JP6974138B2 - Liquid analyzer and sampling device - Google Patents

Description

The present invention relates to a liquid analyzer that continuously analyzes a liquid for water quality inspection and the like, and a sampling apparatus suitable for such a liquid analyzer.

There is a demand for collecting a sample liquid such as sample water from the liquid to be measured and accurately and continuously quantifying the target component contained in the sample liquid. For example, when pure water is produced from raw water by a pure water production system, it is difficult to remove urea in the raw water depending on the ion exchange device or ultraviolet oxidizing device that constitutes the pure water production system, so the urea is removed in advance. It is necessary to supply the raw water to the pure water production system. As a method for removing urea, a method is known in which a drug that produces hypobromous acid (sodium hypobromous acid, etc.) is added to raw water to selectively oxidize urea with hypobromous acid. Since the added chemicals also impose a load on the pure water production system, the smaller the amount of chemicals added, the better. Therefore, it is desired to continuously quantify the urea concentration in the raw water to determine the necessity of the urea removal treatment, and to add an appropriate amount of the drug when the treatment is necessary. Normally, industrial water, city water, etc. are used as the raw water for producing pure water, and the urea concentration in the raw water fluctuates due to the influence of seasonal fluctuations, and the quality of ultrapure water, especially organic matter (TOC; Total Organic). Since it affects the Carbon) concentration, it is necessary to quantify the urea concentration. Further, there is a demand for measurement of a very small amount of urea concentration in pure water obtained from a pure water production system.

As a method for quantifying urea, a quantification method based on a colorimetric method using diacetylmonooxime is known, and is described in, for example, a hygiene test method (Non-Patent Document 1). In the colorimetric method using diacetylmonooxime, other reagents (for example, antipyrine + sulfuric acid solution, semicarbazide hydrochloride aqueous solution, manganese chloride + potassium nitrate aqueous solution, sodium dihydrogen phosphate + sulfuric acid solution, etc.) are used for the purpose of promoting the reaction. Can be used together. When antipyrine is used in combination, diacetylmonooxime is dissolved in an acetic acid solution to prepare a diacetylmonooxime acetic acid solution, and antipyrine (1,5-dimethyl-2-phenyl-3-pyrazolone) is dissolved in, for example, sulfuric acid. An antipyrine-containing reagent solution is prepared, a diacetylmonooxime acetic acid solution and an anlipylin-containing reagent solution are sequentially mixed with sample water, the absorbance at a wavelength of around 460 nm is measured, and quantification is performed by comparison with a standard solution.

The urea quantification method by the colorimetric method using diacetylmonooxime was originally intended for the quantification of urea in pool water or public bath water, for example, and is therefore supplied to a pure water production system. Sensitivity is low for quantifying the urea concentration in water and for measuring the urea concentration in the obtained pure water. Therefore, in Patent Document 1, sample water is sampled from the water to be measured and ppb by applying flow injection analysis (FIA) to a quantitative method based on a colorimetric method using diacetylmonooxime to measure the absorbance. Discloses a method for continuously quantifying urea online in a concentration range of several ppm from.

Here, as an example of quantification of the target component in the sample liquid, the case where the sample water is sampled from the water to be measured and the urea in the sample water is continuously measured has been described, but the components other than urea are continuously measured. There is also a demand for doing.

In order to continuously quantify the target component contained in the liquid to be measured, a mechanism for continuously sampling a sample, that is, a sample liquid from the continuously flowing liquid to be measured is important. In Patent Document 2, as a sample processing device for continuously sampling a sample liquid for an FIA device, the liquid to be measured is diluted at a dilution ratio according to the concentration of the substance to be measured, and the diluted liquid is placed in a storage container. It is disclosed that the sample liquid is temporarily stored and a certain amount of the sample liquid in the storage container is sucked up by a sampling needle for an auto sampler and supplied to the FIA device.

Japanese Unexamined Patent Publication No. 2000-338099 Japanese Unexamined Patent Publication No. 6-289034

Pharmaceutical Society of Japan, Hygiene Test Method, Commentary 1990.4.2.12.3 (13) 1 (1990 edition, 4th printing supplement (1995), p1028), 1995

In the sample processing apparatus described in Patent Document 2, the liquid to be measured is guided to a storage container which is relatively small and has an open upper part, and the sample liquid is collected by a sampling needle for an auto sampler. It is not suitable for stable sampling of a small amount of sample liquid from a liquid. In addition, since the stored solution is an open container, there is a risk of overflow, and there is a risk of contamination or contamination of the sample liquid to be collected. Depending on the situation, it may be necessary to clean the sampling needle.

