SAMPLE PURIFICATION APPARATUS AND ANALYSIS SYSTEM

A sample purification apparatus includes a container for separating, with a heavy solution, a mixed sample based on a specific gravity difference and a collector that collects a component in the mixed sample lighter in specific gravity than the heavy solution by receiving a supernatant flowed out from the container. The container includes a flow-out port provided in an uppermost portion of the container and a flow-out path that guides the supernatant flowed out through the flow-out port to the collector. the container has a horizontal cross-sectional area which gradually decreases upward starting from a prescribed height of the container to a height where the flow-out port is located.

TECHNICAL FIELD

The present disclosure relates to a sample purification apparatus and an analysis system.

BACKGROUND ART

In order to collect a component to be collected, a mixed sample containing the component has conventionally been purified. For example, NPLs 1 and 2 disclose a method of collecting microplastic contained in a mixed sample collected from the sea by purifying the mixed sample.

CITATION LIST

Non Patent Literature

NPL 1: “GUIDELINES FOR THE MONITORING AND ASSESSMENT OF PLASTIC LITTER IN THE OCEAN,” GESAMP Reports and Studies No. 99, National Oceanic and Atmospheric Administration (NOAA), [Searched on Jun. 17, 2020], the Internet <URL:https://environmentlive.unep.org/media/docs/marine_plastics/une_science_division_gesamp_reports.pdf>NPL 2: “Guidelines for Harmonizing Ocean Surface Micro plastic Monitoring Methods,” Version 1.0. [online], May 2019, Ministry of the Environment, [Searched on Jun. 17, 2020], the Internet <URL:http://www.env.go.jp/en/water/marine_litter/guidelines/guidelines.pdt>

SUMMARY OF INVENTION

Technical Problem

According to the sample purification method disclosed in NPLs 1 and 2, in purifying a mixed sample, such a work as introduction of a heavy solution for gravity separation of the mixed sample into a container is performed. Further contrivance to accurately collect microplastic from a supernatant produced by introduction of the heavy solution has been demanded.

The present disclosure was made to solve such problems, and an object thereof is to provide a technique to accurately purify a mixed sample.

Solution to Problem

A sample purification apparatus that purifies a mixed sample according to one aspect of the present disclosure includes a container for separating, with a heavy solution, the mixed sample based on a specific gravity difference and a collector that collects a component in the mixed sample lighter in specific gravity than the heavy solution by receiving a supernatant flowed out from the container, the container includes a flow-out port provided in an uppermost portion of the container and a flow-out path that guides the supernatant flowed out through the flow-out port to the collector, and the container has a horizontal cross-sectional area which gradually decreases upward starting from a prescribed height of the container to a height where the flow-out port is located.

An analysis system according to one aspect of the present disclosure includes the sample purification apparatus described above and an analysis apparatus that analyzes a component collected by the collector of the sample purification apparatus.

Advantageous Effects of Invention

According to the present disclosure, the horizontal cross-sectional area of the container is constructed to gradually decrease upward starting from the prescribed height of the container to the height where the flow-out port is located, so that retention in the container, of the component to be collected in flowing out to the outside of the supernatant produced by introduction of the heavy solution can be prevented as much as possible. Therefore, the mixed sample can accurately be purified.

DESCRIPTION OF EMBODIMENTS

The present embodiment will be described in detail with reference to the drawings. The same or corresponding elements in the drawings have the same reference characters allotted and description thereof will not be repeated in principle.

[Configuration of Sample Purification Apparatus]

FIG.1is a diagram schematically showing a sample purification apparatus1according to the present embodiment. Sample purification apparatus1according to the present embodiment performs processing for collecting, by purifying a mixed sample under the control by a computer500, a component to be collected that is contained in the mixed sample. “Purification” encompasses purification of a mixture to a pure substance, and in the present embodiment, purification encompasses obtaining a pure substance (component) to be collected from a collected mixed sample.

Any mixed sample may be applicable so long as a “mixed sample” to be purified by sample purification apparatus1contains a component to be collected, and exemplary “mixed samples” include seawater and sand collected from the sea or the seashore and processed products such as food and cosmetics. In the present embodiment, seawater and sand collected from the sea or the seashore represent an exemplary “mixed sample.” The “mixed sample” is also simply referred to as a “sample” below.

Any component may be applicable so long as the “component” to be collected by sample purification apparatus1is collected by sample purification apparatus1according to the present embodiment, and exemplary components include microplastic. Microplastic refers, for example, to fine plastic particles each having a length not longer than 5 mm. In the present embodiment, microplastic contained in seawater and sand collected from the sea or the seashore represents an exemplary component.

As shown inFIG.1, sample purification apparatus1includes a sample purification instrument100that purifies a sample and computer500that controls sample purification instrument100.

Sample purification instrument100includes a container50where a sample is accommodated, a plurality of pipes11to15, a plurality of pumps31to34, a plurality of ports61to64, an electromagnetic valve41, a constant-temperature stirrer71, a stirring bar72, a flow-out pipe25, a detection filter21, and a container210.

