Patent Description:
In the "Testing methods for industrial wastewater" (see Non-Patent Literature <NUM> below) of Japanese Industrial Standards, a method in which a reagent such as nitric acid or hydrochloric acid is added to a sample (water sample) and then a heat treatment is carried out is specified as to a pretreatment for an analysis of a metal element contained in the sample. This pretreatment, which is carried out mainly for the purpose of decomposition of an organic matter, a suspended matter, and a metal complex that coexist in a sample, is considerably time-consuming. In addition, the pretreatment requires measures to be taken to prevent a worker from being exposed to acid during the pretreatment.

In these regards, it is desired that, by use of a "flow analysis method" such as a flow injection analysis (abbreviated to "FIA") method or a continuous flow analysis (abbreviated to "CFA") method, the pretreatment is automated and thereby the speed of a treatment of a sample is increased and a working environment is improved.

Document <CIT> relates to a method and a device for extracting a gas component in a liquid and detecting ingredients of the gas component, qualitatively analyzing the gas component. Document <CIT> discloses a method and an apparatus for automated quantitative fluid analysis where suction is applied to remove gas segments. Document <NPL>) relates to a flow synthesis device and a flow synthesis method. Document <NPL>) relates to a flow synthesis method using CO<NUM>. <CIT> discloses a reactor from which samples of a reaction product are obtained and a metal concentration in them are analysed by high pressure liquid chromatography,.

Japanese Industrial Standards "Testing methods for industrial wastewater (JIS K <NUM>)".

The present invention has been developed in view of the above technical problems, and the object thereof is to provide a novel flow analysis method and a novel flow analyzer each of which makes it possible to improve accuracy of an analysis.

A flow analyzer in accordance with an aspect of the present invention, which solves the above technical problems, is a flow analyzer including: a sampling device that is configured to introduce a sample into a tube; a reagent adding device configured to add a reagent to the sample which is transferred through the tube; and an analyzing device configured to quantitatively or qualitatively analyze the sample to which the reagent has been added, the flow analyzer further comprising a gas-liquid separating device configured to sequentially remove gas which is present in the tube (hereinafter, referred to as "claimed analyzer"). The claimed analyzer further includes a heating device configured to carry out a heat treatment at a heating temperature of <NUM> or higher on the sample to which the reagent has been added. The claimed analyzer further includes a pressurizing device including a compressor for introducing compressed air inside the tube to apply, to the gas which is present in the tube and which expands due to the heat treatment, pressure against the flow of the sample which is transferred, thereby preventing expansion of the gas, wherein the pressure is one applied against the flow of the sample which is transferred through the tube, and wherein the quantitative analysis or the qualitative analysis is one targeting a small amount of a metal contained in the sample.

In a preferable aspect, the claimed analyzer further includes a gas bubble segmenting device configured to produce, in the tube, a plurality of segments which are separated by gas bubbles, by carrying out gas bubble segmentation with respect to the sample that is introduced into the tube.

A flow analysis method carried out using the flow analyzer as set forth in claim <NUM> or <NUM>, is a flow analysis method including: a sample introducing step of introducing a sample into a tube, wherein the sample introducing step is carried out using the sampling device; a reagent adding step of adding a reagent to the sample which is transferred through the tube, wherein the reagent adding step is carried out using the reagent adding device; and an analyzing step of quantitatively or qualitatively analyzing the sample to which the reagent has been added, wherein the analyzing step is carried out using the analyzing device, the flow analysis method further including, after the reagent adding step and before the analyzing step, a gas-liquid separating step of sequentially removing gas which is present in the tube, wherein the gas-liquid separating step is carried out using the gas-liquid separating device, wherein after the reagent adding step and before the gas-liquid separating step, a heating step of carrying out a heat treatment at a heating temperature of <NUM> or higher on the sample, wherein the heating step is carried out using the heating device. The method further comprising a pressurizing step of introducing, using the compressor of the pressurizing device, compressed air inside the tube to apply, to the gas which is present in the tube and which expands in the heating step, pressure against the flow of the sample which is transferred, thereby preventing expansion of the gas, wherein the pressure is one applied against the flow of the sample which is transferred through the tube, and, wherein the quantitative analysis or the qualitative analysis is one targeting a small amount of a metal contained in the sample.

