Calibration curve liquid manufacturing system, measurement system, and calibration curve liquid manufacturing method

Abstract

A calibration curve liquid production system for producing and supplying a calibration curve liquid for producing a calibration curve to a measurement device for measuring the total organic carbon concentration of a liquid to be analyzed using the calibration curve, the calibration curve liquid production system comprising: a liquid to be analyzed line (100) for conveying the liquid to be analyzed to a TOC analyzer (500); a standard liquid line (110) that conveys a standard liquid (210) to the analysis target liquid line (100); and a mixing unit (400) that is provided in the analysis target liquid line (100) and that mixes the diluent and the standard liquid (210) to dilute the standard liquid (210), the calibration curve liquid manufacturing system supplying a mixed liquid of the diluent and the standard liquid (210) mixed by the mixing unit (400) as a calibration curve liquid to the TOC analyzer (500).

Description

Technical Field

[0001] The invention relates to a calibration curve liquid manufacturing system, a measuring system and a calibration curve liquid manufacturing method. Background Art

[0002] In general, a total organic carbon analyzer is used to manage the concentration of total organic carbon (TOC) contained in a liquid. The calibration curve used in the total organic carbon analyzer is created using a standard solution.

[0003] As a total organic carbon analyzer for measuring the concentration (low concentration) of TOC, there is conceivable an apparatus for preparing a low-concentration test solution inside the total organic carbon analyzer (for example, refer to Patent Document 1).

[0004] Prior art literature Patent Literature Patent Document 1: Japanese Patent No. 3265830 Summary of the invention

[0005] Technical problem to be solved by the invention The commonly used calibration curve is made using a standard solution whose TOC concentration is in a high concentration area. If the calibration curve made using a standard solution whose TOC concentration is in a high concentration area is used for the determination of TOC concentration (low concentration), the proportion of the error in the high concentration area increases in the low concentration area. As a result, it is impossible to find the accurate TOC concentration. Therefore, in a total organic carbon analyzer that measures the concentration of TOC contained in ultrapure water, it is necessary to use a standard solution with a concentration equivalent to the concentration (low concentration) of TOC contained in ultrapure water to make a calibration curve. On the other hand, the lower the concentration of the standard solution, the greater the influence of pollution from the environment and the influence of human errors in the preparation of the standard solution. In addition, the device described in Patent Document 1 is a device for obtaining a low organic matter concentration by distilling a sample. In this case, equipment such as a combustion tube and a heating furnace is required. Therefore, it is necessary to prepare special equipment, which is time-consuming and costly.

[0006] An object of the present invention is to provide a calibration curve solution production system, a measurement system, and a calibration curve solution production method that can easily produce a calibration curve that can determine a more accurate TOC concentration.

[0007] Technical solutions for solving technical problems The calibration curve liquid manufacturing system of the present invention manufactures and supplies a calibration curve liquid for making a calibration curve to a measuring device that uses a calibration curve to measure the total organic carbon concentration of an analysis target liquid, and the calibration curve liquid manufacturing system comprises: a first liquid delivery line, which delivers a diluent to the assay device; a second liquid delivery line, which delivers a standard solution to the first liquid delivery line; and a mixing unit, which is disposed in the first liquid delivery line and mixes the diluent with the standard solution to dilute the standard solution; The calibration curve solution production system supplies a mixed solution of the diluent and the standard solution mixed by the mixing unit to the measuring device as the calibration curve solution.

[0008] In addition, the measuring system of the present invention comprises a calibration curve liquid manufacturing system and the measuring device, wherein the calibration curve liquid manufacturing system manufactures and supplies the calibration curve liquid for making the calibration curve to the measuring device that measures the total organic carbon concentration of the analysis target liquid using the calibration curve, and comprises: a first liquid delivery line, which delivers a diluent to the assay device; a second liquid delivery line, which delivers a standard solution to the first liquid delivery line; and a mixing unit, which is disposed in the first liquid delivery line and mixes the diluent with the standard solution to dilute the standard solution; The calibration curve solution production system supplies a mixed solution of the diluent and the standard solution mixed by the mixing unit to the measuring device as the calibration curve solution.

