Calibration curve solution production system, measurement system, and calibration curve solution production method

Abstract

The present invention provides a calibration fluid manufacturing system for manufacturing and supplying calibration fluid for a measuring device that uses a calibration fluid to measure the total organic carbon concentration of an analyte solution. The system comprises: an analyte solution line (100) for supplying the analyte solution to a TOC (Total Organic Carbon) meter (500); a standard solution line (110) for supplying a standard solution (210) to the analyte solution line (100); and a mixing unit (400) provided in the analyte solution line (100) for mixing the standard solution (210) with a diluent to dilute the standard solution (210); and supplying the mixture of the diluent and the standard solution (210) formed in the mixing unit (400) as the calibration fluid to the TOC meter (500).

Description

Technical Field

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

[0002] Generally speaking, a total organic carbon analyzer is used to control the concentration of total organic carbon (TOC) in a liquid. The calibration curve used in this total organic carbon analyzer is made using standard solutions.

[0003] As a total organic carbon analyzer for measuring the concentration (low concentration) of TOC, a device for preparing a low-concentration test solution inside the total organic carbon analyzer has been considered (for example, see Patent Document 1). [Prior Art Literature] [Patent Document]

[0004] [Patent Document 1] Japanese Patent No. 3265830 Summary of the Invention

[0005] [Problem that the invention aims to solve]

[0006] The commonly used calibration curve is created using a standard solution with a high TOC concentration range. When a calibration curve created using a standard solution with a high TOC concentration range is applied to the measurement of low TOC concentration, the error ratio in the high concentration range becomes larger in the low concentration range. Consequently, it becomes impossible to determine the correct TOC concentration. Therefore, total organic carbon analyzers that measure TOC concentrations in ultrapure water must use a standard solution with a concentration corresponding to the low TOC concentration in the ultrapure water to create the calibration curve. On the other hand, the lower the concentration of the standard solution, the greater the influence of environmental contamination and human error in preparing the standard solution. Furthermore, the device described in Patent Document 1 achieves low organic matter concentrations by distilling the sample. This requires equipment such as a combustion tube and a heating furnace. This requires dedicated equipment, which is time-consuming and expensive.

[0007] 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 facilitate the production of a calibration curve capable of determining a more accurate TOC concentration. [Technical means to solve the problem]

[0008] The calibration liquid manufacturing system of the present invention, A calibration curve liquid manufacturing system for manufacturing and supplying a calibration curve liquid for a measuring device for measuring the total organic carbon concentration of an analysis target liquid using a calibration curve. It has: a first liquid delivery line for delivering a diluent to the assay device; a second liquid delivery line, delivering a standard liquid to the first liquid delivery line; and a mixing unit, disposed in the first liquid delivery line, configured to mix the standard liquid with the diluent to dilute the standard liquid; The mixed solution of the diluent and the standard solution mixed in the mixing portion is supplied to the measuring device as the calibration liquid.

[0009] Furthermore, the measurement system of the present invention has: A measuring device; and a calibration curve liquid manufacturing system for manufacturing and supplying a calibration curve liquid for preparing a calibration curve to a measuring device for measuring the total organic carbon concentration of an analyte using a calibration curve; The calibration liquid manufacturing system comprises: a first liquid delivery line for delivering the diluent to the measuring device; a second liquid delivery line, delivering a standard liquid to the first liquid delivery line; and A mixing unit is provided in the first liquid delivery line and mixes the standard liquid with the diluent to dilute the standard liquid; and The mixed solution of the diluent and the standard solution mixed in the mixing portion is supplied to the measuring device as the calibration liquid.