Pipe11represents an exemplary “first pipe.” Pipe11is connected to a container110, and through pipe11, an oxidizing agent for treatment of a contaminant is introduced from container110into port61provided in container50. The “contaminant” refers to a foreign matter in the mixed sample, other than a component to be collected. In the present embodiment, an exemplary “contaminant” includes an organic contaminant having a property of an organic substance.

Any oxidizing agent may be applicable so long as the contaminant is treated with the “oxidizing agent.” In the present embodiment, the “contaminant” decomposes an organic contaminant. An exemplary “oxidizing agent” includes oxygenated water (H2O2) and a mixture of oxygenated water (H2O2) and iron (II) oxide (FeO). When seawater and sand are adopted as the “mixed sample,” exemplary “organic contaminants” include a scrap piece of wood mixed in seawater or sand and planktons.

Pipe12represents an exemplary “second pipe.” Pipe12is connected to a container120, and through pipe12, a heavy solution for separating a sample based on a specific gravity difference is introduced from container120into port62provided in container50.

Any heavy solution may be applicable so long as the “heavy solution” separates the sample based on the specific gravity difference. In the present embodiment, the “heavy solution” allows an inorganic contaminant having a property of an inorganic substance to settle based on the specific gravity difference. Exemplary “heavy solutions” include sodium chloride (NaCl), sodium iodide (NaI), and zinc chloride (ZnCl2). When seawater and sand are adopted as the “mixed sample.” exemplary “inorganic contaminants” include sand, glass, and stone. A specific gravity of the “heavy solution” is set to be greater than a specific gravity of the “component” to be collected by sample purification apparatus1and to be smaller than a specific gravity of the “inorganic contaminant.” For example, when microplastic is adopted as the “component” to be collected by sample purification apparatus1and sand, glass, stone, and the like are adopted as the “inorganic contaminant,” the “heavy solution” should only be greater in specific gravity than microplastic and should only be smaller in specific gravity than sand, glass, stone, and the like. Specifically, the specific gravity of the “heavy solution” should only be set approximately to 1.5 to 1.7.

Pipe13represents an exemplary “fourth pipe.” Pipe13is connected to a container130, and through pipe13, a rinse solution for cleaning of the inside of container50is introduced from container130into port63provided in container50.

Any rinse solution may be applicable so long as the inside of container50is cleaned with the “rinse solution,” and an exemplary “rinse solution” includes water.

Pipe14and pipe15represent an exemplary “third pipe.” Pipe14is connected to a container140, and through pipe14, a waste solution in container50is discharged through port64provided in container50into container140. Pipe15is connected to a container ISO, and through pipe15, the waste solution in container50is discharged through port64provided in container50into container150.

Pump31is provided between pipe11and container50, and as valve31aoperates under the control by computer500, pump31suctions the oxidizing agent accommodated in container110and introduces the oxidizing agent toward port61. Pump32is provided between pipe12and container50, and as valve32aoperates under the control by computer500, pump32suctions the heavy solution accommodated in container120and introduces the heavy solution toward port62. Pump33is provided between pipe13and container50, and as valve33aoperates under the control by computer500, pump33suctions the rinse solution accommodated in container130and introduces the rinse solution toward port63. Pump34is provided between each of pipes14and15and container50, and as valve34aoperates under the control by computer500, pump34suctions the waste solution in container50and discharges the waste solution through port64toward container140or150. Each of valves31ato34arepresents an exemplary “switching unit” and switches between entry and exit of a solution by opening and closing of a passage provided in each of pumps31to34.

Any switching unit may be applicable so long as the “switching unit” switches between entry and exit of a solution in each of pipes11to15. For example, the “switching unit” may allow suction and delivery by reciprocating motion of a piston or the like or by rotary motion of a gear or the like. The “solution” includes the oxidizing agent, the heavy solution, the rinse solution, the waste solution, and the like.

Ports61and64serve as an inlet and an outlet for entry and exit of a solution provided in an outer circumferential portion of container50. In the inside of each of ports61to64, a filter (for example, a filter163or164shown inFIG.16which will be described later) is provided so as not to allow discharge of a component contained in a sample to the outside.

Electromagnetic valve41is provided between each of pipes14and15and pump34, and as electromagnetic valve41operates under the control by computer500, electromagnetic valve41switches a path through which the waste solution passes between a path between pipe14and pump34and a path between pipe IS and pump34.

Constant-temperature stirrer71represents an exemplary “stirring unit” and an exemplary “heating unit.” Container50is carried on constant-temperature stirrer71. Constant-temperature stirrer71stirs a sample accommodated in container50by rotation of a stirring bar72provided in container50under the control by computer500. Furthermore, constant-temperature stirrer71applies heat to container50to keep the temperature of the sample accommodated in container50constant.

Flow-out pipe25is connected to a flow-out port20provided at an uppermost portion of container50, and through flow-out pipe25, a supernatant of the sample that overflows container50is flowed out to the outside. Flow-out port20represents an exemplary “flow-out portion.” Flow-out pipe25represents an exemplary “flow-out path.” Detection filter21collects, by filtering the supernatant of the sample flowed out through flow-out pipe25, a component to be collected that is contained in the supernatant. The supernatant that has passed through detection filter21is collected in container210. In a preferred embodiment, detection filter21is a filter capable of trapping microplastic to be collected. A specific example of the filter includes a wire gauze made of SUS (stainless steel) or a membrane filter made of PTFE (made of Teflon™). Detection filter21represents an exemplary “collector.”