In a preferable aspect, the claimed analysis method is arranged such that, in the sample introducing step, a plurality of segments which are separated by gas bubbles are produced by carrying out gas bubble segmentation with respect to the sample that is introduced.

In a preferable aspect, the claimed analysis method is arranged such that a solution which contains hydrogen peroxide is used as the reagent that is added in the reagent adding step.

According to an aspect of the present invention, it is possible to improve accuracy of an analysis.

The following will discuss embodiments of the present invention with reference to the drawings.

<Claimed analyzer <NUM>> <FIG> illustrates an embodiment of the claimed analyzer <NUM>. The claimed analyzer <NUM> includes a "sampling device <NUM>", a "reagent adding device <NUM>", an "analyzing device <NUM>", and a "gas-liquid separating device <NUM>". The claimed analyzer <NUM> further includes a "gas bubble segmenting device <NUM>" and a "heating device <NUM>".

The sampling device <NUM> has a role of sampling a sample and introducing the sample into a tube <NUM>. In Embodiment <NUM>, the sampling device <NUM> is constituted by a thief tube <NUM> through which the sample is led to the tube <NUM> and a sampling pump (peristaltic pump) <NUM> which imparts a suction force to the thief tube <NUM>.

The reagent adding device <NUM> has a role of adding a reagent to the sample which is transferred through the tube <NUM>. In Embodiment <NUM>, the reagent adding device <NUM> is constituted by a reagent addition tube <NUM> through which the reagent is introduced into the tube <NUM> and a reagent addition pump (peristaltic pump) <NUM> which imparts a suction force to the reagent adding tube <NUM>.

The analyzing device <NUM> has a role of quantitatively or qualitatively analyzing the sample to which the reagent has been added. In Embodiment <NUM>, an ICP optical emission spectrometer is used as the analyzing device <NUM>.

The gas-liquid separating device <NUM> has a role of sequentially removing gas which is present in the tube <NUM>. In Embodiment <NUM>, the gas-liquid separating device <NUM> is constituted by (i) a three-way tube which is provided to a downstream end of the tube <NUM> and which branches into an analysis tube <NUM> that extends downward and a degassing tube 50D that extends upward, (ii) an analysis pump (peristaltic pump) <NUM> which imparts a suction force to the analysis tube <NUM>, and (iii) a degassing pump (peristaltic pump) 51D which imparts a suction force to the degassing tube 50D.

The gas bubble segmenting device <NUM> has a role of carrying out gas bubble segmentation with respect to the sample which has been sampled by the sampling device <NUM>. In Embodiment <NUM>, the gas bubble segmenting device <NUM> is constituted by an air introduction tube <NUM> through which air is led to the tube <NUM> and an air introduction pump (peristaltic pump) <NUM> which imparts a suction force to the air introduction tube <NUM>.

The heating device <NUM> has a role of carrying out a heat treatment with respect to the sample which is transferred through the tube <NUM>. In Embodiment <NUM>, the heating device <NUM> is constituted by a heater which is provided in the middle of the tube <NUM>.

The claimed analyzer <NUM> having the above configuration is a device for carrying out the claimed analysis method. In the claimed analysis method, a "sample introducing step", a "reagent adding step", a "gas-liquid separating step", and an "analyzing step" are carried out.

Note that, in Embodiment <NUM>, a "heating step" which is carried out by the heating device <NUM> included in the inventive analyzer <NUM> is also carried out after the reagent adding step is carried out and before the gas-liquid separating step is carried out.

In the sample introducing step, the sample is introduced into the tube <NUM>. As illustrated in <FIG>, in Embodiment <NUM>, the sample is introduced into the tube <NUM> with use of the sampling device <NUM>. Note that, in Embodiment <NUM>, a plurality of segments (S) which are separated by gas bubbles (B) are produced by carrying out gas bubble segmentation, in which air is introduced, with use of the gas bubble segmenting device <NUM> while the sample is introduced into the tube <NUM>.

In the reagent adding step, the reagent is added to the sample which is transferred through the tube <NUM>. As illustrated in <FIG>, in Embodiment <NUM>, the reagent is added to a flow of the sample which is transferred through the tube <NUM>, with use of the reagent adding device <NUM>. By the reagent adding step being carried out, the sample and the reagent contact with each other, and are transferred through the tube <NUM> while reacting with each other. The reaction between the sample and the reagent may cause generation of gas (A), and the gas (A) thus generated turns into bubbles in the plurality of segments (S).