An object of the present invention is a liquid analyzer capable of quantifying trace components in a liquid to be measured continuously and stably for a long period of time by making it possible to stably collect a sample liquid from a liquid to be measured flowing at a large flow rate. , To provide a sampling device suitable for such a liquid analyzer.

The liquid analyzer of the present invention is a liquid analyzer that collects a sample liquid from a liquid to be measured flowing through a mother pipe and continuously analyzes the sample liquid, and is a measuring unit that analyzes the sample liquid and a mother pipe. It has a sample liquid collection unit that collects the sample liquid from the liquid to be measured flowing through the sample, and a liquid supply unit that feeds the sample liquid collected by the sample liquid collection unit to the measurement unit. The sample liquid collection unit is a cylinder. The shape of the liquid flow section, the inflow port that is provided at the lower end of the liquid flow section in the direction of gravity and introduces a part of the liquid to be measured flowing through the mother pipe into the inside of the liquid flow section, and the direction of gravity of the liquid flow section. A sample of a part of the liquid to be measured that is provided at the upper end and discharges the liquid to be measured introduced into the liquid flow part, and a part of the liquid to be measured that opens inside the liquid flow part and flows inside the liquid flow part. It is provided with a sampling device having a sampling unit for collecting a sample liquid by extracting it as a liquid, and the liquid flow unit is closed except for the inlet, the outlet, and the extraction unit.

The sampling device of the present invention is a sampling device used for collecting a sample liquid from a liquid to be measured flowing through a mother tube for continuous analysis of the sample liquid, and has a tubular liquid flow section and a tubular liquid flow unit. It is provided at the lower end of the liquid flow section in the gravity direction and at the inflow port that introduces a part of the liquid to be measured flowing through the mother pipe into the inside of the liquid flow section and at the upper end of the liquid flow section in the gravity direction. The sample liquid is taken out as a sample liquid by extracting a part of the liquid to be measured that flows inside the liquid flow part by opening the outlet inside the liquid flow part and the outlet from which the liquid to be measured introduced into the liquid flow part is discharged. The liquid flow section is closed except for the inlet, outlet, and extract section.

According to the present invention, the liquid flow portion in which the liquid to be measured separated from the mother pipe flows from the lower part in the gravity direction to the upper side in the gravity direction is provided as a space that is not substantially opened to the atmosphere, and the sample liquid is provided through the opening provided in the liquid flow part. By extracting the liquid, it is possible to prevent contamination from the atmosphere and to stably collect the sample liquid from the liquid to be measured flowing at a large flow rate without containing bubbles, which enables continuous and stable measurement over a long period of time. It becomes possible to quantify trace components in the target liquid. In addition, since the liquid can be passed at a high flow velocity, it becomes possible to replace the liquid in the sample liquid collection part in a short time, and the analysis of the liquid to be measured flowing through the mother pipe, for example, the water quality analysis of the raw water flowing through the mother pipe is executed in almost real time. It will be possible to do.

It is a figure which shows the structure of the liquid analyzer of one Embodiment of this invention. It is sectional drawing which shows the structure of the sampling apparatus.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a liquid analyzer according to an embodiment of the present invention. This liquid analyzer is a liquid analyzer that collects a sample liquid from the liquid to be measured flowing through the mother pipe 20 and continuously analyzes the sample liquid, and has a measuring unit 100 that analyzes the sample liquid and a mother pipe. It includes a sample liquid collecting unit 200 that collects a sample liquid from the liquid to be measured flowing through 20, and a liquid feeding unit 300 that feeds the sample liquid collected by the sample liquid collecting unit 200 to the measuring unit 100. Here, assuming that the raw water used for pure water production is flowing through the mother pipe 20, sample water is collected from the raw water flowing through the mother pipe 20, and urea contained in the sample water is used as a target substance by flow injection (FIA) analysis. As an example, the case of continuous quantification online will be described. Therefore, the measuring unit 100 is composed of an FIA device. Of course, the liquid to be measured in the present invention is not limited to the raw water for producing pure water, is not limited to urea as the target substance to be measured, and the measuring unit 100 is also limited to the one configured as an FIA device. It is not possible. The liquid analyzer shown in FIG. 1 also has a function of automatically setting a calibration curve during quantification by FIA.