[0009] In addition, the method for preparing a calibration curve solution of the present invention is a method for preparing a calibration curve solution for preparing a calibration curve and supplying the calibration curve solution to a measuring device for measuring the total organic carbon concentration of an analyte solution using a calibration curve, comprising the following steps: diluting the standard solution by mixing a diluent delivered to a first liquid delivery line leading to the assay device with the standard solution delivered from a second liquid delivery line delivering a standard solution to the first liquid delivery line; and The mixed solution of the diluent and the standard solution is supplied to the measuring device as the calibration curve solution.

[0010] Effects of the Invention In the present invention, it is possible to easily create a calibration curve that can determine a more accurate TOC concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a diagram showing one embodiment of the calibration curve solution production system of the present invention.

[0012] Figure 2 It is used to illustrate Figure 1 FIG. 1 is a diagram showing an example of a method in which the correction unit corrects the calibration curve.

[0013] Figure 3This is a diagram showing an example of output values ​​when a calibration curve is prepared when the TOC concentration is in a high concentration region.

[0014] Figure 4 This is a diagram showing an example of output values ​​when a calibration curve is prepared when the TOC concentration is in a low concentration region.

[0015] Figure 5 It is a diagram showing an application example of the calibration curve solution production system of the present invention. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 FIG. 1 is a diagram showing one embodiment of the calibration curve solution manufacturing system of the present invention. Figure 1 As shown, the calibration curve liquid manufacturing system involved in this embodiment includes an analyte liquid pipeline 100, a standard liquid pipeline 110, a pump 300, a mixing unit 400, and a control unit 600. The calibration curve liquid mixed in the mixing unit 400 of the calibration curve liquid manufacturing system is supplied to the TOC analyzer 500. The correction unit 700 may also be connected to the TOC analyzer 500. In addition, the correction unit 700 may also be arranged inside the TOC analyzer 500. In addition, a flow meter 40 for measuring the flow rate of the analyte liquid transported to the analyte liquid pipeline 100 is provided in the analyte liquid pipeline 100. In addition, the TOC analyzer 500 may also be included as a component of the calibration curve liquid manufacturing system.

[0017] The analysis object liquid pipeline 100 is a first liquid delivery pipeline that delivers the analysis object liquid (for example, ultrapure water in the present embodiment) to the TOC analyzer 500. As the ultrapure water delivered to the TOC analyzer 500, for example, it can be ultrapure water that is sampled from at least a portion of the ultrapure water supplied to the use point from an ultrapure water manufacturing system having a pretreatment device, a primary pure water manufacturing device, and a secondary pure water manufacturing device (subsystem), or it can be ultrapure water stored in a specified storage tank. The analysis object liquid delivered to the analysis object liquid pipeline 100 is used as a diluent for diluting the standard solution 210 described later. The diluent delivered to the analysis object liquid pipeline 100 is not limited to the analysis object liquid, and can also be ultrapure water that is not the analysis object, etc. In this case, the analysis object liquid and the diluent different from the analysis object liquid can also be supplied from different pipes.

[0018] The pump 300 draws the standard solution 210 stored in the container 200. In this embodiment, as the performance of the pump 300, the stability and accuracy of the liquid delivery speed are required. The pump 300 is preferably a pump with less TOC elution from the liquid receiving part. The pump 300 is preferably a double plunger type, but is not limited to this. As long as the pump 300 has the same function, it can also be a device other than a pump. The drawing speed of the pump 300 drawing the standard solution 210 from the container 200 (in other words, the liquid delivery speed of the pump 300 from the container 200 to the analysis object liquid pipeline 100 via the standard liquid pipeline 110 as the second liquid delivery pipeline) is controlled according to the liquid delivery speed of the analysis object liquid pipeline 100 to deliver ultrapure water and the TOC concentration of the standard solution 210. This control will be described later. It should be noted that the standard solution 210 can also be prepared by diluting a standard solution (potassium hydrogen phthalate) associated with an international standard. Alternatively, the standard solution 210 may be prepared by diluting an organic substance contained in ultrapure water, such as a urea solution. The standard solution line 110 transports the standard solution 210 pumped by the pump 300 to the analyte solution line 100 .

