 14, a holding member 15, a first syringe pump section 16, a second syringe pump section 17, a connecting member 18, two sealing members 19 and 20, a first joint 21, and a second joint 22.

[0052] The substrate 10 supports the motor 11, the shaft 13, the slider 14, and the connecting member 18. The substrate 10 is, for example, a rectangular plate with its longitudinal direction aligned along the vertical direction (Z-axis direction). A slit-shaped through-hole 10a is arranged in the center of the substrate 10 and aligned along the vertical direction.

[0053] The motor 11 generates a rotational force that moves the slider 14 up and down via the coupling 12 and the shaft 13. The motor 11 is a known stepping motor. The motor 11 is attached to the rear surface of the substrate 10 with the rotation axis 11a facing downward (in the -Z direction). The operation of the motor 11 is controlled by the control unit 7.

[0054] The coupling 12 transmits the rotational force of the motor 11 to the shaft 13. The coupling 12 is attached to the rotary shaft 11a of the motor 11.

[0055] The shaft 13 rotates in response to the rotational force of the motor 11 transmitted via the coupling 12, causing the slider 14 to reciprocate up and down. The shaft 13 is attached to the rear side of the substrate 10 so that the axial direction thereof is aligned with the up and down direction.

[0056] The slider 14 moves up and down along the shaft 13 in response to the rotation of the shaft 13. The slider 14 is, for example, cubic in shape. The slider 14 has a female threaded hole (not shown) that corresponds to the male threaded surface of the shaft 13. The female threaded hole passes through the slider 14 in the vertical direction. The shaft 13 is inserted into the female threaded hole.

[0057] The holding member 15 holds a first plunger 16b and a second plunger 17b, which will be described later. The holding member 15 is attached to the lower part of the front surface of the slider 14. The holding member 15 is passed through the through hole 10a and moves up and down together with the slider 14. The holding member 15 has, for example, a rectangular parallelepiped shape. A slit hole 15a is arranged in the center of the holding member 15 in the up and down direction, into which the lower ends of the first plunger 16b and the second plunger 17b (first flange portion 16e and second flange portion 17e, which will be described later) are fitted. The slit hole 15a opens forward (in the +Y direction) and left and right (in the X-axis direction) of the holding member 15. Plunger mounting grooves 15b and 15c are arranged above (in the +Z direction) the slit hole 15a of the holding member 15. The plunger attachment grooves 15b and 15c are open to the right and top surfaces of the holding member 15 and to the slit hole 15a. The plunger attachment grooves 15b and 15c are arranged side by side in the front-rear direction.

[0058] The first syringe pump unit 16 aspirates and discharges the first reagent from the first reagent tank T1. The first syringe pump unit 16 is, for example, a known microsyringe. The first syringe pump unit 16 is detachably attached to the holding member 15 and the connecting member 18 so that its axis is aligned in the vertical direction. In this embodiment, the maximum suction capacity of the first syringe pump unit 16 is designed to be greater than the total amount of the first reagent and the second reagent discharged in the oxidation process (S13) and the oxidation termination process (S14) described below. The first syringe pump unit 16 includes a first syringe 16a, a first plunger 16b, and a first gasket 16c.

[0059] The first syringe 16a has a cylindrical shape extending in the vertical direction. The upper end of the first syringe 16a has a reduced diameter, forming a first mounting portion 16d. The outer peripheral surface of the first mounting portion 16d is a male thread surface.

[0060] The first plunger 16b has a cylindrical shape extending in the vertical direction. The first plunger 16b is inserted into the first syringe 16a from the lower end side of the first syringe 16a and is capable of reciprocating (advancing and retreating) in the vertical direction relative to the first syringe 16a. The lower end of the first plunger 16b has an expanded diameter and forms a disk-shaped first flange portion 16e.

[0061] The first gasket 16c has a cylindrical shape extending in the vertical direction. The first gasket 16c is attached to the upper end of the first plunger 16b. The first gasket 16c, together with the first plunger 16b, can reciprocate (advance and retreat) in the vertical direction relative to the first syringe 16a in a liquid-tight state.

[0062] First mounting portion 16d is detachably fitted (screwed) from below into first syringe mounting hole 18a (described later). First flange portion 16e is detachably fitted into slit hole 15a of holding member 15. A portion of first plunger 16b adjacent to first flange portion 16e is fitted into plunger mounting groove 15b of holding member 15. As a result, first plunger 16b moves back and forth (advances and retreats) in the vertical direction relative to first syringe 16a in response to the vertical reciprocating movement of holding member 15.

[0063] The second syringe pump unit 17 aspirates and dispenses the second reagent from the second reagent tank T2. The second syringe pump unit 17 is, for example, a known microsyringe. The second syringe pump unit 17 is detachably attached to the holding member 15 and the connecting member 18 so that the axial direction of the second syringe pump unit 17 is aligned in the vertical direction. The configuration of the second syringe pump unit 17 is the same as the configuration of the first syringe pump unit 16. That is, the second syringe pump unit 17 includes a second syringe 17a, a second plunger 17b, a second gasket 17c, a second mounting portion 17d, and a second flange portion 17e.

[0064] Second mounting portion 17d is detachably fitted (screwed) from below into second syringe mounting hole 18b (described later). Second flange portion 17e is fitted into slit hole 15a of holding member 15. A portion (lower portion) of second plunger 17b adjacent to second flange portion 17e is fitted into plunger mounting groove 15c of holding member 15. As a result, second syringe pump portion 17 is disposed in front of and alongside first syringe pump portion 16. In response to the vertical reciprocating movement of holding member 15, second plunger 17b moves up and down (advances and retreats) relative to second syringe 17a.

[0065] The connecting member 18 connects the first syringe pump unit 16 and the second syringe pump unit 17 to the first reagent pipe L1 (first common pipe L12) and the second reagent pipe L2 (second common pipe L22), respectively. The connecting member 18 has, for example, a rectangular parallelepiped shape. The connecting member 18 is attached to the upper part of the front surface of the substrate 10, and is disposed above the first syringe pump unit 16 and the second syringe pump unit 17, respectively. The connecting member 18 includes a first syringe mounting hole 18a, a second syringe mounting hole 18b, a first pipe mounting hole 18c, a second pipe mounting hole 18d, a first communication hole 18e, and a second communication hole 18f.

