Reduction component, analysis device, and analysis method

Abstract

The present invention provides a continuous analysis device and an analysis method for nitrogen in a sample that do not use cadmium, which is a cause of environmental pollution, and solves the problem of column clogging. This is solved by an analysis method including a sample introduction step of introducing a sample into a pipeline, a reduction step of reducing nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions, and an analysis step of analyzing ammonium ions in the sample generated in the reduction step. In the reduction step, the sample is transferred through a hollow tube made of zinc at least on the inner wall surface to reduce nitrate ions and nitrite ions in the sample.

Description

Technical Field

[0001] The present invention relates to a reduction component, an analysis device, and an analysis method. Background Art

[0002] Conventionally, in the determination of total nitrogen in seawater and brackish water, the copper-cadmium reduction method has been used. However, in the copper-cadmium reduction method, there are problems from the viewpoint of environmental pollution, such as the problem that cadmium is mixed in the wastewater after analysis, and the problem that the copper-cadmium column needs to be discarded as a specially controlled waste.

[0003] As a determination method for solving the problems involved, a method for determining dissolved nitrogen in seawater has been disclosed. In this method, nitrate ions and nitrite ions dissolved in seawater are reduced to ammonium ions using a column filled with copper-coated zinc particles, and the ammonium ions and the ammonium ions originally dissolved in seawater are quantified.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 2009-115758 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The conventional technique disclosed in Patent Document 1 solves the problem of environmental load because it does not use cadmium. However, since this conventional technique uses a column filled with copper-coated zinc particles in the reduction of nitrate ions and nitrite ions, there is a problem of column clogging caused by suspended substances in the sample.

[0009] As a countermeasure against such clogging, it is possible to consider filtering the sample and providing a guard column before the column. However, in these methods, as described in Patent Document 1, in the method of directly analyzing nitrogen in a seawater sample as dissolved inorganic nitrogen (DIN), since suspended substances are removed, there is a problem that the total amounts of nitrate ions, nitrite ions, and ammonium ions in the sample that also contain suspended substances cannot be accurately measured.

[0010] An object of the present invention is to provide a continuous analysis device and an analysis method for nitrogen in a sample that do not use cadmium, which is a cause of environmental pollution, and solve the problem of column clogging.

[0011] Means for Solving the Problems

[0012] The inventors of the present invention conducted in-depth research to solve the above problems, and as a result, found that the above problems can be achieved by using a novel reduction component that has not been used so far, and thus completed the present invention.

[0013] That is, one aspect of the present invention includes the following configuration.

[0014] 〔1〕A reduction component, which is a hollow tube with at least an inner wall surface made of zinc, and a sample is transferred in this tube.

[0015] 〔2〕An analysis device, which includes: an introduction part that introduces a sample into a pipeline; a reduction part that reduces nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions; an analysis part that analyzes the ammonium ions in the sample generated in the reduction part, wherein the reduction part includes the reduction component described in 〔1〕.

[0016] 〔3〕An analysis method, which includes: a sample introduction step that introduces a sample into a pipeline; a reduction step that reduces nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions; an analysis step that analyzes the ammonium ions in the sample generated in the reduction step, wherein in the reduction step, the sample is transferred in a hollow tube with at least an inner wall surface made of zinc to reduce nitrate ions and nitrite ions in the sample.

[0017] Advantages of the Invention

[0018] According to one embodiment of the present invention, it is possible to provide a continuous analysis device and an analysis method for nitrogen in a sample that do not use cadmium, which is a cause of environmental pollution, and solve the problem of column blockage. Brief Description of the Drawings

[0019] Figure 1 It is a diagram showing a schematic configuration of an analysis device according to one embodiment of the present invention.

[0020] Figure 2 It is a diagram showing a schematic configuration of an analysis device according to one embodiment of the present invention.

[0021] Figure 3 It is a diagram showing a schematic configuration of an analysis device according to one embodiment of the present invention.

[0022] Figure 4 It is a diagram schematically showing a gas permeable part of an analysis device according to one embodiment of the present invention.

[0023] Figure 5 It is a diagram showing a baseline in the indophenol blue spectrophotometry using salicylic acid.

[0024] Figure 6 It is a diagram showing a baseline in the indophenol blue spectrophotometry using salicylic acid.

[0025] Figure 7 It is a diagram showing the result of flow analysis in an example.

[0026] Figure 8 It is a diagram schematically showing an example of a reduction component. Detailed implementation mode

[0027] The following provides a detailed description of the implementation modes of the present invention. However, the present invention is not limited to these contents, and various changes can be made within the described scope. Implementation modes obtained by appropriately combining the technical solutions disclosed in different implementation modes are also included in the technical scope of the present invention. In addition, all the academic literatures and patent literatures described in this specification are incorporated into this specification as references. Also, in this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more (including A and greater than A) and B or less (including B and less than B)".

[0028] [1] Reduction component

[0029] The reduction component according to an embodiment of the present invention, the reduction component is a hollow tube at least the inner wall surface of which is made of zinc, and a sample is transferred in the tube. The reduction component according to an embodiment of the present invention, through the involved structure, while transferring the sample in the tube, can reduce nitrate ions and nitrite ions that may be contained in the transferred sample into ammonium ions. According to such a reduction component, there is no problem of blockage in the column filled with copper-coated zinc particles used in the past. In addition, since the sample can be transferred in a state containing suspended substances and the nitrate ions and nitrite ions contained in the sample can be reduced, the total amounts of nitrate ions, nitrite ions, and ammonium ions contained in the sample can be accurately analyzed.

[0030] Here, in this specification, "reducing nitrate ions and nitrite ions that may be contained in the sample into ammonium ions" and "reducing nitrate ions and nitrite ions in the sample into ammonium ions" mean that when the sample contains at least any one of nitrate ions and nitrite ions, at least any one of the contained nitrate ions and nitrite ions is reduced into ammonium ions.

