Microplastic collection container and microplastic collection device

Abstract

Provided are a container and device for collecting microplastics that can reduce the frequency of abnormal peaks appearing in a pyrogram derived from the collected microplastics. [Solution] Microplastics are efficiently collected using a microplastic collection container C and a microplastic collection device 50 equipped with said collection container C. As described above, the collected microplastics are heated together with the collection container C in the polymer sample analyzer to be thermally decomposed or volatilized, or the components contained in the sample are heated to thermally desorb or thermally decompose, generating a gaseous component mixture. The surfaces of the container body C0 and filter F of the metal sample container C are both inactivated.

Description

[Technical Field]

[0001] The present invention relates to a technique for collecting microplastics. [Background technology]

[0002] A conventional technique for capturing microplastics using a filter installed inside a sample cup for a pyrolyzer has been proposed (see, for example, Patent Document 1). Specifically, a substantially planar filter is pressed into a cylindrical sample cup with an opening at the bottom, creating a funnel-shaped filter inside the sample cup. The filter is made of, for example, stainless steel, glass, Teflon (registered trademark), or cellulose acetate resin. The sample cup is placed in the middle of a passageway, and while the downstream side of the passageway is vacuum-suctioned, a liquid such as water is passed through the sample cup from the upstream side of the passageway. The filter installed inside the sample cup captures microplastics contained in the liquid. The sample cup is then dried and placed in the heating furnace of the pyrolyzer. The gas phase components of the captured microplastics are detected and analyzed using a detector such as a mass spectrometer (MS) used in gas chromatography.

[0003] In addition, a method has been proposed in which a roughly circular filter made of woven stainless steel fibers with a wire diameter of 13 μm is welded at its peripheral edge to a roughly cylindrical base to create a roughly bottomed cylindrical sample cup, and microplastics are then collected using this sample cup (see Non-Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Korean Patent Publication No. 10-2537830 [Non-patent literature]

[0005] [Non-Patent Document 1] U.Braun, K.Altmann, C.Bannick et al. (2021) Smart filters for the analysis of microplastic in beverages filled in plastic bottles, Food Additives & Contaminants:PartA, 38:4, 691-700, DOI:10.1080 / 19440049.2021.1889042 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] However, in pyrolysis (Py-) / thermal desorption (TD-) GC / MS analysis, if the metal filter placed in the sample cup is not deactivated, the active metal sites on the filter may cause catalytic decomposition of the analyte, potentially reducing the reliability of the analytical results.

[0007] Therefore, the present invention aims to provide a container and device for collecting microplastics that can reduce the frequency of abnormal peaks in TD-GC / MS chromatograms and / or pyrograms derived from the collected microplastics. [Means for solving the problem]

[0008] The microplastic collection container of the present invention is a metal container body having a liquid passage; a metal filter provided in the container body so as to block the liquid passage while allowing liquid to pass through and capable of capturing microplastics; The surfaces of the container body and the filter are each subjected to a deactivation treatment.

[0009] The microplastic collection device of the present invention is The microplastic collection container; A liquid supply unit that supplies liquid to the liquid passage of the microplastic collection container upstream of the filter; and a vacuum suction device that vacuums the space in the liquid passage of the microplastic collection container that is connected to the downstream side of the filter. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram of the configuration of a microplastic collection device as one embodiment of the present invention. [Figure 2] FIG. 1 is an explanatory diagram of the configuration of a microplastic collection container as one embodiment of the present invention. [Figure 3] FIG. 1 is an explanatory diagram of the configuration of a polymer sample analyzer. [Figure 4] TD-GC / MS chromatogram when the collection container of the example is used. [Figure 5] TD-GC / MS chromatogram when a comparative collection vessel was used. DETAILED DESCRIPTION OF THE INVENTION

[0011] (composition) The microplastic collection device 50 (hereinafter referred to as the "collection device" as appropriate) shown in Figure 1 as one embodiment of the present invention comprises a microplastic collection container C (hereinafter referred to as the "collection container" as appropriate), a liquid supply section 51, a liquid recovery section 52, and a vacuum suction device 53.

[0012] The collection container C according to one embodiment of the present invention shown in FIG. 2 includes a container body C0 and a filter F. The container body C0 is made of a metal such as stainless steel, has a generally cylindrical shape with a bottom, and has a liquid passage extending from an upper liquid inlet C1 to a lower liquid outlet C2. The container body C0 may have various shapes, such as a generally rectangular cylinder with a bottom, a generally hemispherical shape, or a generally semi-elliptical spherical shape, in addition to a generally cylindrical shape with a bottom. For example, the diameter φ1 of the liquid inlet C1 (or the inner diameter of the container body C0) is 3.9 to 4.1 mm, and the diameter φ2 (<φ1) of the liquid outlet C2 is 1 to 3 mm. The filter F is made of a mesh of thin metal wires such as stainless steel with a wire diameter of 10 to 50 μm and a mesh size of 10 to 40 μm. For example, one or more filters F are formed into a generally circular shape slightly larger than the inner diameter of the container body C0, and are then inserted into the liquid passage of the container body C0 through the liquid inlet C1. As a result, the filter F is installed or disposed in the liquid passage of the container body C0 with the outer peripheral edge of the filter F being pressed against the inner peripheral wall of the container body C0 over the entire circumference or substantially the entire circumference.