[0010] Furthermore, the method for producing a calibration liquid of the present invention, A method for producing a calibration curve solution for a device for measuring the total organic carbon concentration of an analyte using a calibration curve, and supplying a calibration curve solution for producing the calibration curve. Mixing the standard solution delivered from the second liquid delivery line to the first liquid delivery line with the diluent delivered in the first liquid delivery line to the measuring device to dilute the standard solution; The mixed solution of the diluent and the standard solution is used as the calibration liquid and supplied to the measuring device. [Effects of the Invention]

[0011] The present invention can facilitate the creation of a calibration curve capable of determining a more accurate TOC concentration. Simple diagram description

[0012] FIG1 is a diagram showing an embodiment of the system for producing a calibration liquid according to the present invention. FIG. 2 is a diagram for explaining an example of a method of correcting the calibration curve by the correction unit shown in FIG. 1 . FIG. 3 is a graph showing an example of output values ​​when a calibration curve is prepared for TOC concentration in a high concentration range. FIG. 4 is a graph showing an example of output values ​​when a calibration curve is prepared for a low-concentration range of TOC concentration. FIG5 is a diagram showing an application example of the calibration liquid production system of the present invention. Implementation Method

[0013] The following describes embodiments of the present invention with reference to the accompanying drawings. FIG1 is a diagram illustrating one embodiment of a calibration curve solution manufacturing system according to the present invention. As shown in FIG1 , the calibration curve solution manufacturing system according to this embodiment includes an analyte solution line 100, a standard solution line 110, a pump 300, a mixing unit 400, and a control unit 600. The calibration curve solution mixed by the mixing unit 400 of this calibration curve solution manufacturing system is supplied to a TOC meter 500. A correction unit 700 may be connected to the TOC meter 500. Alternatively, the correction unit 700 may be internal to the TOC meter 500. Furthermore, a flowmeter 40 is provided in the analyte solution line 100 to measure the flow rate of the analyte solution conveyed therein. Alternatively, the TOC meter 500 may be included as a component of the calibration curve solution manufacturing system.

[0014] The analyte line 100 is the first liquid transport line that transports the analyte (for example, ultrapure water in this embodiment) to the TOC meter 500. The ultrapure water transported to the TOC meter 500 may be, for example, at least a portion of the ultrapure water supplied to the user from an ultrapure water production system comprising a pretreatment device, a primary pure water production device, and a secondary pure water production device (subsystem), or may be ultrapure water stored in a predetermined storage tank. The analyte transported through the analyte line 100 is used as a diluent for diluting the standard solution 210, described later. The diluent transported through the analyte line 100 is not limited to the analyte; it may also be ultrapure water other than the analyte. In this case, the analyte and a diluent different from the analyte may be supplied through separate piping.

[0015] Pump 300 extracts standard solution 210 stored in container 200. In this aspect, the performance of pump 300 requires stable and accurate liquid delivery speed. Pump 300 preferably minimizes TOC elution from liquid-contacting components. A double-piston type is preferred, but not limited to this. Pump 300 may be any other type of pump as long as it performs the same function. The pump 300's extraction speed for standard solution 210 from container 200 (in other words, the speed at which pump 300 delivers standard solution 210 from container 200 via standard solution line 110, serving as a second liquid delivery line, to analyte line 100) is controlled based on the delivery speed of ultrapure water from analyte line 100 and the TOC concentration of standard solution 210. This control will be described later. Alternatively, standard solution 210 may be prepared by diluting a standard solution corresponding to an international standard (potassium hydrogen phthalate). Alternatively, the standard solution 210 may be prepared by diluting an organic substance actually contained in ultrapure water, such as a urea solution. The standard solution line 110 delivers the standard solution 210 pumped by the pump 300 to the analyte solution line 100.

[0016] The mixing section 400 mixes the standard solution 210 pumped by the pump 300 with the ultrapure water supplied from the analyte line 100. The ultrapure water supplied from the analyte line 100 is then used in the mixing section 400 to dilute the standard solution 210 pumped by the pump 300. A mixing coil can also be used as the mixing section 400. The liquids mixed in the mixing section 400 are supplied to the TOC meter 500 as the calibration curve solution.