[0019] The mixing unit 400 mixes the standard solution 210 drawn by the pump 300 with the ultrapure water delivered from the analyte solution line 100. Thus, in the mixing unit 400, the standard solution 210 drawn by the pump 300 is diluted with the ultrapure water delivered from the analyte solution line 100. A mixing coil may be used as the mixing unit 400. The liquid mixed in the mixing unit 400 is supplied to the TOC analyzer 500 as a calibration curve liquid.

[0020] The control unit 600 controls the pumping speed of the standard solution 210 (the amount of the standard solution 210 supplied from the pump 300). The control unit 600 controls the pumping speed of the standard solution 210 by the pump 300 so that the TOC concentration of the liquid mixed by the mixing unit 400 becomes less than a predetermined value based on the liquid feeding speed of the ultrapure water and the TOC concentration of the standard solution 210. For example, when the liquid feeding speed (flow rate) of the ultrapure water in the analysis target liquid line 100 is 1000 mL / min and the TOC concentration of the standard solution 210 is 100 ppb-C, and when the TOC concentration of the liquid mixed by the mixing unit 400 is to be set to a low concentration region (0.1 ppb-C + TOC concentration of ultrapure water), the control unit 600 controls the pump 300 so that the pump 300 draws the standard solution 210 at a pumping speed of 1 mL / min. In this way, the control unit 600 controls the pump 300 to draw the standard solution 210 from the container 200 to a given ratio (for example, 1 / 100) or less of the liquid delivery speed of the analysis target liquid pipeline 100 to deliver ultrapure water. As a result, the dilution ratio of the standard solution 210 using ultrapure water becomes a given ratio (for example, 100 times) or more. By diluting the standard solution 210, even if there is contamination or concentration error in the standard solution 210, the higher the dilution ratio, the smaller the influence of the error. As a result, a standard solution with a more accurate concentration can be prepared. It should be noted that a standard solution with a TOC concentration higher than 100 ppb-C in the standard solution 210 can also be used. In this case, the control unit 600 controls the pump 300 to draw the standard solution 210 at a speed slower than 1 mL / min. In addition, when the pump 300 draws the standard solution 210 at a fixed speed (performance), the TOC concentration of the standard solution 210 is adjusted so that the TOC concentration of the liquid mixed in the mixing unit 400 becomes less than a given value. The control unit 600 has at least a function of stopping or operating the pumping action of the pump 300. The control unit 600 may also input information based on an operation received from the outside, and perform control based on the input information. In addition, the control unit 600 may also receive a signal sent from another device, and perform control based on the information represented by the received signal. In addition, the control unit 600 may also perform a predetermined process on the input information or the information represented by the received signal, and perform control based on the result of the process.

[0021] The TOC analyzer 500 is a measuring device for measuring the total organic carbon concentration of a liquid that is an analysis target liquid. The TOC analyzer 500 has a function of decomposing organic matter in the supplied liquid and outputting the conductivity and resistivity values ​​before and after the decomposition as response values. In addition, the TOC analyzer 500 has a function of making a calibration curve for calculating the total organic carbon concentration based on the difference (output value) between its response values. The TOC analyzer 500 decomposes the organic matter in the calibration curve liquid mixed by the mixing unit 400 and measures the conductivity or resistivity of the liquid after the decomposition of the organic matter. The TOC analyzer 500 calculates the total organic carbon concentration of the liquid using the above-mentioned calibration curve based on the measured conductivity or resistivity. The TOC analyzer 500 is a continuous total organic carbon analyzer that performs measurements periodically. The cycle can also be a pre-set cycle. In addition, the cycle can also be a cycle that can be set from the outside. In addition, the continuous type means that when the TOC analyzer 500 starts to operate, as long as the instruction to end the operation is not input, the measurement is continued at each specified timing. TOC Analyzer 500 is a measuring device that measures total organic carbon concentration in the range of 0.1 to 500 ppb-C. Figure 1 The calibration curve solution preparation system and the TOC analyzer 500 shown constitute a measurement system.

