JP7560052B2 - Per- and polyfluoroalkyl compound sampler - Google Patents

Description

The present invention relates to a per- and polyfluoroalkyl compound collection sampler that collects various forms of per- and polyfluoroalkyl compounds present in the atmosphere.

Per- and polyfluoroalkyl compounds are fluorine-substituted aliphatic compounds that have high thermal stability, high chemical stability, and high surface modification activity. Taking advantage of these properties, per- and polyfluoroalkyl compounds are widely used in industrial and chemical applications such as surface treatment agents, packaging materials, and liquid fire extinguishing agents.

Some per- and polyfluoroalkyl compounds are very stable chemicals and are difficult to decompose under natural conditions after being released into the environment. For this reason, in recent years, per- and polyfluoroalkyl compounds have been recognized as persistent organic pollutants (POPs), and the manufacture and use of perfluorooctanesulfonic acid (PFOS) (IUPAC name: 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfonic acid) has been restricted since 2010 under the Stockholm Convention on Persistent Organic Pollutants (POPs Convention).

Note that perfluoroalkyl compounds have a completely fluorinated linear alkyl group and are substances represented by chemical formula (ii). Examples include perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) (IUPAC name: 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoic acid).

A polyfluoroalkyl compound is a substance in which some of the hydrogen atoms in an alkyl group are replaced with fluorine, and is represented by the chemical formula (iii). For example, there is fluorotelomer alcohol.

Because per- and polyfluoroalkyl compounds continue to persist in nature (in water, soil, and air), the establishment of a quantitative test method for per- and polyfluoroalkyl compounds is being considered. The challenge in the study of a quantitative test method is the development of a sampler with high collection, adsorption, and desorption performance for per- and polyfluoroalkyl compounds. Air, which is a sample containing trace amounts of per- and polyfluoroalkyl compounds, is ventilated, and various forms of per- and polyfluoroalkyl compounds (particle-adsorbent, semi-volatile, volatile) contained in the sample air are collected or adsorbed, and the compounds are desorbed from the collector or adsorbent into the extract by an extraction process and concentrated. After concentration, quantitative measurement is performed using a measuring device such as LC-MS or GC-MS, making it possible to measure the concentration of per- and polyfluoroalkyl compounds contained in the sample.

A method using a high-volume air sampler is known for measuring per- and polyfluoroalkyl compounds in the air (see, for example, Non-Patent Document 1). In this method, a filter paper made of fine fibers such as quartz fiber filter paper is attached inside the high-volume air sampler, and the sampler is allowed to circulate for a certain period of time to collect airborne particles, thereby measuring the PFOS contained in the airborne particles.

However, the substances that can be collected by passing air through the filter paper are limited to non-volatile ionic compounds such as PFOS and PFOA, which are perfluoroalkyl compounds that adsorb to airborne particles. Per- and polyfluoroalkyl compounds that cannot be collected by this sampler include volatile compounds. Volatile per- and polyfluoroalkyl compounds pass through the filter paper, making quantitative measurement impossible.

Therefore, there was a demand for a collection sampler that could capture per- and polyfluoroalkyl compounds that exist in other forms, such as volatile polyfluoroalkyl compounds that are not contained in airborne particles and cannot be captured by the sampler.

In addition, silica gel-based collectors and the like are used as collectors for volatile per- and polyfluoroalkyl compounds. For example, an organic fluorine-based compound adsorbent made of cyclodextrin polymer has been proposed (Patent Document 1). This adsorbent is specialized for adsorption only and cannot desorb the compounds, so it is not suitable for use as a collector for quantitative measurement. In addition, cyclodextrin polymers are in the form of powder or fine particles, which makes them difficult to handle and has high resistance when passing liquid or air, resulting in problems such as the risk of fine powder leaking to the secondary side. Thus, there was a problem that existing adsorbents could not sufficiently collect volatile per- and polyfluoroalkyl compounds, making it impossible to perform accurate quantitative measurement.

JP 2012-101159 A

Michiko Kotani et al., "Weekly Changes in Perfluorooctane Sulfonic Acid (PFOS) Concentrations in Urban Air," Journal of Atmospheric Environment, Vol. 45, No. 6, November 10, 2010, pp. 279-282

The present invention has been made in consideration of the above points, and provides a per- and polyfluoroalkyl compound collection sampler that can efficiently and comprehensively collect per- and polyfluoroalkyl compounds that exist in the air in various forms.