A pump P0 is provided in the mother pipe 20 through which the raw water used for pure water production flows, and the raw water is sent by the pump P0 with a certain pressure. A pipe 21 branching from the raw water mother pipe 20 is provided. The pipe 21 is for supplying raw water, which is the liquid to be measured, from the mother pipe 20 to the sample liquid collection unit 200, and in the middle of the section of the pipe 21 from the sample liquid collection unit 200 to the on-off valve 22 and the flow rate. A total FI is provided. In the present embodiment, since the urea concentration in the raw water is continuously quantified online, the on-off valve 22 is always open during the continuous quantification period.

The sample liquid collecting unit 200 is provided with a sampling device 60 and a back pressure valve 61. Details of the configuration of the sample liquid sampling device 60 are shown in FIG. The sampling device 60 is provided at the cylindrical liquid flow section 81 and the lower end of the liquid flow section 81 in the direction of gravity, and the sample water that branches from the mother pipe 20 and flows from the pipe 21 is inside the liquid flow section 81. Inside the inflow port 84 to be introduced into the liquid flow section 81, the outflow port 85 provided at the upper end of the liquid flow section 81 in the direction of gravity, and the sample water introduced into the liquid flow section 81 to be discharged, and the inside of the liquid flow section 81. It is provided with an extraction unit for extracting a part of the sample water that is opened and flows inside the liquid flow unit 81 to be supplied to the measurement unit 100 via the liquid supply unit 300. Except for the inflow port 84, the outflow port 85, and the extraction section, the liquid flow section 81 is substantially closed.

In the illustrated one, the liquid flow section 81 is composed of a cylinder, and a lower lid 82 and an upper lid 83 are provided at portions corresponding to the lower end and the upper end of the cylinder, respectively, and the lower lid 82 and the upper lid 83 provide a cylindrical liquid. Both ends of the distribution unit 81 are closed. The inflow port 84 is provided in the lower lid 82 and is open to the internal space of the liquid flow section 81. Further, the lower lid 82 is also provided with a joint 86 that communicates with the inflow port 84 and serves as a connection portion with the pipe 21, and the sample water that branches from the mother pipe 20 and flows through the pipe 21 flows from the joint 86. It flows into the internal space of the liquid flow unit 81 through the inlet 84. Similarly, the outlet 85 is provided in the upper lid 83 and is open to the internal space of the liquid flow section 81. The upper lid 83 is also provided with a joint 87 that communicates with the outlet 85 and serves as a connection portion with the pipe 68 so that the sample water supplied into the liquid flow unit 81 is discharged via the pipe 68. It has become. In this configuration, the sample water supplied from the inflow port 84 into the liquid flow section 21 flows in the liquid flow section 81 from the lower side to the upper side in the drawing. At this time, the cross-sectional area of the sample water in the liquid flow section 21 is larger than the cross-sectional area of the sample water at both the inlet 84 and the outlet 85. The liquid flow section 81 is a space that is not substantially open to the atmosphere, and the liquid to be measured that has been diverged from the mother pipe flows in the liquid flow section 81 from the lower part in the gravity direction to the upper part in the gravity direction. The linear velocity of the sample water flowing through the liquid flow section 81 is preferably 0.5 cm / sec to 5 cm / sec. If the linear velocity is too low, it takes time to replace the sample water in the pipe 21 and the fluid flow section 81, which causes a difference from the raw water quality actually flowing through the mother pipe 20. If the line speed is too high, the amount of drainage from the outlet 85 becomes excessive.

In the figure, the inflow port 84 and the outflow port 85 communicate with the joints 86, 87 via the L-shaped curved flow paths 88, 89 formed in the lower lid 82 and the upper lid 83, respectively, and the joint 86, The flow direction at 87 is a direction orthogonal to the flow direction of the sample water in the liquid flow unit 81. However, the arrangement of the inlet 84, the outlet 85 and the joints 86, 87 is not limited to this. For example, below the flow path extending parallel to the flow direction of the sample water in the liquid flow section 81 so that the flow direction at the joints 86 and 87 is also parallel to the flow direction of the sample water in the liquid flow section 81. It may be formed so as to penetrate the lid 82 and the upper lid 83, respectively. Further, in the vicinity of the position closed by the lower lid 82, an opening is provided in the side wall surface of the tubular member constituting the liquid flow portion 81 to serve as the inflow port 84, and similarly, in the vicinity of the position closed by the upper lid 83. In the above, an opening may be provided in the side wall surface of the tubular member of the liquid flow portion 81 and used as the outlet 85.