[0017] The controller 600 controls the pumping rate (the amount of standard solution 210 supplied from the pump 300) of the standard solution 210. The controller 600 controls the pumping rate of the standard solution 210 by the pump 300 based on the ultrapure water delivery rate and the TOC concentration of the standard solution 210 so that the TOC concentration of the liquid after mixing in the mixing section 400 remains below a predetermined value. For example, if the delivery rate (flow rate) of the ultrapure water in the analyte liquid line 100 is set to 1000 mL / min, the TOC concentration of the standard solution 210 is set to 100 ppb-C, and the TOC concentration of the liquid after mixing in the mixing section 400 is to be kept in the low concentration range (0.1 ppb-C + the TOC concentration of the ultrapure water), the controller 600 controls the pump 300 so that the standard solution 210 is delivered at a delivery rate of 1 mL / min. As described above, the controller 600 controls the pump 300 to pump the standard solution 210 from the container 200 at a predetermined ratio (e.g., 1 / 100) or less of the ultrapure water delivery rate through the analyte line 100. This ensures that the dilution ratio of the standard solution 210 diluted with ultrapure water is greater than the predetermined ratio (e.g., 100 times). By diluting the standard solution 210, even if there is contamination or concentration errors in the standard solution 210, the impact of these errors decreases as the dilution ratio increases. This allows the preparation of a standard solution with a more accurate concentration. Furthermore, a standard solution 210 with a TOC concentration higher than 100 ppb-C can be used. In this case, the controller 600 controls the pump 300 to pump the standard solution 210 at a rate slower than 1 mL / min. Furthermore, when the pump 300 pumps the standard liquid 210 at a fixed speed (performance), the TOC concentration of the standard liquid 210 is adjusted so that the TOC concentration of the liquid after mixing in the mixing section 400 is below a predetermined value. The control section 600 has at least the function of stopping or resuming the pumping operation of the pump 300. The control section 600 can also input information based on externally received operations and perform control based on the input information. Furthermore, the control section 600 can receive signals transmitted from other devices and perform control based on the information indicated by the received signals. Furthermore, the control section 600 can perform predetermined processing on the input information or information indicated by the received signals and perform control based on the results of the processing.

[0018] The TOC meter 500 is a measuring device that measures the total organic carbon concentration of a liquid serving as an analysis target liquid. The TOC meter 500 has the function of decomposing organic matter in the supplied liquid and outputting the conductivity or resistivity before and after the decomposition as a response value. Furthermore, the TOC meter 500 has the function of creating a calibration curve for calculating the total organic carbon concentration from the difference between the response values ​​(output value). The TOC meter 500 decomposes the organic matter in the calibration liquid mixed in the mixing section 400 and measures the conductivity or resistivity of the liquid after the decomposition of the organic matter. The TOC meter 500 calculates the total organic carbon concentration of the liquid based on the measured conductivity or resistivity and using the aforementioned calibration curve. The TOC meter 500 is a continuous total organic carbon analyzer that performs periodic measurements. This period may be a pre-set period. Alternatively, this period may be a period that can be set externally. The term "continuous" refers to a method in which TOC meter 500 begins operating and continues measuring at predetermined time points until an instruction to terminate the operation is input. The TOC meter 500 measures total organic carbon concentrations in the range of 0.1 to 500 ppb-C. The calibration fluid preparation system shown in Figure 1 and the TOC meter 500 constitute the measurement system.

[0019] The correction unit 700 uses the standard addition method based on the first and second output values ​​to correct the calibration curve created by the TOC meter 500. The first output value is measured by the TOC meter 500 when the pump 300 is not in operation (or when the controller 600 stops pumping the standard solution 210). The second output value is measured by the TOC meter 500 when the controller 600 is operating 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 extracted by the pump 300 and diluted with ultrapure water to correct the calibration curve created by the TOC meter 500. The correction unit 700 may also be included in the TOC meter 500.