Computer500may be implemented by a general-purpose computer or a dedicated computer for controlling sample purification instrument100. Computer500controls each of valves31ato34a, electromagnetic valve41, and constant-temperature stirrer71in sample purification instrument100.

Specifically, computer500has electric power provided to a motor (not shown) in each of valves31ato34ato drive the motor. Drive force from the motor opens and closes valves31ato34aso that pumps31to34suction and deliver a solution.

Computer500has a current flow to a solenoid (not shown) of electromagnetic valve41to open and close a valve (not shown) to thereby switch between paths through which the waste solution passes.

Furthermore, computer500has electric power provided to a motor (not shown) of constant-temperature stirrer71to drive the motor. Drive force from the motor rotates stirring bar72to thereby stir the sample accommodated in container50. In addition, computer500has electric power provided to a heater (not shown) of constant-temperature stirrer71to apply certain heat to container50.

FIG.2is a diagram schematically showing an internal configuration of sample purification apparatus1according to the present embodiment. As shown inFIG.2, computer500includes, as main hardware elements thereof, a computing device501, a memory502, a network controller503, a display device504, an input device505, a data reading device506, and a storage510.

Computing device501represents an exemplary “control unit.” Computing device501is a processing entity that performs various types of processing by executing various programs. For example, computing device501performs sample purification processing (which will be described later with reference toFIG.14) for controlling each of valves31ato34a, electromagnetic valve41, and constant-temperature stirrer71in sample purification instrument100by executing a control program511which will be described later.

Computing device501is implemented, for example, by a central processing unit (CPU), a field programmable gate array (FPGA), a graphics processing unit (GPU), and the like. Computing device501may be implemented by processing circuitry that performs computing.

Though computing device501included in computer500is provided as an exemplary “control unit” in the present embodiment, the “control unit” may be a controller such as a programmable logic controller (PLC) that subjects each feature to sequence control in accordance with a program created by a user. Furthermore, though the “control unit” is separate from sample purification instrument100in the present embodiment, the “control unit” may be integrated with sample purification instrument100. For example, sample purification instrument100may contain a device corresponding to computing device501.

Memory502provides a storage area where a program code or a work memory is temporarily stored in execution of any program by computing device501. Memory502is implemented, for example, by a volatile memory device such as a dynamic random access memory (DRAM) or a static random access memory (SRAM).

Network controller503carries out transmission and reception to and from another device over a network (not shown). Network controller503is in conformity with any communication scheme such as Ethernet®, wireless local area network (LAN), and Bluetooth®.

Display device504is implemented, for example, by a liquid crystal display (LCD), and shows a program design screen or an alert screen on the occurrence of an abnormal condition.

Input device505is implemented, for example, by a keyboard, a mouse, and the like, and used for input of design information by a user in design of a program. Input device505may be implemented by a start switch for starting sample purification processing by computing device501.

Data reading device506is a device for reading data stored in a storage medium507. Any storage medium such as a compact disc (CD), a digital versatile disc (DVD), and a universal serial bus (USB) memory may be applicable so long as various types of data can be stored in storage medium507.

Storage510provides a storage area where various types of data required for sample purification processing or the like are stored. Storage510is implemented, for example, by a non-volatile memory device such as a hard disk or a solid state drive (SSD). Control program511, control data512, and an operating system (OS)513are stored in storage510.

Control program511is a program in which contents of sample purification processing are described, and executed by computing device501. Control program511may be designed by a user with the use of input device505, read from storage medium507by data reading device506, or obtained through the network from another device such as a server by network controller503.

Control data512is data used in execution of control program511by computing device501. For example, control data512includes data for controlling each of valves31ato34a, electromagnetic valve41, and constant-temperature stirrer71. Control data512may be inputted by a user with the use of input device505, read from storage medium507by data reading device506, or obtained through the network from another device such as a server by network controller503.

OS513provides a basic function for computing device501to perform various types of processing.

A sample purification method with the use of sample purification apparatus1will be described with reference toFIGS.3to13.FIGS.3to13are diagrams for illustrating the sample purification method with the use of sample purification apparatus1according to the present embodiment.

For prior preparation, a user such as a worker prepares container110, container120, container130, container140, container150, container210, and detection filter21. The user places the oxidizing agent in container110and inserts pipe11into container110. The user places the heavy solution in container120and inserts pipe12into container120. The user places the rinse solution in container130and inserts pipe13into container130. The user inserts pipe14into container140and inserts pipe15into container150. At this stage, each of containers140and150is empty. The user arranges detection filter21and container210around an outlet of flow-out pipe25in this order from a side of flow-out pipe25.

As shown inFIG.3, the user introduces the sample (mixed sample) into container50of sample purification apparatus1. For example, the user separates a part of container50constituted of a plurality of members to open container50and feeds the sample into container50. Thereafter, the user performs a start operation with the use of input device505of computer500to start control of sample purification instrument100by computer500.