Next, the extraction unit will be described. The opening constituting the extraction unit may be provided at any position of the liquid flow unit 81, but the sample supplied from the sample water flowing through the liquid flow unit 81 to the measurement unit 100 via the liquid feed unit 300. In order to stably collect water, it is preferable that the flow rate of the sample water extracted is sufficiently smaller than the flow rate of the sample water flowing through the liquid flow section 81. Therefore, it is preferable that the flow path cross-sectional area of the opening provided in the extraction portion is smaller than the flow path cross-sectional area of either the inflow port 84 or the outflow port 85. In the present embodiment, in order to prevent air bubbles from being mixed in the sample water, a thin tube 91 that penetrates the upper lid 83 and extends in parallel with the flow direction of the sample water in the liquid flow section 81 is used as a extraction section. There is. The tip opening 93 of the thin tube 91 is an opening in the extraction portion. At this time, it is preferable that the insertion position of the thin tube 91 is at the center of the flow of the sample water in the liquid flow section 81, that is, penetrates the center of the upper lid 83. Here, the thin tube 91 is inserted into the liquid flow section 81 from the upper lid 83 side, but the same effect can be obtained by inserting the thin tube 91 from the lower lid 82 side. By inserting the thin tube 91 into the liquid flow section 81, for example, when fine bubbles flow in from the inflow port 84 and adhere to the wall surface of the liquid flow section 81, it is possible to prevent the thin tube 91 from sucking the adhered bubbles. .. In FIG. 2, a sealing member 92 is provided at a position where the thin tube 91 penetrates the upper lid 83 in order to prevent liquid leakage from this position. Assuming that the length of the liquid flow portion 81 between the lower lid 82 and the upper lid 83 is L, the position of the tip opening 93 of the thin tube 91 is the position of L / 4 to 3 L / 4 measured from the upper surface of the lower lid 82. It is in. That is, the position of the tip opening 93 of the thin tube 91 is a position that is 1/4 or more and 3/4 or less of the distance between both ends as measured from one of both ends of the liquid flow unit 81. A pipe 65 is connected to the root side (upper end side in the drawing) of the thin tube 91, and the sample water extracted through the thin tube 91 is sent to the liquid feeding unit 300 via the pipe 65.

Here, the extraction portion is configured by the thin tube 91 penetrating the upper lid 83 or the lower lid 82, but the configuration of the extraction portion is not limited to this. For example, at a position near the center of the liquid flow section 81 along the flow direction of the sample water, a thin tube is formed in a direction orthogonal to the flow direction of the sample water so as to penetrate the tubular member constituting the liquid flow section 81. May be inserted into the liquid flow unit 81 to serve as an extraction unit.

In the sampling device 60 shown here, since the sample water is collected from a substantially closed container, there is no risk of overflow or contamination of the sample water from the atmosphere. Further, even if bubbles are generated inside the liquid flow section 81, the bubbles are quickly discharged to the outside from the outlet 85, so that there is a risk that the bubbles may be mixed in the sample water extracted by the thin tube 91. There is no. By using the sampling device 60, it becomes possible to stably collect the sample liquid from the liquid to be measured flowing at a large flow rate without containing bubbles, whereby the liquid to be measured is continuously and stably for a long period of time. You will be able to quantify the target component inside. In order to more reliably prevent air bubbles from being mixed into the sample water, it is preferable to supply the sample water to the inside of the liquid flow section 81 at a pressure higher than the atmospheric pressure. In the sample liquid sampling unit 200 shown in FIG. 1, the pressure inside the liquid flow unit 81 is increased by providing a back pressure valve 61 in the pipe 68 connected to the outlet 85 of the sample collection device 60. The back pressure valve 61 is provided as a pressure adjusting means capable of adjusting the pressure, and for example, a ball valve, a relief valve, or the like may be used. Even if the sample water contains fine bubbles, it is possible to prevent the bubbles from entering the liquid distribution section 81 by setting the pressure to be higher than the solubility of the gas. As a matter of course, the set pressure of the back pressure valve 61 is set to be lower than the pressure of the raw water in the mother pipe 20. If there is no risk of bubbles being generated due to the properties of the liquid to be measured, the back pressure valve 61 may not be provided.

Next, the liquid feeding unit 300 will be described. The liquid feeding unit 300 is a standard liquid containing the sample water collected from the raw water in the sample liquid collecting unit 200 and a known amount of the target substance (urea in the example shown here) with respect to the measuring unit 100 configured by the FIA device. Any one of the above is selected and supplied. The liquid feeding unit 300 is contained in two containers 62 and 63 for storing standard liquids having different concentrations, and in the sample water supplied via the pipe 65 and the standard liquids stored in the standard liquid containers 62 and 63, respectively. A selection valve 64 for selecting one from the above, a sampling valve 10, a pump P1 for supplying carrier water, and a pump P4 for supplying sample water or the like to the sampling valve 10 by sucking the sample water or the like. I have.

