Analysis method of mercury-containing sample

Abstract

The purpose of the present invention is to provide an analysis method whereby a mercury-containing sample can be analyzed with high accuracy, for example, by ICP-MS. The method for analyzing a mercury-containing sample comprises: a pretreatment step for preparing a sample solution by adding an oxidizing agent to a mercury-containing sample so as to form an oxidized state with an oxidation-reduction potential of + 0.80 V or more; and an analysis step for quantitatively analyzing or qualitatively analyzing the sample solution prepared in the pretreatment step while keeping the sample solution in an oxidized state.

Description

Technical Field

[0001] The invention relates to an analysis method for a mercury-containing sample. Background Art

[0002] With mercury's highly toxic nature now recognized, its release has been subject to emission controls in recent years. The Minamata Treaty, which came into effect in 2017, prohibits the extraction of mercury from mines and regulates its import and export, among other things, to protect human health and the environment from the anthropogenic release of mercury and mercury compounds. The European Union has also implemented stricter regulations on the use and import of mercury under the RoHS Directive.

[0003] Pump in Hg 2+ In the state, it can react with Cl without gasification. - On the other hand, if there is a reducing substance, the pump will move from Hg 2+ It is reduced to Hg, which vaporizes when heated and is lost through volatilization. Therefore, it is difficult to achieve a good mercury recovery rate when analyzing mercury-containing samples.

[0004] Therefore, in the reduction vaporization-atomic absorption spectrometry, a representative analysis method for mercury, a solution containing potassium permanganate is added to a mercury-containing sample as a pretreatment to oxidize the solution and convert mercury into Hg 2+ This method is designated as a recognized method for analyzing environmental water, wastewater, drinking water, etc. (see Non-Patent Documents 1 and 2).

[0005] Prior art literature

[0006] Non-patent literature

[0007] Non-Patent Document 1: Appendix 7 of Ministry of Health, Labour and Welfare Notice No. 261, 2001

[0008] Non-Patent Document 2: Appendix 2 of Environmental Agency Notice No. 59, 1977 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, when measuring mercury using methods such as reduction vaporization-atomic absorption spectrometry, sulfuric acid, nitric acid, and potassium permanganate must be added to the sample as a pretreatment. Furthermore, when measuring mercury in such a pretreated sample solution using, for example, inductively coupled plasma mass spectrometry (ICP-MS), which can simultaneously analyze nearly all metallic elements, the large amount of sulfuric acid added can lead to problems such as poor atomization of the atomizer due to its viscosity, and sulfur interference with the mass of other substances.

[0011] Furthermore, when a mercury-containing sample is subjected to the above-mentioned pretreatment and then measured by ICP-MS, there is still room for improvement in the detection accuracy of the mercury-containing sample.

[0012] Therefore, one aspect of the present invention has been developed in view of the above-mentioned problems, and an object of the present invention is to provide an analysis method capable of analyzing a mercury-containing sample with high precision by, for example, ICP-MS.

[0013] Technical solutions to solve problems

[0014] To address the above-mentioned issues, one aspect of the present invention provides a method for analyzing a mercury-containing sample, comprising: a pretreatment step of adding an oxidizing agent to the mercury-containing sample to form an oxidized state having a redox potential of +0.80 V or higher, thereby preparing a sample solution; and an analysis step of performing a quantitative or qualitative analysis on the sample solution prepared in the pretreatment step while maintaining the oxidized state.

[0015] To address the above-mentioned problems, an analysis method for a mercury-containing sample according to one aspect of the present invention adopts a flow analysis method and includes a sample introduction step and an analysis step. The sample introduction step is used to introduce the mercury-containing sample into a pipeline, and the analysis step performs quantitative analysis or qualitative analysis on the sample. The analysis method includes: a pretreatment step of adding an oxidant to the mercury-containing sample to prepare a sample solution before the sample introduction step, and / or a reagent addition step of adding an oxidant to the sample transported through the pipeline to adjust the redox potential to be above +0.80 V; a heating step of heating the sample to which the oxidant has been added; a cooling step of cooling the sample transported through the pipeline after the heat treatment; and a gas-liquid separation step of removing gas present in the pipeline after cooling, and performing quantitative analysis or qualitative analysis on the sample from which the gas has been removed in the gas-liquid separation step.

[0016] Effects of the Invention

[0017] According to one aspect of the present invention, a mercury-containing sample can be analyzed with high precision, for example, by ICP-MS. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a flow analysis device used in the analysis method of the second embodiment.

[0019] Figure 2 It is a schematic diagram of the structure of the second structural example of the flow analysis device used in the analysis method of the second embodiment.

[0020] Figure 3 This is a schematic diagram of a portion of the structure of the flow analysis device constituting Example 1.

[0021] Figure 4This is a schematic diagram of the structure of the marker detection unit in the flow analysis device of Example 1.

[0022] Figure 5 This is a schematic diagram showing a state in which a plurality of segments partitioned by bubbles by bubble partitioning portions are manufactured in a pipeline in the flow analysis device of Configuration Example 1.

[0023] Figure 6 This is a schematic diagram of bubbles in the pipeline after heating treatment in the flow analysis device of Structural Example 1.

[0024] Figure 7 This is a schematic diagram showing a state in which the gas existing in the pipeline is removed by the gas-liquid separation unit in the flow analysis device of Configuration Example 1.

[0025] Figure 8 This is a schematic diagram of a portion of the structure of the flow analysis device of Example 1.

[0026] Figure 9 This is a schematic diagram of an example of a coil portion constituting the cooling section in the flow analysis device of Example 1.

[0027] Figure 10 This is a schematic diagram of the calibration curve prepared in Comparative Example 3.

[0028] Figure 11 This is a schematic diagram of the calibration curve prepared in Example 4. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and various changes can be made within the scope of the description. Embodiments obtained by appropriately combining the technical solutions disclosed in different embodiments are also included in the technical scope of the present invention. In addition, all academic documents and patent documents described in this specification are incorporated into this specification as references. In addition, in this specification, unless otherwise specified, "A to B" indicating a numerical range means "Above A (including A and greater than A) and below B (including B and less than B)".

[0030] [1] Overview of the embodiments of the present invention

[0031] When conducting ICP-MS analysis of metals other than mercury using wastewater or drinking water as a sample, nitric acid is added and heated for decomposition (refer to JIS K 0102 (2016) 5.1 Pretreatment of Samples and Test Procedure (1) Pretreatment in Appendix 64 of Ministry of Health, Labour and Welfare Notice No. 261).

[0032] On the other hand, when mercury is used as the target, pretreatment is performed in the sample solution to convert mercury into stable [HgCl2], [HgCl3] -and [HgCl4] 2- In this pretreatment, hydrochloric acid is added to the sample solution to reduce the Hg 2+ and Cl - However, usually, the sample sometimes contains hydrogen sulfide, sodium sulfite, organic matter, zinc, iron or cadmium, etc. These substances are reducing substances. Therefore, due to these reducing substances, Hg 2+ to Hg + If the organic matter is further decomposed by heating, mercury will be gasified. As a result, as mentioned above, even if the Hg in the sample solution 2+ Add Cl - Mercury will not change into [HgCl2], [HgCl3] in the sample solution due to reducing substances and organic matter. - and [HgCl4] 2- Instead of being in a state of being vaporized, the recovery rate becomes poor.

[0033] The redox potential of mercury is +0.7986. Therefore, the inventors of the present application have found that (1) as a pretreatment, mercury is oxidized to promote the oxidation of the above-mentioned reducing substances, and even in the presence of reducing substances, the solution is oxidized to make mercury [HgCl2], [HgCl3] - and [HgCl4] 2- (2) If the sample solution subjected to this pretreatment is subjected to ICP-MS analysis while maintaining the oxidized state, mercury can be analyzed with high precision, thereby completing the analysis method for mercury-containing samples according to embodiment 1 or 2. The analysis methods according to embodiments 1 and 2 are described in detail below.

[0034] [2] Analysis Method of Mercury-Containing Sample (Implementation Method 1)

[0035] The analysis method of embodiment 1 (hereinafter sometimes referred to as the present analysis method) includes: a pretreatment step of adding an oxidizing agent to a mercury-containing sample to adjust the redox potential to +0.80 V or higher, thereby preparing a sample solution; and an analysis step of performing quantitative or qualitative analysis on the sample solution prepared in the pretreatment step while maintaining the sample solution in an oxidized state.

[0036] According to this analysis method, the redox potential of the sample solution is increased to +0.80 V or higher by the pretreatment step, and mercury is oxidized. Therefore, the oxidation of the reducing substances contained in the sample solution is promoted, and even in the presence of persistent reducing substances, the solution is in an oxidized state, which can prevent Hg from being oxidized in the sample solution. 2+ to Hg + and Hg. Therefore, if Cl is supplied to the sample solution -, then mercury becomes [HgCl2], [HgCl3] - and [HgCl4] 2- Furthermore, in the analysis step, by performing quantitative or qualitative analysis on the pretreated sample solution while maintaining its oxidized state, a high mercury recovery rate can be achieved. Specifically, this analytical method enables high-precision analysis of mercury-containing samples, for example, using ICP-MS.

[0037] Furthermore, when mercury is measured using the aforementioned reduction vaporization-atomic absorption spectrometry, quantitative or qualitative analysis is performed on the pretreated sample solution in a reduced state. Therefore, the principles of this analytical method differ from those of the present method, which involves quantitative or qualitative analysis of the pretreated sample solution in an oxidized state.

[0038] In this analysis method, the redox potential of the sample solution is not less than +0.80 V, preferably not less than +1.00 V, more preferably not less than +1.20 V, and even more preferably not less than +1.30 V. In this analysis method, the redox potential can be measured using a conventionally known redox potentiometer (ORP meter).