[0066] First syringe mounting hole 18a is a bottomed cylindrical hole that opens to the lower surface of connecting member 18. The inner circumferential surface of first syringe mounting hole 18a is an internally threaded surface that corresponds to the externally threaded surface of first mounting portion 16d.

[0067] Second syringe mounting hole 18b is a bottomed cylindrical hole that opens to the lower surface of connecting member 18. The inner circumferential surface of second syringe mounting hole 18b is an internally threaded surface that corresponds to the externally threaded surface of second mounting portion 17d. Second syringe mounting hole 18b is disposed in front of and alongside first syringe mounting hole 18a.

[0068] First pipe mounting hole 18c is a bottomed cylindrical hole that opens to the upper surface of connecting member 18. The inner circumferential surface of first pipe mounting hole 18c is a female thread surface that corresponds to the male thread surface of first joint 21, which will be described later. First pipe mounting hole 18c is disposed above first syringe mounting hole 18a.

[0069] Second pipe mounting hole 18d is a bottomed cylindrical hole that opens to the upper surface of connecting member 18. The inner circumferential surface of second pipe mounting hole 18d is a female thread surface that corresponds to the male thread surface of second joint 22, which will be described later. Second pipe mounting hole 18d is disposed above second syringe mounting hole 18b.

[0070] First communication hole 18e is a cylindrical through-hole that opens to bottom surface 18g of first syringe mounting hole 18a and to bottom surface 18h of first tube mounting hole 18c.

[0071] Second communication hole 18f is a cylindrical through-hole that opens to bottom surface 18i of second syringe mounting hole 18b and to bottom surface 18j of second tube mounting hole 18d.

[0072] Seal members 19 and 20 are, for example, O-rings. Seal member 19 is housed in first syringe mounting hole 18a, and seal member 20 is housed in second syringe mounting hole 18b. Seal member 19 provides a liquid-tight seal between upper end surface 16f of first mounting portion 16d of first syringe pump section 16 and bottom surface 18g of first syringe mounting hole 18a. Seal member 20 provides a liquid-tight seal between upper end surface 17f of second mounting portion 17d of second syringe pump section 17 and bottom surface 18i of second syringe mounting hole 18b.

[0073] In the present invention, the sealing member housed in the first syringe mounting hole (second syringe mounting hole) may be a ring-shaped gasket. Also, the present device does not necessarily have to include a sealing member housed in the first syringe mounting hole (second syringe mounting hole).

[0074] The first joint 21 is a known joint with a seal member 21a that connects the first reagent pipe L1 (first common pipe L12) and the connecting member 18. The outer peripheral surface of the lower end of the first joint 21 is a male threaded surface that corresponds to the female threaded surface of the first pipe mounting hole 18c. The first joint 21 is fitted (screwed) into the first pipe mounting hole 18c from above. One end of the first common pipe L12 is inserted into the first joint 21. As a result, one end of the first common pipe L12 is connected to the first mounting portion 16d of the first syringe pump unit 16 via the first joint 21 and the connecting member 18.

[0075] The seal member 21a provides a liquid-tight seal between the first joint 21 and the first pipe mounting hole 18c. The seal member 21a is, for example, in the shape of an inverted funnel. The upper part of the seal member 21a is inserted into the lower end part of the first joint 21 (first common pipe L12). The lower part of the seal member 21a is sandwiched between the lower end surface 21b of the first joint 21 and the bottom surface 18h of the first pipe mounting hole 18c, providing a liquid-tight seal therebetween.

[0076] The second joint 22 is a known joint with a seal member 22a that connects the second reagent pipe L2 (second common pipe L22) and the connecting member 18. The configuration of the second joint 22 is the same as the configuration of the first joint 21. The second joint 22 is fitted (screwed) into the second pipe mounting hole 18d from above. One end of the second common pipe L22 is inserted into the second joint 22. As a result, one end of the second common pipe L22 is connected to the second mounting portion 17d of the second syringe pump unit 17 via the second joint 22 and the connecting member 18.

[0077] The upper part of the seal member 22a is inserted into the lower end part of the second joint 22 (second common pipe L22). The lower part of the seal member 22a is sandwiched between the lower end surface 22b of the second joint 22 and the bottom surface 18j of the second pipe mounting hole 18d, forming a liquid-tight seal therebetween.

[0078] In the first reagent pump P1 configured as described above, the holding member 15 moves up and down reciprocally in response to the rotation of the motor 11. At this time, the first plunger 16b and the second plunger 17b move up and down reciprocally (advance and retreat) simultaneously with the same stroke relative to the first syringe 16a and the second syringe 17a, respectively. In other words, the motor 11 causes the first syringe pump unit 16 and the second syringe pump unit 17 to perform the same operation simultaneously.

[0079] Furthermore, first syringe pump unit 16 can be easily attached to holding member 15 and connecting member 18 by simply fitting first mounting portion 16d into first syringe mounting hole 18a and fitting first flange portion 16e into slit hole 15a. First syringe pump unit 16 can be easily detached from holding member 15 and connecting member 18 by simply removing first mounting portion 16d from first syringe mounting hole 18a and removing first flange portion 16e from slit hole 15a. The same applies to second syringe pump unit 17.

[0080] ●Operation of the measuring device● Next, the operation of the present device 1, i.e., the present method, will be described. In the following description, Figures 1 to 4 will be referred to as appropriate. The present device 1 executes a normal measurement process (S1), a low concentration measurement process (S2), and a simple span calibration process (S3) under the control of the control unit 7.

[0081] ●Normal measurement process FIG. 5 is a flowchart showing an example of the normal measurement process (S1). 6 is a schematic diagram showing an example of the operation of the first reagent delivery mechanism M1 and the second reagent delivery mechanism M2 in the normal measurement process (S1), where (a) to (c) show the oxidation process (S13) described below, and (d) to (e) show the oxidation stop process (S14) described below. In the figure, the flow of reagents is indicated by thick arrows.

[0082] The "normal measurement process (S1)" is a process for measuring the COD concentration that is carried out when the oxidizable substances contained in the sample water are within the measurement range of the device 1.

[0083] First, the sample water introduction process (S11) is executed. In the sample water introduction process (S11), a predetermined amount of sample water is sent to the reaction vessel 2 by the sample water pump P5.

