Water quality analysis device

Abstract

Provided is a water quality analysis device that measures the concentration of a measurement target substance in sample water, including: a turbidimeter that measures the intensity of scattered light or transmitted light from the measurement target substance and measures the turbidity of the sample water; a fluorometer that measures the fluorescence intensity of the measurement target substance; a fluorescence intensity correction unit that corrects the fluorescence intensity of the measurement target substance based on the turbidity of the sample water; and a concentration calculation unit that sets a concentration correction coefficient for converting the fluorescence intensity of the measurement target substance into the concentration of the measurement target substance based on the measurement result of the fluorescence intensity of a fluorescence intensity correction aqueous solution that contains a fluorescence intensity correction substance having a known concentration and in which the wavelength range in which the fluorescence intensity characteristic has a sensitivity overlaps with the measurement target substance.

Description

Technical Field

[0001] This invention relates to a water quality analysis device. Background Technology

[0002] Previously, water quality analysis devices that combine fluorescence measurement and turbidity measurement functions were known (e.g., Patent Document 1). Patent Document 1: Japanese Patent No. 6436266 The technical problem to be solved by the present invention

[0003] We hope to be able to easily calibrate the water quality analysis equipment. Summary of the Invention

[0004] To address the aforementioned problems, a first aspect of the present invention provides a water quality analysis apparatus. The water quality analysis apparatus can determine the concentration of a target substance in sample water. The water quality analysis apparatus may include a turbidimeter. The turbidimeter can measure the intensity of scattered or transmitted light from the sample water. The turbidimeter can measure the turbidity of the sample water. The water quality analysis apparatus may include a fluorometer. The fluorometer can measure the fluorescence intensity of the target substance. The water quality analysis apparatus may include a fluorescence intensity correction unit. The fluorescence intensity correction unit can correct the fluorescence intensity of the target substance based on the turbidity of the sample water. The water quality analysis apparatus may include a concentration calculation unit. The concentration calculation unit can set a concentration correction coefficient for converting the fluorescence intensity of the target substance into its concentration based on the measurement result of the fluorescence intensity of the fluorescence intensity correction aqueous solution. The fluorescence intensity correction aqueous solution may contain a fluorescence intensity correction substance whose fluorescence intensity characteristics have a sensitivity wavelength range overlapping with the target substance and whose concentration is known.

[0005] Fluorescence intensity correction aqueous solutions may contain formalin.

[0006] The turbidimeter may include a turbidity calculation unit. Based on the measurement results of the intensity of scattered or transmitted light from the turbidity-correcting aqueous solution, the turbidity calculation unit can set a turbidity correction coefficient for converting the intensity of scattered or transmitted light from the sample water into the turbidity of the substance being measured. The turbidity-correcting aqueous solution may contain a turbidity-correcting substance with known turbidity.

[0007] Turbidity-corrected aqueous solutions can be used as fluorescence intensity-corrected aqueous solutions.

[0008] Turbidity-correcting aqueous solutions can contain two or more turbidity-correcting substances.

[0009] The substance to be measured can be PAH.

[0010] A fluorometer can obtain the fluorescence intensity of a fluorescence intensity-corrected aqueous solution within a specific wavelength range. This specific wavelength range overlaps with the wavelength ranges where the fluorescence intensity characteristics of the target substance and the fluorescence intensity-correcting substance have sensitivity. The specific wavelength range can be above 300 nm and below 400 nm.

[0011] A fluorometer can irradiate sample water or fluorescence intensity correction aqueous solution with excitation light in the wavelength range of 200 nm to 300 nm.

[0012] The above summary of the invention does not list all the features of the invention. Furthermore, sub-combinations of these feature groups can also constitute an invention. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating the water quality analysis apparatus 100 involved in the embodiment. Figure 2 This is a diagram illustrating the water quality analysis apparatus 100 involved in the embodiment. Figure 3 This is an example of the results obtained after measuring the fluorescence intensity spectrum of formalhydrazine. Figure 4 This is a flowchart of an embodiment of the calibration method for the water quality analysis device 100. Figure 5 This is a flowchart of an embodiment of the determination method of the water quality analysis device 100. Figure 6 This is a graph illustrating an example of the relationship between turbidity and fluorescence intensity. Detailed Implementation

[0014] The present invention will be described below through embodiments, but these embodiments are not intended to limit the invention as defined in the claims. Furthermore, the combinations of features described in the embodiments are not necessarily all necessary for the solutions provided by the invention.

[0015] Figure 1 This is a diagram illustrating the water quality analysis apparatus 100 according to an embodiment. In this example, the water quality analysis apparatus 100 includes a flow path 1, a flow cell 2, an optical system 10 for turbidity detection, an optical system 20 for fluorescence detection, a signal processing unit 13 for turbidity detection, and a signal processing unit 23 for fluorescence detection. Figure 1 The optical system of the water quality analysis device 100 is shown in the figure.