As control by computer500is started, as shown inFIG.4, computer500controls valve34aand electromagnetic valve41to discharge the waste solution in container50to container140through port64and pipe14. The sample accommodated in container50contains the waste solution such as seawater, and such waste solution is discharged to container140. Microplastic to be collected that is contained in the sample, on the other hand, is not discharged to the outside owing to filter164(seeFIG.16) included in port64but remains in container50.

Then, as shown inFIG.5, computer500controls valve31ato introduce the oxidizing agent accommodated in container110into container50through pipe11and port61. At this time, computer500controls an amount of suction by pump31to introduce the oxidizing agent in an amount set in advance by the user into container50. For example, computer500adjusts opening of valve31aof pump31to control the amount of suction by pump31. Alternatively, computer500may control the amount of suction by pump31based on a detection value of a liquid level sensor provided in container110or container50.

Then, as shown inFIG.6, computer500controls constant-temperature stirrer71to rotate stirring bar72provided in container50while certain heat is applied to container50. A temperature of container50and a rotation speed and a time period of rotation of stirring bar72are set in advance by the user. For example, computer500controls constant-temperature stirrer71to stir the sample accommodated in container50for approximately three days while container50is kept at a temperature around 75 degrees. As the sample is thus stirred, oxidation treatment with the oxidizing agent is performed and an organic contaminant contained in the sample is decomposed. Though heating is not necessarily required in stirring of the sample, decomposition by oxidation treatment tends to be expedited by heating to keep the temperature of the sample constant.

Then, as shown inFIG.7, computer500controls valve34aand electromagnetic valve41to discharge to container140through port64and pipe14, the waste solution in container50contained in the sample where the organic contaminant has been decomposed. Microplastic to be collected that is contained in the sample, on the other hand, is not discharged to the outside owing to filter164included in port64but remains in container50.

Then, as shown inFIG.8, computer500controls pump33to introduce the rinse solution accommodated in container130into container50through pipe13and port63. At this time, computer500controls an amount of suction by pump33to introduce the rinse solution in an amount set in advance by the user into container50. For example, computer500adjusts opening of valve33ato control the amount of suction by pump33. Alternatively, computer500may control the amount of suction by pump33based on a detection value from a liquid level sensor provided in container130or container50.

Then, as shown inFIG.9, computer500controls valve34aand electromagnetic valve41to discharge through port64and pipe14to container140, the waste solution in container50into which the rinse solution has been introduced. The inside of container50is thus cleaned with the rinse solution. Microplastic to be collected that is contained in the sample, on the other hand, is not discharged to the outside owing to filter164included in port64but remains in container50.

Thereafter, computer500has the sample left as it is for a prescribed time period (for example, for one day) to dry the sample. Then, as shown inFIG.10, computer500controls valve32ato introduce the heavy solution accommodated in container120into container50through pipe12and port62. At this time, computer500controls an amount of suction by pump32to introduce the heavy solution in an amount set in advance by the user into container50. For example, computer500adjusts opening of valve32ato control the amount of suction by pump32. Alternatively, computer500may control the amount of suction by pump32based on a detection value from a liquid level sensor provided in container120or container50.

As the heavy solution is thus introduced to the sample, an inorganic contaminant contained in the sample settles around the bottom of container50owing to a specific gravity difference. The liquid level of the sample separated by gravity gradually rises in container50and the supernatant of the sample soon reaches flow-out port20of container50. Then, the supernatant of the sample is flowed out to the outside through flow-out port20and flow-out pipe25. The supernatant of the sample flowed out through flow-out pipe25is filtered by detection filter21, and only the waste solution is collected in container210. Microplastic which is a component lighter in specific gravity than the heavy solution remains at detection filter21. Such gravity separation requires approximately one day, and hence computer500controls introduction of the heavy solution to the sample during that period.

As set forth above, sample purification apparatus1according to the present embodiment can purify the sample through successive works with the use of a single container50. Specifically, as shown inFIGS.3to10, computer500controls sample purification instrument100to automatically introduce the oxidizing agent and the heavy solution to the sample accommodated in container50at appropriate timing for an appropriate period of time and to discharge the waste solution from container50. Therefore, the user himself/herself does not have to introduce the oxidizing agent and the heavy solution into container50and to discharge the waste solution from container50. Thus, time and efforts of the user are not required or variation in accuracy in collection of a component depending on skills of each user is unlikely, and the user can accurately purify the sample with time and efforts being minimized.

After microplastic is collected by purification of the sample, container50is cleaned in post-treatment. Specifically, as shown inFIG.11, computer500controls valve34aand electromagnetic valve41to discharge the waste solution in container50from which microplastic has been collected to container150through port64and pipe15.

Then, as shown inFIG.12, computer500controls valve33ato introduce the rinse solution accommodated in container130into container50through pipe13and port63. At this time, computer500controls the amount of suction by pump33to introduce the rinse solution in an amount set in advance by the user into container50. For example, computer500adjusts opening of valve33ato control the amount of suction by pump33. Alternatively, computer500may control the amount of suction by pump33based on a detection value from the liquid level sensor provided in container130or container50.