[0039] The oxidant used in the pretreatment step is not particularly limited as long as it can make the redox potential of the sample solution be above +0.80V. The oxidant is preferably selected from at least one of hypochlorous acid or its salts and permanganic acid or its salts, preferably hypochlorous acid or its salts. Hypochlorous acid or its salts and permanganic acid or its salts have oxidizing power sufficient to oxidize mercury. In particular, hypochlorous acid or its salts are the oxidants with the strongest oxidizing power at room temperature. On the other hand, nitric acid or hydrogen peroxide, which are common oxidants, do not have oxidizing power sufficient to oxidize mercury alone. Examples of hypochlorous acid salts include sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and sodium dichloroisocyanurate. In addition, examples of permanganic acid salts include potassium permanganate, sodium permanganate, ammonium permanganate, silver permanganate, zinc permanganate, magnesium permanganate, calcium permanganate, and palladium permanganate.

[0040] Furthermore, in this analytical method, the amount of the oxidizing agent added is preferably in excess relative to the mercury in the sample and the reducing substances contained in the solution. The molar ratio of the mercury in the sample and the reducing substances contained in the solution to the oxidizing agent is preferably 1:10 to 1000, more preferably 1:1000 to 100,000. For example, when sodium hypochlorite with 10% available chlorine is used as the oxidizing agent, the amount of sodium hypochlorite added is preferably 0.002% or more, more preferably 0.02% or more, relative to the volume of the mercury-containing sample. Furthermore, when potassium permanganate is used as the oxidizing agent, the amount of potassium permanganate added is preferably 2 mg / L or more, more preferably 20 mg / L or more, relative to the volume of the mercury-containing sample.

[0041] In addition, the present analysis method may further include a nitric acid / hydrochloric acid addition step, wherein nitric acid is added to the sample solution prepared in the pretreatment step while maintaining the sample solution in an oxidized state, and hydrochloric acid is added as needed. In addition to the above-mentioned oxidizing agents, nitric acid can be added as an oxidizing agent, thereby making it easier to adjust the redox potential of the sample solution to +0.80 V or higher. In addition, hydrochloric acid is used to supply Cl to the sample solution. - From the perspective of achieving a good recovery rate of mercury in the sample, the nitric acid / hydrochloric acid addition step is preferably a step of adding nitric acid and hydrochloric acid. Furthermore, the amounts of nitric acid and hydrochloric acid added can be conventionally known amounts used in mercury analysis. In particular, the amount of nitric acid added is preferably 0.1% to 10% of the sample volume, and more preferably 0.5% to 5% of the sample volume. Similarly, the amount of hydrochloric acid added is preferably 0.01% to 5% of the sample volume, and more preferably 0.05% to 3% of the sample volume.

[0042] Hypochlorous acid or its salts exist in different forms depending on the pH, but the chlorine in hypochlorous acid exists in the form of unstable Cl + Moreover, in the sample solution, Cl + Gain two electrons to become Cl - If Cl + The electron donor is mercury, then mercury is Hg → Hg + →Hg 2+ The form changes and with Cl - As a result, in the sample solution, mercury becomes [HgCl2], [HgCl3] - and [HgCl4] 2- Therefore, in this analysis method, hypochlorous acid or its salt functions as an oxidant and can also be used to supply Cl to the sample solution. - The supply source functions.

[0043] Therefore, when hypochlorous acid or a salt thereof is used as the oxidizing agent, hydrochloric acid may be added as needed in the nitric acid / hydrochloric acid addition step, or it may not be necessary. However, from the perspective of improving the recovery rate of mercury, it is preferred to add nitric acid, hydrochloric acid, hypochlorous acid or a salt thereof to the mercury-containing sample.

[0044] In addition, the present analysis method may further include a heating process, in which the sample solution prepared by the pretreatment process or the nitric acid / hydrochloric acid addition process is subjected to a heat treatment while maintaining an oxidized state. Through this heating process, the organic matter contained in the sample is decomposed. The heating temperature in the heating process can be set, for example, to a sample temperature of 40°C or above, preferably 60°C or above, and more preferably 100°C or above. The upper limit of the heating temperature is preferably 140°C or below. In addition, the heating time of the sample is preferably 5 minutes or above, and more preferably 15 minutes or above. The upper limit of the heating time is, for example, 240 minutes or below, and more preferably 120 minutes or below. In addition, in ICP-MS, even if the sample solution contains some organic matter, these organic matter will be decomposed when the sample is ionized at 5000 to 10000K, so analysis can also be performed.

[0045] Moreover, in this analytical method, in the analytical process, quantitative analysis or qualitative analysis is carried out to the sample solution prepared as described above while maintaining an oxidized state. Wherein, the analysis includes the detection of the presence or absence of the analyte or the determination of concentration. In addition, the analysis may be either quantitative analysis or qualitative analysis. There are no particular restrictions on the analytical method, and no matter which analysis method is used, for example, ICP-MS, inductively coupled plasma optical emission spectrometry (ICP-OES / ICP-AES), atomic absorption spectrometry, triple quadrupole inductively coupled plasma mass spectrometry, ion electrode analysis or spectrophotometric analysis can be listed. Wherein, preferably inductively coupled plasma mass spectrometry or inductively coupled plasma optical emission spectrometry.

[0046] For example, when analyzing various metals in a sample by ICP-MS, the salt of hypochlorous acid or permanganic acid or its salt used as an oxidant sometimes contains a metal to be analyzed. For example, manganese or potassium contained in potassium permanganate can be cited. Therefore, in the simultaneous analysis of various metals, a positive error corresponding to the metal component contained in the oxidant will be produced. Therefore, it is necessary to correct this error. From the viewpoint of avoiding this error in analysis, the salt of hypochlorous acid or permanganic acid is preferably a metal salt other than the analyte. When sodium is not present in the assay, sodium hypochlorite is more preferably used.

[0047] The analytical method is not particularly limited to various aqueous samples, including tap water, groundwater, seawater, lake water, various wastewaters from factories, etc., ion-exchanged water, ultrapure water, steel and non-ferrous metals, soil and soil eluates, food, reagents, pharmaceuticals, and reagents used for semiconductors and industrial applications. It can also be used with closed system pretreatment equipment, samples decomposed in the device, or samples decomposed using microwaves. This analytical method can achieve high-precision analysis of mercury. Furthermore, it is suitable for simultaneous analysis of mercury-containing metal elements. This makes it possible to simultaneously analyze mercury and other metal elements, which have previously been difficult to analyze due to volatilization.

[0048] [3] Analysis Method of Mercury-Containing Samples Using Flow Analysis (Implementation Method 2)

[0049] The following describes the flow analysis method according to Embodiment 2. For the sake of convenience, matters already described in [2] will not be repeated.

[0050] Mercury is known to volatilize when heated in an open state. Therefore, from the perspective of achieving a good mercury recovery rate, this analytical method is preferably performed using a flow analysis method that can perform a heat treatment in a closed system pipeline. The analytical method for mercury-containing samples of embodiment 2 (hereinafter sometimes referred to as the present analytical method) differs from embodiment 1 in that it uses a flow analysis method. That is, the analytical method of embodiment 2 uses a flow analysis method and includes a sample introduction step and an analysis step. The sample introduction step introduces the sample into the pipeline, and the analysis step performs a quantitative analysis or a qualitative analysis on the sample. In addition, it includes a pretreatment step and / or a reagent addition step, a heating step, a cooling step, and a gas-liquid separation step. Moreover, in the present analytical method, a quantitative analysis or a qualitative analysis is performed on the sample from which the gas has been removed in the gas-liquid separation step.

[0051] The sample introduction step is a step of introducing a sample into a pipeline. For example, a plurality of samples are collected by a sampling device and are sequentially and continuously introduced into the pipeline at a predetermined flow rate.

[0052] The pretreatment process is a process of adding an oxidant to the mercury-containing sample before the sample introduction process to make the redox potential of the sample solution be +0.80V or more, thereby preparing a sample solution. In the present analysis method, the oxidant used in the pretreatment process is not particularly limited as long as it can make the redox potential of the sample solution be +0.80V or more. As the oxidant, the above-mentioned hypochlorous acid or its salt and permanganic acid or its salt can be used. In the present analysis method, the sample solution used in the pretreatment process preferably adds at least one of hypochlorous acid or its salt and permanganic acid or its salt to the sample that has become acidic by nitric acid or by nitric acid and hydrochloric acid. The oxidant used in the pretreatment process, the amount of the oxidant added, and the amount of the oxidant used as Cl - The amount of hydrochloric acid added to the supply source is as described in [2] and will not be repeated here.

[0053] In addition, the reagent addition step is a step of adding an oxidant to the sample transported through the pipeline to increase the redox potential to +0.80 V or higher. The oxidant used in the reagent addition step is the same as that described in the pretreatment step and in [2], and therefore will not be described in detail. The reagent addition step may be a step of adding at least an oxidant to the sample transported through the pipeline, or may be a step of adding a reagent other than an oxidant. In addition, the oxidant may be added through the reagent introduction portion of the flow analysis device described below.

[0054] A mercury-containing sample analysis method according to one embodiment of the present invention includes: a pretreatment step of adding an oxidizing agent to the mercury-containing sample to raise its redox potential to +0.80 V or higher, thereby preparing a sample solution, and / or a reagent addition step of adding an oxidizing agent to the sample transported through the pipeline to raise its redox potential to +0.80 V or higher. Specifically, the oxidizing agent may be added to the mercury-containing sample to raise its redox potential to +0.80 V or higher, thereby preparing a sample solution, or the oxidizing agent may be added to the sample transported through the pipeline to raise its redox potential to +0.80 V or higher, or both. The mercury-containing sample analysis method according to one embodiment of the present invention preferably adds nitric acid, or nitric acid and hydrochloric acid, and the oxidizing agent to raise its redox potential to +0.80 V or higher, prior to supplying the sample to the sampling device.

[0055] In this analytical method, it is more preferable to perform at least the pretreatment step of the pretreatment step and the reagent addition step, but the pretreatment step is preferably performed before the heating step. This is because the pretreatment step can achieve decomposition of inorganic compounds and organic substances, solubilization of the analyte, and uniformity of the ratio of the oxidant to the sample.