[0031] The inner diameter of the tube of the reduction component according to an embodiment of the present invention is not limited to these contents. Preferably, it is 0.5 mm to 1.5 mm, more preferably 0.6 mm to 1.4 mm, still more preferably 0.7 mm to 1.3 mm, particularly preferably 0.8 mm to 1.2 mm, and most preferably 0.9 mm to 1.1 mm. If the inner diameter is 0.5 mm or more, the sample can be transferred in the tube at an appropriate speed. Also, if the inner diameter is 1.5 mm or less, the frequency of contact between the sample transferred in the tube and the tube wall increases, so the nitrate ions and nitrite ions in the sample can be fully reduced, which is preferred.

[0032] The thickness of the tube wall of the reduction component according to an embodiment of the present invention is not limited to these values, and is preferably 0.1 mm to 1.5 mm, more preferably 0.2 mm to 1.0 mm, still more preferably 0.3 mm to 0.7 mm, and most preferably 0.4 mm to 0.6 mm. If the thickness is 0.1 mm or more, the strength of the reduction component is sufficient, so it is preferred. Also, if the thickness is 1.5 mm or less, it can be processed into a desired shape, so it is preferred.

[0033] The length of the tube of the reduction component according to an embodiment of the present invention is not limited to these values, and is preferably 100 mm to 1000 mm, more preferably 200 mm to 900 mm, still more preferably 300 mm to 800 mm, and most preferably 400 mm to 700 mm. If the length is 100 mm or more, the frequency of contact between the sample transferred in the tube and the tube wall increases, so the nitrate ions and nitrite ions in the sample can be sufficiently reduced, so it is preferred. Also, if the length is 1000 mm or less, the transfer of the sample does not take too much time, so the analysis time can be shortened.

[0034] The cross-sectional shape of the tube of the reduction component according to an embodiment of the present invention is usually circular, but it can also be elliptical or polygonal.

[0035] The shape of the tube of the reduction component according to an embodiment of the present invention is not particularly limited, and can be linear or curved. Among them, the shape is more preferably curved, and still more preferably a shape that moves in a direction perpendicular to the plane of the figure while drawing a figure such as a circle. The figure is not particularly limited, for example, a circle, an ellipse, an 8-shaped figure, etc. As the shape of the tube, for example, a spiral shape, an 8-shaped spiral shape, etc. can be cited. Figure 8 Examples of the reduction component are schematically shown. Figure 8 (a) is a spiral reduction component, and (b) is an 8-shaped spiral reduction component. According to the shape, since the sample transferred in the tube is transferred while rotating in the tube, the frequency of contact with the tube wall increases while the sample is uniformly mixed. Therefore, the nitrate ions and nitrite ions in the sample can be sufficiently reduced, so it is preferred. The number of turns of the spiral such as the spiral shape and the 8-shaped spiral shape is not particularly limited, for example, 1 turn to 20 turns, more preferably 2 turns to 10 turns, still more preferably 4 turns to 7 turns. If the number of turns is 1 turn or more, the frequency of contact with the tube wall increases while the sample is relatively uniformly mixed, so it is preferred. Also, if the number of turns is 20 turns or less, miniaturization of the device can be achieved, so it is preferred.

[0036] When the shape of the tube is, for example, spiral, the outer diameter of the spiral (referred to as the "coil diameter") is not particularly limited, and is, for example, 10 mm to 70 mm, more preferably 15 mm to 60 mm, still more preferably 20 mm to 50 mm, and most preferably 25 mm to 40 mm. If the coil diameter is 10 mm or more, the liquid can be stably transported, so it is preferred. Also, if the coil diameter is 70 mm or less, the liquid can be more appropriately mixed, so it is preferred.

[0037] When the shape of the tube is, for example, spiral, the coil pitch is not particularly limited, and is, for example, 0.7 mm to 40 mm, more preferably 0.8 mm to 30 mm, still more preferably 0.9 mm to 25 mm. If the coil pitch is 0.7 mm or more, a reducing member for winding the tube with a preferred tube diameter can be formed, so it is preferred. Also, if the coil diameter is 40 mm or less, the size of the reducing member is a size that does not occupy space, so it is preferred. Also, when the shape of the tube is, for example, spiral, it is preferred that the tubes be filled and wound without leaving gaps between the tubes. In this case, the coil pitch is also not particularly limited, and is, for example, 0.7 mm to 5.0 mm, more preferably 1.0 mm to 4.5 mm, still more preferably 1.2 mm to 4.0 mm.

[0038] When the shape of the tube is, for example, figure-eight spiral, the maximum length of the figure-eight is the same as the coil diameter in the case of a spiral, and the pitch is the same as the coil pitch in the case of a spiral.

[0039] The tube of the reducing member according to an embodiment of the present invention only needs to be a tube whose inner wall surface is at least made of zinc. According to this configuration, zinc functions as a reducing agent and can reduce nitrate ions and nitrite ions to ammonium ions. Also, by using zinc, it becomes possible not to use cadmium, and the problem of environmental load is solved. From the viewpoints of the safety of the metal used, the ease of manufacture, and the ability to be used as a reducing agent for a long time, it is more preferred that the entire tube be made of zinc.

[0040] In one embodiment of the present invention, zinc forming the inner wall surface of the tube or the tube is preferably coated with copper at least on the inner side of the tube. By coating copper on the inner side of the tube, the reduction rate of nitrate ions and nitrite ions to ammonium ions can be increased. The thickness of the copper coating is not particularly limited, for example, it is 0.5 μm to 300 μm, and more preferably 10 μm to 200 μm. If the thickness of the copper coating is 0.5 μm or more, the reduction rate of nitrate ions and nitrite ions to ammonium ions can be increased for a long time, so it is preferred. Also, if the thickness of the copper coating is 300 μm or less, the inner diameter of the tube will not be too small, so it is preferred. The method of coating the zinc of the tube with copper is not particularly limited, and examples thereof include a method of immersing the hollow tube having at least an inner wall surface made of zinc in an aqueous copper sulfate solution containing a chelating agent such as ethylenediaminetetraacetic acid (EDTA). In this method, the content of the chelating agent relative to the total weight of the aqueous copper sulfate solution is preferably 1% by weight to 10% by weight. Also, the content of copper sulfate relative to the total weight of the aqueous copper sulfate solution is preferably 0.5% by weight to 5% by weight. The pH of the aqueous copper sulfate solution for immersing the tube is preferably 6 to 8, and the immersion time is preferably 12 hours to 24 hours. Alternatively, the zinc of the inner wall surface of the tube or the tube can be coated with copper by flowing the aqueous copper sulfate solution in the tube of the hollow tube having at least an inner wall surface made of zinc or by retaining the aqueous copper sulfate solution in the tube.