Then, as shown inFIG.13, computer500controls valve34aand electromagnetic valve41to discharge to container150through port64and pipe15, the waste solution in container50into which the rinse solution has been introduced. The inside of container50is thus cleaned with the rinse solution.

As set forth above, according to sample purification apparatus1according to the present embodiment, after microplastic is collected, computer500controls sample purification instrument100to automatically clean used container50. Therefore, the user himself/herself does not have to clean container50so that time and efforts are minimized.

FIG.14is a flowchart for illustrating sample purification processing performed by sample purification apparatus1according to the present embodiment. Each step shown inFIG.14is performed by execution of OS513and control program511by computing device501of computer500. “S” in the drawings is used as abbreviation of “STEP”.

When computer500receives a start operation through input device505while the sample is located in container50of sample purification apparatus1, computer500performs sample purification processing shown inFIG.14. As shown inFIG.14, computer500initially controls valve34aand electromagnetic valve41to discharge the waste solution in container50to container140(S1).

Then, computer500determines whether or not discharge of the waste solution has been completed (S2). For example, computer500determines whether or not discharge of the waste solution has been completed based on opening of valve34aor a detection value from the liquid level sensor provided in container140or container50.

When discharge of the waste solution has not been completed (NO in S2), computer500repeats processing in S2. When discharge of the waste solution has been completed (YES in S2), computer500controls valve31ato introduce the oxidizing agent accommodated in container110into container50(S3).

Then, computer500determines whether or not introduction of the oxidizing agent has been completed (S4). For example, computer500determines whether or not introduction of the oxidizing agent has been completed based on opening of valve31aor a detection value from the liquid level sensor provided in container110or container50.

When introduction of the oxidizing agent has not been completed (NO in S4), computer500repeats processing in S4. When introduction of the oxidizing agent has been completed (YES in54), computer500controls constant-temperature stirrer71to stir the sample with stirring bar72while constant heat is applied to the sample (S5).

Then, computer500determines whether or not stirring of the sample has been completed (S6). For example, computer500determines whether or not stirring of the sample has been completed based on a count value from a timer (not shown).

When stirring of the sample has not been completed (NO in56), computer500repeats processing in S6. When stirring has been completed (YES in S6), computer500controls valve34aand electromagnetic valve41to discharge to container140, the waste solution in container50contained in the sample in which the organic contaminant has been decomposed (S7).

Then, computer500determines whether or not discharge of the waste solution has been completed (8). For example, computer500determines whether or not discharge of the waste solution has been completed based on opening of valve34aor a detection value from the liquid level sensor provided in container140or container50.

When discharge of the waste solution has not been completed (NO in S8), computer500repeats processing in S8. When discharge of the waste solution has been completed (YES in S8), computer500controls valve33ato introduce the rinse solution accommodated in container130into container50(S9).

Then, computer500determines whether or not introduction of the rinse solution has been completed (S10). For example, computer500determines whether or not introduction of the rinse solution has been completed based on opening of valve33aor a detection value from the liquid level sensor provided in container130or container50.

When introduction of the rinse solution has not been completed (NO in S10), computer500repeats processing in S10. When introduction of the rinse solution has been completed (YES in S10), computer500controls valve34aand electromagnetic valve41to discharge the waste solution in container50into which the rinse solution has been introduced to container140(S11).

Then, computer500determines whether or not discharge of the waste solution has been completed (S12). For example, computer500determines whether or not discharge of the waste solution has been completed based on opening of valve34aor a detection value from the liquid level sensor provided in container140or container50.

When discharge of the waste solution has not been completed (NO in S12), computer500repeats processing in S12. When discharge of the waste solution has been completed (YES in S12), computer500controls valve32ato introduce the heavy solution accommodated in container120into container50(S13).

Then, computer500determines whether or not introduction of the heavy solution has been completed (S13). For example, computer500determines whether or not introduction of the heavy solution has been completed based on opening of valve32aor a detection value from the liquid level sensor provided in container120or container50.

When introduction of the heavy solution has not been completed (NO in S14), computer500repeats processing in S14.

As the heavy solution is thus introduced, an inorganic contaminant contained in the sample settles around the bottom of container50owing to the specific gravity difference, while the supernatant of the sample is flowed out to the outside through flow-out port20and flow-out pipe25. Then, the supernatant of the sample flowed out through flow-out pipe25is filtered through detection filter21, which collects microplastic.

When introduction of the heavy solution has been completed (YES in S14), that is, after microplastic is collected by gravity separation over approximately one day, computer500controls valve34aand electromagnetic valve41to discharge the waste solution in container50from which microplastic has been collected to container150.

Then, computer500determines whether or not discharge of the waste solution has been completed (S16). For example, computer500determines whether or not discharge of the waste solution has been completed based on opening of valve34aor a detection value from a liquid level sensor provided in container150or container50.

When discharge of the waste solution has not been completed (NO in S16), computer500repeats processing in S16. When discharge of the waste solution has been completed (YES in S16), computer500controls valve33ato introduce the rinse solution accommodated in container130into container50(S17).

Then, computer500determines whether or not introduction of the rinse solution has been completed (S18). For example, computer500determines whether or not introduction of the rinse solution has been completed based on opening of valve33aor a detection value from the liquid level sensor provided in container130or container50.