In the heating step, the heat treatment is carried out with respect to the sample which is transferred through the tube <NUM>. In Embodiment <NUM>, the heating step is carried out by heating a part of the tube <NUM> with use of the heating device <NUM> and causing the sample to sequentially pass through the heated part of the tube <NUM>. By carrying out the heating step, the reaction between the sample and the reagent is promoted. As illustrated in <FIG>, the gas (A) which has been generated by the reaction between the sample and the reagent expands while the heating step is carried out. Further, the gas bubbles (B) which have been introduced into the tube <NUM> together with the sample while the sample introducing step is carried out also expand.

In the gas-liquid separating step, the gas (A) which is present in the tube <NUM> is sequentially removed. As illustrated in <FIG>, in Embodiment <NUM>, the gas (A) which is present in the tube <NUM> is removed with use of the gas-liquid separating device <NUM>. The gas (A) which is present in the tube <NUM> rises upward, and is therefore removed through the degassing tube 50D which extends upward at the downstream end of the tube <NUM> (degassing). Note that the gas bubbles (B) which have been introduced into the tube <NUM> together with the sample are also removed through the degassing tube 50D. The degassing pump 51D which is provided in the middle of the degassing tube 50D has a role of determining the speed of discharge of the gas (A) and the gas bubbles (B).

In the analyzing step, the sample which has been reacted with the reagent is quantitatively or qualitatively analyzed. As illustrated in <FIG>, in Embodiment <NUM>, the analyzing step is carried out by introducing the sample from which the gas (S) has been removed into the analyzing device <NUM> through the analysis tube <NUM> which extends downward at the downstream end of the tube <NUM>. The analysis pump <NUM> which is provided in the middle of the analysis tube <NUM> has a role of determining the speed of introduction of the sample which is introduced into the analyzing device <NUM> through the analysis tube <NUM>.

In the claimed analysis method in which the aforementioned steps are carried out, the analyzing step is carried out after the gas-liquid separating step of removing the gas (A) and the like which are present in the tube <NUM> is carried out at the downstream end of the tube <NUM>. Therefore, the gas (A) and the like do not become inhibitors, such as noise, which inhibit measurement, and accordingly it is possible to improve accuracy of an analysis.

By the way, in Embodiment <NUM>, a mechanism is employed such that, while the sample is introduced into the tube <NUM> in the sample introducing step, the plurality of segments (S) which are separated by the gas bubbles (B) are produced by carrying out the gas bubble segmentation, in which air is introduced, with use of the gas bubble segmenting device <NUM> (i.e., mechanism pursuant to a continuous flow analysis method). Note, however, that in an embodiment of the present claimed invention, the plurality of segments (S) do not necessarily need to be produced while the sample is introduced into the tube <NUM>. Further, in Embodiment <NUM>, the heating step of carrying out the heat treatment with respect to the sample to which the reagent has been added is carried out.

That is, in an embodiment of the present invention, for example, a mechanism may be employed such that the sample is introduced directly into the tube <NUM> (i.e., mechanism pursuant to a flow injection analysis method) as in another aspect of the claimed analyzer <NUM> illustrated in <FIG>. Alternatively, in an embodiment not according to the claimed invention, a mechanism may be employed such that the heating step is not carried out.

Note, however, that in a case according to the claimed invention where the heating step is carried out, the reaction between the sample and the reagent is promoted and thereby an increased amount of the gas (A) is generated. In a case where the mechanism pursuant to the continuous flow analysis method is employed and the heating step is carried out, not only the gas (A) but also the gas bubbles (B) expand. However, in the claimed analysis method in which the gas (A) and the gas bubbles (B) are removed by carrying out the gas-liquid separating step, even in a case where the heating step and the mechanism pursuant to the continuous flow analysis method are employed, the gas (A) and the gas bubbles (B) do not become inhibitors, and the reaction is promoted by the heating step. Further, by carrying out the gas bubble segmentation in the sample introducing step, it is possible to prevent diffusion of the sample in the tube <NUM>.