[0016] Sample water 3 flows within flow path 1 (indicated by dashed lines) and flow cell 2. Sample water 3 contains the analyte. In this example, the analyte is a polycyclic aromatic hydrocarbon (PAH). Flow cells 2 are respectively located in the turbidity detection optical system 10 and the fluorescence detection optical system 20. The flow cells 2 of the turbidity detection optical system 10 and the fluorescence detection optical system 20 are connected in series in flow path 1. Figure 1 In the middle, import and export sample water 3 following the direction of the arrow.

[0017] The water quality analysis apparatus 100 measures the concentration of the analyte in the sample water 3. The water quality analysis apparatus 100 is a fluorescence detection method water quality analysis apparatus. When the sample water 3 contains fluorescent substances such as PAH, when ultraviolet light (excitation light L3) irradiates the sample water 3, fluorescence L4 at the inherent wavelength of that substance is generated. Since the fluorescence intensity is proportional to the concentration of the contained fluorescent substance, the concentration of the fluorescent substance can be accurately measured. In this example, the water quality analysis apparatus 100 measures the concentration of the analyte based on the fluorescence intensity of the sample water 3. The fluorescence intensity is measured in the fluorescence detection optical system 20. The fluorescence intensity signal s2 is output from the fluorescence detection signal processing unit 23. The fluorescence detection optical system 20 and the fluorescence detection signal processing unit 23 are an example of a fluorometer used to measure the fluorescence intensity of the sample water 3. In this specification, there are cases where the "intensity signal" is simply referred to as "intensity".

[0018] When the sample water 3 contains suspended solids, the excitation light L3 and fluorescence L4 may be attenuated due to light scattering and absorption from the suspended solids (particles). This phenomenon is called the internal filtering effect. Due to the internal filtering effect, the accuracy of fluorescence intensity measurement may deteriorate in environments with high suspended solids concentration (hereinafter referred to as turbidity). Therefore, to improve the accuracy of fluorescence intensity measurement, it is preferable to correct the fluorescence intensity based on the turbidity of the sample water 3. In this example, the water quality analysis apparatus 100 measures the fluorescence intensity and the turbidity of the sample water 3 simultaneously. The water quality analysis apparatus 100 measures the turbidity of the sample water 3 based on the intensity of the scattered or transmitted light from the sample water 3. The intensity of the scattered or transmitted light of the sample water 3 is measured in the turbidity detection optical system 10. The intensity signal s1 of the scattered or transmitted light of the sample water 3 is output from the turbidity detection signal processing unit 13.

[0019] First, the measurement of turbidity in sample water 3 will be explained. The optical system 10 for turbidity detection includes a light-emitting unit 11 for turbidity detection and a light-receiving unit 12 for turbidity detection. The light-emitting unit 11 for turbidity detection illuminates infrared light L1. The light-emitting unit 11 for turbidity detection illuminates the sample water 3 inside the flow cell 2 with the infrared light L1. An example of the light-emitting unit 11 for turbidity detection is an LED (Light Emitting Diode) or a laser irradiation device.

[0020] Infrared light L1 irradiates the sample water 3 inside the flow cell 2, generating scattered or transmitted light (referred to as emitted light L2). Scattered light is generated by light scattering from the sample water 3. Transmitted light is light that is not absorbed by suspended matter in the sample water 3. The turbidity detection light receiver 12 receives the emitted light L2. The turbidity detection light receiver 12 converts the emitted light L2 into an electrical intensity signal. A photodiode is used as an example of the turbidity detection light receiver 12.

[0021] The turbidity detection signal processing unit 13 processes the intensity signal from the turbidity detection light receiving unit 12. The turbidity detection signal processing unit 13 can amplify the intensity signal from the turbidity detection light receiving unit 12. The turbidity detection signal processing unit 13 can remove noise from the intensity signal from the turbidity detection light receiving unit 12. The turbidity detection signal processing unit 13 processes the intensity signal from the turbidity detection light receiving unit 12 and outputs it as an intensity signal s1 of scattered light or transmitted light. The intensity signal s1 of scattered light or transmitted light can be an intensity signal corresponding to at least one of the intensity of scattered light and the intensity of transmitted light.