[0056] The analysis process is a process for analyzing the sample transported along the pipeline. The analysis process is the same as that described in [2], so it will not be repeated here.

[0057] The heating process is a process for heating the sample to which an oxidant is added, the cooling process is a process for cooling the sample transported through the pipeline after being heated in the heating process, the gas-liquid separation process is a process for removing the gas present in the pipeline after being cooled in the cooling process, and then the sample from which the gas is removed in the gas-liquid separation process is analyzed through an analysis process.

[0058] The present analysis method includes the sample introduction step, the pretreatment step and / or the reagent addition step, the heating step, the cooling step, the gas-liquid separation step, and the analysis step. Between the sample introduction step and the next sample introduction step, a marker introduction step for introducing a marker into the pipeline is included. Preferably, the marker introduction step and the sample introduction step are performed so that the marker and one or more predetermined number of samples are alternately introduced into the pipeline.

[0059] Furthermore, the present analysis method includes a marker detection step of detecting the marker and outputting a detection signal to an analysis device, and the analysis step of acquiring analysis data based on the detection signal.

[0060] This analytical method can be a method using continuous flow analysis (CFA) or a method using flow injection analysis (FIA). If the analytical method is a method using continuous flow analysis (CFA), the analytical method includes a bubble isolation step, which isolates bubbles from the sample and marker introduced into the pipeline and creates multiple sections in the pipeline divided by bubbles. If the analytical method is a method using flow injection analysis (FIA), the analytical method can include a carrier introduction step before the sample introduction step and the marker introduction step.

[0061] Furthermore, in this analysis method, it is preferable not to perform bubble isolation after the gas-liquid separation step. This allows the analysis step to be performed without volatilizing mercury in the sample, thereby preventing a decrease in analysis accuracy due to mercury volatilization.

[0062] [3.1] Flow analysis device for performing the analysis method of embodiment 2 (configuration example 1)

[0063] A flow analysis device for performing the analysis method of the second embodiment (hereinafter sometimes referred to as the present flow analysis device) will be described. Figure 1 This is a schematic diagram of the structure of the configuration example 1 of the flow analysis device.

[0064] The flow analysis device includes: a sample introduction part 1, which is used to introduce a sample into a pipeline 2; a marker introduction part 8, which is used to introduce a marker into the pipeline 2; a bubble isolation part 10, which isolates bubbles from the sample and marker introduced into the pipeline 2 and creates a plurality of sections divided by bubbles in the pipeline 2; a reagent introduction part 3, which adds a reagent to the flow of the sample transported through the pipeline 2; a heating part 5, which heats the sample transported through the pipeline 2 and to which the reagent is added; a cooling part 6, which cools the sample after the heating treatment; a gas-liquid separation part 7, which removes the gas present in the pipeline after cooling; an analysis part 4, which performs quantitative analysis or qualitative analysis on the sample from which the gas is removed in the gas-liquid separation part 7; a marker detection part 9, which detects the marker and outputs a detection signal to the analysis part 4, and the analysis part 4 obtains analysis data based on the detection signal.

[0065] (Sample introduction section)

[0066] Sample introduction unit 1 is a device for introducing a sample into pipeline 2, for example, sampling and introducing the sample into pipeline 2. Sample introduction unit 1 includes a collection tube for introducing the sample into pipeline 2 and a sampling pump for applying suction to the collection tube. The sampling pump introduces the sample into pipeline 2 at a predetermined flow rate. In one embodiment of the present invention, nitric acid, or a combination of nitric acid and hydrochloric acid, and the oxidant are preferably added prior to supply to the sampling device to achieve an oxidation-reduction potential of +0.80 V or higher.

[0067] (Marker introduction section)

[0068] Marker introduction unit 8 is a device for introducing a marker into pipeline 2. In one embodiment of the present invention, marker introduction unit 8 comprises a collection tube for introducing the marker into pipeline 2 and a pump for applying suction to the collection tube. The marker can include a substance detectable by marker detection unit 9 and can be the substance itself, a solution containing the substance, or a dispersion containing the substance.

[0069] The marker introduction section 8 and the sample introduction section 1 are capable of alternately introducing the marker and one or more predetermined quantities of samples into the conduit 2. Specifically, the marker is introduced into the conduit 2 from the marker introduction section 8, and one or more predetermined quantities of samples are introduced into the conduit 2 from the sample introduction section 1, alternately switching between them. This switching can be performed manually or automatically.

[0070] If the marker and a sample can be introduced alternately into the pipeline 2, the marker is introduced into the pipeline 2 before each sample. Furthermore, for each sample, the marker detection unit 9 detects the marker and outputs a detection signal to the analysis unit 4, which then acquires analytical data based on the detection signal. This ensures consistent timing for acquiring analytical data, enabling stable and continuous sample measurement even when liquid delivery from sample introduction to the analysis unit 4 is not uniform.

[0071] In addition, in the case where the marker and two or more specified numbers of samples can be introduced alternately into the pipeline 2, the marker is introduced into the pipeline 2 once before the two or more specified numbers of samples. Moreover, the marker detection unit 9 that detects the marker outputs the detection signal of the marker to the analysis unit 4, and the analysis unit 4 sequentially obtains the analysis data of the specified number of samples based on the detection signal. Thus, since the deviation of the timing of obtaining the analysis data can be reduced to a certain range, even in the case where the liquid cannot be stably transported at a uniform time from the introduction of the sample to the analysis unit, the sample can be stably and continuously measured. The upper limit of the specified number can be appropriately selected according to the type of sample, the pretreatment method, etc., for example, it can be 80, 70, 50, 20, 15 or 10.

[0072] There are no particular limitations on the markers detectable by the marker detection section 9, and preferably, the marker is a substance not contained in the sample and / or a substance other than the substance to be analyzed. Furthermore, the marker is preferably a substance that is not decomposed by the reagents and heat added between the introduction line 2 and the marker detection section 9. For example, the marker can be a substance detectable by a spectrophotometer. Related substances are not particularly limited, and examples include rhodium, palladium, nickel, copper, chromium, manganese, iodine, cobalt, nitrate ions, phosphate ions, and silicate ions. Alternatively, the substance can be a substance detectable by a voltammeter. Related substances are not particularly limited, and examples include copper, cadmium, nickel, mercury, arsenic, and selenium. Alternatively, the substance can be a substance detectable by an ion electrode. Related substances are not particularly limited, and examples include calcium, potassium, fluorine, and ammonia. Alternatively, the substance can be a substance detectable by an ion chromatograph. Related substances are not particularly limited, and examples include ions of inorganic and organic acids, phenol, hydrazine, amino acids, and polysaccharides. Alternatively, the substance can be a substance detectable by a turbidimeter. The related substance is not particularly limited, and examples thereof include silica, which is a particulate material insoluble in acids other than fluoric acid. Alternatively, the substance can be a substance detectable by a fluorescence photometer. The related substance is not particularly limited, and examples thereof include benzene, coumarin, and naphthalene. Among these, particularly preferred markers due to ease of detection include rhodium, palladium, cobalt, nickel, and copper.

[0073] (Bubble barrier)

[0074] like Figure 5 As shown, the bubble isolation section 10 is a device for performing bubble isolation on the sample and marker introduced into the pipeline 2 and creating a plurality of sections divided by bubbles 13 in the pipeline 2. In one embodiment of the present invention, the bubble isolation section 10 includes: a gas inlet pipe 10a, which introduces gas into the pipeline 2; and a gas introduction pump (not shown) which applies suction to the gas inlet pipe. By performing bubble isolation, reagents and the like can be appropriately mixed through vortexes in the isolation liquid divided by the bubbles 13. In addition, the isolation liquid, that is, the sample forming each section divided by the bubbles 13, is divided by the bubbles 13 and flows independently in the pipeline 2, thereby preventing the samples from diffusing with each other. The gas for bubble isolation is preferably air, but it can also be an inert gas such as argon and helium, and various gases such as nitrogen and oxygen can also be used. These gases can be used alone or in combination of two or more. In this way, a method in which a reagent is introduced into a continuous flow of a sample in a pipeline separated by air bubbles, a reaction operation is performed, and then the bubbles are removed and analysis is performed using a detector located downstream is called continuous flow analysis (CFA). In this specification, downstream refers to the downstream of the flow of the sample in the pipeline of the flow analysis.

[0075] (Reagent introduction section)

[0076] The reagent introduction section 3 is a device for adding reagents to the sample flowing through the pipeline 2. In the reagent introduction section 3, the aforementioned oxidant can be added to the sample conveyed through the pipeline 2 to raise the redox potential to +0.80 V or higher. The reagent introduction section 3 includes a reagent introduction tube for introducing the reagent into the pipeline 2 and a reagent introduction pump for applying suction to the reagent introduction tube. The reagent may be one added during sample pretreatment. Examples of such reagents include, but are not limited to, acids such as nitric acid, hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid, and fluoric acid; mercury stabilizers such as L-cysteine ​​and gold; and bases such as sodium hydroxide, potassium hydroxide, sodium peroxide, calcium carbonate, and sodium carbonate. These reagents may be used alone or in combination. When using two or more reagents, multiple reagent introduction sections 3 may be provided. Alternatively, as long as at least two of the reagents can be mixed and introduced, the miscible reagents may be mixed and introduced into a single reagent introduction section 3. The reagent can be appropriately selected depending on the analysis target and analysis method, but from the perspective of high-precision mercury analysis, it is more preferable to include at least one oxidizing agent selected from hypochlorous acid or its salts and permanganic acid or its salts. In addition, when using inductively coupled plasma mass spectrometry (ICP-MS) as the analysis method, it is preferably to include hypochlorous acid or its salts. When nitric acid or nitric acid and hydrochloric acid and an oxidizing agent are added to the standard solution and the measurement sample in advance, it is preferable to flow a reagent solution containing the same acid or oxidizing agent into the reagent introduction part 3 as a buffer. Alternatively, the reagent introduction part 3 can also be omitted.