[0022] The correction unit 700 corrects the calibration curve prepared by the TOC analyzer 500 using the standard addition method based on the first output value and the second output value. The first output value is a value measured by the TOC analyzer 500 in a state where there is no pump 300 (or a state where the control unit 600 stops the pump 300 from pumping the standard solution 210). In addition, the second output value is a value measured by the TOC analyzer 500 in a state where the control unit 600 operates the pump 300. Specifically, the correction unit 700 adds the total organic carbon concentration of the ultrapure water obtained using the standard addition method to the total organic carbon concentration of the standard solution 210 that is pumped by the pump 300 and diluted with ultrapure water to correct the calibration curve prepared by the TOC analyzer 500. The correction unit 700 may also be included in the TOC analyzer 500.

[0023] Figure 2 It is used to illustrate Figure 1 FIG. 7 is a diagram showing an example of a method of correcting a calibration curve by the correction unit 700 shown in FIG. Figure 2In the figure, the x-axis represents the TOC concentration of the standard solution 210 pumped by the pump 300 ("0" means that the standard solution 210 is not pumped by the pump 300). The y-axis represents the output value of the TOC analyzer 500. The correction unit 700 uses at least the TOC concentration output values ​​of the TOC analyzer 500 for a total of two points, namely, 1 point (first concentration) when the added concentration of the pump 300 is 0 and 1 point (second concentration) when the added concentration of the pump 300 is not "0". The correction unit 700 preferably uses the TOC concentration output values ​​of the TOC analyzer 500 for a total of three or more points, namely, 1 point when the added concentration of the pump 300 is "0" and 2 or more points when the added concentration of the pump 300 is not "0". Figure 2 The graph shown plots the output values ​​of three points: when the concentration added by the pump 300 is "0" (when the pump 300 is stopped), when the TOC concentration of the diluted standard solution 210 pumped by the pump 300 is 0.5 ppb-C, and when the TOC concentration is 1.0 ppb-C. Figure 2 In the graph shown, a straight line connecting the three drawn points is represented by a solid line. When the addition concentration of the pump 300 is "0" (x=0), the ultrapure water from the analysis object liquid pipeline 100 also contains TOC, so the measured value of the TOC analyzer 500 is not "0" (y=0). Therefore, the correction unit 700 uses the standard addition method to extend the solid line (represented by a dotted line) and find the intersection of the dotted line and the x-axis. The concentration corresponding to the distance between the coordinates of the intersection of the dotted line and the x-axis and "0" becomes the TOC concentration of the ultrapure water. The correction unit 700 moves the calibration curve of the solid line part and the dotted line part toward the positive direction of the x-axis by the amount of the TOC concentration of the ultrapure water. The straight line after the shift is represented by a single-point dashed line. The single-point dashed line becomes the corrected calibration curve.

[0024] Figure 3 This is a diagram showing an example of output values ​​when a calibration curve is prepared when the TOC concentration is in a high concentration region. Figure 3 The output value shown is the conductivity, resistivity or other values ​​measured by the TOC analyzer 500 to calculate the TOC concentration, and is used when calculating the TOC concentration. Figure 4 Same. Figure 3 Indicates that the measurement error of the device is within 1%. Figure 3As shown in the figure, when the TOC concentration of the standard solution is 500 ppb-C, the theoretical output value is "500", but the actual output value is "502". In addition, when the TOC concentration of the standard solution is 1000 ppb-C, the theoretical output value is "1000", but the actual output value is "997". In addition, when the TOC concentration of the standard solution is 1500 ppb-C, the theoretical output value is "1500", but the actual output value is "1494". These results are shown as a graph. Figure 3 The relationship between the TOC concentration (x) and the output value (y) (calibration curve) is y = 0.992x + 5.6667. If the output value when the TOC concentration is a low concentration of 1 ppb-C is calculated based on this calibration curve, it becomes "6.6587", resulting in a large error. In this way, if the output value obtained by measuring a low concentration is converted using a calibration curve made with a high-concentration standard solution, the measured value obtained by this conversion becomes a value with low reliability.