[0022] When turbidity is low, the intensity of scattered light is proportional to the turbidity. On the other hand, when turbidity is high, scattered light attenuates due to the internal filtering effect, making it difficult to measure turbidity based on the intensity of scattered light. The turbidity detection signal processing unit 13 can calculate the reference turbidity by the intensity of transmitted light and decide whether to use the intensity of scattered light or transmitted light in the turbidity measurement based on the reference turbidity. The reference turbidity is a temporarily calculated turbidity. The reference turbidity can also be calculated using the intensity of scattered light. For example, when the reference turbidity is 0 to 40 FNU (low turbidity), the turbidity is calculated using the intensity of scattered light. Alternatively, when the reference turbidity is 40 to 400 FNU (high turbidity), the reference turbidity is set as the turbidity. FNU is one of the units of turbidity. FNU is the formalinium turbidity unit. Furthermore, the turbidity calculation unit described later can calculate the reference turbidity by the intensity of transmitted light and decide whether to use the intensity of scattered light or transmitted light in the turbidity measurement based on the reference turbidity.

[0023] Alternatively, the turbidity detection signal processing unit 13 can output a scattered light or transmitted light intensity signal s1 using both the intensity of the scattered light and the intensity of the transmitted light. For example, the scattered light or transmitted light intensity signal s1 can be the ratio of the intensity of the scattered light to the intensity of the transmitted light (scattered light intensity / transmitted light intensity). By setting the scattered light or transmitted light intensity signal s1 as the ratio of the intensity of the scattered light to the intensity of the transmitted light, errors in the intensity of the scattered light and the intensity of the transmitted light can be offset. When the reference turbidity is 0 to 400 FNU, the turbidity detection signal processing unit 13 can output the ratio of the intensity of the scattered light to the intensity of the transmitted light as the scattered light or transmitted light intensity signal s1. Alternatively, the turbidity detection signal processing unit 13 can output the intensity of the scattered light and the intensity of the transmitted light, and the turbidity calculation unit can calculate the ratio of the intensity of the scattered light to the intensity of the transmitted light.

[0024] Next, the measurement of the fluorescence intensity of sample water 3 will be explained. The fluorescence detection optical system 20 includes a fluorescence detection emitting unit 21 and a fluorescence detection receiving unit 22. The fluorescence detection emitting unit 21 illuminates an excitation light L3. The turbidity detection emitting unit 21 illuminates the sample water 3 inside the flow cell 2 with the excitation light L3. Ultraviolet light is used as an example of the excitation light L3. The fluorescence detection emitting unit 21 may contain an ultraviolet light source. A xenon flash lamp is used as an example of the ultraviolet light source. The ultraviolet light source can be an LED or a laser irradiation device.

[0025] The fluorescence detection luminescent unit 21 may contain a filter. Because it contains a filter, the fluorescence detection luminescent unit 21 can illuminate the flow cell 2 with light within a specified wavelength range of the excitation light L3. In this example, the substance to be measured is PAH. PAH emits fluorescence most effectively at an excitation light wavelength of approximately 250 nm. Therefore, as an example, the transmission wavelength of the filter inside the fluorescence detection luminescent unit 21 is set to be between 200 nm and 300 nm.

[0026] Excitation light L3 irradiates the sample water 3 inside the flow cell 2, thereby generating fluorescence L4. A fluorescence detection light-receiving unit 22 receives the fluorescence L4. The fluorescence detection light-receiving unit 22 converts the fluorescence L4 into a fluorescence intensity signal. An example of a fluorescence detection light-receiving unit 22 is a photodiode.

[0027] The fluorescence detection light-receiving unit 22 may contain a filter. Because it contains a filter, the fluorescence detection light-receiving unit 22 can receive light within a specified wavelength range of fluorescence L4. In this example, the substance being measured is PAH. When the wavelength of the excitation light for PAH is around 250 nm, the fluorescence wavelength is around 350 nm. Therefore, as an example, the transmission wavelength of the filter inside the fluorescence detection light-receiving unit 22 is set to be between 300 nm and 400 nm.

[0028] The fluorescence detection signal processing unit 23 processes the fluorescence intensity signal from the fluorescence detection light-receiving unit 22. The fluorescence detection signal processing unit 23 can amplify the signal from the fluorescence detection light-receiving unit 22. The fluorescence detection signal processing unit 23 can remove noise from the signal from the fluorescence detection light-receiving unit 22. The fluorescence detection signal processing unit 23 processes the fluorescence intensity signal from the fluorescence detection light-receiving unit 22 and outputs it as the fluorescence intensity signal s2.

[0029] Figure 2 This is a diagram illustrating the water quality analysis apparatus 100 according to an embodiment. In this example, the water quality analysis apparatus 100 includes... Figure 1 The structure and control calculation unit 30. The control calculation unit 30 includes an infrared light illumination circuit 31, an excitation light illumination circuit 32, a turbidity calculation unit 33, a fluorescence intensity correction unit 34, and a concentration calculation unit 35.