[0041] [2] Analytical device

[0042] The analytical device according to one embodiment of the present invention includes: an introduction unit that introduces a sample into a pipeline; a reduction unit that reduces nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions; and an analysis unit that analyzes ammonium ions in the sample generated in the reduction unit, wherein the reduction unit includes the reduction component according to one embodiment of the present invention as described above.

[0043] According to the analytical device, continuous analysis of nitrogen etc. (total amount of nitric acid, nitrous acid, and ammonia) in a sample (for example, a sample in a seawater - brackish water area) without using cadmium that causes environmental pollution and solving the problem of column blockage becomes possible.

[0044] In one embodiment of the present invention, the analytical device may be a flow analysis device. According to the flow analysis device, a sample can be continuously introduced into a pipeline, reduction can be performed in the pipeline, a reagent can be introduced into the pipeline and caused to react, and analysis data can be continuously measured in the analysis unit.

[0045] [2.1] Embodiment 1

[0046] An embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1Shows the schematic configuration of the flow analysis device according to Embodiment 1 of the present invention.

[0047] The flow analysis device according to Embodiment 1 of the present invention includes: a sample introduction unit 1 that introduces a sample into a conduit 7; a bubble separation unit 4 that separates bubbles from the sample introduced into the conduit 7 and creates a plurality of segments divided by bubbles in the conduit 7; a reagent introduction unit 5 that adds a reagent to the flow of the sample transferred in the conduit 7; a reduction unit 2 that reduces nitrate ions and nitrite ions in the sample transferred in the conduit 7 to ammonium ions; a reagent introduction unit 5 that adds a reagent to the flow of the sample containing ammonium ions transferred in the conduit 7 via the reduction unit 2; a gas permeation unit 6; a reagent introduction unit 5 that adds a reagent to the flow of the sample containing ammonium ions transferred in the conduit 7 via the gas permeation unit 6; and an analysis unit 3 that analyzes ammonium ions in the sample.

[0048] The sample introduction unit 1 is a device for sampling a sample and introducing it into the conduit 7. In one embodiment of the present invention, the sample introduction unit 1 includes a collection tube that introduces the sample into the conduit 7 and a sampling pump that applies a suction force to the collection tube. Using the sampling pump, the sample is introduced into the conduit 7 at a predetermined flow rate. The sample is a liquid containing a substance or element to be analyzed.

[0049] The bubble separation unit 4 is a device for separating bubbles from the sample introduced into the conduit 7 and creating a plurality of segments divided by bubbles in the conduit 7. In one embodiment of the present invention, the bubble separation unit 4 includes a gas introduction tube that introduces gas into the conduit 7 and a gas introduction pump that applies a suction force to the gas introduction tube. By separating bubbles, it is possible to appropriately mix reagents and the like in the vortices in the separation liquid divided by bubbles, and at the same time, in the reduction unit 2, increase the frequency of contact between the sample transferred in the tube and the inner wall of the reduction unit 2. Therefore, nitrate ions and nitrite ions in the sample can be sufficiently reduced to ammonium ions. Also, the separation liquid is divided by bubbles and flows independently in the conduit 7, thereby preventing the diffusion of samples to each other. In this way, a method of introducing a reagent into the continuous flow in the conduit in which the sample is separated by bubbles, performing a reaction operation, and then analyzing with a detector provided downstream is called continuous flow analysis (CFA). As the gas for bubble separation, inert gases such as argon and helium, and various gases such as nitrogen can be used. These gases can be used alone or in combination of two or more. Among them, the gas is preferably nitrogen, and / or inert gases such as argon and helium. If the gas is nitrogen, and / or inert gases such as argon and helium, since the gas does not contain oxygen, oxidation of the inner wall of the reduction unit 2 caused by oxygen can be prevented. Therefore, a high reduction rate of nitrate ions and nitrite ions to ammonium ions can be maintained, which is preferable.

[0050] The reagent introduction unit 5 is a device for adding a reagent into the flow of a sample being transferred in the pipeline 7. The reagent introduction unit 5 includes: a reagent introduction pipe for introducing the reagent into the pipeline 7, and a reagent introduction pump for applying a suction force to the reagent introduction pipe. Examples of the reagent added in the reagent introduction unit 5 provided downstream of the bubble separation unit 4 and upstream of the reduction unit 2 include chelating agents such as EDTA, citric acid, and trans-1,2-cyclohexanediaminetetraacetic acid-hydrate (CyDTA). Upstream of the reduction unit 2, by adding the chelating agent, when zinc ions or copper ions dissolve from the reduction component into the sample in the subsequent reduction unit 2, the chelating agent forms a stable complex with these dissolved ions, and the concentration of free zinc ions or copper ions can be reduced. Therefore, the potential between zinc ions-zinc or copper ions-copper can be reduced, and the reduction of nitrate ions and nitrite ions to ammonium ions can be effectively carried out. In Figure 1 the example, the reagent introduction unit 5 is provided downstream of the bubble separation unit 4 and upstream of the reduction unit 2, but it may also be provided downstream of the sample introduction unit 1 and upstream of the bubble separation unit 4.

[0051] The reduction unit 2 is a device for reducing nitrate ions and nitrite ions in the sample being transferred in the pipeline 7 to ammonium ions. The reduction unit 2 includes the reduction component according to an embodiment of the present invention as described above, and the sample is transferred in this pipe. The pipeline 7 is connected to both ends of the pipe of the reduction component of the reduction unit 2, and the sample being transferred in the pipeline 7 is directly and continuously transferred in the pipe of the reduction component, and the sample passing through the pipe is then continuously transferred in the pipeline 7. In other words, the pipe of the reduction component of the reduction unit 2 becomes the pipeline 7. The connection portions of both ends of the pipeline 7 to the pipe of the reduction component of the reduction unit 2 are connected in such a way that the sample and gas being transferred in the pipe are sealed in the pipeline. The inner diameter of the pipeline 7 and the inner diameter of the pipe of the reduction component of the reduction unit 2 may be the same or different as long as the sample can be continuously transferred.