[0025] Figure 4 This is a diagram showing an example of output values ​​when a calibration curve is prepared when the TOC concentration is in a low concentration region. Figure 4 Indicates that the measurement error of the device is within 1%. Figure 4 As shown in the figure, when the TOC concentration of the standard solution is 0.5 ppb-C, the theoretical output value is "0.5", but the actual output value is "0.52". In addition, when the TOC concentration of the standard solution is 1.0 ppb-C, the theoretical output value is "1.0", but the actual output value is "0.997". In addition, when the TOC concentration of the standard solution is 1.5 ppb-C, the theoretical output value is "1.5", but the actual output value is "1.494". These results are shown as a graph. Figure 4 The relationship between the TOC concentration (x) and the output value (y) (calibration curve) is y = 0.992x + 0.0057. If the output value is calculated based on the calibration curve when the TOC concentration is a low concentration of 1 ppb-C, it becomes "0.9977", and the error becomes smaller. In this way, if the output value obtained by the measurement is converted using a calibration curve made using a standard solution near the concentration of the measurement object, the measurement value obtained by this conversion becomes a highly reliable value.

[0026] In this way, in order to obtain a high reliability of the measured value obtained using the calibration curve, it is necessary to use a low-concentration standard solution to prepare a calibration curve for a measuring device for measuring low TOC concentrations. However, the standard solution is usually likely to be contaminated by the environment after preparation and before use. For example, if it is assumed that the increase in TOC concentration caused by pollution from the environment is 5ppb-C, even if a low-concentration 5ppb-C standard solution is prepared, the TOC concentration will become 10ppb-C when used due to the environment. The increase ratio of TOC concentration becomes 100%. On the other hand, in the case of preparing a standard solution with a commonly used TOC concentration of 250ppb-C, due to the environment, the TOC concentration becomes 255ppb-C when used. The increase ratio of TOC concentration becomes 2%. In this way, it is preferred to prepare a low-concentration standard solution for use. However, a low-concentration standard solution is difficult to modulate because the error of its concentration becomes large. Therefore, a standard solution with a commonly used TOC concentration is used during preparation, and when it is supplied to the measuring device, the standard solution needs to be diluted to a low concentration for use. Therefore, using the present invention, a standard solution with a TOC concentration equivalent to the commonly used TOC concentration is mixed with ultrapure water by adjusting the liquid delivery speed of the ultrapure water from the analysis object liquid pipeline and the speed of sucking the standard solution with a pump. Then, the mixed liquid is diluted in a manner such that the TOC concentration becomes a low concentration, and is supplied to the measuring device online. Furthermore, in order to take into account the TOC concentration contained in the ultrapure water mixed with the standard solution, the calibration curve is corrected using the TOC concentration of the analysis object liquid obtained by the standard addition method. As a result, when measuring the TOC concentration in the low concentration area (for example, below 1 ppb-C), a calibration curve with a small measurement error can be prepared.

[0027] Figure 5 FIG. 2 is a diagram showing an application example of the calibration curve solution production system of the present invention. Figure 5 In the example shown, an ultrapure water tank 10, a pump 20, a heat exchanger 30, an ultraviolet oxidation device 31, a non-regenerative ion exchange device 32, a membrane degassing device 33, an ultrafiltration device 34, a flow meter 40, an analysis liquid pipeline 100, a container 200 storing a standard liquid 210, a pump 300, a control unit 600, a mixing coil 410, a TOC analyzer 500 and a correction unit 700 are provided.

[0028] Ultrapure water is supplied from the ultrapure water tank 10 to the heat exchanger 30 using a pump 20, and is transported from the heat exchanger 30 to the analysis target liquid pipeline 100 via the ultraviolet oxidation device 31, the non-regeneration type ion exchange device 32, the membrane degassing device 33 and the ultrafiltration device 34. The analysis target liquid pipeline 100 is provided with a flow meter 40. The treatment in each of the heat exchanger 30, the ultraviolet oxidation device 31, the non-regeneration type ion exchange device 32, the membrane degassing device 33 and the ultrafiltration device 34, which are water treatment devices, is the same as that in a general water treatment system.

[0029] In addition, the flow meter 40, the container 200, the standard solution 210, the pump 300, the control unit 600, the TOC analyzer 500 and the correction unit 700 are respectively connected to Figure 1 The components shown are the same. The hybrid coil 410 is equivalent to Figure 1 The mixing unit 400 is shown. The mixing coil 410 mixes the standard solution 210 pumped by the pump 300 with the ultrapure water sent from the analyte liquid line 100 to dilute the standard solution 210 .