[0030] The infrared light illumination circuit 31 is connected to the turbidity detection light-emitting unit 11 of the turbidity detection optical system 10. The infrared light illumination circuit 31 is a circuit that controls the operation of the turbidity detection light-emitting unit 11. The excitation light illumination circuit 32 is connected to the fluorescence detection light-emitting unit 21 of the fluorescence detection optical system 20. The excitation light illumination circuit 32 is a circuit that controls the operation of the fluorescence detection light-emitting unit 21.

[0031] The turbidity calculation unit 33 calculates the turbidity D1 of the sample water 3. The turbidity calculation unit 33 calculates the turbidity D1 of the sample water 3 based on the signal from the turbidity detection signal processing unit 13. That is, the turbidity calculation unit 33 calculates the turbidity D1 of the sample water 3 based on the intensity signal s1 of the scattered light or transmitted light. The turbidity calculation unit 33 can calculate the turbidity D1 of the sample water 3 by multiplying the turbidity correction coefficient calculated through turbidity correction by the intensity signal s1 of the scattered light or transmitted light. Furthermore, the turbidity detection optical system 10, the turbidity detection signal processing unit 13, and the turbidity calculation unit 33 are an example of a turbidity meter used to measure the turbidity D1 of the sample water 3. The turbidity calculation unit 33 can output the turbidity D1 to an external device, etc.

[0032] The fluorescence intensity correction unit 34 corrects the fluorescence intensity. The fluorescence intensity correction unit 34 corrects the fluorescence intensity signal s2 from the fluorescence detection signal processing unit 23 based on the turbidity D1 of the sample water 3. For example, since the higher the turbidity D1 of the sample water 3, the lower the fluorescence intensity, the fluorescence intensity signal s2 is multiplied by a correction coefficient that increases with the turbidity D1 of the sample water 3 to calculate the fluorescence intensity signal s3 (refer to...). Figure 6 The correction coefficients are preferably obtained in advance.

[0033] The concentration calculation unit 35 calculates the concentration C1. The concentration calculation unit 35 calculates the concentration C1 based on the fluorescence intensity signal s3. In this example, the concentration calculation unit 35 calculates the concentration C1 based on the fluorescence intensity signal s3 corrected by the fluorescence intensity correction unit 34. The concentration calculation unit 35 multiplies the concentration correction coefficient calculated through concentration correction with the fluorescence intensity signal s3 to calculate the concentration C1. The concentration calculation unit 35 can output the concentration C1 to an external device, etc.

[0034] Turbidity correction is explained below. In this specification, to calculate the turbidity D1 of sample water 3, the turbidity calculation unit 33 sets a turbidity correction coefficient b1. The turbidity correction coefficient b1 converts the intensity signal s1 of scattered or transmitted light from sample water 3 into the turbidity D1 of sample water 3. The turbidity correction coefficient b1 makes the following mathematical formula 1 true. In mathematical formula 1, the offset is set to e1. ​​The offset e1 can be a constant. The offset e1 can also be 0. The turbidity correction coefficient b1 can be a constant coefficient. The turbidity correction coefficient b1 can also be a variable. The turbidity correction coefficient b1 can be a variable that changes with the intensity signal s1. When the turbidity correction coefficient b1 is a variable, correction is performed using turbidity standard samples with multiple different turbidities. Alternatively, the turbidity calculation unit 33 can also set a function f that makes the turbidity D1 of sample water 3 = f(intensity signal s1) true instead of the turbidity correction coefficient b1. In this case, correction is also performed using turbidity standard samples with different turbidities.

Mathematical Formula 1

[0035] In turbidity correction, turbidity standard samples are used. Turbidity standard samples serve as the reference for turbidity measurement. The concentration of the turbidity standard sample is known. Therefore, in turbidity correction, by measuring the intensity signal of the turbidity standard sample, the turbidity correction coefficient b1 can be calculated using mathematical formula 1. Turbidity standard samples typically use formalin, kaolin, and polystyrene. Formalin is a mixed aqueous solution prepared by polymerizing hydrazine sulfate and hexamethyltetramine. Kaolin is an aqueous solution of purified and adjusted kaolinite particles. Polystyrene is a suspension of polystyrene particles.

[0036] The concentration correction is explained below. In this specification, to calculate the concentration C1, the concentration calculation unit 35 sets a concentration correction coefficient b2. The concentration correction coefficient b2 converts the fluorescence intensity of the analyte into the concentration C1 of the analyte. The concentration correction coefficient b2 makes the following mathematical formula 2 true. In mathematical formula 2, the offset is set to e2. The offset e2 can be a constant. The offset e2 can also be 0. The concentration correction coefficient b2 can be a constant coefficient. The concentration correction coefficient b2 can also be a variable. The concentration correction coefficient b2 can be a variable that changes with the fluorescence intensity signal s3. When the concentration correction coefficient b2 is a variable, the concentration of a standard sample with multiple different fluorescence intensities is used for correction. Alternatively, the concentration calculation unit 35 can set a function g that makes the concentration C1 = g(fluorescence intensity signal s3) true instead of the concentration correction coefficient b2. In this case, the concentration of a standard sample with multiple different fluorescence intensities is also used for correction.