That is, the first invention relates to a sampler for collecting per- and polyfluoroalkyl compounds in a sample atmosphere, comprising an intake section for sucking in the sample atmosphere, a particle-adsorbent compound collection area connected to the intake section and equipped with an inertial impactor section for collecting particle-adsorbent per- and polyfluoroalkyl compounds in the atmosphere, a semi-volatile compound collection area connected to the particle-adsorbent compound collection area and equipped with a urethane foam filter section for collecting semi-volatile per- and polyfluoroalkyl compounds in the atmosphere, a volatile compound collection area connected to the semi-volatile compound collection area and equipped with a filter section made of adsorbent activated carbon having a BET specific surface area of 900 ^m2 /g or more for collecting volatile per- and polyfluoroalkyl compounds in the atmosphere, and an exhaust section connected to the volatile compound collection area and through which the atmosphere that has been ventilated through each of the areas is exhausted.

The second invention relates to a per- and polyfluoroalkyl compound collection sampler according to the first invention, in which the particle-adsorbing compound collection area is made up of multiple layers of the inertial impactor section that sequentially collects particulate per- and polyfluoroalkyl compounds in the atmosphere in multiple particle sizes in descending order of particle diameter.

The third invention relates to a per- and polyfluoroalkyl compound collection sampler according to the first or second invention, in which the amount of surface oxide on the adsorbent activated carbon is 0.10 meq/g or more.

A fourth invention relates to a sampler for collecting per- and polyfluoroalkyl compounds according to any one of the first to third inventions, wherein the sum of the micropore volumes of the adsorbent activated carbon having a size of 1 nm or less (V _mic ) is 0.35 cm ³ /g or more.

A fifth invention relates to a sampler for collecting per- and polyfluoroalkyl compounds according to any one of the first to third inventions, wherein the sum of the volumes of mesopores of 2 to 60 nm (V _met ) of the adsorbent activated carbon is 0.02 cm ³ /g or more.

The sixth invention is the fourth invention, wherein the sum of the mesopore volumes of 2 to 60 nm of the adsorbent activated carbon (V _Met ) is 0.02 cm ³ /g or more.

The seventh invention relates to a per- and polyfluoroalkyl compound collection sampler according to the sixth invention, wherein the volume difference (V _s ) between the sum of the micropore volumes (V _mic ) and the sum of the mesopore volumes (V _met ) of the adsorbent activated carbon as defined in the following formula (i) is 0.45 or more.

According to the first invention, the per- and polyfluoroalkyl compound collection sampler is a sampler for collecting per- and polyfluoroalkyl compounds in a sample air, and is equipped with an intake section for sucking in the sample air, a particle-adsorbent compound collection area connected to the intake section and equipped with an inertial impactor section for collecting particle-adsorbent per- and polyfluoroalkyl compounds in the air, a semi-volatile compound collection area connected to the particle-adsorbent compound collection area and equipped with a urethane foam filter section for collecting semi-volatile per- and polyfluoroalkyl compounds in the air, a volatile compound collection area connected to the semi-volatile compound collection area and equipped with a filter section made of adsorbent activated carbon having a BET specific surface area of 900 ^m2 /g or more for collecting volatile per- and polyfluoroalkyl compounds in the air, and an exhaust section connected to the volatile compound collection area and through which the air that has been ventilated through each of the areas is exhausted, thereby making it possible to efficiently and comprehensively collect per- and polyfluoroalkyl compounds present in the air in various forms. In addition, since per- and polyfluoroalkyl compounds are selectively collected in each area according to their various forms, they are collected separately from other forms of per- and polyfluoroalkyl compounds, minimizing analytical errors due to co-elution in the measuring device and enabling highly accurate quantitative measurement.

According to the second invention, the per- and polyfluoroalkyl compound collection sampler of the first invention is such that the particle-adsorbing compound collection area is made up of multiple layers of the inertial impactor section that sequentially collects the particulate per- and polyfluoroalkyl compounds in the atmosphere in multiple particle sizes in descending order of particle diameter, so that the particulate per- and polyfluoroalkyl compounds in the atmosphere can be efficiently collected in any particle size.

According to the per- and polyfluoroalkyl compound collection sampler of the third invention, in the first or second invention, the amount of surface oxide of the adsorbent activated carbon is 0.10 meq/g or more, so that the sampler has not only the adsorption performance due to the pores of the activated carbon but also a chemical adsorption ability, and the adsorption performance of per- and polyfluoroalkyl compounds can be further improved.