[0052] Downstream of the reduction unit 2 and upstream of the air-permeable unit 6, there is provided a reagent introduction unit 5 for adding a reagent to the flow of the sample of ammonium ions transferred through the reduction unit 2 in the pipeline 7. The reagent introduction unit 5 includes: a reagent introduction pipe for introducing the reagent into the pipeline 7, and a reagent introduction pump for applying a suction force to the reagent introduction pipe. As the reagent added in the reagent introduction unit 5 provided downstream of the reduction unit 2 and upstream of the air-permeable unit 6, for example, as a reagent for making the pH alkaline, alkalis such as sodium hydroxide can be cited. By adding an alkali downstream of the reduction unit 2 and upstream of the air-permeable unit 6, the ammonium ions in the sample can be vaporized into ammonia gas. Also, a buffer solution containing boric acid or the like can be added to the alkali such as sodium hydroxide. As the alkali, it is not limited to sodium hydroxide, and a reagent for making the pH alkaline can be appropriately selected. For the reagent used to prepare the buffer solution, it is not limited to boric acid, and other buffer solutions can also be appropriately selected and added.

[0053] The air-permeable unit 6 is a device that separates by allowing gaseous ammonia to pass through. Figure 4 It is a diagram schematically showing the air-permeable unit 6. As Figure 4 shown, if a sample containing gaseous ammonia ( Figure 4 in which is recorded as "sample + reagent") is transferred to the air-permeable unit 6, only the ammonia gas in the sample passes through the polytetrafluoroethylene (PTFE) porous filter 12 of the air-permeable unit 6, and the remaining part in the sample is discharged as waste liquid. The ammonia gas passing through the PTFE porous filter 12 is absorbed by the receiving reagent and becomes ammonium ions again. The receiving reagent that has absorbed the ammonium ions is transferred in the pipeline 7 connected to the downstream of the air-permeable unit 6 and is used for analysis. In addition, in Figure 4 , in order to show that ammonia gas passes through the PTFE porous filter 12, NH is also described after passing through the PTFE porous filter 12 3 , but then it is absorbed by the receiving reagent and becomes NH4 + . The receiving reagent is not particularly limited as long as it is a reagent that can absorb gaseous ammonia and convert it into ammonium ions. For example, an acid such as sulfuric acid can be used. As the acid, it is not limited to sulfuric acid, and a reagent that can absorb gaseous ammonia can be appropriately selected. Also, a reagent for detecting ammonium ions can be contained together with an acid such as sulfuric acid. As the reagent involved, for example, a reagent used in the detection of ammonium can be cited. The reagent involved is not particularly limited, and for example, reagents such as sodium nitroprusside used in the indophenol blue spectrophotometric method can be cited. The receiving reagent can also be supplied with a bubble barrier. As the gas used in this bubble barrier, various gases such as inert gases such as argon and helium, nitrogen, oxygen, and air can be used. Also, in Figure 4 the example, a PTFE porous filter is used, but as long as it is a filter that selectively passes gaseous ammonia, it is not limited to these.

[0054] The ammonia in gaseous form is selectively permeated and separated through the air-permeable part 6, so that the amount of ammonium ions in the sample reduced in the reduction part 2 can be accurately analyzed. In other words, the total amount of nitrogen in nitrate ions (nitrate nitrogen) reduced to ammonium ions, the amount of nitrogen in nitrite ions (nitrite nitrogen) reduced to ammonium ions, and the amount of nitrogen in ammonium ions (ammonia nitrogen) originally contained in the sample can be accurately analyzed.

[0055] In addition, by providing the air-permeable part 6, as shown in the following embodiments, in the quantification of ammonium ions according to the indophenol blue spectrophotometric method using salicylic acid, the baseline of the measurement chart can be stabilized. The indophenol blue spectrophotometric method using salicylic acid is preferable in that it does not use the harmful chemical substance phenol to the human body and phenol is not discharged into the environment compared with the indophenol blue spectrophotometric method using phenol. However, the present inventors analyzed according to the indophenol blue spectrophotometric method using salicylic acid with a device not provided with the air-permeable part 6 and found that Figure 5 as shown, the baseline is unstable. In particular, in a sample containing trace amounts of nitrate nitrogen, nitrite nitrogen, and ammonia nitrogen, a stable baseline is required. Therefore, the present inventors analyzed according to the indophenol blue spectrophotometric method using salicylic acid with a device provided with the air-permeable part 6, and as Figure 6 shown, the baseline is significantly stabilized. Thus, even for a sample containing trace amounts of nitrogen, more accurate measurement can be performed. Here, as a reason for the significant stabilization of the baseline by using a device provided with the air-permeable part 6, it can be considered that inhibitory substances such as metal elements present in the sample and metal elements eluted from the reduction components in the reduction part 2 make the baseline unstable, and by using a device provided with the air-permeable part 6, such inhibitory substances are removed.

[0056] Downstream of the air-permeable section 6 and upstream of the analysis section 3, a reagent introduction section 5 is provided for adding a reagent to the flow of the sample of ammonium ions transferred through the air-permeable section 6 in the pipeline 7. The reagent introduction section 5 includes: a reagent introduction tube for introducing the reagent into the pipeline 7, and a reagent introduction pump for applying a suction force to the reagent introduction tube. As the reagent added in the reagent introduction section 5 provided downstream of the air-permeable section 6 and upstream of the analysis section 3, for example, salicylic acid, phenol, etc., reagents for quantifying ammonium ions generated by the reduction of nitrate ions and nitrite ions according to the indophenol blue spectrophotometric method can be cited. In the indophenol blue spectrophotometric method using salicylic acid, as the reagent, for example, salicylic acid and hypochlorous acid, such as sodium hypochlorite (NaClO), are added. In this case, salicylic acid and NaClO are preferably added from two different sample introduction sections. The order of adding salicylic acid and NaClO, etc., can be any one first, but it is more preferable to add NaClO after adding salicylic acid. In the indophenol blue spectrophotometric method using phenol, except that phenol is used instead of salicylic acid, it is the same as the indophenol blue spectrophotometric method using salicylic acid. As the reagent, for example, phenol and NaClO are added. In this case, phenol and NaClO are preferably added from two different sample introduction sections. The order of adding phenol and NaClO can be any one first, but it is more preferable to add NaClO after adding phenol.