Mathematical Formula 2

[0037] In fluorescence intensity correction (concentration correction), a fluorescence intensity standard sample is used. The concentration of the fluorescence intensity standard sample is known. Therefore, in fluorescence intensity correction, the concentration correction factor b2 can be calculated using mathematical formula 2 by measuring the fluorescence intensity of the fluorescence intensity standard sample. If the turbidity of the fluorescence intensity standard sample is known, the fluorescence intensity can also be corrected using the turbidity of the standard sample, and the concentration correction factor b2 can be calculated. The fluorescence intensity standard sample varies depending on the substance being measured. In this example, the substance being measured is PAH; therefore, as an example, a material containing benzoate, amine, etc., can be used as the fluorescence intensity standard sample. Alternatively, the fluorescence intensity standard sample can also be PAH.

[0038] In a water quality analysis apparatus 100 without a set turbidity correction factor b1, turbidity correction is performed before concentration measurement. In a water quality analysis apparatus 100 without a set concentration correction factor b2, concentration correction is performed before concentration measurement. Furthermore, the turbidity correction factor b1 and concentration correction factor b2 may change due to fouling inside the flow cell 2 through which the sample water 3 flows or aging of optical components. To correct for the effects of fouling inside the flow cell 2 through which the sample water 3 flows and aging of optical components, it is preferable to periodically update the turbidity correction factor b1 and concentration correction factor b2.

[0039] The water quality analysis device 100 in this example includes both fluorescence measurement and turbidity measurement functions. Therefore, turbidity correction and fluorescence intensity correction (concentration correction) are performed separately. Turbidity standard samples are safe and highly stable substances, and samples with specified concentrations are commercially available, making them convenient to use without requiring specialized knowledge or equipment.

[0040] On the other hand, the standard samples for fluorescence intensity vary depending on the substance being measured. If the substance being measured is difficult to handle or is hazardous, calibration reagents must be prepared. Furthermore, the preparation of reagents is generally complex and requires specialized knowledge. Additionally, if the substance being measured is hazardous, specialized equipment is required. Therefore, moving the corresponding water quality analyzer from the measurement site to a location with specialized equipment presents time and costly calibration procedures. Therefore, in fluorescence intensity calibration, a method that is easy to perform is preferred.

[0041] Figure 3 This is an example of the result after measuring the fluorescence intensity spectrum of formalin. The fluorescence intensity spectrum is measured, for example, by a fluorescence spectrophotometer. The fluorescence intensity spectrum can also be measured by an optical system 20 for fluorescence detection. Figure 3 In this process, the wavelength of the excitation light is 254 nm.

[0042] exist Figure 3 In the fluorescence intensity spectrum, the fluorescence intensity characteristics exhibit sensitivity in the wavelength range of 350 nm to 370 nm. Sensitivity in fluorescence intensity characteristics means that the fluorescence intensity is higher compared to other wavelength ranges. The fluorescence intensity characteristics can have a peak in the wavelength range of 350 nm to 370 nm. The inventors have discovered that the fluorescence intensity characteristics of formalin are essentially the same as those of the analyte, namely PAH. Therefore, formalin can be used instead of PAH in fluorescence intensity calibration. PAH is a volatile and toxic substance, making it difficult to handle. On the other hand, formalin is easy to handle, and solutions of specified concentrations are readily available commercially. Therefore, calibration of the water quality analysis device 100 can be performed simply.

[0043] Figure 4 This is a flowchart illustrating an embodiment of the calibration method for the water quality analyzer 100. The calibration method for the water quality analyzer 100 includes a calibration aqueous solution injection stage S101, a fluorescence detection stage S102, a fluorescence calibration stage S103, a concentration calibration coefficient calculation stage S104, a scattered light and transmitted light detection stage S105, a turbidity calibration coefficient calculation stage S106, and a calibration completion stage S107. Each stage will be described below.