[0020] Figure 2 is a diagram illustrating an example of how correction unit 700 corrects the calibration curve shown in Figure 1. In Figure 2, the x-axis shows the TOC concentration of standard solution 210 pumped by pump 300 ("0" indicates no pumping of standard solution 210 by pump 300). The y-axis shows the output value of TOC meter 500. Correction unit 700 uses the TOC concentration output by TOC meter 500 for at least two points: "a point where the concentration of the additive pumped by pump 300 is 0 (first concentration)" and "a point where the concentration of the additive pumped by pump 300 is not 0 (second concentration)." Correction unit 700 preferably uses the TOC concentration output by TOC meter 500 for a total of three or more points: "one point when the concentration of the additive pumped by pump 300 was '0'" and "two or more points when the concentration of the additive pumped by pump 300 was not '0'." The graph shown in Figure 2 plots the output values ​​for three points: "when the concentration of the additive pumped by pump 300 was '0' (when pump 300 was stopped), and "when the TOC concentration of the diluted standard solution 210 pumped by pump 300 was 0.5 ppb-C and 1.0 ppb-C." The graph in Figure 2 shows a solid line connecting the three plotted points. Since the ultrapure water from the analyte line 100 also contains TOC when the spike concentration pumped by pump 300 is "0" (x=0), the measured value of the TOC meter 500 will not be "0" (y=0). Therefore, the correction unit 700 uses the standard addition method and extends the solid line (indicated by the dashed line) to determine the intersection of the dashed line and the x-axis. The concentration obtained from the distance between the coordinates of the intersection of the dashed line and the x-axis and "0" is defined as the TOC concentration of the ultrapure water. The correction unit 700 shifts the calibration curve between the solid and dashed lines in the positive direction of the x-axis according to the TOC concentration of the ultrapure water. The shifted straight line is represented by a dotted chain line. This dotted chain line is defined as the corrected calibration curve.

[0021] Figure 3 is a graph showing an example of output values ​​when a calibration curve is created for TOC concentration in the high concentration range. The output values ​​shown in Figure 3 are the conductivity, resistivity, or other values ​​measured by the TOC meter 500 to calculate the TOC concentration, and are used to calculate the TOC concentration. This output value also applies to Figure 4 described below. Figure 3 shows a case where the device's measurement error is within 1%. As shown in Figure 3, the theoretical output value for a TOC concentration of 500 ppb-C in the standard solution is 500, but the actual output value is 502. Furthermore, the theoretical output value for a TOC concentration of 1000 ppb-C in the standard solution is 1000, but the actual output value is 997. Furthermore, 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 in the lower panel of Figure 3. The relationship (calibration curve) between TOC concentration (x) and output value (y) is y = 0.992x + 5.6667. Using this calibration curve, the output value for a low TOC concentration of 1 ppb-C is calculated as "6.6587," resulting in a large error. As mentioned above, if the output value obtained from a low-concentration measurement is converted using a calibration curve created using a high-concentration standard solution, the resulting measured value will be unreliable.

[0022] Figure 4 shows an example of the output value when a calibration curve is created for a low-TOC concentration range. Figure 4 illustrates a situation where the device's measurement error is within 1%. As shown in Figure 4, 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. Furthermore, 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. Furthermore, 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 graphically presented in the lower panel of Figure 4. The relationship (calibration curve) between TOC concentration (x) and output value (y) is y = 0.992x + 0.0057. When calculating the output value at a low TOC concentration, i.e., 1 ppb-C, using this calibration curve, the output value is 0.9977, minimizing the error. As mentioned above, if the output value obtained by measurement is converted using a calibration curve created using a standard solution with a concentration close to the target concentration, the resulting measured value will be highly reliable.

[0023] As mentioned above, calibration curves for measuring devices used to measure low TOC concentrations require the use of low-concentration standard solutions to ensure greater reliability of the measured values. However, standard solutions are generally subject to environmental contamination from preparation to use. For example, if the TOC concentration increases by 5 ppb-C due to environmental contamination, even if a low-concentration 5 ppb-C standard solution is prepared, the TOC concentration will increase to 10 ppb-C during use due to environmental factors. The rate of increase in TOC concentration is 100%. On the other hand, if a standard solution with a commonly used TOC concentration of 250 ppb-C is prepared, the TOC concentration will increase to 255 ppb-C during use due to environmental factors. The rate of increase in TOC concentration is 2%. As mentioned above, it is best to prepare low-concentration standard solutions for use. However, low-concentration standard solutions are difficult to prepare because they can lead to greater concentration errors. Therefore, it is necessary to use a standard solution of a commonly used TOC concentration during preparation and dilute it to a lower concentration before supplying it to the measuring device. Therefore, using the present invention, the speed of ultrapure water delivered from the analyte pipeline and the speed of the standard solution pumped out are adjusted to mix the standard solution with the ultrapure water at a TOC concentration equivalent to that of commonly used TOC. The mixed solution is then diluted to a lower TOC concentration and supplied to the measuring device within the pipeline. Furthermore, considering the TOC concentration in the ultrapure water mixed with the standard solution, the calibration curve is corrected using the TOC concentration of the analyte obtained by the standard addition method. This allows the creation of a calibration curve with minimal measurement error when measuring TOC concentrations in the low concentration range (e.g., below 1 ppb-C).