[0057] The analysis section 3 is a device for analyzing ammonium ions in a sample. In one embodiment of the present invention, when the indophenol blue spectrophotometric method is adopted as the analysis method, the analysis section 3 is, for example, an absorptiometer. As the absorptiometer, a flow cell type absorptiometer is more preferable. However, the analysis section 3 is not limited to these, and can be appropriately selected according to the analysis method used. For example, a distillate reduced in the reduction section 2 can also be prepared, and the sample in the prepared or continuous flow analysis device can be measured by an ion chromatograph. Or, the measurement can be carried out by ion electrode method, titration method, voltammetry and ion chromatography. The analysis can be quantitative analysis or qualitative analysis.

[0058] In Figure 1 the example of, the flow analysis device is provided with the reagent introduction section 5 at three positions, but in addition to the above reagent introduction section 5, another reagent introduction section 5 can also be provided as needed. Also, as long as the reagent can be mixed and introduced, the reagent introduction section can be reduced. As the reagent introduced into the relevant reagent introduction section 5, it is not limited to these, and for example, acids such as nitric acid, hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid, hydrogen peroxide and hydrofluoric acid, and alkalis such as sodium peroxide, calcium carbonate and sodium carbonate can be cited. By adding these reagents, the pH of the sample can be adjusted. Also, as the reagent used in the analysis, it is not limited to the above reagents, and can be appropriately selected according to the analysis method.

[0059] In Figure 1 the example of, the flow analysis device includes a breathable part 6. However, the flow analysis device does not necessarily need to include the breathable part 6, and it may also be configured without the breathable part 6.

[0060] Although it is not included in Figure 1 the example of, the flow analysis device according to an embodiment of the present invention may further include a mixing coil for mixing the reagent added to the reagent introduction part 5 with the sample flowing in the pipeline 7. The mixing coil is a pipeline 7 formed in a coil shape, and when the sample passes through the mixing coil, the reagent is mixed with the sample flowing in the pipeline 7. The shape of the mixing coil is not particularly limited, and it may be the same as the shape of the reduction part as shown in Figure 8 . The position where the mixing coil is provided may be after each reagent introduction part 5, or after a plurality of reagent introduction parts 5.

[0061] Although it is not included in Figure 1 the example of, the flow analysis device according to an embodiment of the present invention may further include a heating tank for heating the sample transferred in the pipeline 7. The heating tank may be a constant temperature tank with a heater. However, the configuration of the heating tank is not limited to these, and it may also be an ultrasonic decomposition device, microwave, high-pressure steam decomposition device, etc. Also, in the heating tank, the pipeline 7 forms a coil or a spiral. In an embodiment of the present invention, the heating tank is provided downstream of the reagent introduction part 5 or downstream of the mixing coil. By heating the sample added with the reagent or the sample mixed with the reagent, the reaction between the sample and the reagent can be promoted.

[0062] Although it is not included in Figure 1 the example of, the flow analysis device according to an embodiment of the present invention may further include a storage tank (liquid storage device) in the middle of the pipeline 7. Since the flow analysis device uses a method of flowing the sample in a closed space for analysis, there may be a situation where the pressure increases. Even in this case, by providing a storage tank, the pressure can be released, and the capacity required for each process can be appropriately dispensed and collected. Regarding the means for releasing the pressure in the flow analysis device, in addition to the storage tank, for example, a defoamer, a pressure reducing valve, etc. that can appropriately discharge air (gas) and liquid may also be provided. Also, when the flow analysis device includes a storage tank, a defoamer, a pressure reducing valve, etc., a bubble separation part 4 for redirecting the gas to the pipeline 7 may also be provided on its downstream side. The flow analysis device may also include a plurality of storage tanks, defoamers, pressure reducing valves, etc. Also, the flow analysis device may include a plurality of bubble separation parts 4.

[0063] Further, the flow analysis device according to an embodiment of the present invention may include a pressurizing device that applies pressure against the flow of the sample from the downstream side of the heating tank. The pressurizing device includes, for example, a compressor and a valve. By providing the pressurizing device, the reaction in the heating tank can be promoted through the suppression of the expansion of bubbles in the heating tank and the synergistic effect of heating and pressurization. The pressure applied by the heating tank is not particularly limited, for example, it is 0.14 MPa or less.

[0064] Further, in the flow analysis device according to an embodiment of the present invention, an automatic sampler can be used as the sample introduction unit 1. Further, before sampling, an ultrasonic homogenizer or a stirrer may be provided to crush and / or stir the sample.

[0065] Alternatively, the flow analysis device according to an embodiment of the present invention may further include a dilution device in the middle of the pipeline 7. Thereby, when dilution is required according to the concentration of the sample, the desired dilution can be automatically performed in the flow analysis device. As the dilution device, a commercially available automatic dilution device can be appropriately used.

[0066] According to the flow analysis device according to an embodiment of the present invention, the total amount of dissolved nitrogen (nitrate nitrogen, nitrite nitrogen, ammonia nitrogen) contained in the sample can be quantified. In addition, the flow analysis device according to an embodiment of the present invention may also be a device that introduces a pretreatment unit that pretreats the sample and converts the total nitrogen in the sample into nitrate ions into the sample introduction unit 1, or a device that introduces it upstream of the sample introduction unit 1. The total nitrogen in the sample can be converted into nitrate ions, for example, by oxidative decomposition with potassium persulfate. By providing the pretreatment unit, the total nitrogen in the sample can be decomposed into nitrate ions in the pretreatment unit, and then the nitrate ions can be reduced to ammonium ions and quantified, so that continuous determination of the total nitrogen in the sample becomes possible. In particular, in samples such as seawater and brackish water, due to the influence of coexisting bromide ions and salts, the copper-cadmium reduction method has been used so far. However, according to the flow analysis device according to an embodiment of the present invention, continuous analysis of nitrogen (such as nitric acid, nitrous acid, total nitrogen) in the sample (such as a sample in the seawater-brackish water area) can be performed without using cadmium that causes environmental pollution and solving the problem of column blockage. And by introducing the pretreatment unit into the flow analysis device according to an embodiment of the present invention, the process from pretreatment to analysis can be carried out coherently. As the pretreatment unit, a device that preferably performs pretreatment automatically, for example, a fully automatic pretreatment device that can appropriately add reagents, mix, heat, and make up the volume can be used. However, this pretreatment may also be carried out separately without introducing it into the flow analysis device as the pretreatment unit, and the pretreated sample is introduced from the sample introduction unit 1.