Therefore, an aspect of the present claimed invention is such that the heating step of carrying out the heat treatment with respect to the sample is carried out. Further, a preferable aspect of the present invention is such that, while the sample introducing step is carried out, the plurality of segments which are separated by the gas bubbles are produced by carrying out the gas bubble segmentation with respect to the sample that is introduced.

Note that, according to the present claimed invention, in a case where a heating temperature in the heating step is set high or a heating time in the heating step is set long, the gas (A) or the gas bubbles (B) may extremely expand. In such a case, it is confirmed that it is possible to prevent the expansion of the gas (A) and the gas bubbles (B) by carrying out, with use of a pressurizing device <NUM> which includes a compressor and the like, a pressurizing step of applying pressure against the flow of the sample which is transferred through the tube <NUM>, as illustrated in <FIG>. Thus, in the claimed analysis method, where the pressurizing step is employed, it is possible to select the heating temperature and the heating time each of which cannot not be employed in the conventional flow analysis method.

In the claimed analysis method, where the pressurizing step is employed, it is possible to set the heating temperature in the heating step to, for example, not lower than <NUM> (more preferably not lower than <NUM>), and it is possible to set the heating time in the heating step to, for example, not shorter than <NUM> minutes (more preferably not shorter than <NUM> minutes) per unit of the sample which has been introduced. The pressure applied in the pressurizing step is not limited in particular, and can be determined, as appropriate, depending on the heating temperature and the heating time in the heating step. Preferably, the pressure is set to any pressure of not more than <NUM> MPa (including negative pressure of less than <NUM> MPa, more preferably more than <NUM> MPa and not more than <NUM> MPa).

In Embodiment <NUM>, the ICP optical emission spectrometer is used as the analyzing device <NUM>, which is for carrying out the analyzing step. Note, however, that the analyzing device <NUM> is not limited to any particular one, and any one of various analyzing devices (for example, flame atomic absorption spectrometer, electrothermal atomic absorption spectrometer, ICP mass spectrometer) can be selected and used as appropriate.

The reagent which is introduced into the tube <NUM> in the reagent adding step is not limited to any particular one, and is selected as appropriate, depending on necessity of a pretreatment of the sample. Further, a plurality of types of reagents may be added simultaneously or stepwise, if necessary in an analysis. As the reagent, an acidic reagent such as hydrochloric acid, nitric acid, perchloric acid, or sulfuric acid or a basic reagent such as sodium hydroxide or potassium hydroxide can be, for example, selected and used as appropriate. Note, here, that it is confirmed that, in a case where a solution containing hydrogen peroxide is used as the reagent, an increased amount of the gas (A) is generated in the tube <NUM>. In the claimed analysis method in which the gas-liquid separating step is carried out, it is possible to suitably carry out an analysis even in a case where the solution containing hydrogen peroxide is used as the reagent.

<FIG> illustrates an embodiment of the claimed analyzer <NUM> for carrying out the claimed analysis method. The claimed analyzer <NUM> includes a "sampling device <NUM>", three "reagent adding devices <NUM> (3F, <NUM>, and 3T)", an "analyzing device <NUM>", and two "gas-liquid separating devices <NUM> (5F and <NUM>)". The claimed analyzer <NUM> in accordance with Embodiment <NUM> further includes a "gas bubble segmenting device <NUM>", two "heating devices <NUM> (7F and <NUM>)", and a "pressurizing device <NUM>".

The claimed analyzer <NUM> having the above configuration is a device for carrying out the claimed analysis method. In The claimed analysis method, after a "sample introducing step" is carried out, "reagent adding steps (first through third reagent adding steps)" which are carried out in three stages, two "gas-liquid separating steps (first and second gas-liquid separating steps)", and an "analyzing step" are carried out. Furthermore, after the second reagent adding step is carried out and after the third reagent adding step is carried out, "heating steps (first and second heating steps)" are respectively carried out (twice in total).

In the sample introducing step, a sample is introduced into a tube <NUM>. In Embodiment <NUM>, industrial wastewater (water sample) is, for example, used as the sample. Note that, in Embodiment <NUM>, while the sample is introduced into the tube <NUM>, the sample is introduced into the tube <NUM> with use of the sampling device <NUM>, and gas bubble segmentation, in which air is introduced, is carried out with use of the gas bubble segmenting device <NUM>.