[0024] FIG5 is a diagram illustrating an example application of the calibration curve solution production system of the present invention. The example shown in FIG5 includes 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 degassing membrane device 33, an ultrafilter 34, a flowmeter 40, an analyte liquid line 100, a container 200 storing a standard solution 210, a pump 300, a controller 600, a mixing coil 410, a TOC meter 500, and a correction unit 700.

[0025] Ultrapure water is supplied from the ultrapure water tank 10 to the heat exchanger 30 using a pump 20. From the heat exchanger 30, it passes through the ultraviolet oxidation device 31, the non-regenerative ion exchange device 32, the degassing membrane device 33, and the ultrafilter 34, and is then transported to the analyte line 100. A flow meter 40 is provided in the analyte line 100. The treatment processes in the heat exchanger 30, ultraviolet oxidation device 31, the non-regenerative ion exchange device 32, the degassing membrane device 33, and the ultrafilter 34, which serve as water treatment devices, are the same as those in a typical water treatment system.

[0026] The flowmeter 40, container 200, standard solution 210, pump 300, controller 600, TOC meter 500, and correction unit 700 are identical to those shown in FIG1 . The mixing coil 410 corresponds to the mixing unit 400 shown in FIG1 . The mixing coil 410 mixes the standard solution 210 pumped by the pump 300 with the ultrapure water supplied from the analyte line 100 to dilute the standard solution 210.

[0027] While each component has been described above individually, their configurations may be arbitrarily combined, or they may be distributed across one or more devices. For example, as described above, the correction unit 700 may be included in the TOC meter 500. Furthermore, the control unit 600 and the correction unit 700 may be included in the TOC meter 500. Furthermore, the control unit 600 and the correction unit 700 may be included in a device separate from the TOC meter 500, with the device communicating with the TOC meter 500 to transmit signals. Furthermore, the system may include a conventional ultrapure water production device or water treatment device (e.g., an ultrafilter).

[0028] While the present invention has been described above with reference to the embodiments, the present invention is not limited to the embodiments described above. Various modifications can be made to the configuration and details of the present invention within the scope of the present invention as would be understood by those skilled in the art.

[0029] This application claims the benefit of priority based on Japanese patent application No. 2022-083008, filed on May 20, 2022, and incorporates herein the entire disclosure thereof.

[0030] 10:Ultra-pure sink 100:Analysis liquid pipeline 110: Standard liquid pipeline 20: Pump 200:Container 210: Standard solution 30:Heat exchanger 31: Ultraviolet oxidation device 32: Non-regenerative ion exchange device 33: Degassing membrane device 34:Ultrafilter 300: Pump 40: Flow meter 400: Mixing section 410: Mixing coil 500:Total organic carbon meter 600: Control Department 700:Correction Department