[0084] Next, pretreatment (S12) is performed. In pretreatment (S12), a predetermined amount of third reagent (sulfuric acid) is pumped into the reaction tank 2 by the third reagent pump P2 to acidify the sample water. Also, a predetermined amount of fourth reagent (silver nitrate) is pumped into the reaction tank 2 by the fourth reagent pump P3 to remove chloride ions from the sample water. As a result, a water sample (analyte solution) after pretreatment (S12) is produced.

[0085] In the present invention, the fourth reagent (silver nitrate) may be added to the sample water depending on the specifications of the measuring device and the sample water (e.g., sample water containing chloride ions), and the fourth reagent (silver nitrate) may not be added.

[0086] Next, an oxidation process (S13) is performed. In the oxidation process (S13), a required amount of the first reagent is delivered to the analysis liquid in the reaction vessel 2. Specifically, in the oxidation process (S13), a suction process (first suction step), a bubble removal process (first bubble removal step), a solution delivery process (first solution delivery step), and a heating process are performed in this order.

[0087] The "required amount" in the oxidation treatment (S13) is an amount greater than the amount of oxidizable substances contained in the water sample (analyte). The required amount is set, for example, based on the results of past measurements of the COD concentration of the water sample. In other words, the required amount is a variable amount. The required amount in the oxidation treatment (S13) is an example of the first required amount in the present invention.

[0088] In this embodiment, an acidic potassium permanganate method (acidic method) using sulfuric acid is employed, but the present invention can also be realized by an alkaline potassium permanganate method (alkaline method) using sodium hydroxide instead.

[0089] 6(a), in the suction process, the control unit 7 controls the operation of the first valve V1 to connect the first tank pipe L11 and the first common pipe L12, and controls the operation of the second valve V2 to connect the second tank pipe L21 and the second common pipe L22. Next, the control unit 7 controls the operation of the motor 11 to lower the slider 14 by the maximum amount. As a result, the first syringe pump unit 16 aspirates the maximum amount of the first reagent (potassium permanganate solution), and the second syringe pump unit 17 aspirates the maximum amount of the second reagent (sodium oxalate solution).

[0090] The bubble removal process removes air bubbles that may be mixed in the first reagent and the second reagent. Because the first syringe pump unit 16 is arranged vertically, air bubbles in the first syringe 16a gather at the upper end (first mounting unit 16d). After the first reagent is aspirated, air bubbles may also be mixed into the first reagent remaining in the path from the first reagent tank T1 to the first syringe pump unit 16, i.e., the first tank pipe L11, the first valve V1, the first common pipe L12, and the connecting member 18 (the seal member 19, the first communication hole 18e, and the lower part of the seal member 21a). Similarly, air bubbles may also be mixed into the path through which the second reagent is aspirated.

[0091] Referring also to FIG. 6(b), the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that a small amount of the first reagent is dispensed from the first syringe pump unit 16. The amount of the dispensed first reagent is set to be greater than the volume "V12" of the first common pipe L12. Specifically, the amount of the dispensed first reagent is set to be equal to the combined volume "V11 / 2+V12" of the volume "V12" of the first common pipe L12 and approximately half the volume "V11" of the first tank pipe L11. As a result, at least the first reagent in the path from the upper end (first mounting portion 16d) of the first syringe pump unit 16 to the first valve V1 is returned to the first tank pipe L11 together with air bubbles. That is, of the first reagent aspirated from the first reagent tank T1, the first reagent between the upper end of the first syringe pump unit 16 and the first valve V1 is returned to the first tank pipe L11 (first reagent tank T1) together with air bubbles. Therefore, the first reagent remaining from the first syringe pump unit 16 to the first valve V1 does not contain air bubbles. Similarly, at least the second reagent in the path from the upper end (second mounting unit 17d) of the second syringe pump unit 17 to the second valve V2 is returned to the second tank pipe L21 together with air bubbles. That is, of the second reagent aspirated from the second reagent tank T2, the second reagent between the upper end of the second syringe pump unit 17 and the second valve V2 is returned to the second tank pipe L21 (second reagent tank T2) together with air bubbles. Therefore, the second reagent remaining from the second syringe pump unit 17 to the second valve V2 does not contain air bubbles.

[0092] Referring also to FIG. 6(c), in the liquid transfer process, first, the control unit 7 controls the operation of only the first valve V1 to connect the first common pipe L12 and the first liquid transfer pipe L13. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of first reagent is transferred from the first syringe pump unit 16 to the reaction vessel 2. As a result, the required amount of first reagent is transferred to the reaction vessel 2. Because the motor 11 is a stepping motor, the first reagent is transferred with high precision. As described above, the bubble removal process is performed immediately before the liquid transfer process, so no air bubbles are mixed into the reaction vessel 2. At this time, the second syringe pump unit 17 is also operating simultaneously, and an amount of the second reagent equal to the required amount of the first reagent is returned to the second reagent tank T2. Next, the control unit 7 controls the operation of only the first valve V1 to connect the first tank pipe L11 and the first common pipe L12. The solution delivery process is an example of the first solution delivery step of the present invention.

[0093] In the heat treatment, the analyte solution in the reaction vessel 2 is heated to 100°C for 30 minutes. The heating is performed by heating the heating vessel 3 with the heater 4. As a result, the oxidizable substances contained in the analyte solution are oxidized by the potassium permanganate.

[0094] Next, an oxidation stopping process (S14) is performed. In the oxidation stopping process (S14), a required amount of the second reagent is delivered to the analysis solution in the reaction vessel 2. Specifically, in the oxidation stopping process (S14), a bubble removal process (second bubble removal step) and a solution delivery process (second solution delivery step) are performed in this order. As a result, unreacted potassium permanganate remaining in the analysis solution reacts with sodium oxalate, thereby stopping the oxidation reaction of the oxidizable substance.

[0095] The "required amount" in the oxidation stopping process (S14) is determined by the amount of potassium permanganate solution delivered in the oxidation process (S13). That is, the required amount is variable. The required amount in the oxidation stopping process (S14) is an example of the second required amount in the present invention.

[0096] During the 30-minute heating process, gas dissolved in the second reagent may form as bubbles inside the second syringe pump unit 17 and the path from the second syringe pump unit 17 to the second valve V2. The control unit 7 executes a bubble removal process to remove any bubbles that may form in the second reagent. Also see FIG. 6(d), the bubble removal process of the oxidation stop process (S14) executes the same operation as the bubble removal process of the oxidation process (S13). As a result, no bubbles are contained in the second reagent remaining from the second syringe pump unit 17 to the second valve V2. Similarly, no bubbles are contained in the first reagent remaining from the first syringe pump unit 16 to the first valve V1.