When introduction of the rinse solution has not been completed (NO in S18), computer500repeats processing in S18. When introduction of the rinse solution has been completed (YES in S18), computer500controls valve34aand electromagnetic valve41to discharge the waste solution in container50into which the rinse solution has been introduced to container150(S19) and quits the present process.

Through such post-treatment as introduction of the rinse solution and discharge of the waste solution, the inside of container50is cleaned.

As set forth above, according to sample purification apparatus1according to the present embodiment, as computer500executes control program511, the oxidizing agent and the heavy solution are automatically introduced to the sample accommodated in container50and the waste solution is discharged from container50at appropriate timing for an appropriate period of time. Therefore, the user himself/herself does not have to introduce the oxidizing agent and the heavy solution into container50and to discharge the waste solution from container50. Time and efforts of the user are not required or variation in accuracy in collection of a component depending on skills of each user is unlikely, and the user can accurately purify the sample with time and efforts being minimized.

Furthermore, according to sample purification apparatus1according to the present embodiment, computer500executes control program511to automatically clean used container50after microplastic is collected. Therefore, the user himself/herself does not have to clean container50so that time and efforts are minimized.

[Shape of Container of Sample Purification Apparatus]

FIGS.15and16are diagrams for illustrating a shape of container50in sample purification apparatus1according to the present embodiment. As described above, in sample purification apparatus1, the sample can be purified with the use of container50in sample purification instrument100. The shape of container50is devised to accurately purify the sample.

Specifically, as shown inFIGS.15and16, container50includes main body portions51to54. Main body portion51represents an exemplary “first main body portion” Main body portion52represents an exemplary “second main body portion.” Main body portion53represents an exemplary “third main body portion.”

Main body portion54is located at a lowermost portion of the container and includes a bottom surface155and a side surface154. Side surface154of main body portion54is formed to surround a central axis160of columnar container50, and in a part thereof, a hole156leading to port63and a hole157leading to port64are provided. In the inside of port63, filter163is provided. In the inside of port64, filter164is provided. Each of port63(hole156) and port64(hole157) is provided at a position below a central portion of main body portion54and in a portion close to bottom surface155. Though not shown, a filter is provided also in the inside of each of other ports61and62.

Main body portion51is provided above main body portion54and includes a side surface151formed as being contiguous to side surface154of main body portion54. Side surface151is formed to surround central axis160of container50and to increase in diameter downward (toward bottom surface155) from an upper side of container50(a side of flow-out port20).

Main body portion52is provided above main body portion51and includes a side surface152formed as being contiguous to side surface151of main body portion51. Side surface152is formed to surround central axis160of container50and to expand from an upper portion521and a lower portion522of main body portion52toward a portion located between upper portion521and lower portion522. In other words, side surface152is formed to expand from central axis160of container50toward an outer circumferential side of main body portion52. From another point of view, a horizontal cross-sectional area (or an inner diameter) of main body portion52is constructed to continuously increase from each of upper portion521and lower portion522of main body portion52toward the portion located between upper portion521and lower portion522.

Main body portion53is provided above main body portion52and includes a side surface153formed as being contiguous to side surface152of main body portion52. Side surface153is formed to surround central axis160of container50and to be tapered upward (the side of flow-out port20) from a lower side of container50(a side of bottom surface155). From another point of view, a horizontal cross-sectional area (or an inner diameter) of main body portion52is constructed to continuously decrease in an upward direction where flow-out port25is located. The horizontal cross-sectional area (or the inner diameter) of container50is thus constructed to continuously decrease upward between at least a prescribed height of container50(in this example, a height where upper portion521of main body portion52is located) and flow-out port25. Though side surface153of main body portion53is linear in the present embodiment, it may be curved, and the horizontal cross-sectional area (or the inner diameter) of main body portion53should only be constructed to continuously decrease in the upward direction where flow-out port25is located.

Flow-out port20is a hole which is provided at a position opposed to bottom surface155of container50, as being contiguous to side surface153of container50, and leads to flow-out pipe25. Flow-out port20is smaller in horizontal cross-sectional area (or inner diameter) than each of upper portion521and lower portion522of main body portion52.

Main body portion53is formed as being integrated with main body portion52. Main body portion52and main body portion51can be separated from each other, and the user can open container50by separating main body portion52from main body portion51to feed the sample into container50.

As set forth above, according to sample purification apparatus1according to the present embodiment, side surface153of a part of container50is formed as being tapered from the side of bottom surface155toward flow-out port20. In other words, the horizontal cross-sectional area of container50is constructed to continuously decrease upward between the at least prescribed height of container50and flow-out port25. Therefore, a boundary between side surface153of container50and flow-out port20can be smoothened as much as possible. Thus, in flowing out of the supernatant of the sample separated by gravity with the use of the heavy solution to the outside through flow-out port20, retention of microplastic in container50can be prevented as much as possible. For example, when the boundary between the side surface of container50and flow-out port20is not smooth but square-cornered, the supernatant of the sample separated by gravity with the use of the heavy solution may impinge on the square-cornered portion and microplastic to be collected may adhere to the inside of container50, and the microplastic may be retained in container50without moving to flow-out port25. In contrast, the boundary between side surface153of container50and flow-out port20is smoothened as much as possible as in container50according to the present embodiment, so that adhesion and retention of microplastic in container50can be prevented as much as possible. Therefore, the user can accurately purify the sample.