[0013] For example, one or more filters F may be formed into a substantially circular or rectangular shape larger than the inner diameter of the container body C0, and then pushed into the liquid passage of the container body C0 through the liquid inlet C1, whereby the filter F is deformed into a substantially bottomed cylindrical or cage shape, and the filter F is installed or placed in the liquid passage of the container body C0 with its outer surface pressed against the inner peripheral wall of the container body C0 over the entire or nearly entire circumference.

[0014] At least a portion of the bottom wall and / or side wall of the bottomed cylindrical container body C0 may be made of a filter F, and the liquid outflow portion may be made of the filter F. In this case, the peripheral edge of the filter F may be welded to the container body C0.

[0015] The surfaces of the container body C0 and the filter F are chemically inactivated. For example, the container body C0 and the filter F are individually or together heat-treated at approximately 600°C in an air-excluded atmosphere in the presence of silane (SiH4), thereby forming a thin Si film 0.01 to 0.1 μm thick on the surface of the container body C0 and the filter F, and the oxygen in the air reacts with the Si to form a thin silica glass film on the surface. Alternatively, a thin glass film such as SiO2 may be formed on the surface of the container body C0 and the filter F by CVD.

[0016] The liquid supply unit 51 drips or supplies a liquid W such as water to the liquid passage from the liquid inlet C1 of the collection container C. The liquid recovery unit 52 is composed of a container that airtightly supports the collection container C at its upper portion and stores the liquid W that flows out from the liquid outlet C2 of the collection container C. The vacuum suction device 53 is composed of a vacuum pump that draws a vacuum from the internal space of the liquid recovery unit 52, i.e., the space that communicates with the liquid passage of the collection container C downstream of the filter F.

[0017] (Microplastic collection method) Liquid W is supplied to the liquid passage of collection container C by liquid supply unit 51, and the internal space of liquid recovery unit 52 is vacuum-suctioned by vacuum suction device 53. As a result, minute specimens such as microplastics contained in liquid W are collected by filter F, and the liquid W flows out of container body C0 from liquid outlet C2 through filter F and is recovered by liquid recovery unit 52.

[0018] (Microplastics analysis method) The microplastics collected by the sample container C or its filter F are analyzed, for example, by a polymer sample analyzer (gas phase component analyzer (gas chromatograph)). The polymer sample analyzer shown in FIG. 3 comprises a gas phase component generator 10, a thermostatic chamber 20, a detector 40, and a control device 200.

[0019] The gas phase component generator 10 (pyrolyzer) generates a gas phase component mixture by heating microplastics, which are polymer samples collected in a collection container C, together with the collection container C to thermally decompose or volatilize the sample, or by heating the sample to thermally desorb or pyrolyze the components contained in the sample. The gas phase component generator 10 is made of a chemically inert, approximately cylindrical quartz tube and includes a heating furnace 101 that houses the collection container C, a first heater 102 that is provided around the heating furnace 101, and an introduction section 12 (GC introduction section) into which the tip of the heating furnace 101 is inserted. The introduction section 12 includes a second heater 122.

[0020] The heating furnace 101 is connected to the upper part of the introduction part 12 via a heated pipe, or is itself detachably attached to the upper part of the introduction part 12 without using a pipe or the like. The heating furnace 101 may be configured as a stainless steel tube, instead of a quartz tube, which is inactivated by forming a thin quartz film on the inner surface thereof.

[0021] The gas phase component generation device 10 is equipped with a sample introduction section (not shown) connected above the heating furnace 101. A carrier gas supply line L1, which introduces a carrier gas from a carrier gas source into the heating furnace 101, is connected to the sample introduction section. A flow rate control device is provided in the carrier gas supply line L1.

[0022] The polymer sample analyzer is equipped with a split vent L2 that can be opened and closed using a valve (not shown). When split vent L2 is open, it introduces a portion of the gaseous component mixture introduced from the pyrolysis furnace 101 into the inlet 12 into the separation column 22, while discharging the remainder to the outside. In split vent L2, a split ratio, which is the ratio of the components introduced into the separation column 22 to the total amount of the gaseous component mixture, is set to a predetermined value (for example, 1 / 10 to 1 / 100). It is also possible to use splitless injection, in which the split vent L2 is closed and the entire amount of the gaseous component mixture introduced from the pyrolysis furnace 101 into the inlet 12 is introduced into the separation column 22.