[0097] In the present invention, if no bubbles are generated in the second reagent during the heat treatment (or if bubbles are generated, the amount is extremely small), the apparatus does not need to perform the second bubble removal step.

[0098] Referring also to FIG. 6(e), in the liquid transfer process, the control unit 7 controls the operation of only the second valve V2 to connect the second common pipe L22 and the second liquid transfer pipe L23. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of the second reagent is transferred from the second syringe pump unit 17 to the reaction vessel 2. As a result, the required amount of the second reagent is transferred to the reaction vessel 2. Because the motor 11 is a stepping motor, the second reagent is transferred with high precision. As described above, the bubble removal process is performed immediately before the liquid transfer process, so no air bubbles are mixed into the reaction vessel 2. At this time, the first syringe pump unit 16 is also operating simultaneously, and an amount of the first reagent equal to the required amount of the second reagent is returned to the first reagent tank T1. Next, the control unit 7 controls the operation of only the second valve V2 to connect the second tank pipe L21 and the second common pipe L22. The solution delivery process is an example of the second solution delivery step in the present invention.

[0099] Next, a titration process (S15) is performed. In the titration process (S15), a first reagent is titrated into the analysis liquid. Specifically, in the titration process (S15), a suction process (second suction step), a bubble removal process (third bubble removal step), and a solution delivery process (third solution delivery step) are performed.

[0100] In the suction process, the same operation as in the suction process of the oxidation process (S13) is performed. Similarly, in the bubble removal process, the same operation as in the bubble removal process of the oxidation process (S13) is performed. As a result, no air bubbles are contained in the first reagent remaining from the first syringe pump unit 16 to the first valve V1. Similarly, no air bubbles are contained in the second reagent remaining from the second syringe pump unit 17 to the second valve V2.

[0101] In the liquid delivery process, the control unit 7 first controls the voltage between the two electrodes 6, 6 so that a constant current flows between them. Next, the control unit 7 controls the operation of only the first valve V1 to connect the first common pipe L12 and the first liquid delivery pipe L13. Next, the control unit 7 controls the operation of the motor 11 to gradually raise the slider 14 so that the first reagent is delivered little by little from the first syringe pump unit 16 to the reaction tank 2. Because the motor 11 is a stepping motor, the first reagent is delivered with high precision. At this time, the control unit 7 measures the potential difference between the electrodes 6, 6. The point at which the potential difference suddenly changes and reaches its maximum is designated as the equivalence point, and the amount of the first reagent delivered up to that point is acquired. Next, the control unit 7 calculates the COD concentration of the analysis solution based on the amount of the first reagent delivered. During the titration of the first reagent, the second syringe pump unit 17 also operates simultaneously, and the second reagent is returned to the second reagent tank T2 in an amount equal to the amount of the first reagent delivered. Next, the control unit 7 controls the operation of only the first valve V1 to connect the first tank pipe L11 and the first common pipe L12.

[0102] As described above, the motor 11 is a stepping motor. Therefore, the first reagent pump P1 can deliver each of the first and second reagents with high accuracy during the normal measurement process (S1). Furthermore, the first reagent pump P1 can perform a highly accurate bubble removal process corresponding to the volumes of the respective paths of the first and second reagents during the normal measurement process (S1). Furthermore, during the normal measurement process (S1), air bubbles contained in each of the first and second reagents are removed immediately before each of the first and second reagents is delivered to the reaction vessel 2. Therefore, in the present device 1, even if the amounts of sample water and each reagent used are reduced, highly accurate delivery that is not affected by bubbles can be achieved.

[0103] In this manner, in the present device 1, the control unit 7 simultaneously operates the first syringe pump unit 16 and the second syringe pump unit 17 using one motor 11. That is, in the present device 1, two syringe pumps are operated by the operation of one stepping motor, and two types of reagents are delivered with high precision. As a result, compared to a conventional measuring device (hereinafter referred to as a "conventional device") in which only one pump is driven by one motor, the present device 1 reduces the number of motors, reduces manufacturing costs, and reduces power consumption. Furthermore, in the present device 1, the use of a stepping motor and a bubble removal process reduces the amount of each reagent used in the delivery process. Furthermore, the control unit 7 controls the operation of each of the first valve V1 and the second valve V2 to switch the connection destinations of the first common pipe L12 and the second common pipe L22, thereby switching the delivery destinations of the first reagent and the second reagent. Therefore, in this device 1, the suction process, bubble removal process, and liquid delivery process can be performed for two reagents while first plunger 16b and second plunger 17b each move forward and backward one stroke. As a result, this device 1 does not require the suction process for each reagent and the bubble removal process except for the dissolved components, thereby shortening the time required for one measurement and suppressing deterioration of first gasket 16c and second gasket 17c. In this device 1, the total advance / retract distances of first gasket 16c and second gasket 17c are exactly the same, so the replacement intervals for first syringe 16a and second syringe 17a are the same, reducing the complexity of maintenance.

[0104] Low concentration measurement processing FIG. 7 is a flowchart showing an example of the low concentration measurement process (S2).

[0105] The "low concentration measurement process (S2)" is a COD concentration measurement process performed when the concentration of oxidizable substances contained in the sample water is lower than the measurement range of the device 1. Because sodium oxalate functions as an oxidizable substance, in the low concentration measurement process (S2), the concentration of oxidizable substances contained in the sample water is adjusted (increased) by sodium oxalate to fall within the measurement range (range) of 0 to 20 mg / L, as specified in JIS K 0806 "Automatic Chemical Oxygen Demand (COD) Meter." The low concentration measurement process (S2) is common to the normal measurement process (S1) except for the inclusion of the concentration adjustment process (S21), which will be described later. Therefore, in the following description of the low concentration measurement process (S2), steps common to the normal measurement process (S1) are assigned the same process numbers as the normal measurement process (S1), and detailed descriptions are omitted.

[0106] In the low-concentration measurement process of the present invention, the concentration of the oxidizable substance may be adjusted to a measurement range of 0.5 to 11 mgO / L (2.5 to 55% of the full scale of 20 mgO / L), as described in the remarks of JIS K 0806, 5. Measurement range.

[0107] First, a sample water introduction process (S11) is carried out.