According to the per- and polyfluoroalkyl compound collection sampler of the fourth invention, in any one of the first to third inventions, the sum of the micropore volumes of 1 nm or less (V _mic ) of the adsorbent activated carbon is 0.35 cm ³ /g or more, so that the adsorption performance of per- and polyfluoroalkyl compounds by the pores of the adsorbent activated carbon can be improved.

According to the per- and polyfluoroalkyl compound collection sampler of the fifth invention, in any one of the first to third inventions, the sum of the volumes of the 2-60 nm mesopores (V _met ) of the adsorbent activated carbon is 0.02 cm ³ /g or more, so that the adsorption performance of the per- and polyfluoroalkyl compounds by the pores of the adsorbent activated carbon can be improved.

According to the sixth aspect of the present invention, the per- and polyfluoroalkyl compound collection sampler of the fourth aspect of the present invention is characterized in that the sum of the mesopore volumes of 2 to 60 nm of the adsorbent activated carbon (V _Met ) is 0.02 cm ³ /g or more, the adsorption performance of the per- and polyfluoroalkyl compounds by the pores of the adsorbent activated carbon can be improved.

According to the seventh invention, the per- and polyfluoroalkyl compound collection sampler of the sixth invention , since the volume difference (V _s ) between the sum of the micropore volumes (V _mic ) and the sum of the mesopore volumes (V _met ) of the adsorbent activated carbon defined in the above formula (i) is 0.45 or more, the adsorption performance of per- and polyfluoroalkyl compounds by the pores of the adsorbent activated carbon can be improved.

FIG. 1 is a perspective view showing one embodiment of a per- and polyfluoroalkyl compound collection sampler of the present invention. FIG. 2 is a central cross-sectional view of the sampler of FIG. 1 . FIG. 3 is an enlarged view of the upper part of FIG. 2 . FIG. 2 is a plan view showing an example of the shape of an impactor plate. FIG. 3 is an enlarged view of the lower part of FIG. 2 .

The purpose of the per- and polyfluoroalkyl compound collection sampler is to comprehensively collect per- and polyfluoroalkyl compounds that exist in various forms in the air. Per- and polyfluoroalkyl compounds present in the air are roughly classified into three types. One type is particle-adsorbed per- and polyfluoroalkyl compounds that adhere to the surface of fine particles suspended in the air (e.g., dust such as pollen and soil particles), many of which are ionic compounds.

The second type are semi-volatile per- and polyfluoroalkyl compounds such as N-ethylperfluorooctanesulfonic acid amidoethanol (hereinafter referred to as "N-EtFOSE") and N-methylperfluorooctanesulfonic acid amidoethanol (hereinafter referred to as "N-MeFOSE"). According to the definition of the World Health Organization (WHO), semi-volatile organic compounds are compounds with a boiling point of 260 to 380°C. It is known that PFOS and PFOA are produced by the decomposition of semi-volatile per- and polyfluoroalkyl compounds. N-EtFOSE is a substance represented by the following chemical formula (iv), and N-MeFOSE is a substance represented by the chemical formula (v).

And the third type is volatile per- and polyfluoroalkyl compounds that exist as a gas in the atmosphere, such as fluorotelomer alcohols (hereinafter referred to as "FTOHs") as shown in the above chemical formula (iii). Volatile organic compounds are defined by the World Health Organization (WHO) as compounds with a boiling point of 50 to 160°C.

As mentioned above, the per- and polyfluoroalkyl compounds that are the subject of the present invention exist in the atmosphere mainly in three forms. For this reason, the sampler of the present invention is formed by dividing it into areas for collecting per- and polyfluoroalkyl compounds in each form, as shown in Figures 1 and 2.

The sampler 10 of the present invention is formed by arranging a particle-adsorbing compound collection area 20, a semi-volatile compound collection area 30, and a volatile compound collection area 40 in this order from the upstream where the sample air is sucked in to the downstream where the air is discharged. The sample air is sucked in from the intake section 12 by a suction pump or the like arranged on the downstream side of the sampler, passes through the particle-adsorbing compound collection area 20 that collects particle-adsorbing per- and polyfluoroalkyl compounds, then passes through the semi-volatile compound collection area 30 that collects semi-volatile per- and polyfluoroalkyl compounds, and then passes through the volatile compound collection area 40 that collects volatile per- and polyfluoroalkyl compounds, before being discharged from the exhaust section 13.