[0077] (Heating section)

[0078] The heating section 5 is a device for heating the sample transported through the pipeline 2. The heating section 5 can be a constant temperature bath with a heater. However, the structure of the heating section 5 is not limited thereto, and can also be an ultrasonic decomposition device, a microwave, a high-pressure steam decomposition device, etc. In addition, in the heating section 5, the pipeline 2 can also form, for example, a coil. In one embodiment of the present invention, the heating section 5 is provided downstream of the reagent introduction section 3. By heating the sample to which the reagent is added, the reaction between the sample and the reagent can be promoted, and pretreatment can be performed. In the heating section 5, for example, thermal decomposition and high-temperature and high-pressure decomposition of the sample can be performed.

[0079] The heating temperature in the heating unit 5 can be set, for example, so that the sample reaches 50°C or higher, 60°C or higher, 70°C or higher, or 80°C or higher. The upper limit of the heating temperature is preferably 140°C or lower, 130°C or lower, or 120°C or lower. Furthermore, the sample heating time is, for example, 5 minutes or higher, 10 minutes or higher, or 20 minutes or higher per unit of sample introduced (one sample). The upper limit of the heating time is, for example, 80 minutes or lower, and more preferably 40 minutes or lower. By setting the heating temperature and heating time in the heating unit 5 within the above ranges, compounds including mercury compounds in the sample can be fully decomposed.

[0080] Figure 6 This is a schematic diagram of bubbles in the pipeline after heating treatment in this flow analysis device. Figure 6 As shown, the heat treatment expands the bubbles 13 introduced into the bubble barrier 10. Alternatively, the reaction between the sample and the reagent may involve the generation of gas. In such cases, the heat treatment also causes the generated gas to expand. The gas generated and expanded by this reaction disperses as bubbles 14 in the barrier fluid or becomes integrated with the bubbles 13 introduced into the bubble barrier 10. At this point, at least a portion of the mercury contained in the sample is vaporized by the heat treatment, transforming into the gas phase of bubbles 13 or 14.

[0081] exist Figure 1 In the example of FIG, the flow analysis apparatus includes a pretreatment unit consisting of a reagent introduction section 3 and a heating section 5 provided downstream thereof. However, a plurality of reagent introduction sections 3 may be provided upstream of the heating section 5 to add a plurality of reagents instead of a single reagent introduction section 3. In addition, the pretreatment unit referred to here is not a unit for performing the "pretreatment step of adding an oxidant to the mercury-containing sample to prepare a sample solution before the sample introduction step" described in [3].

[0082] In addition, Figure 1 In the example shown, the flow analysis device includes a pretreatment unit consisting of a reagent introduction section 3 and a heating section 5 located downstream thereof. However, the device may also include one or more reagent introduction sections 3, a heating section 5 located downstream thereof, and another reagent introduction section 3 located downstream of the heating section 5 and upstream of the analysis section 4. Nitric acid, hydrochloric acid, or both nitric acid and hydrochloric acid can be added as reagents to the reagent introduction section 3 located downstream of the heating section 5 and upstream of the analysis section 4. When using inductively coupled plasma mass spectrometry (ICP-MS), adding hydrochloric acid to the nitric acid solution upstream of the heating section 5 or downstream of the heating section 5 and upstream of the analysis section 4 enables more stable mercury measurement.

[0083] In addition, Figure 1In the example shown, the flow analysis device includes a single pretreatment unit. However, the flow analysis device may also include multiple pretreatment units. In this case, each of the multiple pretreatment units may include a different number of reagent introduction units 3. By including multiple pretreatment units, it is possible to perform pretreatment such as acid decomposition under heating followed by acid addition and subsequent acid decomposition under heating. When multiple reagent introduction units 3 are included, the reagents added through each reagent introduction unit 3 may be the same or different.

[0084] In addition, Figure 1 In the example, the reagent introduction part 3 is provided downstream of the bubble barrier 10, but the configuration of the reagent introduction part 3 is not limited thereto. The reagent introduction part 3 may also be provided upstream of the bubble barrier 10. In the case where a plurality of reagent introduction parts 3 are provided, the reagent introduction part 3 may also be provided upstream and downstream of the bubble barrier 10. Alternatively, there is also a case where the reagent introduced through the reagent introduction part 3 is a reagent for detecting a marker (for example, a color developing solution, etc.). In this case, the reagent introduction part 3 is sometimes provided downstream of the heating part 5. Alternatively, one or more reagent introduction parts 3 for introducing reagents for pretreatment may be provided upstream of the heating part 5, and one or more reagent introduction parts 3 for introducing reagents for detecting markers may be provided downstream of the heating part 5.

[0085] (Cooling section)

[0086] The cooling section 6 is a device for cooling the sample transported through the pipeline 2 after the heating treatment in the heating section 5. The cooling section 6 is configured to transport the sample therein, and preferably includes a tube of 0.5 m to 3.0 m. The pipeline 2 is connected to both ends of the tube of the cooling section 6, and the sample transported through the pipeline 2 after the heating treatment in the heating section 5 is directly and continuously transported in the tube of the cooling section 6, and the sample passing through the tube continues to be continuously transported through the pipeline 2. In other words, the tube of the cooling section 6 becomes the pipeline 2. The pipeline 2 is connected to the connecting parts at both ends of the tube of the cooling section 6, so that the sample and gas transported in the tube are sealed in the pipeline. The inner diameter of the pipeline 2 and the inner diameter of the tube of the cooling section 6 may be the same or different if they can continuously transport the sample.

[0087] The sample transported through the pipeline 2 after heat treatment in the heating section 5 is introduced into the tube and cooled during transportation in the tube. The length of the tube is more preferably 0.7m to 2.5m, and more preferably 1.0m to 2.0m. If the length of the tube is 0.5m or longer, it is preferred that the heated sample be sufficiently cooled during transportation in the tube. In the past, in flow analysis devices with a gas-liquid separation section downstream of the heating section, the length of the pipeline from the heating section to the gas-liquid separation section was usually 0.5cm to 20cm. In analyses that do not target mercury, there is no need to lengthen the pipeline from the heating section to the gas-liquid separation section. This is because even if the gas is removed from the sample in the pipeline at a high temperature, there is no problem of the element being measured and the gas being removed at the same time. In the case of mercury being the object of measurement, since mercury is contained in the gas phase when the temperature in the pipeline is high, the mercury can be reduced to a liquid phase by lowering the temperature in the pipeline, thereby avoiding the simultaneous removal of mercury and gas. Furthermore, if the length of the tube is 3 m or less, the transportation of the sample does not take much time, thereby shortening the time required for analysis and achieving miniaturization of the device.

[0088] There is no particular limitation on the cooling method in the cooling section 6. Examples of the cooling method include air cooling of the pipe 2 for transporting the heated sample, or cooling with a refrigerant such as water (e.g., water cooling, ice water cooling), etc.

[0089] The material of the tube is not particularly limited, as long as it is inert to the sample transported within the tube. Examples include fluororesins such as perfluoroalkoxyalkanes (PFA) and polytetrafluoroethylene (PTFE); olefin resins such as polypropylene and polyethylene; glass; and PEEK (polyetheretherketone) resin. Furthermore, the material of the tubing 2 in this flow analyzer is not particularly limited, as long as it is inert to the sample transported within the tube. For example, the same material as that of the aforementioned tube can be used.

[0090] The inner diameter of the tube is not limited thereto, but is preferably 0.5 mm to 3.0 mm, more preferably 1.2 mm to 2.5 mm, even more preferably 1.5 mm to 2.3 mm, particularly preferably 1.8 mm to 2.2 mm, and most preferably 1.9 mm to 2.1 mm. An inner diameter of 0.5 mm or greater allows the sample to be transported within the tube at a suitable speed. Furthermore, an inner diameter of 3.0 mm or less is preferred because the sample transported within the tube comes into contact with the tube wall more frequently, enabling faster cooling of the sample.

[0091] The shape of the tube is not particularly limited and can be straight or curved. Preferably, the tube includes a coil portion. The coil portion can be in the shape of, for example, a spiral or an 8-shaped spiral. Figure 9 An example of the coil portion is schematically shown in FIG. Figure 9 (a) is a spiral coil portion, and (b) is a figure-eight spiral coil portion. By including the coil portion, the sample transported within the tube rotates while being transported within the tube, thereby agitating and mixing the sample. This facilitates the conversion of mercury in the vapor phase to the liquid phase while the sample is cooled. This prevents mercury loss due to vaporization, enabling high-precision analysis, making this a preferred method.

[0092] When the tube includes the coil portion, the tube may consist solely of the coil portion or include both the coil portion and the linear portion. However, from the perspective of achieving higher-precision analysis, it is more preferable to include both the coil portion and the linear portion. The reason for this is unclear, but the coil portion, by stirring and mixing the sample, functions to simultaneously cool the sample and convert mercury in the gaseous phase into a liquid phase. Since the linear portion cools the sample more effectively, it is speculated that combining the two can more effectively prevent mercury loss due to vaporization. The arrangement of the coil portion and the linear portion is not limited to this, but one example is a configuration in which the coil portion is located downstream of the linear portion. In this configuration, it is conceivable that the heated sample is primarily cooled in the linear portion, and the mercury in the sample, which is present as a gas, is then stirred and mixed in the coil portion, converting it into a liquid phase. In this case, the ratio of the length of the linear portion to the length of the coil portion of the tube is, for example, 1:1 to 10:1, and more preferably 2:1 to 5:2. Furthermore, in the ratio of the length of the straight portion of the tube to the length of the coil portion, "the length of the coil portion" refers to the length of the tube forming the coil portion, that is, the length of the tube when the coil portion is stretched into a straight line. Furthermore, in the configuration in which the coil portion is arranged downstream of the straight portion, a second straight portion may also exist downstream of the configuration in which the coil portion is arranged downstream of the straight portion. In this case, the ratio of the length of the straight portion of the tube to the length of the coil portion is intended to indicate the ratio of the length of the straight portion upstream of the coil portion to the length of the coil portion, without taking into account the length of the second straight portion.