[0108] Next, the concentration adjustment process (S21) is executed. Specifically, in the concentration adjustment process (S21), a suction process, a bubble removal process, and a liquid delivery process are executed in this order.

[0109] In the suction process, the first reagent and the second reagent are respectively aspirated, similarly to the suction process in the oxidation process (S13).

[0110] In the bubble removal process, bubbles contained in the first reagent and the second reagent are removed, similar to the bubble removal process in the oxidation process (S13).

[0111] In the liquid transfer process, first, the control unit 7 controls the operation of only the second valve V2 to connect the second common pipe L22 and the second liquid transfer pipe L23. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of second reagent is transferred from the second syringe pump unit 17 to the reaction tank 2. As a result, the required amount of second reagent is transferred to the reaction tank 2. As a result, in the reaction tank 2, a pseudo-sample water is generated in which the concentration of the oxidizable substance contained in the sample water is adjusted (increased) by the second reagent (sodium oxalate) to within the measurement range of the device 1. At this time, the first syringe pump unit 16 is also operating simultaneously, and an amount of the first reagent equal to the required amount of the second reagent is returned to the first reagent tank T1. Next, the control unit 7 controls the operation of only the second valve V2 to connect the second tank pipe L21 and the second common pipe L22.

[0112] The "required amount" in the concentration adjustment process (S21) is the amount required to adjust the concentration of the oxidizable substance contained in the simulated sample water until it falls within the measurement range of the device 1.

[0113] Next, pretreatment (S12), oxidation treatment (S13), oxidation stopping treatment (S14), and titration treatment (S15) are performed. In the titration treatment (S15), the control unit 7 calculates the original COD concentration of the sample water by subtracting the increase in the amount of oxidizable substances in the concentration adjustment treatment (S21) from the calculated COD concentration. Here, since the volume of the sample water increases by the volume of the sodium oxalate solution added to increase the concentration of oxidizable substances, the volume is corrected as necessary when calculating the COD concentration of the sample water.

[0114] ● Simple span calibration process (automatic preparation of span solution and span calibration) FIG. 8 is a flowchart showing an example of the simple span calibration process (S3).

[0115] The "simple span calibration process (S3)" is a process in which the second reagent, which is sodium oxalate, is diluted with pure water to automatically prepare a pseudo-analyte solution of the same concentration as the span calibration solution, and the pseudo-analyte solution is used to automatically perform span calibration of the device 1. In the following description of the simple span calibration process (S3), processes that are common to the normal measurement process (S1) are assigned the same process numbers as the normal measurement process (S1), and detailed descriptions are omitted.

[0116] First, a pure water introduction process (S31) is performed. In the pure water introduction process (S31), a predetermined amount of pure water is sent to the reaction tank 2 by the pure water pump P4. Specifically, in the pure water introduction process (S31), a suction process, a bubble removal process, and a liquid sending process are performed in this order.

[0117] In the suction process, the control unit 7 controls the operations of the third valve V3 and the pure water pump P4 to make the pure water pump P4 suck in the maximum amount of pure water.

[0118] In the bubble removal process, the control unit 7 controls the operations of the third valve V3 and the pure water pump P4 to remove bubbles contained in the pure water, similar to the bubble removal process in the oxidation process (S13).

[0119] In the liquid sending process, the control unit 7 controls the operations of the third valve V3 and the pure water pump P4 to send a predetermined amount of pure water (the amount necessary for dilution) to the reaction vessel 2.

[0120] Next, a reagent introduction process (S32) is executed. In the reagent introduction process (S32), first, a predetermined amount of the second reagent is delivered to the reaction vessel 2 by the first reagent pump P1. Specifically, in the reagent introduction process (S32), a suction process, a bubble removal process, and a delivery process are executed in this order.

[0121] In the suction process, the first reagent and the second reagent are respectively aspirated, similarly to the suction process in the oxidation process (S13).

[0122] In the bubble removal process, bubbles contained in the first reagent and the second reagent are removed, similar to the bubble removal process in the oxidation process (S13).

[0123] In the liquid transfer process, first, the control unit 7 controls the operation of only the second valve V2 to connect the second common pipe L22 and the second liquid transfer pipe L23. Next, the control unit 7 controls the operation of the motor 11 to raise the slider 14 so that the required amount of the second reagent is transferred from the second syringe pump unit 17 to the reaction tank 2. As a result, the required amount of the second reagent is transferred to the reaction tank 2, and a pseudo-analyte solution containing sodium oxalate of a known concentration (the same concentration as the span calibration solution) is prepared (generated). At this time, the first syringe pump unit 16 is also operating simultaneously, and an amount of the first reagent equal to the required amount of the second reagent is returned to the first reagent tank T1. Next, the control unit 7 controls the operation of only the second valve V2 to connect the second tank pipe L21 and the second common pipe L22. In this way, since the second solution is diluted with pure water, the concentration of sodium oxalate contained in the pseudo-analyte solution is lower than the concentration of sodium oxalate contained in the second solution.

[0124] The "required amount" in the reagent introduction process (S32) is the amount required to dilute the sodium oxalate added to the pure water so that its concentration (i.e., COD concentration) becomes the same as that in the span calibration solution. The required amount of the second reagent in the reagent introduction process (S32) is different from the required amount of the second reagent in the oxidation stop process (S14).

[0125] In the present invention, the "required amount" in the reagent introduction process may be changed depending on the purpose, and a pseudo-analyte solution containing sodium oxalate of another known concentration may be prepared.

[0126] Next, the solution obtained by adding the second reagent to pure water undergoes the same pretreatment (S12), oxidation treatment (S13), and oxidation stop treatment (S14) as in the normal measurement process (S1). That is, predetermined amounts of the third reagent (sulfuric acid) and the fourth reagent (silver nitrate) are added to the solution, and the required amount of the first solution is added to the resulting solution, which is then heated at 100°C for 30 minutes. Next, the required amount of sodium oxalate solution is added to the heated solution to stop the oxidation reaction. Through these processes, the span calibration solution is prepared.

[0127] In the present invention, if the fourth reagent (silver nitrate) is not added to the sample water, the fourth reagent is not added when preparing the span calibration solution. Also, if the normal measurement process is performed using the alkaline method, the span calibration solution is treated in the same manner as the sample water.

[0128] Next, a span calibration process (S33) is performed. In the span calibration process (S33), a process similar to the titration process (S15) is performed. In this case, the amount of the first solution delivered in the titration process (S15) is an example of the first required amount in the present invention.