The selection valve 64 uses any one of the sample water supplied by the pipe 65, the standard liquid in the container 62 supplied through the pipe 66, and the standard liquid in the container 63 supplied via the pipe 67. It is selected to supply the selected liquid to the sampling valve 10 via a pipe 70 connected to the selection valve 64. By driving the pump P4, the liquid selected by the selection valve 64 is constantly supplied to the sampling valve 10. In the example described here, two standard solutions having different concentrations of the target substance (here, urea) are prepared, but the number of standard solutions is not limited to two. If you want to express the calibration curve with a curve such as a quadratic curve, prepare three or more types of standard solutions with different concentrations. Although it is possible to use only a single standard solution, it is preferable to use at least two or more standard solutions having different concentrations from the viewpoint of quantification accuracy. When the function of automatically setting the calibration curve is not required, the sample water pipe 65 may be directly connected to the port 2 described later of the sampling valve 10 without providing the containers 62 and 63 and the selection valve 64.

Next, the sampling valve 10 will be described. The sampling valve 10 is supplied with sample water or a standard solution selected by the selection valve 64. For the sake of simplification of the description, when the term "sample water" is used in the following description regarding the sampling valve 10, it shall include the case of a standard solution.

The sampling valve 10 has a configuration generally used for supplying a sample liquid to the FIA apparatus in the FIA method, and includes a hexagonal valve 11 and a sample loop 12. The six-way valve 11 includes six ports indicated by circled numbers in the illustration. The pipe 70 from the selection valve 64 is connected to the port 2. Further, a pipe 23 to which carrier water is supplied via the pump P1 is connected to the port 6, and a pipe 25 for draining the sample water via the pump P4 is connected to the port 3. A sample loop 12 for collecting a predetermined volume of sample water is connected between the port 1 and the port 4. One end of the pipe 24, which is the outlet of the sampling valve 11, is connected to the port 5. The carrier water is water that does not substantially contain urea, for example, pure water. The pipe 24 is provided in the measuring unit 100, and one end thereof extends to the liquid feeding unit 300.

When the communication between the port X and the port Y in the hexagonal valve 11 is expressed as (XY), the hexagonal valve 11 is (1-2), (3-4), (5-6). The first state and the second state (2-3), (4-5), and (6-1) can be switched. In FIG. 1, the connection relationship between the ports in the first state is shown by a solid line, and the connection between the ports in the second state is shown by a dotted line. In the first state, the carrier water flows in the order of the pipe 23 → the port 6 → the port 5 → the pipe 24 and flows out from the sampling valve 10 to the downstream side, that is, the measuring unit 100. The sample water flows from the pipe 70 → the port 2 → the port 1 → the sample loop 12 → the port 4 → the port 3 and is discharged from the pipe 25. When the first state is switched to the second state, the sample water flows from the pipe 70 → the port 2 → the port 3 and is discharged from the pipe 25, and the carrier water flows from the pipe 23 → the port 6 → the port 1 →. The sample loop 12 → port 4 → port 5 → pipe 24 flows and flows out to the downstream side. At this time, the sample water that has already flowed in in the first state and fills the inside of the sample loop 12 flows from the port 5 to the pipe 24 prior to the carrier water, and flows from the sampling valve 10 to the measuring unit 100. Flows. The volume of the sample water flowing through the pipe 24, that is, the volume of the sample water to be measured by the measuring unit 100 is defined by the sample loop 12. Therefore, by repeatedly switching between the first state and the second state (for example, by rotating the hexagonal valve 11 in the direction of the arrow in the figure), a predetermined volume of sample water can be repeatedly sent to the measuring unit 100. Switching between the first state and the second state is performed every predetermined time in consideration of the residence time required for the reaction described later and the time until urea is detected by the detector 32 provided in the measuring unit 100. Can be done. It is also possible to detect that the sample water introduced into the detector 32 has been discharged from the detector 32 and perform switching. In this way, by automatically switching between the first state and the second state, urea can be continuously quantified.

Next, the measuring unit 100, which is an FIA device, will be described. In this embodiment, the FIA method is applied to the quantification of urea by the colorimetric method using diacetylmonooxime. Therefore, as a reaction reagent used for the quantification of urea, a diacetylmonooxime acetic acid solution (hereinafter, also referred to as reagent A) and an antipyrine-containing reagent solution (hereinafter, also referred to as reagent B) are used. Here, a case where an antipyrine-containing reagent solution is used as a reagent used in combination with diacetylmonooxime will be described, but the reagent used in combination with diacetylmonooxime is not limited to the antipyrine-containing reagent solution. Reagent A and Reagent B are stored in storage tanks 41 and 42, respectively.