[0030] In the above, each component is described separately, but its structure can be combined arbitrarily, and one or more devices can share them. For example, as described above, the correction unit 700 can be provided in the TOC analyzer 500. In addition, the control unit 600 and the correction unit 700 can also be provided in the TOC analyzer 500. In addition, the control unit 600 and the correction unit 700 can also be provided in a device different from the TOC analyzer 500, and the device communicates with the TOC analyzer 500 to exchange signals. Furthermore, the system can also be provided with a general ultrapure water production device or a water treatment device (such as an ultrafiltration device).

[0031] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0032] This application claims the benefit of priority based on Japanese patent application No. 2022-083008, filed on May 20, 2022, the disclosure of which is incorporated herein in its entirety by reference.

Claims

1. A calibration curve liquid manufacturing system, which manufactures and supplies a calibration curve liquid for preparing a calibration curve to a measuring device that uses a calibration curve to measure the total organic carbon concentration of an analysis target liquid, the calibration curve liquid manufacturing system comprising: a first liquid delivery line, which delivers a diluent to the assay device; a second liquid delivery pipeline, which delivers a standard solution to the first liquid delivery pipeline; as well as a mixing unit, which is disposed in the first liquid delivery line and mixes the diluent with the standard solution to dilute the standard solution; The calibration curve solution production system supplies a mixed solution of the diluent and the standard solution mixed by the mixing unit to the measuring device as the calibration curve solution.

2. The calibration curve liquid manufacturing system according to claim 1, in, The calibration curve liquid manufacturing system comprises: a pump, which is disposed on the second liquid delivery line and supplies the standard solution to the first liquid delivery line; as well as a control unit that controls the supply amount of the pump, The control unit controls the pump based on the liquid feeding rate of the diluent in the first liquid feeding line and the total organic carbon concentration of the standard solution so that the total organic carbon concentration of the calibration curve solution is equal to or less than a given value.

3. The calibration curve liquid manufacturing system according to claim 2, in, The given value is 100 ppb-C.

4. The calibration curve liquid manufacturing system according to claim 2 or 3, in, The control unit controls the pump so as to supply the standard solution to the first solution supply line at a solution supply rate that is 1 / 100 or less of a solution supply rate of the diluent in the first solution supply line.

5. The calibration curve liquid manufacturing system according to claim 2 or 3, in, The calibration curve liquid manufacturing system comprises a correction unit, The correction unit corrects the calibration curve produced by the measuring device based on the total organic carbon concentration of the diluent obtained using the standard addition method, according to the first concentration measured by the measuring device when the control unit stops the pump and delivers the diluent to the measuring device, and the second concentration measured by the measuring device when the control unit operates the pump and delivers the calibration curve liquid to the measuring device.

6. The calibration curve liquid manufacturing system according to claim 5, in, The correction unit corrects the calibration curve created by the measuring device by adding the total organic carbon concentration of the dilution solution obtained by the standard addition method to the total organic carbon concentration of the standard solution diluted with the dilution solution by operating the pump.

7. The calibration curve liquid manufacturing system according to any one of claims 1 to 3, in, The calibration curve solution manufacturing system manufactures a calibration curve solution for preparing a calibration curve for a measuring device as described below, The measuring device decomposes organic matter in the liquid mixed in the mixing unit, measures the conductivity or resistivity of the liquid after the organic matter is decomposed, and calculates the total organic carbon concentration of the liquid based on the measured conductivity or resistivity.

8. The calibration curve liquid manufacturing system according to any one of claims 1 to 3, in, The measuring range of the total organic carbon concentration of the measuring device is 0.1~500ppb-C. 9 . A measurement system comprising the calibration curve solution production system according to claim 1 and the measurement device.

10. A method for preparing a calibration curve solution, comprising preparing and supplying a calibration curve solution for preparing a calibration curve to a measuring device for measuring the total organic carbon concentration of an analyte solution using a calibration curve, the method comprising the following steps: diluting the standard solution by mixing a diluent delivered to a first liquid delivery line leading to the assay device with the standard solution delivered from a second liquid delivery line delivering the standard solution to the first liquid delivery line; and The mixed solution of the diluent and the standard solution is supplied to the measuring device as the calibration curve solution.

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