Claims

1. A calibration curve liquid manufacturing system for manufacturing calibration curve liquid and supplying it to a measuring apparatus for determining the total organic carbon concentration of an analyte using the calibration curve liquid; comprising: a first liquid delivery line for delivering a diluent to the measuring apparatus; a second liquid delivery line for delivering a standard solution to the first liquid delivery line; a mixing unit disposed in the first liquid delivery line for mixing the standard solution with the diluent to dilute the standard solution; a pump disposed in the second liquid delivery line for supplying the standard solution to the first liquid delivery line; a control unit for controlling the supply amount of the pump; and a correction unit for correcting the calibration curve manufactured by the measuring apparatus based on a standard addition method, using a first concentration measured by the measuring apparatus when the pump is stopped by the control unit and the diluent is delivered to the measuring apparatus, and a second concentration measured by the measuring apparatus when the pump is operated by the control unit and the calibration curve liquid is delivered to the measuring apparatus, to obtain the total organic carbon concentration of the diluent liquid; Furthermore, the correction unit, in an XY coordinate plane where the total organic carbon concentration of the standard solution supplied by the pump to the first liquid delivery line is used as the X coordinate and the total organic carbon concentration measured by the measuring device is used as the Y coordinate, connects the point where the control unit stops the pump (X=0) with the point where the total organic carbon concentration of the standard solution after dilution is reached when the control unit operates the pump to supply the first liquid delivery line, and extends the line using the standard addition method. The distance from the intersection of the extended line and the X-axis of the XY coordinate plane to the origin is used to move the line in the positive direction of the X-axis to correct the calibration line. Furthermore, the mixture of the diluted solution and the standard solution prepared in the mixing unit is used as the calibration line solution and supplied to the measuring device.

2. The calibration line liquid manufacturing system as described in claim 1, wherein, The control unit controls the pump based on the delivery rate of the diluent in the first liquid delivery line and the total organic carbon concentration of the standard solution, so that the total organic carbon concentration of the calibration liquid is reduced to below a predetermined value.

3. The calibration line liquid manufacturing system as described in claim 2, wherein, The given value is 100 ppb-C.

4. The calibration fluid manufacturing system as described in claim 2 or 3, wherein, The control unit controls the pump to supply the standard solution to the first liquid delivery line at a delivery rate of less than 1 / 100th of the delivery rate of the diluent in the first liquid delivery line.

5. The calibration fluid manufacturing system as described in any one of claims 1 to 3, wherein, It manufactures the calibration fluid used to make the calibration line of the measuring device; The measuring device decomposes the organic matter in the liquid after mixing in the mixing section, measures the conductivity or resistivity of the liquid after the organic matter has been decomposed, and calculates the total organic carbon concentration of the liquid based on the measured conductivity or resistivity.

6. The calibration fluid manufacturing system as described in any one of claims 1 to 3, wherein, The total organic carbon concentration of this measuring device is measured in the range of 0.1 to 500 ppb-C.

7. A measuring system having a measuring fluid manufacturing system as described in any one of claims 1 to 3; and the measuring device.

8. A method for manufacturing a calibration line solution, comprising: manufacturing and supplying a calibration line solution for a measuring apparatus used to determine the total organic carbon concentration of an analyte solution; diluting the standard solution by mixing it with a diluent supplied to the measuring apparatus in the first liquid supply line from a second liquid supply line for supplying the standard solution to a first liquid supply line; supplying the standard solution to the first liquid supply line by means of a pump installed in the second liquid supply line; controlling the supply amount of the pump by means of a control unit; and correcting the calibration line manufactured by the measuring apparatus by using a standard addition method, based on a first concentration measured by the measuring apparatus in a state where the pump installed in the second liquid supply line and supplying the standard solution to the first liquid supply line is stopped and the diluent is supplied to the measuring apparatus, and a second concentration measured by the measuring apparatus in a state where the pump is operated and the calibration line solution is supplied to the measuring apparatus. In this correction, in an XY coordinate plane where the total organic carbon concentration of the standard solution supplied by the pump to the first liquid delivery line is used as the X coordinate and the total organic carbon concentration measured by the measuring device is used as the Y coordinate, a straight line is drawn connecting the point where the control unit stops the pump (X=0) and the point where the control unit operates the pump to supply the first liquid delivery line with any total organic carbon concentration after dilution. This straight line is then extended using the standard addition method, and the distance from the intersection of the extended straight line and the X-axis of the XY coordinate plane to the origin is used to move the straight line in the positive direction of the X-axis to correct the calibration line. The mixture of the diluted solution and the standard solution is then used as the calibration line solution and supplied to the measuring device.

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