[0129] In this way, the present apparatus 1 can automatically prepare the span calibration solution. Therefore, the present apparatus 1 eliminates the need for the user of the apparatus 1 to manually prepare the span calibration solution, making span calibration simple (easy). Furthermore, the present apparatus 1 can easily deliver any amount of second reagent to prepare the span calibration solution (pseudo-analyte solution) using only one first reagent pump P1. Furthermore, the present apparatus 1 can easily confirm the linearity of measurement results by preparing pseudo-analyte solutions of multiple COD concentrations. Furthermore, the present apparatus 1 can easily confirm the reproducibility of measurement results by repeatedly preparing pseudo-analyte solutions of the same concentration and measuring the COD concentration. Thus, the present apparatus 1 can deliver different amounts of reagent using only one first reagent delivery mechanism M1. In contrast, conventional apparatuses, which use a leveling method to measure the reagent by sucking up the unnecessary amount, require separate piping and valves for each reagent concentration.

[0130] Furthermore, if a measurement value is determined to be abnormal due to factors that affect the measurement value (e.g., threshold, trend, coefficient of variation (CV), bubbles, measurement accuracy, other measurement processing, etc.), the device 1 can confirm whether or not there is an abnormality in the measurement device by preparing a pseudo-analyte solution of known concentration using a simple span calibration process (S3) and measuring the pseudo-analyte solution. In this case, the measurement of the pseudo-analyte solution may be performed manually by the user. Furthermore, the concentration of the pseudo-analyte solution is not limited to the concentration of the span calibration solution. That is, for example, the concentration of the pseudo-analyte solution may be adjusted to a concentration that is close to the concentration normally observed in sample water. Similarly, the device 1 can easily confirm, as needed, that the obtained measurement value is accurate without being affected by the aforementioned factors (i.e., the soundness of the measurement results).

[0131] Furthermore, for example, if the concentration of a potassium permanganate solution fluctuates over time, the concentration of the potassium permanganate solution can be determined using a sodium oxalate solution of known concentration. That is, by performing a simple span calibration process (S3) using a sodium oxalate solution prepared by the method described in JIS K 0806, the potassium permanganate solution can be standardized (factor determined) from its equivalence point. In this case, the fourth reagent (silver nitrate) is not added, and the solution is heated to approximately 60°C (preferably 55°C to 60°C).

[0132] As mentioned above, even if a potassium permanganate solution of unknown concentration is used, the device 1 can determine (standardize) the concentration of the potassium permanganate solution by performing the simple span calibration process (S3). These operations are controlled by the control unit 7, and the result is calculated as the concentration (or factor) of the potassium permanganate solution, not as a COD value.

[0133] In the simplified span calibration process of the present invention, the pure water introduction process may be performed after the reagent introduction process, i.e., the second reagent may be delivered to the reaction vessel before the pure water is delivered to the reaction vessel.

[0134] Summary According to the embodiment described above, when a first solution is delivered to the reaction vessel 2, the control unit 7 connects the first common pipe L12 and the first liquid delivery pipe L13 to the first valve V1, connects the second common pipe L22 and the second tank pipe L21 to the second valve V2, and operates the motor 11 to discharge a required amount of the first solution from the first syringe pump unit 16. On the other hand, when a second solution is delivered to the reaction vessel 2, the control unit 7 connects the first common pipe L12 and the first tank pipe L11 to the first valve V1, connects the second common pipe L22 and the second liquid delivery pipe L23 to the second valve V2, and operates the motor 11 to discharge a required amount of the second solution from the second syringe pump unit 17. According to this configuration, the device 1 can simultaneously operate the first syringe pump unit 16 and the second syringe pump unit 17 by operating one motor 11, thereby delivering the first and second reagents in desired amounts with high precision. Therefore, the device 1 has a reduced number of motors, which reduces manufacturing costs and power consumption compared to conventional devices. Furthermore, while the first reagent is being delivered, the second reagent is returned to the second tank pipe L21 (second reagent tank T2) together with air bubbles. Similarly, while the second reagent is being delivered, the first reagent is returned to the first tank pipe L11 (first reagent tank T1) together with air bubbles. Therefore, the device 1 reduces the influence of air bubbles on the measurement of COD concentration. Thus, the device 1 can deliver the first and second reagents with high precision while suppressing the influence of air bubbles without increasing manufacturing costs.

[0135] Furthermore, according to the embodiment described above, the control unit 7 executes a bubble removal process immediately before the liquid transfer process. In the bubble removal process, the control unit 7 operates the motor 11 so that the first syringe pump unit 16 ejects a larger volume of the first reagent than the volume "V12" of the first common pipe L12. Similarly, in the bubble removal process, the control unit 7 operates the motor 11 so that the second syringe pump unit 17 ejects a larger volume of the second reagent than the volume "V22" of the second common pipe L22. With this configuration, the first reagent present inside the path from the upper end (first mounting portion 16d) of the first syringe pump unit 16 to the first valve V1 is reliably returned together with air bubbles into the first tank pipe L11. Similarly, the second reagent present inside the path from the upper end (second mounting portion 17d) of the second syringe pump unit 17 to the second valve V2 is reliably returned together with air bubbles into the second tank pipe L21. Therefore, in this device 1, bubbles do not affect the measurement of COD concentration.

[0136] Furthermore, according to the embodiment described above, the control unit 7 controls the operation of the first valve V1, the second valve V2, and the motor 11 so that the bubble removal process and the liquid delivery process for the first reagent are performed while the first plunger 16b moves forward and backward one stroke relative to the first syringe 16a. In addition to this control, the control unit 7 also controls the operation of the first valve V1, the second valve V2, and the motor 11 so that the bubble removal process and the liquid delivery process for the second reagent are performed while the second plunger 17b moves forward and backward one stroke relative to the second syringe 17a. In other words, the bubble removal process and the liquid delivery process are performed for the first reagent and the second reagent, respectively, while the first plunger 16b and the second plunger 17b move forward and backward one stroke. This configuration eliminates the need for the device 1 to perform aspiration for each reagent and bubble removal (excluding dissolved components) for each reagent. Therefore, the time required for one measurement is shortened, the number of strokes of each of first plunger 16b and second plunger 17b in one measurement is reduced, and deterioration of each of first gasket 16c and second gasket 17c is suppressed.