The present inventors prepared these reagents, and when they were kept at room temperature for a long period of time (for example, several days or more) for continuous quantification of urea, the peak intensity in the absorbance measurement decreased, and this peak. It has been found that the decrease in strength can be prevented by refrigerating the reagent (particularly reagent B). In order to perform stable quantification, it is preferable that the peak intensity in the absorbance measurement does not decrease. Therefore, in the measuring unit 100 in the present embodiment, the storage tanks 41 and 42 are provided in the refrigerating unit 40. Reagent A is prepared by dissolving diacetylmonooxime in an acetic acid solution, but when the refrigerating section 40 is provided, the preparation itself is performed in the storage tank 41, or reagent A is stored in the storage tank 41 after its preparation. do. Similarly, reagent B is prepared by dissolving antipyrine in, for example, sulfuric acid, but the preparation itself is performed in the storage tank 42, or reagent B is stored in the storage tank 42 after its preparation. The refrigerating section 40 shields the storage tanks 41 and 42 from light and cools the storage tanks 41 and 42, whereby the temperatures of the reagents A and B in the storage tanks 41 and 42 are kept at 20 ° C. or lower, preferably 3 ° C. or higher and 20 ° C. Hereinafter, it is more preferably maintained at 5 ° C. or higher and 15 ° C. or lower. The storage tank 41 for storing the reagent A does not necessarily have to be arranged in the refrigerating section 40 as long as it can be stored in a light-shielded manner. Even if the refrigerating temperature of the reagent is less than 5 ° C., it does not matter as long as crystals do not precipitate in the reagent. According to the hygiene test method (Non-Patent Document 1), an antipyrine sulfuric acid solution in which antipyrine is dissolved in sulfuric acid can be used for 2 to 3 months if it is stored in a brown bottle, and it is redissolved even if crystals are precipitated and returned to room temperature. Although it is stated that refrigerated storage is not suitable because it does not, the present inventors have confirmed by experiments that the antipyrine sulfuric acid solution prepared according to the hygiene test method does not crystallize even at 3 ° C.

One end of the pipe 26 is connected to the storage tank 41, and the other end of the pipe 26 is connected to the pipe 24 by the mixing portion 43. The pipe 26 is provided with a pump P2 for sending the reagent A to the pipe 24 at a predetermined flow rate. Similarly, one end of the pipe 27 is connected to the storage tank 42, and the other end of the pipe 27 is connected to the pipe 24 from the liquid feeding unit 300 by the mixing unit 44. The pipe 27 is provided with a pump P3 for sending the reagent B to the pipe 24 at a predetermined flow rate. The mixing units 43 and 44 have a function of uniformly mixing the reagent A and the reagent B with respect to the flow of the liquid in the pipe 24, respectively. The other end of the pipe 24 is connected to the inlet of the reaction coil 31 provided in the reaction constant temperature bath 30. The reaction coil 31 causes a color reaction between urea and diacetylmonooxime in the presence of antipyrine, and its length and the flow velocity inside the reaction coil 31 are the residence time required for the reaction. It is appropriately selected according to the above. The reaction constant temperature bath 30 raises the temperature of the reaction coil 31 to a temperature suitable for the reaction. For example, the reaction coil 31 is heated to a temperature of 50 ° C. or higher and 150 ° C. or lower, preferably 90 ° C. or higher and 120 ° C. or lower. ..

At the end, that is, the outlet of the reaction coil 31, a detector 32 for measuring the absorbance of the color developed in the liquid by the color development reaction is provided for the liquid flowing out of the reaction coil 31. The detector 32 measures, for example, the absorbance at a wavelength of around 460 nm and outputs it as a detection result. At the outlet of the detector 32, a back pressure coil 33 that applies back pressure to the pipeline from the pump P1 to the detector 32 via the sampling valve 10, the pipe 24, and the reaction coil 31 is provided. A pressure gauge PI is connected to a position between the outlet of the detector 32 and the inlet of the back pressure coil 33. The drainage of this FIA device flows out from the outlet of the back pressure coil 33.