[0067] In addition, the flow analysis device according to an embodiment of the present invention may be a device that introduces a device for pretreating a sample other than a liquid such as a pretreated solid and preparing a liquid sample into the sample introduction unit 1, or a device upstream of the sample introduction unit 1. The flow analysis device is a device that analyzes a liquid sample using a flow analysis method and cannot directly measure a sample other than a liquid such as a solid. Therefore, by assembling a device for pretreating a sample other than a liquid such as a solid to prepare a liquid sample, it is possible to continuously perform the pretreatment of a sample other than a liquid such as a solid up to the analysis.

[0068] [2.2] Embodiment 2

[0069] Figure 2 The schematic configuration of the flow analysis device according to Embodiment 2 of the present invention is shown. In addition, for the convenience of explanation, components having the same functions as those described in Embodiment 1 may be assigned the same reference numerals, and the description thereof will not be repeated.

[0070] The flow analysis device according to Embodiment 2 of the present invention uses the flow injection analysis method (FIA), that is, a reagent is introduced into the flow of a sample that is not partitioned by a bubble in a pipeline, a reaction operation is performed, and then analysis is performed using a detector provided downstream.

[0071] The flow analysis device according to Embodiment 2 of the present invention includes: a carrier introduction unit 8 that introduces a carrier into a pipeline 7; a sample introduction unit 1 that introduces a sample into the pipeline 7; a reagent introduction unit 5 that adds a reagent to the flow of the sample transferred in the pipeline 7; a reduction unit 2 that reduces nitrate ions and nitrite ions in the sample transferred in the pipeline 7 to ammonium ions; a reagent introduction unit 5 that adds a reagent to the flow of the sample containing ammonium ions transferred in the pipeline 7 via the reduction unit 2; a gas permeable unit 6; a reagent introduction unit 5 that adds a reagent to the flow of the sample containing ammonium ions transferred in the pipeline 7 via the gas permeable unit 6; and an analysis unit 3 that analyzes ammonium ions in the sample.

[0072] The flow analysis device according to Embodiment 2 has a carrier introduction unit 8 upstream of the sample introduction unit 1 for introducing a sample into the pipeline 7, and has the same configuration as the Figure 1 shown flow analysis device except that a bubble partition unit is not provided.

[0073] The flow analysis device according to Embodiment 2 is an analysis device based on the flow injection analysis method (FIA). The carrier introduction unit 8 is used to introduce a carrier into the pipeline 7, and a sample is introduced using the sample introduction unit 1 into the flow of the carrier in the pipeline 7.

[0074] The carrier is not particularly limited as long as it is a liquid that does not have an adverse effect on the pretreatment and analysis of the sample, and examples thereof include water, surfactants, acidic solutions, and alkaline solutions.

[0075] Regarding other configurations of the flow analysis device according to Embodiment 2, since they are the same as those described in Embodiment 1, the description thereof is omitted.

[0076] [3] Analysis method

[0077] Hereinafter, the analysis method according to an embodiment of the present invention will be described. In addition, for the sake of convenience of explanation, the matters already described in the reduction component of [1] and the analysis device of [2] will not be repeated.

[0078] The analysis method according to an embodiment of the present invention includes: a sample introduction step of introducing a sample into a pipeline; a reduction step of reducing nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions; and an analysis step of analyzing ammonium ions in the sample generated in the reduction step, wherein in the reduction step, the sample is transferred through a hollow tube made of zinc at least on the inner wall surface to reduce nitrate ions and nitrite ions in the sample.

[0079] The sample introduction step is a step of introducing a sample into a pipeline. For example, various samples are collected by a sampling device and continuously introduced into the pipeline 7 in a prescribed flow rate in sequence.

[0080] The reduction step is a step of reducing nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions. In this step, the sample is transferred through a hollow tube made of zinc at least on the inner wall surface, that is, the reduction component, to reduce nitrate ions and nitrite ions in the sample.

[0081] The analysis step is a step of analyzing ammonium ions in the sample generated in the reduction step. Here, the analysis includes detection of the presence or absence of the analysis target or determination of the concentration. Further, the analysis can be quantitative analysis or qualitative analysis. The analysis method is not particularly limited and can be any analysis, and examples thereof include indophenol blue spectrophotometry using salicylic acid, indophenol blue spectrophotometry using phenol, ion chromatography, ion electrode method, titration method, voltammetry, etc.

[0082] 〔Summary〕

[0083] An embodiment of the present invention includes the following configurations.

[0084] [1] A reduction component, which is a hollow tube made of zinc at least on the inner wall surface, and a sample is transferred through the tube.

[0085] [2] Analytical device, the analytical device comprising: an introduction unit that introduces a sample into a pipeline; a reduction unit that reduces nitrate ions and nitrite ions in the sample transferred in the pipeline into ammonium ions; an analysis unit that analyzes the ammonium ions in the sample generated in the reduction unit, wherein the reduction unit includes the reduction component described in [1].

[0086] [3] The analytical device according to [2], wherein the hollow tube with at least the inner wall surface made of zinc is spiral or figure-eight spiral.

[0087] [4] The analytical device according to [2] or [3], wherein at least the inner side of the hollow tube is coated with copper.

[0088] [5] The analytical device according to any one of [2] to [4], which is a flow analysis device.

[0089] [6] The analytical device according to any one of [2] to [5], which is provided with a bubble separation unit that separates the sample introduced into the pipeline by bubbles and creates multiple segments divided by bubbles in the pipeline.