In the first reagent adding step, a first reagent is added to the sample which is transferred through the tube <NUM>, with use of the reagent adding device <NUM> (3F). In Embodiment <NUM>, a nitric acid aqueous solution is, for example, used as the first reagent.

In the second reagent adding step, a second reagent is added to the sample to which the first reagent has been added, with use of the reagent adding device <NUM> (<NUM>). In Embodiment <NUM>, a perchloric acid aqueous solution is, for example, used as the second reagent.

In the first heating step, a heat treatment is carried out with respect to the sample to which the first and second reagents have been added, with use of the heating device <NUM> (7F). By carrying out the first heating step, a reaction between the sample and the first and second reagents is promoted. In a case where a metal component is contained in the sample, gas (for example, hydrogen) is generated in the tube <NUM> due to the reaction between the sample and the reagents. The gas thus generated (and the air which has been introduced with use of the gas bubble segmenting device <NUM>) attempts to expand by the first heating step being carried out. However, in Embodiment <NUM>, a pressurizing step of applying pressure against a flow of the sample which is transferred through the tube <NUM> is carried out with use of the pressurizing device <NUM>. Therefore, the expansion of the gas is prevented.

In the first gas-liquid separating step, the gas which is present in the tube <NUM> is removed with use of the gas-liquid separating device <NUM> (5F).

In the third reagent adding step, a third reagent is added to the sample which has been subjected to the first gas-liquid separating step, with use of the reagent adding device <NUM> (3T). In Embodiment <NUM>, a hydrogen peroxide aqueous solution is, for example, used as the third reagent.

In the second heating step, a heat treatment is carried out with respect to the sample to which the third reagent has been added, with use of the heating device <NUM> (<NUM>). By carrying out the second heating step, a reaction between the sample and the third reagent is promoted, and gas (for example, oxygen) is generated in the tube <NUM> as a result of, for example, decomposition of hydrogen peroxide).

In the second gas-liquid separating step, the gas which is present in the tube <NUM> is removed with use of the gas-liquid separating device <NUM> (5F).

In the analyzing step, the sample which has been reacted with the first through third reagents is quantitatively or qualitatively analyzed.

The claimed analysis method in which the above steps are carried out is established so that a small amount of metal contained in a water sample is automatically analyzed. In the "Testing methods for industrial wastewater" of Japanese Industrial Standards, a pretreatment for an analysis of a metal element contained in a water sample is specified. However, the pretreatment involves a reaction system in which gas is generated, and therefore an automatic analysis by a conventional flow analysis method is not practically carried out. That is, the claimed analysis method in accordance with Embodiment <NUM> makes it possible to carry out an automatic analysis of a metal element contained in a water sample.

Note, here, that in a conventional analysis method, operations, such as addition of acid, heating, cooling, and dilution in a measuring flask, in a pretreatment need to be manually carried out by a human. In contrast, in the claimed analysis method, it is possible to automatically carry out the operations in the pretreatment, by employing an automatic analysis by a flow analysis method. As a result, in the claimed analysis method, it is possible to prevent occurrence of a human error, increase the speed of a treatment, and improve the efficiency of operations.

The other matters are similar to those described in Embodiment <NUM>, and therefore descriptions thereof will not be repeated and will be omitted.

Claim 1:
A flow analyzer (<NUM>) comprising:
- a sampling device (<NUM>) configured to introduce a sample into a tube (<NUM>);
- a reagent adding device (<NUM>) configured to add a reagent to the sample which is transferred through the tube (<NUM>); and
- an analyzing device (<NUM>) configured to quantitatively or qualitatively analyze the sample to which the reagent has been added,
- said flow analyzer (<NUM>) further comprising:
- a gas-liquid separating device (<NUM>) configured to sequentially remove gas which is present in the tube (<NUM>);
- a heating device (<NUM>) configured to carry out a heat treatment at a heating temperature of <NUM> or higher on the sample to which the reagent has been added; and
- a pressurizing device (<NUM>) including a compressor for introducing compressed air inside the tube (<NUM>) to apply, to the gas which is present in the tube (<NUM>) and which expands due to the heat treatment, pressure against the flow of the sample which is transferred, thereby preventing expansion of the gas,
- wherein the pressure is one applied against the flow of the sample which is transferred through the tube (<NUM>), and
- wherein the quantitative analysis or the qualitative analysis is one targeting a small amount of a metal contained in the sample.