In the liquid analyzer of the present embodiment, as described above, the hexagonal valve 11 is driven to switch between the first state and the second state, and the sample water or one of the standards is switched by the selection valve 64. A control unit 50 is further provided to select the liquid. The detection result of the detector 32 is input to the control unit 50. The control unit 50 controls the selection valve 64 and the sampling valve 10 (particularly the hexagonal valve 11), calculates a calibration curve based on the detection result when the standard solution is selected by the selection valve 64, and selects the sample water. Then, by applying the detection result for the sample water to the calculated calibration curve, the urea concentration in the sample water is determined and output as a quantification result. When calculating the calibration curve or determining the urea concentration, the control unit 50 determines the peak value (that is, peak intensity) in the detection result input from the detector 32, or the peak area obtained by integrating the detection result with respect to time. Calculate and use. At that time, the absorbance when the carrier water is flowing is used as the baseline, and the peak intensity or the peak area with respect to this baseline is obtained.

Next, the calculation of the calibration curve when continuously quantifying urea will be described. Consider a case where the urea concentration in the sample water is continuously measured over a long period of time by measuring the urea concentration at a predetermined time interval t using the liquid analyzer of the present embodiment. At this time, the control unit 50 first controls the selection valve 64 so that the standard liquids in the containers 62 and 63 are sequentially supplied to the sampling valve 10, and further controls the sampling valve 10 to control these standards. Perform measurements on the liquid. Then, the control unit 50 calculates a calibration curve based on the detection result obtained by the detector 32 for each standard solution. Subsequently, the control unit 50 controls the selection valve 64 so that the sample water is supplied to the sampling valve 10, and controls the sampling valve 10 so that the sample water is introduced into the pipe 24 at every time interval t. do. The control unit 50 determines the urea concentration in the sample water by applying the result obtained from the detector 32 to the calibration curve generated earlier for the sample water, and outputs the result as a quantification result. As a result, the urea concentration was obtained at each time interval t.

If the measurement period for continuous quantification is long and there is concern about denaturation of each reagent or fluctuation of the detection characteristics of the detector 32 during that period, the control unit 50 may perform a calibration curve. Every time the calculation interval T (where T ≧ t), a process of redrawing the calibration curve, that is, a process of recalculating the calibration curve is performed. In the process of recalculating the calibration curve, the control unit 50 controls the selection valve 64 to select the standard solution at a timing that does not affect the measurement of the sample water, and controls the sampling valve 10 in that state to control the standard solution. Is introduced into the pipe 24. Then, the calibration curve is recalculated based on the detection result from the detector 32 at that time. After recalculating the calibration curve, the urea concentration in the sample water is calculated based on the recalculated calibration curve. In this embodiment, the calibration curve is calculated using two types of standard solutions, but if it is not possible to secure enough time to measure both standard solutions during the measurement interval t of the sample water, one of them is used. The standard solution may be measured, then the sample water may be measured once, and then the other standard solution may be measured and the calibration curve may be recalculated. In order to suppress the consumption of the standard solution and avoid the time lag in the analysis result of the sample water, the selection valve 64 selects the sample water during the period other than the period required for the measurement of the standard solution. Is preferable. In other words, in order to know the ever-changing urea concentration in the raw water without delay, the calibration curve is set based on the fact that the pump P4 for feeding the sample water is provided on the outlet side of the sampling valve 10. It is preferable that the selection valve 64 selects the sample water so that the sample water flows through the pipe 70, except for the minimum required period. It is preferable that the calibration curve calculation interval T can be arbitrarily set according to the reagent to be used and the configuration of the measuring unit 100. Further, it is preferable that the calibration curve calculation interval T can be appropriately changed even in the middle of a long measurement period. For example, under conditions where the measurement environment temperature is different, the rate of decrease in peak intensity in the absorbance measurement is different. The calibration curve calculation interval T is set at equal intervals immediately after the start of measurement, and if the rate of decrease in the peak intensity of the standard solution calculated before and after the calibration curve calculation interval T exceeds a certain range, the calibration curve calculation interval T can be shortened automatically. Further, if the rate of decrease in the peak intensity of the standard solution calculated before and after the calibration curve calculation interval T falls within a certain range, the calibration curve calculation interval T can be automatically extended. By extending the calibration curve calculation interval T, it becomes possible to reduce the amount of the standard solution used. The calibration curve calculation interval T differs depending on the composition and properties of the sample water.

In the apparatus of this embodiment, since the above-mentioned sampling apparatus 60 is used and the FIA method is used, urea in the sample water can be continuously measured online for a long period of time by the colorimetric method using diacetylmonooxime. Moreover, since the calibration curve is automatically recalculated even if the reagent or the device fluctuates during that period, urea can be quantified stably and with high accuracy over a long period of time. Further, as the reagent A (diacetylmonooxime acetic acid solution) and the reagent B (antipyrine-containing reagent solution) used for the reaction, particularly the reagent B, which was maintained at 20 ° C. or lower after the preparation of these reagents, was used. , It becomes possible to perform continuous quantification of urea more stably over a long period of time.