First, the particle-adsorbent compound collection area 20 will be described with reference to Figures 3 and 4. The particle-adsorbent compound collection area 20 includes an inertial impactor section 21 that collects particle-adsorbent per- and polyfluoroalkyl compounds in the atmosphere.

An inertial impactor is used to collect fine particles (aerosols) suspended in gas. It passes particles from a nozzle toward an impactor plate (collection plate), where the particles collide with the impactor plate by inertial force and are collected on the impactor plate. Inertial impactors with different nozzle diameters can be connected in multiple stages, making it possible to collect particles of different particle diameters on the impactor plate of each stage.

The inertial impactor section 21 is equipped with a collection filter paper 22 in the center of a disk-shaped object, an impactor plate 23 with multiple through holes 24 formed on its outer periphery, a clearance section 25 on the upstream side of the impactor plate 23, and a connecting hole 27 on the downstream side. The inertial impactor section 21 classifies and collects fine particles (aerosols) using inertial force. By suddenly changing the direction of the airflow of the sample air flowing in from the upstream side, particles with a certain particle size or larger are collided with the collection filter paper to collect the fine particles by utilizing the particle size dependency of the inertial motion of the fine particles. In the inertial impactor section, the fine particles and gas do not pass through the filter paper, so that the material exchange between the collected particles on the filter paper and the gas being ventilated, which is a concern in existing methods where the particles pass through the filter paper, is minimized.

In addition, it is preferable that the inertial impactor section 21 is arranged in multiple layers. The size of the fine particles that can be captured can be adjusted appropriately depending on the shape, diameter size, and distance to the lower plate of the through-hole 24 formed in the impactor plate 23. For example, the shape of the through-hole 24 formed in the impactor plate 23 can be a shape as shown in FIG. 4. Therefore, it is possible to capture fine particles of different particle sizes in each layer. In this case, if multiple layers of the inertial impactor section 21 are arranged so that the fine particles are captured in order of the largest particle diameter from the upstream side to the downstream side, the collection efficiency is increased. Furthermore, it is preferable that the downstream side of the impactor plate 23 has an acceleration nozzle 26 that accelerates the airflow formed on a tapered surface toward the downstream side.

The sample air that flows into the clearance section from the upstream side flows toward the through-holes 24 formed in the impactor plate 23. Because the through-holes 24 in the impactor plate 23 are not arranged in a straight line from the air inflow direction, the flow path of the gas bends to the outside where the through-holes 24 are located. Particles above a certain size cannot ride the airflow that bends outward due to inertia, and collide with the collection filter paper 22 and are collected. By connecting multiple layers of inertial impactor sections, each with a modified shape of the through-hole, it is possible to collect fine particles of any particle size. A publicly known inertial impactor section 21 can be used.

In the particle-adsorbing compound collection area 20 of this embodiment, three or four stages of inertial impactors 21 are provided, and particle-adsorbing perfluoroalkyl compounds with particle diameters of 10 μm or more, 2.5 to 10 μm, and 1.0 to 2.5 μm are collected from the upstream by the inertial impactor section of each stage. In addition, in the lowest stage, a very small particle collection section 29 equipped with a collection filter paper 22 is formed on the upper surface of a disk-shaped object 28 having a plurality of through holes 24 in order to collect particle-adsorbing perfluoroalkyl compounds and polyfluoroalkyl compounds smaller than 1.0 μm. Note that the very small particle collection section 29 may be omitted depending on the purpose.

Next, the semi-volatile compound collection area 30 connected to the particle-adsorbing compound collection area 20 will be described. As shown in FIG. 5, the semi-volatile compound collection area 30 includes a urethane foam filter section 31 made of urethane foam 32 that collects semi-volatile per- and polyfluoroalkyl compounds. In this embodiment, the urethane foam 32 is a cylindrical polyurethane foam with a diameter of 47 mm and a length of 50 mm that is filled into the sampler cylinder.

Next, the volatile compound collection area 40 connected to the semi-volatile compound collection area 30 will be described. As shown in FIG. 5, the volatile compound collection area 40 includes a filter section 41 made of adsorbent activated carbon C that collects volatile per- and polyfluoroalkyl compounds that exist in a gaseous state in the atmosphere. The filter section 41 may be arranged in multiple layers.