[0093] Alternatively, the configuration in which the coil portion is arranged downstream of the straight portion may be repeated multiple times, for example, 2 to 10 times. In this case, the "length of the coil portion" is also as described above. In addition, in the configuration in which the coil portion is arranged downstream of the straight portion, there may also be a straight portion of the final segment downstream of the configuration that is repeated multiple times. In this case, the ratio of the length of the straight portion of the tube to the length of the coil portion is intended to indicate the ratio of the total length of the straight portion upstream of the plurality of coil portions to the total length of the plurality of coil portions, without taking into account the length of the straight portion of the final segment.

[0094] The number of turns of the spiral, figure-eight, or other spirals of the coil portion is also not particularly limited, and may range from 1 to 20 turns, more preferably from 2 to 10 turns, and even more preferably from 4 to 7 turns. A turn of 1 or more is preferred because it allows for more uniform stirring and mixing of the sample, thereby facilitating the conversion of mercury in the gas phase to the liquid phase while the sample is cooled. Furthermore, a turn of 20 or fewer is preferred because it allows for miniaturization of the device and shortens the analysis time.

[0095] When the shape of the coil portion is, for example, a 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, more preferably 20 mm to 50 mm, and most preferably 25 mm to 40 mm. If the coil diameter is 10 mm or more, liquid can be stably transported, which is preferred. In addition, if the coil diameter is 70 mm or less, liquid can be more appropriately mixed, which is preferred.

[0096] When the coil portion is, for example, spiral, its coil pitch is not particularly limited, and may be, for example, 0.7 mm to 40 mm, more preferably 0.8 mm to 30 mm, and even more preferably 0.9 mm to 25 mm. A coil pitch of 0.7 mm or greater is preferred because it allows the coil portion to be wound around a tube of a preferred diameter. Alternatively, a coil pitch of 40 mm or less is preferred because the coil portion is a compact size.

[0097] When the shape of the coil portion is, for example, an 8-shaped spiral, the maximum length of the 8 is the same as the coil diameter in the spiral shape, and the pitch is the same as the coil pitch in the spiral shape.

[0098] The cooling temperature in the cooling unit 6 can be set, for example, to a temperature below 30°C, preferably below 20°C, and more preferably below 10°C. The sample cooling time is not particularly limited, as long as it allows sufficient cooling of the sample. Examples include 2 minutes, 3 minutes, or 5 minutes per unit of sample introduced. The upper limit of the cooling time is, for example, 15 minutes per unit of sample introduced. By setting the cooling temperature and cooling time in the cooling unit 6 within the above ranges, mercury present as a gas in the sample can be converted to a liquid form.

[0099] The cooling unit 6 is disposed between the heating unit 5 and the gas-liquid separation unit 7 . The sample and the bubbles 13 and 14 transported through the pipe 2 and cooled in the cooling unit 6 are then transported to the gas-liquid separation unit 7 through the pipe 2 .

[0100] (Gas-liquid separation section)

[0101] The gas-liquid separator 7 is a device for sequentially removing the gas present in the pipeline 2 . Figure 7 This is a schematic diagram of a state in which the gas in the pipeline 2 is removed by the gas-liquid separation unit 7. Figure 7 As shown, the gas-liquid separation part 7 includes: a three-way pipe 7b, which includes a pipeline (pipeline 2) that continuously transports the sample in the horizontal direction or downward in the downstream direction of the pipeline 2 and a degassing pipe 7a that branches upward; a pump (not shown) that applies attraction to the pipeline 2 that continuously transports the sample in the horizontal direction or downward; a degassing pump (not shown) that applies attraction to the degassing pipe.

[0102] like Figure 7 As shown, since the gas (bubbles 13 and 14) existing in the pipe 2 floats upward, it is removed (degassed) through the degassing pipe branched upward from the tee pipe.

[0103] (Analysis Department)

[0104] The analysis unit 4 is a device for analyzing the sample after the reagent is added, and is also a device for analyzing the sample after being heat-treated by the heating unit 5, cooled by the cooling unit 6 after the heat treatment, and removed from the gas by the gas-liquid separation unit 7 after cooling. In one embodiment of the present invention, the analysis unit 4 can be an inductively coupled plasma mass spectrometry (ICP-MS) device. However, the analysis unit 4 is not limited thereto, and can also be any type of analysis device, for example, it can also be an inductively coupled plasma emission spectrometry (ICP-OES) device, an atomic absorption spectrometer, a triple quadrupole inductively coupled plasma mass spectrometer, an ion electrode instrument or a spectrophotometer. The analysis unit 4 is not limited to a device for only measuring the presence or concentration of mercury, and is also preferably capable of batch determination of devices for other metal elements. In addition, the analysis can be either quantitative analysis or qualitative analysis.

[0105] (Marker Detection Department)

[0106] The marker detection unit 9 is connected to a branch pipe between the gas-liquid separation unit 7 and the analysis unit 4. This branch pipe extracts the sample and markers flowing sequentially through the pipeline 2 from the pipeline 2. In other words, after gas removal in the gas-liquid separation unit 7 and before introduction into the analysis unit 4, the pipeline 2 branches into two branches: one branch (also referred to as pipeline 2 after the branch) connects to the analysis unit 4, and the other branch pipe connects to the marker detection unit 9. The marker detection unit 9 continuously measures the liquid extracted from the pipeline 2 through the branch pipe. If the marker is detected, a detection signal is output to the analysis unit 4. In one embodiment of the present invention, upon receiving the detection signal, the analysis unit 4 begins acquiring analytical data. In one embodiment of the present invention, the marker detection unit 9 is a spectrophotometer. If rhodium is detected in the marker, a detection signal is output to the analysis unit 4. However, the marker detection unit 9 is not limited to a spectrophotometer and may also be, for example, a voltammeter, an ion electrode meter, an ion chromatograph, a turbidimeter, or a fluorophotometer. The marker and the sample flowing in sequence are introduced from the pipeline 2 and the branch pipe to the analysis unit 4 and the marker detection unit 9, respectively, at the same timing. Alternatively, the timing of introducing the marker and the sample flowing in sequence to the analysis unit 4 and the marker detection unit 9 may be different, that is, there may be a deviation. In the case where there is a deviation in the timing, it is necessary to introduce the marker and the sample flowing in sequence to the marker detection unit 9 at a timing earlier than that of the analysis unit 4. In addition, in one embodiment, the analysis unit 4 is set to start acquiring analysis data immediately after receiving the detection signal, but it may also be set to start acquiring analysis data after a specified time interval after receiving the detection signal.

[0107] In one embodiment of the present invention, the analyzing unit 4 and the marker detecting unit 9 are arranged in parallel as described above. However, the analyzing unit 4 and the marker detecting unit 9 may also be arranged in parallel as described above. Figure 4 The embodiment shown is configured in series. Figure 4 In the embodiment shown, the marker detection unit 9 is arranged between the gas-liquid separation unit 7 and the analysis unit 4. After the gas is removed by the gas-liquid separation unit 7 and before the liquid is introduced into the analysis unit 4, the marker detection unit 9 continuously measures the liquid introduced from the pipeline 2, and if the marker is detected, the detection signal is output to the analysis unit 4. Moreover, after receiving the detection signal, the analysis unit 4 starts to acquire analysis data. In this case, the timing of starting to acquire analysis data can be adjusted so that the analysis unit 4 can measure the arrived sample. For example, it can be set so that the analysis unit 4 starts to acquire analysis data after a specified time interval after receiving the detection signal.

[0108] exist Figure 1In the example, the sample after the gas is removed by the gas-liquid separation section 7 is transported to the marker detection section 9 or analysis section 4 downstream thereof. However, a mixing coil for further mixing the sample may be provided between the gas-liquid separation section 7 and the marker detection section 9 or analysis section 4. The mixing coil is a pipe 2 formed in a coil shape. When the sample passes through the mixing coil, the sample flowing through the pipe 2 is mixed. The shape of the mixing coil is not particularly limited and may be similar to the following: Figure 9 The shape shown is the same shape.

[0109] The flow analyzer according to the first embodiment continuously introduces a sample into the pipeline to isolate bubbles, introduces a reagent, promotes the reaction using a heating unit, cools the sample and bubbles using a cooling unit, converts vaporized mercury into a liquid phase, and then removes the gas using a gas-liquid separator. This prevents mercury loss due to vaporization and allows the analyzer to continuously measure analytical data. Furthermore, the flow analyzer includes a marker introduction unit that introduces a marker into the pipeline, and a marker detection unit that detects the marker and outputs a detection signal to the analyzer. The analyzer acquires analytical data based on the detection signal, enabling stable and continuous sample measurement.

[0110] Typically, flow analyzers equipped with a gas-liquid separation unit often have a bubble blocker installed downstream of the unit to redirect the gas back into the pipeline. However, in this flow analyzer, no bubble blocker is installed between the gas-liquid separation unit and the analysis unit. This allows mercury in the sample to be introduced into the analysis unit 4 without volatilization, thus preventing a decrease in analytical accuracy caused by mercury volatilization.

[0111] In addition, the flow analysis device may further include a pressurizing unit that applies pressure to the heating unit 5 from the downstream side of the heating unit 5 to resist the flow of the sample. Figure 3 and Figure 8 1 is a partial structural diagram of an example of a flow analysis device including a pressurizing section 12 for applying pressure against sample flow from the downstream side of the heating section 5 or from the downstream side of the cooling section 6. Figure 3 and Figure 8 In the example, pressure to resist the flow of the sample is applied from a pressurizing section 12 provided on the downstream side of the gas-liquid separation section. The pressurizing section 12 includes, for example, a compressor and a valve. By including the pressurizing section, the sample can be decomposed at high temperature and high pressure in the heating section 5. Therefore, the decomposition of impurities including organic matter and the like and the dissolution of mercury in the solution can be effectively performed, which is preferred. The pressure applied by the pressurizing section 12 can be appropriately selected according to the heating temperature and heating time in the heating section 5, and is not particularly limited. For example, it is 0.14 MPa or less, and includes a negative pressure of less than 0.1 MPa depending on the situation. The pressure is more preferably greater than 0.1 MPa and less than 0.13 MPa.