[0090] [7] The analytical device according to [6], wherein the bubbles are nitrogen, argon or helium.

[0091] [8] The analytical device according to any one of [2] to [7], which is provided with a reagent introduction unit that introduces a reagent for quantitatively analyzing the ammonium ions generated in the reduction unit by indophenol blue spectrophotometry using salicylic acid.

[0092] [9] The analytical device according to any one of [2] to [8], which is provided with a gas-permeable unit for vaporizing and separating the ammonium ions generated in the reduction unit.

[0093]

[10] The analytical device according to any one of [2] to [9], which is further provided with a pretreatment unit that converts total nitrogen into nitrate ions.

[0094]

[11] Analytical method, the analytical method comprising: a sample introduction step that introduces a sample into a pipeline; a reduction step that reduces nitrate ions and nitrite ions in the sample transferred in the pipeline into ammonium ions; an analysis step that analyzes the ammonium ions in the sample generated in the reduction step, wherein in the reduction step, the sample is transferred in a hollow tube with at least the inner wall surface made of zinc to reduce nitrate ions and nitrite ions in the sample.

[0095] Examples

[0096] The present invention will be described in more detail by the following embodiments, but the present invention is not limited to these embodiments, and embodiments obtained by appropriately combining the technical solutions disclosed in each embodiment are also included within the scope of the present invention.

[0097] [Reagents]

[0098] The reagents used in the embodiments are as follows.

[0099] (1) EDTA reagent

[0100] Add 7.5 g of EDTA-2Na (disodium ethylenediaminetetraacetate) to about 600 mL of pure water to dissolve it, and add an 80 g / L aqueous sodium hydroxide solution to make the pH 11. Add pure water to the resulting solution to make it 1000 mL.

[0101] (2) Boric acid reagent

[0102] Dissolve 30 g of boric acid and 30 g of sodium hydroxide in pure water to make it 1000 mL.

[0103] (3) Sodium nitroprusside reagent

[0104] Add 0.1 g of sodium nitroferricyanide(III) dihydrate to about 800 mL of pure water to dissolve it. Add 1.0 mL of sulfuric acid to the resulting aqueous solution, and then add pure water to make it 1000 mL.

[0105] (4) Salicylic acid reagent

[0106] After dissolving 50 g of sodium salicylate, 30 g of boric acid, 30 g of sodium hydroxide, and 10 g of potassium sodium tartrate tetrahydrate in about 300 mL of pure water, add pure water to make it 500 mL.

[0107] (5) NaClO

[0108] A commercially available product with an available chlorine of about 10% is diluted 50 times before use.

[0109] [Apparatus]

[0110] Use Figure 3The flow analysis device (CFA) shown. This flow analysis device is a device including the following: a sample introduction unit that introduces a sample into a conduit 7; a bubble separation unit that performs bubble separation of the sample introduced into the conduit 7 using nitrogen; a reagent introduction unit that adds an EDTA reagent to the flow of the sample transferred in the conduit 7; a mixing coil 11 that mixes the sample with the added EDTA reagent in each section separated by nitrogen bubbles; a reduction unit 2 that reduces nitrate ions and nitrite ions in the sample transferred in the conduit 7 to ammonium ions; a reagent introduction unit that adds the boric acid reagent (a buffer solution of boric acid added to sodium hydroxide) to the flow of the sample containing ammonium ions transferred in the conduit 7 via the reduction unit 2; a mixing coil 11 that mixes the sample with the boric acid reagent in each section separated by nitrogen bubbles; a gas permeation unit 6 that allows gaseous ammonia generated by the addition of the boric acid reagent to permeate and allows the permeated gaseous ammonia to be absorbed by the nitroprusside Na reagent (a solution containing sulfuric acid and nitroprusside Na) separated by air; a reagent introduction unit that adds a salicylic acid reagent to the flow of the nitroprusside Na reagent that has absorbed ammonia gas; a mixing coil 11 that mixes the sample with the salicylic acid reagent in each section separated by air; a reagent introduction unit that further adds NaClO to the reagent transferred in the conduit 7; a mixing coil 11 that mixes the sample with NaClO in each section separated by air; a heating bath 9 that causes ammonium ions, salicylic acid, and NaClO in the sample to react; an analysis unit that analyzes ammonium ions in the sample. The analysis unit uses a flow cell type absorptiometer (manufactured by BLTEC Co., Ltd., SCIC3000). The cell length of the flow cell 10 is 50 mm, and measurement is performed at a wavelength of 660 nm.

[0111] A mixing coil is arranged in the heating bath 9, and the temperature in the heating bath 9 is 45°C.

[0112] Furthermore, as the reduction component of the reduction unit 2, a hollow zinc tube coated with copper on the inside is used. As this hollow zinc tube, a coil formed by winding a tube with a length of 300 mm, an inner diameter of 1 mm, and an outer diameter of 1.5 mm into a spiral shape is used. The thickness of the copper coating is 10 μm to 20 μm. Furthermore, the coil diameter (outer diameter) is 30 mm.

[0113] [Example 1: Determination of Standard Solution]

[0114] Ammonium nitrogen (ammonium ions), nitrate nitrogen (nitrate ions), and nitrite nitrogen (nitrite ions) are continuously introduced into the flow analysis device in the order of ammonium nitrogen, ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, ammonium nitrogen, and the concentration of each nitrogen is made 0.25 mg / L, and flow analysis is performed. The measurement results are as Figure 7 shown.

[0115] AsFigure 7 As shown, when nitrite nitrogen and nitrate nitrogen are introduced, the same peaks as when ammonium nitrogen is introduced can also be obtained. From this result, it can be seen that either nitrate nitrogen (nitrate ion) or nitrite nitrogen (nitrite ion) is 100% reduced to ammonium ion and can be accurately measured.

[0116] [Example 2: Determination of Standard Solution]

[0117] The measurement was carried out in the same manner as in Example 1 except that the partitioned nitrogen was changed to argon. Similar to Example 1, when nitrite nitrogen and nitrate nitrogen are introduced, the same peaks as when ammonium nitrogen is introduced can also be obtained (the illustration of the results is omitted).