By collecting semi-volatile per- and polyfluoroalkyl compounds in the semi-volatile compound collection area 30, which is arranged in front of the volatile compound collection area 40, it is possible to prevent the micropores of the adsorbent activated carbon C in the filter section 41 provided in the volatile compound collection area 40 from being blocked, and it is expected that the deterioration of the adsorption performance will be reduced. In addition, the urethane foam filter section 31 can remove fine particles that have slipped through the particle-adsorbent compound collection area 20, so the deterioration of the performance of the filter section 41 of the volatile compound collection area 40 is further suppressed.

In this way, by collecting particles (compounds adsorbed to particles), semi-volatile compounds, and volatile compounds in different areas, particle-adsorbed per- and polyfluoroalkyl compounds, semi-volatile per- and polyfluoroalkyl compounds, and volatile per- and polyfluoroalkyl compounds can be collected separately. This makes it possible to analyze each form of per- and polyfluoroalkyl compound independently, while preventing co-elution, reducing analytical errors in the measuring device, and improving measurement accuracy.

The per- and polyfluoroalkyl compound adsorbing activated carbon is made of fibrous activated carbon or powdered activated carbon. Fibrous activated carbon is activated carbon obtained by carbonizing and activating suitable fibers, such as phenolic resin-based, acrylic resin-based, cellulose-based, and coal pitch-based. The fiber length and cross-sectional diameter are appropriate. If the fiber cross-sectional diameter is too large, the surface area is reduced and the contact efficiency is reduced, so from the viewpoint of improving the adsorption capacity, it is preferable that the fiber cross-sectional diameter is 30 μm or less.

The raw materials for powdered activated carbon include wood (waste wood, thinned wood, sawdust), coffee bean residue, rice husks, coconut shells, bark, and fruit. These naturally derived raw materials are prone to developing pores through carbonization and activation. In addition, since it is a secondary use of waste, it can be procured at low cost. Other raw materials that can be used include tires, petroleum pitch, burned synthetic resins such as urethane resins and phenolic resins, and even coal. If the particle size of the activated carbon is small, the density of the filter body increases, and the adsorption performance of per- and polyfluoroalkyl compounds improves. On the other hand, if the particle size is large, the density of the filter body decreases, and the breathability improves. For these reasons, the average particle size of the powdered activated carbon can be adjusted appropriately according to the conditions of use, and the adsorption performance of per- and polyfluoroalkyl compounds can be improved while maintaining breathability.

The activated carbon raw material is heated and carbonized at temperatures between 200°C and 600°C as necessary to form micropores. The activated carbon raw material is then activated by exposing it to water vapor and carbon dioxide at temperatures between 600°C and 1200°C. This results in activated carbon with various types of developed pores. Other activation methods include zinc chloride activation. Sequential washing is also performed.

The physical properties of the activated carbon thus produced determine its adsorption performance for the adsorbed substance. The adsorption performance of the activated carbon for adsorbing per- and polyfluoroalkyl compounds, which are the adsorbed substances of interest in the present invention, is determined by the specific surface area, which is an index showing the amount of pores formed in the activated carbon. Note that in this specification, the specific surface area of each prototype is measured by the BET method (Brunauer, Emmett and Teller method).

Activated carbon is also defined by the pore size. In the case of an adsorbent such as activated carbon, there are micropores, mesopores, and macropores. The adsorption target and performance of the activated carbon change depending on which range of pores is developed more. The activated carbon desired in this invention is one that effectively adsorbs molecules of per- and polyfluoroalkyl compounds in a desorbable manner.

In addition, acidic functional groups are present on the surface of activated carbon. The acidic functional groups that increase due to surface oxidation of activated carbon are mainly hydrophilic groups such as carboxyl groups and phenolic hydroxyl groups. The acidic functional groups on the surface of activated carbon affect the collection capacity. The amount of these acidic functional groups can be understood as the amount of surface oxide. When the amount of surface oxide of activated carbon increases, the hydrophilicity of the activated carbon surface increases, and it is believed that the collection performance of per- and polyfluoroalkyl compounds, particularly fluorotelomer compounds that have hydrophilic groups, is improved.