[0044] In the calibration aqueous solution injection stage S101, a calibration aqueous solution is injected into the flow cell 2. The calibration aqueous solution can be a fluorescence intensity calibration aqueous solution. That is, the calibration aqueous solution can contain a fluorescence intensity calibration substance whose fluorescence intensity characteristics have a sensitivity wavelength range that overlaps with the analyte, namely PAH. Alternatively, the calibration aqueous solution can contain a fluorescence intensity calibration substance at a known concentration. As an example, the fluorescence intensity calibration substance is formalin, as described above. The calibration aqueous solution can contain formalin. By using formalin as the fluorescence intensity calibration substance, the reproducibility of the measurement can be improved. The fluorescence intensity calibration substance is not limited to formalin. Additionally, the calibration aqueous solution can also contain kaolin. The calibration aqueous solution can also contain polystyrene.

[0045] Furthermore, the correcting aqueous solution can be a turbidity correcting aqueous solution. That is, the correcting aqueous solution can contain a turbidity correcting substance with known turbidity. As an example, the turbidity correcting substance is formalin, as mentioned above. Turbidity correcting substances are not limited to formalin.

[0046] The corrective aqueous solution can contain two or more turbidity correcting substances. As an example, the corrective aqueous solution contains formalin and kaolin. Even with more than two turbidity correcting substances, the correction process can be easily performed.

[0047] In the fluorescence detection stage S102, the fluorometer (fluorescence detection optical system 20 and fluorescence detection signal processing unit 23) detects (measures) the fluorescence intensity signal of the calibration aqueous solution. The fluorescence intensity of the calibration aqueous solution is output to the fluorescence intensity correction unit 34.

[0048] The fluorometer can obtain the fluorescence intensity of the calibration aqueous solution within a specific wavelength range. This specific wavelength range overlaps with the wavelength ranges in which the fluorescence intensity characteristics of the target substance (PAH in this example) and the fluorescence intensity calibration substance (formazan in this example) are sensitive. The specific wavelength range can be above 300 nm and below 400 nm. Additionally, the fluorometer can illuminate the calibration aqueous solution with excitation light in a wavelength range of above 200 nm and below 300 nm.

[0049] In the fluorescence correction stage S103, the fluorescence intensity correction unit 34 corrects the fluorescence intensity of the correction aqueous solution. When the correction aqueous solution is a turbidity correction aqueous solution, the known turbidity of the correction aqueous solution can be input to the fluorescence intensity correction unit 34. The fluorescence intensity correction unit 34 can correct the fluorescence intensity of the correction aqueous solution based on the known turbidity. For example, the fluorescence intensity correction unit 34 calculates a correction coefficient based on the known turbidity and multiplies the correction coefficient by the fluorescence intensity to correct the fluorescence intensity. Alternatively, if a turbidity correction coefficient b1 is set in the turbidity calculation unit 33, the turbidity can also be calculated based on the intensity of scattered or transmitted light from the correction aqueous solution. The turbidity can also be calculated based on the turbidity correction coefficient b1 and the intensity of scattered or transmitted light in the correction aqueous solution, and the fluorescence intensity of the correction aqueous solution can be corrected accordingly. That is, the fluorescence intensity correction unit 34 can correct the fluorescence intensity by multiplying the correction coefficient determined by the turbidity calculated based on the turbidity correction coefficient b1 and the intensity of scattered or transmitted light in the correction aqueous solution by the fluorescence intensity.

[0050] In the concentration correction coefficient calculation stage S104, the concentration calculation unit 35 calculates the concentration correction coefficient b2. The concentration calculation unit 35 calculates the concentration correction coefficient b2 based on the measurement result of the fluorescence intensity of the correction aqueous solution. The concentration correction coefficient b2 can be calculated based on the measurement result of the fluorescence intensity of the correction aqueous solution, the concentration of the correction aqueous solution (known), and mathematical formula 2. The concentration calculation unit 35 sets the calculated concentration correction coefficient b2. By setting the concentration correction coefficient b2, the concentration of the target substance can be measured based on the fluorescence intensity.

[0051] In the scattered light and transmitted light detection stage S105, the turbidimeter (turbidity detection optical system 10, turbidity detection signal processing unit 13, and turbidity calculation unit 33) detects (measures) the intensity of the scattered light or transmitted light of the correction aqueous solution. The turbidity detection signal processing unit 13 outputs the intensity of the scattered light or transmitted light of the correction aqueous solution to the turbidity calculation unit 33.

[0052] In the turbidity correction coefficient calculation stage S106, the turbidity calculation unit 33 calculates the turbidity correction coefficient b1. It calculates the turbidity correction coefficient b1 based on the measurement results of the intensity of scattered or transmitted light from the correction aqueous solution. The turbidity correction coefficient b1 can be calculated based on the measurement results of the intensity of scattered or transmitted light from the correction aqueous solution, the turbidity of the correction aqueous solution (known), and mathematical formula 1. The turbidity calculation unit 33 sets the calculated turbidity correction coefficient b1. By setting the turbidity correction coefficient b1, the turbidity of the target substance can be measured based on the intensity of scattered or transmitted light.