[0137] Furthermore, according to the embodiment described above, the device 1 executes the low concentration measurement process (S2). With this configuration, the device 1 can accurately measure the COD concentration even for sample water with a concentration lower than the measurement range of the device 1.

[0138] Furthermore, according to the embodiment described above, the apparatus 1 executes a simplified span calibration process (S3). This configuration allows the apparatus 1 to automatically execute span calibration between normal measurement processes (S1). Therefore, the apparatus 1 eliminates the need for the user of the apparatus 1 to manually prepare a span calibration solution, allowing for simple (easy) span calibration. This configuration also allows for the preparation of pseudo-analyte solutions with multiple COD concentrations, making it easy to confirm the linearity of the measurement results. Furthermore, the apparatus 1 allows for the preparation of pseudo-analyte solutions with the same concentration and the measurement of COD concentrations to be repeated, making it easy to confirm the reproducibility of the measurement results.

[0139] Furthermore, according to the embodiment described above, first pipe mounting hole 18c is disposed above first syringe mounting hole 18a, and seal member 21a provides a liquid-tight seal between lower end surface 21b of first fitting 21 and bottom surface 18h of first pipe mounting hole 18c. Second pipe mounting hole 18d is disposed above second syringe mounting hole 18b, and seal member 22a provides a liquid-tight seal between lower end surface 22b of second fitting 22 and bottom surface 18j of second pipe mounting hole 18d. With this configuration, during the bubble removal process, air bubbles do not remain in first pipe mounting hole 18c, nor do they enter between the male thread surface of first fitting 21 and the female thread surface of first pipe mounting hole 18c. Similarly, air bubbles do not remain in second pipe mounting hole 18d, nor do they enter between the male thread surface of second fitting 22 and the female thread surface of second pipe mounting hole 18d.

[0140] Other embodiments In the bubble removal process of the present invention, the ejection amount of the first reagent may be greater than the volume "V12" of the first common tube, and is not limited to the embodiment described above. That is, for example, the ejection amount of the first reagent may be greater than the combined volume "V11+V12" of the volume "V12" of the first common tube and the volume "V11" of the first tank tube. In this configuration, the first reagent present at the upper end of the first syringe pump unit is reliably returned to the first tank tube or the first reagent tank together with the air bubbles. Similarly, in the bubble removal process of the present invention, the ejection amount of the second reagent may be greater than the volume "V22" of the second common tube, and is not limited to the embodiment described above.

[0141] Furthermore, in the normal measurement process of the present invention, the control unit may execute the titration process while the first plunger and the second plunger each advance and retract one stroke. That is, in the normal process, the control unit does not need to execute the second suction step. In this case, the capacities of the first syringe pump unit and the second syringe pump unit are set to be larger than those in the above-described embodiment. In this configuration, the number of strokes of the first plunger and the second plunger in one measurement is further reduced, further suppressing deterioration of the first gasket and the second gasket.

[0142] Furthermore, in the present invention, the control unit may move each of the first plunger and the second plunger forward and backward by one stroke during each of the oxidation process, the oxidation stopping process, and the titration process. In this configuration, the capacity of each of the first syringe and the second syringe can be made small.

[0143] Furthermore, in the present invention, the sealing member provided in the first fitting may be an O-ring or gasket disposed between the tip end of the first fitting and the bottom surface of the first pipe mounting hole. Similarly, the sealing member provided in the second fitting may be an O-ring or gasket disposed between the tip end of the second fitting and the bottom surface of the second pipe mounting hole.

[0144] Furthermore, in the present invention, the first reagent pump may include three or more syringe pump units. That is, for example, the first reagent pump may also include a syringe pump unit that draws in and discharges pure water. In this case, a pure water pump is not required, further reducing the manufacturing cost of the device. Note that the motor only needs to have a torque that can withstand the load generated when each plunger moves forward and backward.

[0145] Furthermore, in the present invention, the first syringe pump section and the second syringe pump section may be arranged side by side in the X-axis direction.

[0146] Furthermore, in the present invention, the first and second reagents may be selected according to the components to be measured by the measuring device that functions as the present device. That is, the first reagent is not limited to a potassium permanganate solution, and the second reagent is not limited to a sodium oxalate solution.

[0147] Furthermore, in the present invention, the relationship between the volumes of the pipes is not limited to that of this embodiment, as long as it is suitable for the bubble removal process.

[0148] Furthermore, in the present invention, the arrangement and number of each pipe and each valve are not limited to those shown in Fig. 1. That is, for example, the present device may be equipped with other valves, and the air pipe may be connected to the sample water pipe or the waste liquid pipe.

[0149] Furthermore, in the present invention, the device does not necessarily have to include the fourth reagent delivery mechanism. [Explanation of symbols]

[0150] 1. Measuring equipment 2. Reaction vessel 7 Control Unit 11 Motor (stepping motor) 16 First syringe pump section 16a First syringe 16b First plunger 17 Second syringe pump section 17a Second syringe 17b Second plunger 18 Connecting member 18a First syringe mounting hole 18b Second syringe mounting hole 18c First pipe mounting hole 18d Second pipe mounting hole 21 First joint 21a sealing member (first sealing member) 22 Second joint 22a sealing member (second sealing member) L11 First tank pipe L12 1st common pipe L13 First liquid supply pipe L21 Second tank pipe L22 2nd common pipe L23 Second liquid supply pipe M5 pure water delivery mechanism T1 First reagent tank (first tank) T2 Second reagent tank (second tank) V1 First valve V2 Second valve