The following methods can be used to increase the amount of surface oxides on activated carbon. One method is to promote the oxidation of surface residues by undergoing a heating process again, thereby increasing the amount of acidic functional groups. In other words, this is oxidation in an air or oxygen atmosphere. Alternatively, air at a temperature of 25-40°C and a humidity of 60-90% is also introduced at the same time in an air atmosphere. There, activated carbon is heated at 150-900°C for 1-10 hours to obtain activated carbon with an increased amount of surface oxides. It is thought that heating with moist air oxidizes hydrocarbon groups such as alkyl groups present on the activated carbon surface, and hydroxyl groups from water are introduced to the surface, increasing the amount of acidic functional groups.

Another method is to oxidize the surface of activated carbon with an oxidizing agent to increase the amount of surface oxide. Examples of oxidizing agents include hypochlorous acid and hydrogen peroxide. Activated carbon with an increased amount of surface oxide can be obtained by immersing activated carbon in a liquid containing such an oxidizing agent and then drying it. The amount of acidic functional groups on the surface of the activated carbon can be measured as the amount of surface oxide, as shown in the prototype examples below.

The adsorption performance of activated carbon, which adsorbs volatile per- and polyfluoroalkyl compounds in a releasable manner, is exhibited by making the specific surface area 900 ^m2 /g or more, as will be explained in the examples described later. The formation of a certain number of pores in the activated carbon ensures the adsorption performance of the compounds.

It was also found that the pore distribution formed in the activated carbon contributes to the adsorption of volatile per- and polyfluoroalkyl compounds.In this specification, the micropore refers to a pore with a pore diameter of 1 nm or less, and as will be derived from the examples described later, when the total pore volume (V _mic ) of the micropores is 0.35 cm ³ /g or more, the adsorption performance of volatile per- and polyfluoroalkyl compounds is improved.In this specification, the micropore volume of 1 nm or less in each prototype is measured by the MP method (Micropore method).It is considered that the formation of a certain number of micropores makes it easier for the compound to be collected in the pores.

In this specification, mesopores refer to pores with a pore diameter in the range of 2 to 60 nm, and as will be derived from the examples described later, when the total pore volume (V _met ) of the mesopores is 0.02 cm ³ /g or more, the adsorption performance of volatile per- and polyfluoroalkyl compounds is improved. Note that in this specification, the mesopore volume in the range of 2 to 60 nm in each prototype example is measured by the DH method (Dollimore-Heal method). Since the measurement is based on the DH method, the measurement targets were pores with a diameter of 2.43 to 59.72 nm. It is believed that the formation of a certain number of mesopores or more allows the compound to easily penetrate into the micropores.

In addition, it is believed that the difference between the pore volume of the micropores and the pore volume of the mesopores also contributes to the efficient adsorption of per- and polyfluoroalkyl compounds.As will be derived from the examples described below, by making the volume difference ( _Vs ) between the sum of the micropore volumes ( _Vmic ) and the sum of the mesopore volumes ( _Vmet ) 0.45 or more, volatile per- and polyfluoroalkyl compounds can be adsorbed efficiently in a desorbable manner.In addition to not overdeveloping the mesopores, by making the activated carbon have well-developed micropores, it is believed that the adsorption performance of per- and polyfluoroalkyl compounds can be improved, and the compounds can be smoothly desorbed during the subsequent extraction operation, thereby allowing quantitative measurement to be performed well.

Next, by making the surface oxide amount 0.10 meq/g or more, the hydrophilicity of the activated carbon surface can be increased, allowing per- and polyfluoroalkyl compounds to be adsorbed efficiently.

[Study on collection performance of atmospheric per- and polyfluoroalkyl compounds 1]
[Create a sampler]
In order to prepare a sampler for collecting per- and polyfluoroalkyl compounds, the inventors prepared a sampler using polypropylene resin with the following composition.

Intake section: Intake hole: Inner diameter 11.0 mm
Particle-adsorbent compound collection area 1st stage: Particle-adsorbent compound collection area for collecting fine particles of 10 μm or more Clearance section: Inner diameter 40 mm
Collection filter paper: Quartz fiber filter, diameter 25 mm
Impactor plate: Shape of FIG. 4(a), diameter 47 mm
Connection hole: Inner diameter 4.3 mm
Second stage: Particle-adsorbent compound collection area for collecting fine particles of 2.5 to 10 μm Clearance section: Inner diameter 40 mm
Collection filter paper: Quartz fiber filter, diameter 25 mm
Impactor plate: Shape of FIG. 4(a), diameter 47 mm
Connection hole: Inner diameter (diameter) 2.2mm
3rd stage: Particle-adsorbing compound collection area for collecting fine particles of 1.0 to 2.5 μm Clearance section: Inner diameter 40 mm
Collection filter paper: Quartz fiber filter, diameter 25 mm
Impactor plate: Shape of FIG. 4(a), diameter 47 mm
Connection hole: Inner diameter (diameter) 40mm
4th stage: particle-adsorbing compound collection area for collecting fine particles of 1.0 μm or less Clearance section: inner diameter 40 mm
Collection filter paper: Quartz fiber filter, diameter 47 mm
Impactor plate: Shape of Fig. 4(b), diameter 47 mm
Connection hole: Inner diameter (diameter) 40mm