20 Mother tube 60 Sampling device 61 Back pressure valve 81 Liquid flow section 82 Lower lid 83 Top lid 84 Inflow port 85 Outlet 91 Thin tube 92 Tip opening 100 Measuring section 200 Sample solution sampling section 300 Liquid feeding section

Claims (10)

A liquid analyzer that collects a sample liquid from the liquid to be measured flowing through the mother tube and continuously analyzes the sample liquid.
The measuring unit that analyzes the sample liquid and
A sample liquid collection unit that collects the sample liquid from the liquid to be measured flowing through the mother tube, and a sample liquid collection unit.
A liquid feeding unit that feeds the sample liquid collected by the sample liquid collecting unit to the measuring unit, and a liquid feeding unit.
Have,
The sample liquid sampling unit is provided at the cylindrical liquid flow unit and the lower end of the liquid flow unit in the direction of gravity, and a part of the liquid to be measured flowing through the mother tube is inside the liquid flow unit. an inlet for introducing a flow outlet wherein the measurement target liquid introduced into the liquid flow portion provided at an end portion in the gravity direction above the liquid circulation unit is drained, open to the interior of the liquid flow portion A part of the liquid to be measured flowing inside the liquid flow unit is extracted as the sample liquid to collect the sample liquid, and a back pressure is applied to the inside of the liquid flow unit by connecting to the outlet. A sampling device having a valve for adding a liquid, and having the liquid flow section closed except for the inlet, the outlet, and the extraction section.
A liquid analyzer in which the liquid to be measured is passed through the liquid flow section at a pressure higher than atmospheric pressure. The liquid analyzer according to claim 1, wherein the extraction unit is composed of a thin tube extending in the liquid flow section, and the sample liquid is extracted through the thin tube from an opening formed at the tip of the thin tube. The liquid analyzer according to claim 2, wherein the thin tube extends in parallel with the flow direction of the liquid to be measured in the liquid flow section. The liquid according to claim 3, wherein the position of the opening at the tip of the thin tube is a position that is 1/4 or more and 3/4 or less of the distance between the both ends as measured from one of the both ends of the liquid flow unit. Analysis equipment. The flow path cross-sectional area of the measurement target liquid in the liquid flow section is larger than both the flow path cross-sectional area of the measurement target liquid at the inlet and the flow path cross-sectional area of the measurement target liquid at the outlet. Claims 2 to 4 that the flow path cross-sectional area inside the thin tube is smaller than both the flow path cross-sectional area of the liquid to be measured at the inlet and the flow path cross-sectional area of the liquid to be measured at the outlet. The liquid analyzer according to any one of the above items. The liquid analyzer according to any one of claims 1 to 5, wherein the measuring unit is composed of a flow injection analyzer. A sampling device used to collect the sample liquid from the liquid to be measured flowing through the mother tube for continuous analysis of the sample liquid.
Cylindrical liquid distribution section and
An inflow port provided at the lower end of the liquid flow section in the direction of gravity and introducing a part of the liquid to be measured flowing through the mother pipe into the inside of the liquid flow section.
An outlet provided at the upper end of the liquid flow section in the direction of gravity and draining the liquid to be measured introduced into the liquid flow section,
An extraction unit for collecting the sample liquid by opening a part of the liquid to be measured that opens inside the liquid distribution unit and flows inside the liquid distribution unit as the sample liquid.
A valve connected to the outlet and applying back pressure to the inside of the liquid flow section,
Have,
The liquid flow section is closed except for the inlet, the outlet, and the extraction section.
A sampling device in which the liquid to be measured is passed through the liquid flow section at a pressure higher than atmospheric pressure. The sampling device according to claim 7, wherein the extraction unit is composed of a thin tube extending in the liquid flow section, and the sample liquid is extracted from an opening formed at the tip of the thin tube through the thin tube. The thin tube extends parallel to the flow direction of the liquid to be measured in the liquid flow section.
The sample according to claim 8, wherein the position of the opening at the tip of the thin tube is a position which is 1/4 or more and 3/4 or less of the distance between the both ends as measured from one of the both ends of the liquid flow section. Sampling device. The flow path cross-sectional area of the measurement target liquid in the liquid flow section is larger than both the flow path cross-sectional area of the measurement target liquid at the inlet and the flow path cross-sectional area of the measurement target liquid at the outlet. 8. The sampling device described in 1.

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