Since side surface152in a part of container50is formed to expand from upper portion521and lower portion522toward the portion located between upper portion521and lower portion522, adhesion and retention of microplastic in container50can be prevented as much as possible. Furthermore, side surface152of the part (main body portion52) of container50once expands, and additionally thereabove, the horizontal cross-sectional area of the part (main body portion53) of container50continuously decreases toward flow-out port25. Therefore, the supernatant of the sample that has risen by introduction of the heavy solution can spread in main body portion52, and thereafter, owing to the tapered portion of main body portion53, the supernatant can be directed to flow-out port25with great strength.

Since tapered main body portion53and main body portion52formed to expand are formed as being integrated with each other, strength of container50can be enhanced. Furthermore, since there is no boundary between main body portion53and main body portion52, the supernatant of the sample that has risen owing to introduction of the heavy solution does not adhere to the boundary between main body portion53and main body portion52and the supernatant can more efficiently be directed to flow-out port25.

FIG.17is a diagram schematically showing an analysis system1000according to the present embodiment. Analysis system1000includes sample purification apparatus1according to the present embodiment described above, a classification apparatus600, and an analysis apparatus700.

Classification apparatus600classifies microplastic collected by sample purification apparatus1for each size of particles. An exemplary classification apparatus600includes a field flow fractionation apparatus that classifies particles with the use of centrifugation.

Analysis apparatus700analyzes microplastic classified by classification apparatus600. As an analysis result obtained by analysis apparatus700is shown on a screen (not shown), a user obtains the analysis result.

In analysis system1000configured as described above, under the control by computer500, sample purification apparatus1collects microplastic, and thereafter classification apparatus600classifies microplastic and analysis apparatus700analyzes the microplastic.

As set forth above, according to analysis system1000according to the present embodiment, since a series of works from introduction of the sample into sample purification apparatus1until analysis of microplastic by analysis apparatus700is automated by control by computer500, convenience of the user is improved.

Analysis system1000does not have to include classification apparatus600, and analysis apparatus700may directly obtain microplastic collected by sample purification apparatus1and then analyze the same.

Though sample purification apparatus1and analysis system1000according to the present embodiment are described above, the configuration thereof can further variously be modified and applied. A modification will be described below.

FIG.18is a diagram schematically showing a sample purification apparatus1A according to a second embodiment. As shown inFIG.18, in a sample purification instrument100A of sample purification apparatus1A, through pipe12for introduction of the heavy solution and pipe13for introduction of the rinse solution, solutions may be introduced to port62common therebetween.

Specifically, a pump232(a valve232a) and an electromagnetic valve242are provided between each of pipes12and13and port62of container50.

Electromagnetic valve242operates under the control by a computer500A to switch a path for passage of a solution between a path between pipe12and pump232and a path between pipe13and pump232.

Thus, the heavy solution suctioned from container120through pipe12is introduced to port62through electromagnetic valve242and pump232. The rinse solution suctioned from container130through pipe13is introduced to port62through electromagnetic valve242and pump232.

As set forth above, according to sample purification apparatus1A according to the second embodiment, pump232(valve232a) provided between pipe12and port62of container50is identical to pump232(valve232a) provided between pipe13and port62of container50, so that the number of parts of sample purification apparatus1A can be reduced and cost can be suppressed.

FIG.19is a diagram schematically showing a sample purification apparatus1B according to a third embodiment. As shown inFIG.19, a sample purification instrument100B of sample purification apparatus1B may be constructed to introduce a sample from above container50.

Specifically, sample purification instrument100B includes a flow-out pipe25A through which the supernatant of the sample that overflows container50is flowed out toward detection filter21and an introduction pipe25B through which the sample containing microplastic is introduced from the outside into container50. Flow-out pipe25A represents an exemplary “flow-out path” and introduction pipe25B represents an exemplary “introduction path.” An electromagnetic valve45is provided between each of flow-out pipe25A and introduction pipe25B and flow-out port20of container50. Electromagnetic valve45operates under the control by a computer500B to switch a path for passage of a solution between a path between flow-out pipe25A and flow-out port20and a path between introduction pipe25B and flow-out port20.

Thus, under the control by computer500, the supernatant of the sample that overflows container50is flowed out to detection filter21through electromagnetic valve45and flow-out pipe25A. Under the control by computer500, an externally introduced sample is introduced into container50through introduction pipe25B and electromagnetic valve45.

As set forth above, according to sample purification apparatus1B according to the third embodiment, the sample can be introduced from above container50by making use of flow-out port20, so that more convenient sample purification apparatus1B can be provided to the user.

Illustrative embodiments described above are understood by a person skilled in the art as specific examples of aspects below.