[0023] The thermostatic bath 20 (oven) accommodates a separation column 22. The thermostatic bath 20 is equipped with a thermostatic bath heater 202.

[0024] The separation column 22 has an inlet that is detachably connected to the inlet 12 of the gas phase component generator 10, and an outlet that is connected to the detector 40. A liquid phase 220 (polymer) is provided inside the separation column 22 (see FIGS. 3A to 3C), and separates the gas phase component mixture carried by the carrier gas from the heating furnace 101 via the inlet 12 and the separation column 22 into individual gas phase components. The inner surface of the separation column 22 is chemically inert. The separation column 22 may be, for example, a stainless steel or fused quartz capillary column having an inner diameter of 0.1 to 0.5 mm, a length of 30 m, and a 0.25 μm-thick fixed layer (liquid phase 220) made of a copolymer of diphenylpolysiloxane and dimethylpolysiloxane in a molar ratio of 5:95.

[0025] The detector 40 is connected to the outlet of the separation column 22 and detects the individual gas phase components separated by the separation column 22. The detector 40 is composed of a mass spectrometer (MS) such as a quadrupole mass spectrometer detector, a flame ionization detector (FID), an electron capture detector (ECD), or the like.

[0026] (function) The microplastic collection container C configured as described above and the microplastic collection device 50 equipped with the collection container C allow for efficient collection of microplastics. The collected microplastics are heated together with the collection container C in the polymer sample analyzer as described above, causing thermal decomposition or volatilization, or are heated to thermally desorb or pyrolyze the components contained in the sample, generating a gaseous mixture of components. The surfaces of the container body C0 and filter F of the metal sample container C are both inactivated. Therefore, the gaseous mixture of components is introduced into the separation column 22 without reacting with the stainless steel or other metals that make up the container body C0 and filter F.

[0027] Therefore, a TD-GC / MS chromatogram and / or pyrogram derived from the microplastics is obtained in the TD-GC / MS chromatogram and / or pyrogram (Py-GC / MS chromatogram).

[0028] (Example) Figure 4 shows a TD-GC / MS chromatogram obtained when a 0.5 μg sample of DeBDE (decabromodiphenyl ether), a brominated flame retardant, was placed in a microplastic collection container C (Example 1) whose container body and filter were deactivated according to one embodiment of the present invention. As shown in Figure 4, the TD-GC / MS chromatogram of the sample obtained using the microplastic collection container C (Example 1) shows a slight peak for the isomer NBDEs (nonabromidophenyl ethers) from which one bromine atom has been removed, but no peak for the isomer OBDEs (octabromodiphenyl ethers) from which two bromine atoms have been removed. Instead, there is a relatively large peak for DeBDE. This is because DeBDE does not undergo catalytic decomposition with the filter F (which has not been deactivated) because the container body (C0) constituting the microplastic collection container C (Example 1) is deactivated.

[0029] (Comparative Example) Figure 5 shows a TD-GC / MS chromatogram obtained when 0.5 μg of DeBDE was placed in a comparative example of microplastic collection container C, whose filter had not been deactivated according to the prior art. As shown in Figure 5, the TD-GC / MS chromatogram of the sample obtained using the comparative example of microplastic collection container C shows peaks for DeBDE as well as peaks for isomers of NBDEs and OBDEs. This is because DeBDE was catalytically decomposed by the undeactivated filter F that constitutes the comparative example of microplastic collection container C.

[0030] Table 1 shows the peak area ratios of each component in the TD-GC / MS chromatogram when the microplastic collection containers C of the examples and comparative examples were used. [Table 1] [Explanation of symbols]

[0031] 10. Gas phase component generator (pyrolyzer) 101‥Heating furnace 102‥1st heater 12‥Introduction part (GC introduction part) 122‥Second heater 20. Thermostatic bath (oven) 22. Separation column (separation column) 200...Control device 202‥Thermostatic bath heater 40. Detector 0. Detector 51‥Liquid supply device 52. Liquid recovery device 53‥Vacuum suction device C. Microplastic collection container C0‥Liquid passage C1‥Liquid inlet C2‥Liquid outlet F...Filter CGS - Carrier gas source L1: Carrier gas supply line L2...Split vent.

Claims

1. a metal container body having a liquid passage; a metal filter provided in the container body so as to block the liquid passage while allowing liquid to pass through and capable of capturing microplastics; The surfaces of the container body and the filter are inactivated. Microplastic collection container.

2. The microplastic collection container according to claim 1; A liquid supply unit that supplies liquid to the liquid passage of the microplastic collection container upstream of the filter; and a vacuum suction device that vacuums the space in the liquid passage of the microplastic collection container that is in communication with the downstream side of the filter. Microplastic collection device.

Images