Claims

1. A measuring device for measuring the water quality of a water sample, a first syringe pump unit disposed along the vertical direction and configured to suck in and discharge the first solution; a second syringe pump unit disposed along the vertical direction and configured to suck in and discharge the second solution; a first tank for storing the first solution; a second tank for storing the second solution; a reaction tank to which the sample water, the first solution discharged from the first syringe pump unit, and the second solution discharged from the second syringe pump unit are delivered; a first valve that switches the destination of the first solution; a first tank pipe connected to the first valve and the first tank; a first common pipe connected to the first valve and an upper end of the first syringe pump unit; a first liquid transfer pipe connected to the first valve and the reaction tank; a second valve that switches the destination of the second solution; a second tank pipe connected to the second valve and the second tank; a second common pipe connected to the second valve and an upper end of the second syringe pump unit; a second liquid transfer pipe connected to the second valve and the reaction tank; a stepping motor that always causes the first syringe pump unit and the second syringe pump unit to perform the same operation simultaneously; a control unit that controls the operations of the first valve, the second valve, and the stepping motor; and The control unit When the first solution is delivered from the first syringe pump unit to the reaction tank, The first common pipe and the first liquid supply pipe are connected to the first valve, The second valve is connected to the second common pipe and the second tank pipe, operating the stepping motor so that a first required amount of the first solution is discharged from the first syringe pump unit through the first liquid supply pipe into the reaction tank, and the second solution is discharged from the second syringe pump unit through the second tank pipe into the second tank; When the second solution is delivered from the second syringe pump unit to the reaction tank, The first common pipe and the first tank pipe are connected to the first valve, The second common pipe and the second liquid supply pipe are connected to the second valve, operating the stepping motor so that a second required amount of the second solution is discharged from the second syringe pump unit through the second liquid supply pipe into the reaction tank, and the first solution is discharged from the first syringe pump unit through the first tank pipe into the first tank; A measuring device characterized by:

2. The control unit before the first required amount of the first solution is discharged from the first syringe pump unit, The first common pipe and the first tank pipe are connected to the first valve, The second valve is connected to the second common pipe and the second tank pipe, operating the stepping motor so that the first solution is discharged from the first syringe pump unit in a volume greater than the volume of the first common tube; before the second required amount of the second solution is discharged from the second syringe pump unit; The first common pipe and the first tank pipe are connected to the first valve, The second valve is connected to the second common pipe and the second tank pipe, operating the stepping motor so that the second solution is discharged from the second syringe pump unit in an amount greater than the volume of the second common tube; The measuring device according to claim 1 .

3. The control unit before the first required amount of the first solution is discharged from the first syringe pump unit; operating the stepping motor so that the first solution is discharged from the first syringe pump unit in a volume greater than the combined volume of the first common pipe and the first tank pipe; before the second required amount of the second solution is discharged from the second syringe pump unit; operating the stepping motor so that the second solution is discharged from the second syringe pump unit in an amount greater than the combined volume of the second common pipe and the second tank pipe; The measuring device according to claim 2 .

4. The first syringe pump unit includes: a cylindrical first syringe; a first plunger inserted into the first syringe from a lower end side of the first syringe; With The second syringe pump unit includes: a cylindrical second syringe; a second plunger inserted into the second syringe from a lower end side of the second syringe; With the stepping motor moves the first plunger forward and backward relative to the first syringe and simultaneously moves the second plunger forward and backward relative to the second syringe, The control unit While the first plunger moves forward and backward by one stroke relative to the first syringe, controlling the operations of the first valve, the second valve, and the stepping motor so that the first solution is discharged from the first syringe pump unit in a volume greater than the capacity of the first common pipe, thereby discharging the first required amount of the first solution; While the second plunger moves forward and backward by one stroke relative to the second syringe, controlling the operations of the first valve, the second valve, and the stepping motor so that the second solution is discharged from the second syringe pump unit in an amount greater than the volume of the second common pipe, thereby discharging the second required amount of the second solution.

4. The measuring device according to claim 2 or 3.

5. the measuring device is a chemical oxygen demand (COD) measuring device that measures a COD concentration of the sample water, the first solution is a potassium permanganate solution; the second solution is a sodium oxalate solution; The control unit The second solution is discharged from the second syringe pump unit so that the sample water sent to the reaction tank contains sodium oxalate at a concentration within a predetermined concentration range, thereby generating a pseudo sample water in which the concentration of an oxidizable substance contained in the sample water is adjusted by the sodium oxalate, controlling operations of the first valve, the second valve, and the stepping motor so that the first required amount of the first solution is delivered to the reaction tank after the pseudo water sample is produced; controlling operations of the first valve, the second valve, and the stepping motor so that, after the first required amount of the first solution has been delivered, the second required amount of the second solution is delivered to the reaction tank; 4. The measuring device according to claim 1.

6. The measuring device is a pure water delivery mechanism that delivers pure water to the reaction tank based on the control of the control unit; and The second solution is a known concentration of an oxidizable substance, Including, The control unit causing the pure water delivery mechanism to deliver a predetermined amount of the pure water to the reaction tank; before or after the pure water is fed, operations of the first valve, the second valve, and the second syringe pump unit are controlled so that an amount of the second solution different from the second required amount is fed to the reaction tank, thereby preparing a pseudo-analyte solution having a lower concentration than the known concentration and containing the oxidizable substance at a known concentration; controlling operations of the first valve, the second valve, and the first syringe pump unit so that the first required amount of the first solution is delivered to the reaction vessel after the pseudo-analyte solution has been prepared; controlling operations of the first valve, the second valve, and the stepping motor so that, after the first required amount of the first solution has been delivered, the second required amount of the second solution is delivered to the reaction tank; 4. The measuring device according to claim 1.

7. a connecting member disposed above each of the first syringe pump unit and the second syringe pump unit and connected to the upper end portion of each of the first syringe pump unit and the second syringe pump unit; a first joint that connects the first common pipe and the connecting member; a second joint that connects the second common pipe and the connecting member; and The connecting member is a first syringe mounting hole into which the upper end of the first syringe pump portion is fitted from below; a second syringe mounting hole into which the upper end of the second syringe pump portion is fitted from below; a first pipe mounting hole disposed above the first syringe mounting hole and into which a lower end of the first joint is fitted from above; a second pipe mounting hole disposed above the second syringe mounting hole and into which a lower end of the second joint is fitted from above; With The first joint is a first seal member that provides a liquid-tight seal between a lower end surface of the first joint and a bottom surface of the first pipe mounting hole; With The second joint is a second seal member that provides a liquid-tight seal between a lower end surface of the second joint and a bottom surface of the second pipe mounting hole; Equipped with The measuring device according to claim 1 .

8. A method for measuring the water quality using the measurement device according to any one of claims 1 to 3, comprising: The control unit a first solution delivery step of delivering the first required amount of the first solution to the reaction tank by controlling the operations of the first valve, the second valve, and the stepping motor after the sample water has been delivered to the reaction tank; a second solution delivery step of delivering the second required amount of the second solution to the reaction vessel by controlling operations of the first valve, the second valve, and the stepping motor after the first required amount of the first solution has been delivered; Including, A measuring method characterized by:

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