(Clause 1) A sample purification apparatus that purifies a mixed sample according to one aspect includes a container for separating, with a heavy solution, the mixed sample based on a specific gravity difference and a collector that collects a component in the mixed sample lighter in specific gravity than the heavy solution by receiving a supernatant flowed out from the container, the container includes a flow-out port provided in an uppermost portion of the container and a flow-out path that guides the supernatant flowed out through the flow-out port to the collector, and the container has a horizontal cross-sectional area which gradually decreases upward starting from a prescribed height of the container to a height where the flow-out port is located.

According to the sample purification apparatus described in Clause 1, the horizontal cross-sectional area of the container is constructed to continuously decrease upward between at least the prescribed height of the container and the flow-out port, so that retention in the container, of the component to be collected in flowing out to the outside of the supernatant produced by introduction of the heavy solution can be prevented as much as possible. Therefore, the mixed sample can accurately be purified.

(Clause 2) In the sample purification apparatus described in Clause 1, the container includes a first main body portion, a second main body portion provided above the first main body portion, and a third main body portion provided above the second main body portion, a horizontal cross-sectional area of the third main body portion is constructed to continuously decrease in an upward direction where the flow-out port is located, and a horizontal cross-sectional area of the second main body portion is constructed to continuously increase from each of an upper portion and a lower portion of the second main body portion toward a portion located between the upper portion and the lower portion.

According to the sample purification apparatus described in Clause 2, adhesion and retention of the component to be collected in the container can be prevented as much as possible. Furthermore, the second main body portion of container50once expands, and additionally thereabove, the horizontal cross-sectional area of the third main body portion of container50continuously decreases toward the flow-out port. Therefore, the supernatant of the mixed sample that has risen by introduction of the heavy solution can spread in the second main body portion, and thereafter, owing to the tapered portion of the third main body portion, the supernatant can be directed to the flow-out port with great strength.

(Clause 3) In the sample purification apparatus described in Clause 2, the third main body portion is formed as being integrated with the second main body portion. According to the sample purification apparatus described in Clause 3, since the tapered third main body portion and the second main body portion formed to expand are formed as being integrated with each other, strength of the container can be enhanced. Furthermore, since there is no boundary between the third main body portion and the second main body portion, the supernatant of the mixed sample that has risen owing to introduction of the heavy solution does not adhere to the boundary between the third main body portion and the second main body portion and the supernatant can more efficiently be directed to the flow-out port.

(Clause 4) The sample purification apparatus described in any one of Clauses 1 to 3 includes a first pipe for introduction into the container, of an oxidizing agent for treatment of a contaminant contained in the mixed sample, a second pipe for introduction of the heavy solution into the container, a third pipe for discharge of a waste solution in the container, a fourth pipe for introduction into the container, of a rinse solution for cleaning of the inside of the container, and at least one port provided in the container, a solution coming in and going out between the at least one port and the first pipe, the second pipe, the third pipe, and the fourth pipe.

According to the sample purification apparatus described in Clause 4, since the mixed sample can be purified through successive works with the use of a single container, the mixed sample can accurately be purified with time and efforts of a user such as a worker being minimized.

(Clause 5) In the sample purification apparatus described in Clause 4, the at least one port corresponding to each of the first pipe, the second pipe, and the fourth pipe is different from the at least one port corresponding to the third pipe.

According to the sample purification apparatus described in Clause 5, since the port through which a solution passes can be different between the pipe through which the solution (the oxidizing agent, the heavy solution, or the rinse solution) is introduced into the container and the pipe through which the waste solution is flowed out from the container to the outside, the mixed sample can more accurately be purified.

(Clause 6) In the sample purification apparatus described in Clause 4, the at least one port corresponding to the second pipe is identical to the at least one port corresponding to the fourth pipe.

According to the sample purification apparatus described in Clause 6, the number of parts of the sample purification apparatus can be reduced and cost can be suppressed.

(Clause 7) In the sample purification apparatus described in any one of Clauses 4 to 6, the at least one port includes a filter.

According to the sample purification apparatus described in Clause 7, discharge to the outside, of a component to be collected that is contained in the mixed sample can be prevented as much as possible.

(Clause 8) In the sample purification apparatus described in any one of Clauses 1 to 7, the flow-out port is connected to the flow-out path, and connected to an introduction path for introduction of the mixed sample into the container.

According to the sample purification apparatus described in Clause 8, the mixed sample can be introduced from above the container by making use of the flow-out port, so that a more convenient sample purification apparatus can be provided to the user.

(Clause 9) The sample purification apparatus described in Clause 8 includes at least one switching unit provided between each of the introduction path and the flow-out path and the flow-out port, the at least one switching unit switching between entry and exit of a solution.

According to the sample purification apparatus described in Clause 9, since the mixed sample can be purified with the use of the switching unit, the mixed sample can accurately be purified with time and efforts of a user being minimized.

(Clause 10) An analysis system according to one aspect includes the sample purification apparatus described in any one of Clauses 1 to 9 and an analysis apparatus that analyzes the component collected by the collector of the sample purification apparatus.

According to the analysis system described in Clause 10, since a series of works from introduction of the mixed sample into the sample purification apparatus until analysis of the component to be collected by the analysis apparatus is automated by control by the control unit, convenience of the user is improved.

REFERENCE SIGNS LIST