[0053] In the calibration completion stage S107, the turbidity correction coefficient b1 and the concentration correction coefficient b2 are set in the turbidity calculation unit 33 and the concentration calculation unit 35, respectively, thereby completing the calibration. After calibration, the calibration aqueous solution is removed. Furthermore, when calibration is performed using different concentrations of turbidity or fluorescence intensity correction substances, calibration aqueous solutions with different concentrations of turbidity or fluorescence intensity correction substances are injected into the flow cell 2, and the same calibration operation is repeated.

[0054] exist Figure 4 In this process, the corrective aqueous solution is used as the fluorescence intensity corrective aqueous solution. Additionally, the corrective aqueous solution is used as the turbidity corrective aqueous solution. That is, the turbidity corrective aqueous solution containing formalin is used as the fluorescence intensity corrective aqueous solution. In other words, the fluorescence intensity corrective aqueous solution and the turbidity corrective aqueous solution are identical. By using the turbidity corrective aqueous solution as the fluorescence intensity corrective aqueous solution, the correction operation can be performed quickly without the need for additional injection of the fluorescence intensity corrective aqueous solution.

[0055] The turbidity correction solution and the fluorescence intensity correction solution can also be different. That is, the correction solutions are changed separately for turbidity correction and fluorescence intensity correction. For example, the turbidity correction solution may contain kaolin, while the fluorescence intensity correction solution may contain formalin. Even when the turbidity correction solution and the fluorescence intensity correction solution are different, the correction operation can still be performed easily.

[0056] Figure 5 This is a flowchart illustrating an embodiment of the measurement method of the water quality analysis device 100. The measurement method of the water quality analysis device 100 includes a sample water injection stage S201, a fluorescence detection stage S202, a scattered light and transmitted light detection stage S203, a turbidity calculation stage S204, a fluorescence correction stage S205, a concentration calculation stage S206, and a measurement completion stage S207. The following describes the method using… Figure 2 The labels are used to explain each stage.

[0057] In the sample water injection stage S201, sample water 3 is injected into flow cell 2. In this example, sample water 3 contains the analyte, PAH.

[0058] In the fluorescence detection stage S202, the fluorometer (fluorescence detection optical system 20 and fluorescence detection signal processing unit 23) detects (measures) the fluorescence intensity of the sample water 3. The fluorescence intensity signal s2 of the sample water 3 is output to the fluorescence intensity correction unit 34.

[0059] The fluorometer can obtain the fluorescence intensity of sample water 3 within a specific wavelength range. This specific wavelength range overlaps with the wavelength ranges where the fluorescence intensity characteristics of the target substance (PAH in this example) and the fluorescence intensity correction substance (formazan in this example) have sensitivity. The specific wavelength range can be above 300 nm and below 400 nm. The fluorometer can irradiate sample water 3 with excitation light in the wavelength range of above 200 nm and below 300 nm.

[0060] In the scattered light and transmitted light detection stage S203, the turbidimeter (turbidity detection optical system 10, turbidity detection signal processing unit 13, and turbidity calculation unit 33) detects (measures) the intensity signal s1 of the scattered light or transmitted light of the sample water 3. The turbidity detection signal processing unit 13 outputs the intensity signal s1 of the scattered light or transmitted light of the sample water 3 to the turbidity calculation unit 33.

[0061] In the turbidity calculation stage S204, the turbidity meter measures the concentration D1 of the sample water 3. The turbidity calculation unit 33 calculates the turbidity D1 of the sample water 3 based on the signal from the turbidity detection signal processing unit 13. The turbidity calculation unit 33 calculates the turbidity D1 of the sample water 3 based on the intensity signal s1 of the scattered or transmitted light of the sample water 3. The turbidity calculation unit 33 can multiply the turbidity correction coefficient b1 calculated by turbidity correction by the intensity signal s1 of the scattered or transmitted light of the sample water 3 to calculate the turbidity D1 of the sample water 3. The turbidity D1 of the sample water 3 is output to the fluorescence intensity correction unit 34.

[0062] In the fluorescence correction stage S205, the fluorescence intensity correction unit 34 corrects the fluorescence intensity. The fluorescence intensity correction unit 34 corrects the fluorescence intensity signal s2 from the fluorescence detection signal processing unit 23 based on the turbidity D1 of the sample water 3. For example, since the higher the turbidity D1 of the sample water 3, the lower the fluorescence intensity, the fluorescence intensity signal s3 is calculated by multiplying the fluorescence intensity signal s2 by a correction coefficient that increases with the turbidity D1 of the sample water 3 (see reference). Figure 6 ).