[0112] In addition, in the present flow analysis device, an automatic sampler can be used as a sample introduction unit. In addition, an ultrasonic homogenizer or a stirrer can be included to grind and / or stir the sample before sampling.

[0113] Alternatively, the flow analyzer may also include a dilution unit midway through the pipeline. Thus, if dilution is required based on the sample concentration, the desired dilution can be automatically performed within the flow analyzer. A commercially available automatic dilution unit may be used as the dilution unit.

[0114] Furthermore, the flow analyzer preferably pre-adds nitric acid, or nitric acid and hydrochloric acid, and an oxidizing agent to the standard solution and the sample being measured. Mercury can sometimes adsorb to the tubes, so adding an oxidizing agent to the standard solution and sample pre-adding nitric acid or nitric acid and hydrochloric acid can prevent this adsorption. As a pre-treatment, a preparation device can be assembled to the sample introduction section, or upstream of the sample introduction section, where the preparation device adds an oxidizing agent to the mercury-containing sample to raise the redox potential to above +0.80 V, thereby preparing the sample solution. In this case, the oxidizing agent added to the adjustment device is not particularly limited, as long as it can raise the redox potential of the sample solution to above +0.80 V. Hypochlorous acid or its salts and permanganic acid or its salts can be used as the oxidizing agent. Specifically, the oxidizing agent added to the adjustment device is preferably at least one of hypochlorous acid or its salts and permanganic acid or its salts. Furthermore, the flow analyzer can be assembled to the sample introduction section, or upstream of the sample introduction section, with a device for pre-treating samples other than solids and liquids to prepare liquid samples. Flow analyzers analyze liquid samples using flow analysis and are not capable of directly measuring samples other than solids or liquids. Therefore, by assembling a device that pre-treats samples other than solids or liquids to prepare liquid samples, the entire process from pre-treatment to analysis of samples other than solids or liquids can be performed. Such devices are more preferably fully automated for pre-treating samples other than solids or liquids. For example, fully automated acid hydrolysis pre-treatment devices that automatically perform reagent addition, mixing, heating, and volume determination can be suitably used.

[0115] [3.2] Flow analysis device for performing the analysis method of embodiment 2 (configuration example 2)

[0116] Another configuration example 2 of the flow analysis device will be described. Figure 2 2 is a schematic diagram of the structure of the flow analysis device according to the second embodiment. For the sake of convenience, the components having the same functions as those described in [3.1] are denoted by the same reference numerals and will not be described again.

[0117] The flow analysis device of Example 2 uses the flow injection analysis (FIA) method, that is, a reagent is introduced into the flow of a sample in a pipeline that is not isolated by bubbles, and after a reaction operation, analysis is performed by a detector installed downstream.

[0118] The flow analysis device of construction example 1 is constructed as follows, including: a carrier introduction part 11, which introduces a carrier into the pipeline 2; a sample introduction part 1, which is used to introduce a sample into the flow of the carrier in the pipeline 2; a marker introduction part 8, which is used to introduce a marker into the flow of the carrier in the pipeline 2; a reagent introduction part 3, which adds a reagent to the flow of the sample transported through the pipeline 2; a heating part 5, which heats the sample transported through the pipeline 2 and to which the reagent is added; a cooling part 6, which cools the sample after the heating treatment; a gas-liquid separation part 7, which removes the gas present in the pipeline after cooling; an analysis part 4, which performs quantitative analysis or qualitative analysis on the sample from which the gas is removed in the gas-liquid separation part 7; a marker detection part 9, which detects the marker and outputs a detection signal to the analysis part 4, and the analysis part 4 obtains analysis data based on the detection signal.

[0119] The flow analysis device of Example 2 is configured such that a carrier introduction portion 11 is provided upstream of a sample introduction portion 1 for introducing a sample into a pipeline 2 and a marker introduction portion 8 for introducing a marker into a pipeline 2. The flow analysis device is similar to the example 2 except that a bubble barrier portion is not provided. Figure 1 The flow analysis devices shown have the same configuration.

[0120] The flow analysis device of Example 2 is an analysis device that uses flow injection analysis (FIA), in which the carrier is introduced into the pipeline 2 through the carrier introduction part 11, the sample is introduced into the flow in the pipeline 2 for the carrier to flow through the sample introduction part 1, and the marker is introduced through the marker introduction part 8.

[0121] The carrier is not particularly limited as long as it is a liquid that does not adversely affect the pretreatment and analysis of the sample, and examples thereof include water, surfactants, acidic solutions, and alkaline solutions.

[0122] The rest of the configuration of the flow analysis device of Configuration Example 2 is the same as that described in Configuration Example 1 and will not be described in detail.

[0123] [4] Summary

[0124] One embodiment of the present invention includes the following configurations.

[0125] <1> A method for analyzing a mercury-containing sample includes: a pretreatment step of adding an oxidant to the mercury-containing sample to form an oxidized state with a redox potential of +0.80 V or higher, thereby preparing a sample solution;

[0126] The analysis step is to perform quantitative analysis or qualitative analysis on the sample solution prepared in the pretreatment step while maintaining the sample solution in an oxidized state.

[0127] <2> A method for analyzing a mercury-containing sample employs a flow analysis method and includes a sample introduction step and an analysis step. The sample introduction step is used to introduce the mercury-containing sample into a pipeline, and the analysis step performs quantitative analysis or qualitative analysis on the sample. The analysis method includes: a pretreatment step, prior to the sample introduction step, adding an oxidant to the mercury-containing sample to adjust the redox potential to +0.80 V or higher, thereby preparing a sample solution; and / or a reagent addition step, adding an oxidant to the sample transported through the pipeline to adjust the redox potential to +0.80 V or higher; a heating step, heating the sample to which the oxidant has been added; a cooling step, cooling the heated sample transported through the pipeline; and a gas-liquid separation step, removing gas present in the pipeline after cooling, and performing quantitative analysis or qualitative analysis on the sample from which the gas has been removed in the gas-liquid separation step.

[0128] <3> according to <1> or <2> In the analysis method for mercury-containing samples, the oxidant is selected from at least one of hypochlorous acid or its salts and permanganic acid or its salts.

[0129] <4> according to <2> or <3> The analysis method of the mercury-containing sample includes a bubble isolation step, which performs bubble isolation on the sample introduced into the pipeline, and creates a plurality of sections divided by bubbles in the pipeline.

[0130] <5> according to <2> to <4> In any one of the above methods for analyzing a mercury-containing sample, bubble isolation is not performed after the gas-liquid separation step.

[0131] <6> according to <1> to <5> In any one of the methods for analyzing a mercury-containing sample, the amount of the oxidizing agent added is in excess relative to the mercury in the sample.

[0132] <7> according to <1> to <6> The method for analyzing a mercury-containing sample according to any one of the preceding claims includes a nitric acid / hydrochloric acid step of adding nitric acid and hydrochloric acid to the sample to which the oxidizing agent has been added.

[0133] <8> according to <1> to <7> In any one of the methods for analyzing a mercury-containing sample, in the analysis step, the quantitative analysis or the qualitative analysis is performed by inductively coupled plasma mass spectrometry or inductively coupled plasma optical emission spectrometry.

[0134] Example

[0135] The present invention will be described in more detail through the following embodiments, but the present invention is not limited to these embodiments. Embodiments obtained by appropriately combining the technical solutions disclosed in the embodiments are also within the scope of the present invention.

[0136] [Installation]

[0137] As a flow analysis device, Figure 1 The flow analysis device shown in the figure does not include the reagent introduction part 3, Figure 1 The B part is Figure 4 An analysis device having a structure of . This flow analysis device comprises: a sample introduction section 1 for introducing a sample into a pipeline 2; a marker introduction section 8 for introducing a marker into the pipeline 2; a bubble barrier 10 for isolating bubbles from the sample and marker introduced into the pipeline 2; a heating section 5 for heating the sample transported along the pipeline 2; a cooling section 6 for cooling the heated sample; a gas-liquid separator 7 for removing gas present in the pipeline after cooling; an analysis section 4 for performing quantitative or qualitative analysis on the sample from which gas has been removed in the gas-liquid separator 7; and a marker detection section 9 for detecting the marker and outputting a detection signal to the analysis section 4, which acquires analytical data based on the detection signal. A bubble barrier for reintroducing gas into the pipeline is not provided between the gas-liquid separator 7 and the analysis section 4.

[0138] Air was used as the bubble barrier gas and introduced into pipeline 2 at a rate of once every four seconds. Palladium was used as a marker and introduced into pipeline 2 as a palladium nitric acid solution (palladium concentration: 100 mg / L). The palladium nitric acid solution and the sample were alternately introduced into pipeline 2. In addition, a spectrophotometer (manufactured by BLTEC Co., Ltd., SCIC4000) was used as the detection device of the marker detection unit 9, and an inductively coupled plasma mass spectrometer (manufactured by Agilent Technologies, Inc., Agilent 7800ICP-MS) was used as the analysis device of the analysis unit 4.

[0139] A pressure of 0.12 MPa was applied to the heating section 5 from the downstream side thereof by a compressor. This pressure was a pressure that resisted the flow of the sample. The heating temperature in the heating section 5 was set so that the sample reached 100°C.

[0140] The cooling section 6 consisted of a 1.5m long PFA tube with an inner diameter of 2.0mm. Starting from the outlet of the heating section 5, the tube consisted of a 1.2m straight section, a 0.6m coil section, and a 0.3m straight section. The coil section had five turns, a coil diameter of 40mm, and a coil pitch of 3.0mm. Cooling was performed by air cooling, and the ambient temperature of the cooling section 6 was maintained at 15°C.