[0118] [Example 3: Determination of Standard Solution]

[0119] The measurement was carried out in the same manner as in Example 1 except that the partitioned nitrogen was changed to helium. Similar to Example 1, when nitrite nitrogen and nitrate nitrogen are introduced, the same peaks as when ammonium nitrogen is introduced can also be obtained (the illustration of the results is omitted).

[0120] [Example 4: Measurement Using a Device without Venting Part 6]

[0121] The measurement was carried out in the same manner as in Example 1 except that the device did not have a venting part 6 and a reagent was added from the reagent introduction part where the salicylic acid reagent was added to the sample reduced in the reduction part 2. Figure 5 It is a diagram showing the baseline of the obtained measurement chart. On the other hand, the baseline of the measurement chart in Example 1 is as Figure 6 shown. As Figure 5 shown, by using a device without a venting part 6 and analyzing according to the indophenol blue spectrophotometric method using salicylic acid, the baseline was unstable. In contrast, in Example 1 where a device with a venting part 6 was used and analyzed according to the indophenol blue spectrophotometric method using salicylic acid, as Figure 6 shown, the baseline was stable.

[0122] [Example 5: Addition Recovery Experiment]

[0123] Ammonium nitrogen, nitrite nitrogen, and nitrate nitrogen were each added to a 3 wt% aqueous sodium chloride solution at 0.1 mg / L, and an addition recovery experiment was carried out.

[0124] Recovery rates of approximately 100% can be obtained in all cases. From this result, it can be seen that the analysis of ammonium nitrogen, nitrite nitrogen, and nitrate nitrogen in a sample containing sodium chloride is possible.

[0125] [Example 6: Addition Recovery Experiment]

[0126] To the seawater off the coast of Tottori Prefecture, ammonium nitrogen, nitrite nitrogen, and nitrate nitrogen were added at 0.1 mg / L each, and the addition and recovery were carried out. Since the seawater contains nitrogen components, the value of the seawater without the addition of ammonium nitrogen, nitrite nitrogen, and nitrate nitrogen was subtracted as a blank and the result was calculated.

[0127] Recovery rates of approximately 100% were obtained in all cases. From this result, it can be seen that the analysis of ammonium nitrogen, nitrite nitrogen, and nitrate nitrogen in seawater is possible.

[0128] [Example 7: Reduction rate in continuous measurement]

[0129] A nitrate nitrogen standard solution was added to seawater to adjust the concentration of nitrate nitrogen to 5 mg / L. The sample thus prepared was continuously introduced into the pipeline from the sample introduction section 60 times for measurement.

[0130] Then, nitrate nitrogen (nitrate ion) and nitrite nitrogen (nitrite ion) were continuously introduced into the flow analysis device so that the concentration of each nitrogen was 0.25 mg / L, and flow analysis was performed. Based on the obtained results, the reduction rates of nitrate ion and nitrite ion were calculated. Even after 60 measurements, the reduction rates of nitrate ion and nitrite ion were approximately 100%.

[0131] Industrial applicability

[0132] According to the present invention, it is possible to provide a continuous analysis device and an analysis method for nitrogen etc. (nitric acid, nitrous acid, total nitrogen) in a sample (for example, a sample in a seawater-brackish water area) that do not use cadmium which causes environmental pollution and solves the problem of column clogging.

[0133] With such a configuration, the environmental load can be reduced. As a result, it is possible to contribute to achieving Goals 14 and 15 of the Sustainable Development Goals (SDGs).

[0134] Symbol description

[0135] 1 Sample introduction section

[0136] 2 Reduction section

[0137] 3 Analysis section

[0138] 4 Bubble separation section

[0139] 5 Reagent introduction section

[0140] 6 Air permeation section

[0141] 7 Pipeline

[0142] 8 Carrier introduction section

[0143] 9 Heating bath

[0144] 10 Flow cell

[0145] 11 Mixing coil

[0146] 12 PTFE porous filter

Claims

1. Reduction component, the reduction component is a hollow tube with at least an inner wall surface made of zinc, in which a sample is transferred. Copper is coated on the inner side of the tube. While transferring the sample, the tube reduces nitrate ions and nitrite ions in the sample to form ammonium ions, and the inner diameter of the tube is 0.5 mm to 1.5 mm.

2. Analytical device, the analytical device comprises: A sample introduction part which introduces a sample into a pipeline; A reduction part which reduces nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions; An analysis part which analyzes ammonium ions in the sample generated in the reduction part, wherein, The reduction part includes the reduction component described in Claim 1.

3. The analytical device according to Claim 2, wherein the hollow tube with at least an inner wall surface made of zinc is spiral.

4. The analytical device according to Claim 3, wherein the hollow tube with at least an inner wall surface made of zinc is an 8-shaped spiral.

5. The analytical device according to Claim 2, which is a flow analysis device.

6. The analytical device according to Claim 2, which is provided with a bubble separation part for separating bubbles of the sample introduced into the pipeline and creating multiple segments divided by bubbles in the pipeline.

7. The analytical device according to Claim 6, wherein the bubbles are nitrogen, argon or helium.

8. The analytical device according to Claim 2, which is provided with a reagent introduction part for introducing a reagent for quantitatively analyzing ammonium ions generated in the reduction part by indophenol blue spectrophotometry using salicylic acid.

9. The analytical device according to Claim 2, which is provided with a gas permeable part for vaporizing and separating ammonium ions generated in the reduction part.

10. The analytical device according to Claim 2, which is further provided with a pretreatment part for converting total nitrogen into nitrate ions.

11. Analytical method, the analytical method comprises: A sample introduction step of introducing a sample into a pipeline; A reduction step of reducing nitrate ions and nitrite ions in the sample transferred in the pipeline to ammonium ions; An analysis step of analyzing ammonium ions in the sample generated in the reduction step, wherein, In the reduction step, the sample is transferred in a hollow tube with at least an inner wall surface made of zinc, and while transferring the sample, the tube reduces nitrate ions and nitrite ions in the sample to form ammonium ions; The inner diameter of the tube is 0.5 mm to 1.5 mm.

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