[0063] In the concentration calculation stage S206, the concentration calculation unit 35 calculates the concentration C1 based on the signal from the fluorescence intensity correction unit 34. The concentration calculation unit 35 calculates the concentration C1 based on the fluorescence intensity signal s3. The concentration calculation unit 35 can calculate the concentration C1 by multiplying the concentration correction coefficient b2 calculated by fluorescence intensity correction with the fluorescence intensity signal s3.

[0064] In the measurement completion stage S207, the concentration C1 is output to other devices and stored. Alternatively, the turbidity D1 of sample water 3 can also be output to other devices and stored. After the measurement is completed, sample water 3 is removed.

[0065] Figure 6This is a graph illustrating an example of the relationship between turbidity and fluorescence intensity. Figure 6 In the diagram, solid lines represent ideal values, and dashed lines represent measured values.

[0066] like Figure 6 As shown, due to the internal filtering effect, the difference between the ideal and measured fluorescence intensity increases when the turbidity increases. Therefore, preferably, the fluorescence intensity correction unit 34 corrects the fluorescence intensity to approximate the ideal value. Figure 6 In the example shown, the fluorescence intensity correction unit 34 multiplies the fluorescence intensity by a correction factor that increases with increasing turbidity, thereby correcting the fluorescence intensity. As an example, the correction factor is expressed as the ideal value of the fluorescence intensity divided by the measured value of the fluorescence intensity.

[0067] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. Various changes or improvements can be made based on the above embodiments, which will be obvious to those skilled in the art. As can be seen from the claims, the various changes or improvements described above are also included within the technical scope of the present invention.

[0068] Please note that the execution order of actions, processes, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specification, and drawings can be implemented in any order, unless explicitly stated as "before" or "previously," and unless the output of a previous process is used in a subsequent process. The use of terms such as "firstly" and "then" in the action flow descriptions in the claims, specification, and drawings for ease of explanation does not imply that the actions must be performed in this order. Label Explanation

[0069] 1. Flow path, 2. Flow cell, 3. Sample water, 10. Optical system for turbidity detection, 11. Light-emitting unit for turbidity detection, 12. Light-receiving unit for turbidity detection, 13. Signal processing unit for turbidity detection, 20. Optical system for fluorescence detection, 21. Light-emitting unit for fluorescence detection, 22. Light-receiving unit for fluorescence detection, 23. Signal processing unit for fluorescence detection, 30. Control and calculation unit, 31. Infrared light illumination circuit, 32. Excitation light illumination circuit, 33. Turbidity calculation unit, 34. Fluorescence intensity correction unit, 35. Concentration calculation unit, 100. Water quality analysis device.

Claims

1. A water quality analysis device for determining the concentration of a target substance in sample water, characterized in that, include: A turbidimeter that measures the intensity of scattered or transmitted light from the sample water and measures the turbidity of the sample water; A fluorometer for measuring the fluorescence intensity of the substance to be measured; A fluorescence intensity correction unit that corrects the fluorescence intensity of the analyte based on the turbidity of the sample water; and The concentration calculation unit, based on the measurement result of the fluorescence intensity of the fluorescence intensity correction aqueous solution, sets a concentration correction coefficient for converting the fluorescence intensity of the analyte into the concentration of the analyte. The fluorescence intensity correction aqueous solution contains a fluorescence intensity correction substance whose fluorescence intensity characteristics have a sensitive wavelength range that overlaps with the analyte and whose concentration is known. The substance being measured is PAH. The fluorescence intensity correction substance is at least one of formalin, kaolin, and polystyrene.

2. The water quality analysis device as described in claim 1, characterized in that, The turbidimeter has a turbidimetric calculation unit that sets a turbidimetric correction coefficient for converting the intensity of scattered or transmitted light from the sample water into the turbidimetric turbidity of the sample water based on the measurement results of the intensity of scattered or transmitted light from the turbidimetric water containing a turbidimetric correction substance with known turbidimetry.

3. The water quality analysis device as described in claim 2, characterized in that, The turbidity-correcting aqueous solution contains two or more of the aforementioned turbidity-correcting substances.

4. The water quality analysis device as described in claim 1, characterized in that, The fluorometer obtains the fluorescence intensity of the fluorescence intensity correction aqueous solution within a specific wavelength range, which is the overlapping range of wavelengths in which the fluorescence intensity characteristics of the measured substance and the fluorescence intensity correction substance have sensitivity.

5. The water quality analysis device as described in claim 4, characterized in that, The specific wavelength range is above 300nm and below 400nm.

6. The water quality analysis device as described in claim 1, characterized in that, The fluorometer irradiates the sample water or the fluorescence intensity correction aqueous solution with an excitation light in the wavelength range of 200 nm to 300 nm.

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