[0141] The marker detection unit 9 and the analysis unit 4 are as follows Figure 4 As shown, the apparatus is arranged in series, and the sample removed by the gas-liquid separator 7 is continuously measured by the marker detector 9 before being introduced into the analysis unit 4. Upon detecting the marker, the marker detector 9 outputs a detection signal to the analysis unit 4, and upon receiving the detection signal, the analysis unit 4 begins acquiring analytical data.

[0142] [Example 1]

[0143] <1. Preparation of sample solution, internal standard solution and washing water>

[0144] The concentration of metal elements in the sample was measured using the flow analyzer. As the sample, the environmental water, wastewater, or treated water listed in Table 1 below was used.

[0145] Nitric acid (70%) for the electronics industry, hydrochloric acid (35%) for the electronics industry, and sodium hypochlorite with 10% available chlorine were added to each sample to prepare a sample solution. The volume of nitric acid, hydrochloric acid, and sodium hypochlorite relative to the volume of the sample was 1%, 0.2%, and 0.02%, respectively. Ultrapure water was used instead of each sample to measure the redox potential of a blank solution prepared in the same manner. The measured value was +1.38V. Considering that the redox potential of the sample solution does not depend on each sample, it can be said to be +1.38V. In addition, the redox potential was measured using an oxidation-reduction potentiometer (ORP meter).

[0146] Separately, an internal standard solution was prepared by adding electronics-grade nitric acid (70%), electronics-grade hydrochloric acid (35%), and sodium hypochlorite with 10% available chlorine to the mercury standard solution. The volumes of nitric acid, hydrochloric acid, and sodium hypochlorite relative to the mercury standard solution were the same as those for the sample solution. Similarly, the redox potential of the internal standard solution can be estimated to be +1.38 V.

[0147] Separately, nitric acid (70%) and hydrochloric acid (35%) for the electronics industry were added to pure water to prepare sampler washing water as a substrate. The volume of nitric acid and hydrochloric acid relative to the volume of pure water was the same as that of the sample solution.

[0148] <2. Sample Analysis 1 (Sodium Hypochlorite Addition)>

[0149] The internal standard solution was added to each sample solution to achieve the environmental standard value of mercury, 0.5 μg / L, and an addition recovery test was performed. Furthermore, after the addition recovery test, the sampler wash water was circulated through the flow analyzer to clean the flow path.

[0150] <3. Sample Analysis 2 (No Sodium Hypochlorite Added)>

[0151] The sample solution and internal standard solution were prepared using the same method as in 1. above, except that sodium hypochlorite containing 10% available chlorine was omitted. Furthermore, using these sample solutions and internal standard solutions, an addition recovery test was conducted using the same method as in 2. above. Furthermore, in Analysis 2, the redox potential of a similarly prepared blank solution was measured using ultrapure water instead of each sample. The measured value was +0.66 V. Considering that the redox potential of the sample solution does not depend on the sample, it can be said to be +0.66 V.

[0152] The test results obtained in the above analysis 1 were compared with the test results obtained in the above analysis 2. The comparison results are shown in Table 1.

[0153]

Table 1

[0154]

[0155]

[0156] In the table, for samples diluted 10-fold or 50-fold, each reagent was added after dilution because the samples contained a lot of matrix or a lot of salt, such as seawater.

[0157] As can be seen from the results in Table 1, when no sodium hypochlorite was added, the recovery rate varied. On the other hand, when sodium hypochlorite was added, a good recovery rate was obtained.

[0158] [Comparative Example 1]

[0159] The concentration of metal elements in the sample was measured using the flow analyzer. As the sample, environmental water, wastewater, or treated water listed in Table 2 below was used.

[0160] In Comparative Example 1, an addition recovery test was conducted using hydrogen peroxide having a strong oxidizing ability instead of sodium hypochlorite.

[0161] Specifically, nitric acid (70%) for the electronics industry, hydrochloric acid (35%) for the electronics industry, and hydrogen peroxide (approximately 30%) were added to each sample to prepare a sample solution. The volumes of nitric acid, hydrochloric acid, and hydrogen peroxide were 1%, 0.2%, and 0.2%, respectively, relative to the volume of the sample. Furthermore, the redox potential of a blank solution prepared in the same manner was measured using ultrapure water instead of each sample. The measured value was +0.77 V. Considering that the redox potential of the sample solution does not depend on the sample, it can be said to be +0.77 V.

[0162] Separately, an internal standard solution was prepared by adding electronics-grade nitric acid (70%), electronics-grade hydrochloric acid (35%), and hydrogen peroxide (approximately 30%) to the mercury standard solution. The volumes of nitric acid, hydrochloric acid, and hydrogen peroxide relative to the mercury standard solution were the same as those for the sample solution. Similarly, the redox potential of the internal standard solution can be estimated to be +0.77 V.

[0163] In addition, sampler washing water as a substrate was prepared in the same manner as in Example 1.

[0164] The internal standard solution was added to each sample solution to achieve the environmental standard value for mercury, 0.5 μg / L, and a spike-recovery test was performed. Furthermore, after the spike-recovery test, the sampler wash water was circulated through the flow analyzer to clean the flow path. The results of the spike-recovery test are shown in Table 2.

[0165]

Table 2

[0166]

[0167]

[0168] As can be seen from the results in Table 2, when hydrogen peroxide was used as the oxidizing agent, a good recovery rate could not be obtained.

[0169] [Example 2]

[0170] In Example 2, the concentration of metal elements in the sample was measured manually without using the flow analyzer. As the sample, environmental water, wastewater, or treated water listed in Table 3 below was used.

[0171] Take 50 mL of the sample and place it in a beaker. Then, add nitric acid (70%) for the electronics industry, hydrochloric acid (35%) for the electronics industry, and sodium hypochlorite with 10% effective chlorine to the sample to prepare a sample solution. The volumes of nitric acid, hydrochloric acid, and sodium hypochlorite relative to the volume of the sample are 1%, 0.2%, and 0.02%, respectively. Then, add a mercury standard solution to the sample solution to reach the environmental standard value of mercury of 0.5 μg / L. Set the hot plate to 100°C, and heat and decompose the sample solution adjusted in this way for 3 hours. Then, after standing and cooling, the sample solution is fixed to 50 mL with ultrapure water, and the mercury concentration is measured by ICP-MS. The measurement results are shown in Table 3. In addition, ultrapure water is used instead of each sample to measure the redox potential of the blank solution prepared in the same way. The measured value is +1.38 V. Considering that the redox potential of the sample solution does not depend on each sample, it can be said to be +1.38 V.

[0172]

Table 3

[0173]

[0174]

[0175] From the results in Table 3, it can be seen that even when the flow analysis device is not used, a good recovery rate can be obtained if sodium hypochlorite is used as the oxidant.

[0176] [Comparative Example 2]

[0177] The mercury concentrations in the samples were measured using the same method as in Example 2, except that the samples listed in Table 4 below and sodium hypochlorite without 10% available chlorine were used. The results are shown in Table 4. Furthermore, the redox potential of blank solutions prepared in the same manner was measured using ultrapure water instead of each sample. The measured value was +0.66 V. Considering that the redox potential of the sample solutions does not depend on the sample, it can be considered to be +0.66 V.

[0178]

Table 4

[0179]

[0180] As can be seen from the results in Table 4, a good recovery rate could not be obtained compared with the results in Example 2 (Table 3).

[0181] [Example 3]

[0182] In Example 3, the concentration of metal elements in a sample was measured using the flow analyzer. As the sample, environmental water, wastewater, or treated water listed in Table 5 below was used.

[0183] Sample solutions, internal standard solutions, and washing water were prepared in the same manner as in <1. Preparation of sample solutions, internal standard solutions, and washing water> of Example 1, except that hydrochloric acid (35%) for the electronics industry was not added to each sample.

[0184] The internal standard solution was added to each sample solution to achieve the environmental standard value for mercury, 0.5 μg / L, and a spike-recovery test was performed. Furthermore, after the spike-recovery test, the sampler wash water was circulated through the flow analyzer to clean the flow path. The results are shown in Table 5.

[0185]

Table 5

[0186]

[0187] From the results in Table 5, it can be seen that when sodium hypochlorite is used as the oxidant, a good recovery rate can be obtained even without adding hydrochloric acid.

[0188] [Comparative Example 3]

[0189] Mercury standard solutions containing mercury in a concentration range of 0.025 μg / L to 1 μ / L were prepared. Nitric acid (70%) for the electronics industry and hydrochloric acid (35%) for the electronics industry were added to the prepared mercury standard solutions of each concentration to prepare internal standard solutions. The mercury concentration of the internal standard solutions of each mercury concentration was then measured using the flow analyzer, and a calibration curve was prepared. In addition, the volumes of nitric acid and hydrochloric acid were 1% and 0.2%, respectively, relative to the volume of the mercury standard solution. In addition, ultrapure water was used instead of each sample to measure the redox potential of a blank solution prepared in the same manner. The measured value was +0.66 V. Considering that the redox potential of the sample solution does not depend on the sample, it can be said to be +0.66 V.

[0190] Nitric acid (70%) and hydrochloric acid (35%) for the electronics industry were added to pure water to prepare sampler washing water as a substrate. The volume of nitric acid and hydrochloric acid was 1% and 0.2% of the volume of pure water, respectively.

[0191] The obtained calibration curve is as follows Figure 10 As shown, the coefficient of determination R is 0.9983. In addition, it can be seen that the calibration curve is slightly curved.

[0192] [Example 4]

[0193] Except adding sodium hypochlorite with 10% available chlorine, use the same method as Comparative Example 3 to prepare internal standard solution and sampler washing water. In the internal standard solution, the capacity of nitric acid, hydrochloric acid, and sodium hypochlorite is respectively 1%, 0.2%, and 0.02% relative to the capacity of the mercury standard solution. In addition, in the sampler washing water, the capacity of nitric acid, hydrochloric acid, and sodium hypochlorite is respectively 1%, 0.2%, and 0.02% relative to the capacity of pure water. In addition, ultrapure water is used to replace each sample to measure the redox potential of the blank solution prepared in the same manner. The measured value is +1.38V. Considering that the redox potential of the sample solution does not depend on each sample, it can be said to be +1.38V.

[0194] Then, the mercury concentration of the internal standard solution of each mercury concentration was measured using the flow analyzer, and a calibration curve was prepared.

[0195] The obtained calibration curve is as follows Figure 11 As shown in FIG. 1 , the determination coefficient R is 0.9999, indicating that good linearity can be obtained.

[0196] Next, use Figure 10 or Figure 11 The recovery rates of the concentrations of the mercury standard solutions at various concentrations were calculated using the calibration curve shown in Table 6.

[0197]

Table 6

[0198]

[0199] The results in Table 6 show that when sodium hypochlorite is not added to the mercury standard solution, the recovery rate at low concentrations deteriorates significantly. On the other hand, when sodium hypochlorite is added to the standard solution, good recovery rates are achieved across the entire concentration range.

[0200] [Example 4]

[0201] The concentration of metal elements in the sample was measured using the flow analysis device. As the sample, the environmental water, wastewater, or treated water listed in Table 7 below was used.

[0202] In Example 4, potassium permanganate having strong oxidizing ability was used instead of sodium hypochlorite to conduct an addition recovery test.

[0203] Specifically, nitric acid (70%) for the electronics industry, hydrochloric acid (35%) for the electronics industry, and potassium permanganate were added to each sample to prepare a sample solution. The volume of nitric acid and hydrochloric acid relative to the volume of the sample was 1% and 0.2%, respectively. In addition, the volume of potassium permanganate relative to the volume of the sample was 20 mg / L. Furthermore, ultrapure water was used instead of each sample, and the redox potential of a blank solution prepared in the same manner was measured. The measured value was +1.24 V. Considering that the redox potential of the sample solution does not depend on the sample, it can be said to be +1.24 V.

[0204] Separately, an internal standard solution was prepared by adding electronics-grade nitric acid (70%), electronics-grade hydrochloric acid (35%), and potassium permanganate to the mercury standard solution. The volumes of nitric acid and hydrochloric acid relative to the mercury standard solution were the same as those for the sample solution. Furthermore, the amount of potassium permanganate relative to the mercury standard solution was also the same as for the sample solution. Similarly, the redox potential of the internal standard solution can be estimated to be +1.24 V.

[0205] In addition, sampler washing water as a substrate was prepared in the same manner as in Example 1.

[0206] The aforementioned internal standard solution was added to each sample solution to achieve the environmental standard value for mercury, 0.5 μg / L, and a spike-recovery test was performed. Furthermore, after the spike-recovery test, the sampler wash water was circulated through the flow analyzer to clean the flow path. The results of the spike-recovery test are shown in Table 7.

[0207]

Table 7

[0208]

[0209]

[0210] From the results in Table 7, it can be seen that even if potassium permanganate is used as the oxidant instead of sodium hypochlorite, a good recovery rate can be obtained.

[0211] [Example 5]

[0212] Mercury has an oxidation-reduction potential of 0.7986 and is an easily reducible metal. 2+ Mercury is easily vaporized when reduced to Hg. To prevent mercury from being reduced, the sample solution is preferably in an oxidized state. Therefore, the redox potentials of the sample solutions containing potassium permanganate, sodium hypochlorite, or hydrogen peroxide used in Examples 1 to 4 or Comparative Examples 1 to 3 were measured.

[0213] Specifically, the redox potentials of the following blank solutions A to J were measured.

[0214] A: Add nitric acid (70%) for the electronics industry to pure water to make the volume of nitric acid reach 1% solution.

[0215] B: Add nitric acid (70%) for the electronics industry and hydrochloric acid (35%) for the electronics industry to pure water to make a solution with a volume of nitric acid and hydrochloric acid of 1% and 0.2% respectively.

[0216] C: Add sodium hypochlorite with 10% available chlorine to solution B to make it a 0.002% solution.

[0217] D: Add sodium hypochlorite with 10% available chlorine to solution B to make it a 0.02% solution.

[0218] E: Add sodium hypochlorite with 10% available chlorine to solution B to make it a 0.2% solution.

[0219] F: Add hydrogen peroxide to solution B to make it a 0.02% solution,

[0220] G: Add hydrogen peroxide to solution B to make it a 0.2% solution,

[0221] H: Add potassium permanganate to solution B to make it a 2 mg / L solution.

[0222] I: Add potassium permanganate to solution B to make it a 20 mg / L solution,

[0223] J: Potassium permanganate was added to solution B to make a 200 mg / L solution.

[0224] The results are shown in Table 8.

[0225]

Table 8

[0226]

[0227]

[0228] As shown in Table 8, the blank solutions C to E containing sodium hypochlorite and the blank solutions H to J containing potassium permanganate have higher redox potentials. It is also speculated that these blank solutions can oxidize mercury and thus retain Hg 2+ state, it is possible to perform measurement without vaporizing mercury through reduction, and thus a good recovery rate can be obtained.

[0229] Furthermore, considering that the redox potential of a sample solution prepared with the same composition as the blank solution is almost independent of the redox potential of the very small amount of target substance contained in the sample, it can be said to be the same as the redox potential of the blank solution. Therefore, the redox potential of a sample solution prepared with the same composition as blank solutions A to J can be said to be the redox potential of blank solutions A to J. Furthermore, the sample solutions used in Examples 1 to 4, which had a redox potential greater than that of mercury, were based on the compositions of blank solutions D and I.

[0230] [Example 6]

[0231] In Example 6, the flow analyzer was used to simultaneously measure the concentrations of metal elements in a sample. Mineral water to which various metal standard solutions listed in Table 9 were added at predetermined concentrations was used as the sample.

[0232] Nitric acid (70%) for the electronics industry, hydrochloric acid (35%) for the electronics industry, sodium hypochlorite with 10% available chlorine, and the metal standard solutions listed in Table 9 were added to mineral water to prepare a sample solution. The volumes of nitric acid, hydrochloric acid, and sodium hypochlorite relative to the volume of mineral water were 1%, 0.2%, and 0.02%, respectively. In addition, sampler wash water was prepared as a substrate in the same manner as in Example 1. The redox potential of a blank solution prepared in the same manner was measured using ultrapure water instead of mineral water. The measured value was +1.38 V. Considering that the redox potential of the sample solution does not depend on the mineral water, it can be said to be +1.38 V.

[0233] The sample solution recovery test was conducted using the flow analyzer. Furthermore, the metal concentration of the sample solution was calculated by subtracting the metal concentration in the mineral water from the measured concentration of each metal. The results are shown in Table 9.

[0234]

Table 9

[0235]

[0236] As shown in Table 9, good recovery rates were achieved for all metals. This established a method for measuring mercury-containing metals using flow analysis.

[0237] Industrial Application Possibilities

[0238] According to the present invention, an analysis method and a flow analysis method capable of continuously analyzing a mercury-containing sample with high accuracy can be provided.

[0239] According to such a configuration, it is possible to contribute to the reduction of pollution of environmental water, tap water, etc. Thus, it is possible to contribute to the achievement of Goals 14 and 15 of the Sustainable Development Goals (SDGs).

[0240] Explanation of symbols

[0241] 1. Sample introduction part

[0242] 2 pipelines

[0243] 3. Reagent introduction part

[0244] 4Analysis Department

[0245] 5Heating unit

[0246] 6 Cooling unit

[0247] 7Gas-liquid separation unit

[0248] 8. Marker introduction unit

[0249] 9 Marker Detection Department

[0250] 10 Bubble partition

[0251] 11. Vector introduction unit

[0252] 12 Pressurization unit

[0253] 13 bubbles

[0254] 14 bubbles

Claims

1. A method for analyzing a mercury-containing sample, comprising: a pretreatment step of adding an oxidizing agent to the mercury-containing sample to form an oxidized state having an oxidation-reduction potential of +0.80 V or higher, thereby preparing a sample solution; The analysis step is to perform quantitative analysis or qualitative analysis on the sample solution prepared in the pretreatment step while maintaining the sample solution in an oxidized state.

2. A method for analyzing a mercury-containing sample, which uses a flow analysis method and includes a sample introduction step and an analysis step. The sample introduction step is used to introduce a mercury-containing sample into the pipeline, and the analysis step performs quantitative analysis or qualitative analysis on the sample, wherein: The analysis method comprises: a pretreatment step of adding an oxidant to the mercury-containing sample to increase the redox potential to +0.80 V or higher, thereby preparing a sample solution, before the sample introduction step, and / or a reagent addition step of adding an oxidant to the sample transported through the pipeline to increase the redox potential to +0.80 V or higher; a heating step of heating the sample to which the oxidant has been added; a cooling step for cooling the sample transported through the pipeline after the heating treatment; A gas-liquid separation process, which removes the gas present in the pipeline after cooling, The sample from which gas has been removed in the gas-liquid separation step is subjected to quantitative or qualitative analysis.

3. The method for analyzing a mercury-containing sample according to claim 1 or 2, wherein the oxidizing agent is at least one selected from the group consisting of hypochlorous acid or a salt thereof and permanganic acid or a salt thereof.

4. The method for analyzing a mercury-containing sample according to claim 2, further comprising a bubble isolation step of isolating the sample introduced into the pipeline by bubbles, thereby creating a plurality of sections divided by bubbles in the pipeline. 5 . The method for analyzing a mercury-containing sample according to claim 2 , wherein bubble isolation is not performed after the gas-liquid separation step. 6 . The method for analyzing a mercury-containing sample according to claim 1 , wherein the amount of the oxidizing agent added is in excess relative to the mercury in the sample.

7. The method for analyzing a mercury-containing sample according to claim 1 or 2, comprising a nitric acid / hydrochloric acid step of adding nitric acid and hydrochloric acid to the sample to which the oxidizing agent has been added. 8 . The method for analyzing a mercury-containing sample according to claim 1 , wherein in the analysis step, the quantitative analysis or the qualitative analysis is performed by inductively coupled plasma mass spectrometry or inductively coupled plasma optical emission spectrometry.

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