Quartz fiber filters manufactured by Shibata Scientific Co., Ltd. were used as collection filters for each particle-adsorbing compound collection area.

Semi-volatile compound collection area Urethane foam filter part: polyurethane foam (manufactured by Shibata Scientific Co., Ltd.), diameter 47 mm, height 50 mm

Volatile Compound Area: Circular sheets (diameter 47 mm, thickness 2 mm) were prepared using the adsorbent activated carbon samples 1 to 5 listed below, and two sheets were placed on top of each other to form a filter section.

[Activated carbon adsorbent used]
The inventors used the following raw materials to prepare per- and polyfluoroalkyl compound-adsorbing activated carbon:
Fibrous activated carbon: Filamentous activated carbon "CF" (average fiber diameter: 15 μm) manufactured by Futamura Chemical Co., Ltd.
{Hereinafter referred to as C1.}
Futamura Chemical Co., Ltd.: Fibrous activated carbon "FE3010" (average fiber diameter: 15 μm)
{Hereinafter referred to as C2.}
Futamura Chemical Co., Ltd.: Fibrous activated carbon "FE3012" (average fiber diameter: 15 μm)
{Hereinafter referred to as C3.}
Futamura Chemical Co., Ltd.: Fibrous activated carbon "FE3013" (average fiber diameter: 15 μm)
(Hereinafter referred to as C4.)
Futamura Chemical Co., Ltd.: Fibrous activated carbon "FE3015" (average fiber diameter: 15 μm)
(Hereinafter referred to as C5.)
Futamura Chemical Co., Ltd.: Fibrous activated carbon "FE3018" (average fiber diameter: 15 μm)
(Hereinafter referred to as C6.)
Granular activated carbon: Futamura Chemical Co., Ltd.: coconut shell activated carbon "CW480SZ" (average particle size: 250 μm)
{Hereinafter referred to as C7.}
Futamura Chemical Co., Ltd.: Phenol resin activated carbon "QW250" (average particle size: 250 μm)
(Hereinafter referred to as C8.)

[Activated carbon treatment]
<Prototype Example 1>
The activated carbon of the first prototype was a fibrous activated carbon "CF" (C1) obtained by carbonizing phenolic resin fiber, which is the same raw material as FE3010, at 600°C.

<Prototype Example 2>
The activated carbon for prototype 2 was fibrous activated carbon "FE3015" (C5) manufactured by Futamura Chemical.

<Prototype Example 3>
10 g of fibrous activated carbon "FE3010" (C2) manufactured by Futamura Chemical was immersed in 500 ml of a 6% hydrogen peroxide solution, left to stand for 150 hours, then taken out and dried to obtain the activated carbon of prototype 3.

<Prototype Example 4>
10 g of fibrous activated carbon "FE3015" (C5) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 6% hydrogen peroxide solution, left to stand for 70 hours, then taken out and dried to obtain the activated carbon of prototype 4.

<Prototype Example 5>
10 g of fibrous activated carbon "FE3018" (C6) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 6% hydrogen peroxide solution, left to stand for 50 hours, then taken out and dried to obtain the activated carbon of prototype 5.

[Measurement of adsorbent activated carbon]
The amount of surface oxide (meq/g) was determined by applying the Boehm method, in which the adsorbent activated carbon of each example was shaken in a 0.05N aqueous solution of sodium hydroxide, filtered, and the filtrate was neutralized and titrated with 0.05N hydrochloric acid to determine the amount of sodium hydroxide.

The specific surface area (m ² /g) was determined by measuring the nitrogen adsorption isotherm at 77K using an automatic specific surface area/pore distribution measuring device "BELSORP-miniII" manufactured by Microtrack-Bel Co., Ltd. and by the BET method (BET specific surface area).

The average pore diameter (nm) was calculated from the formula (vi) using the pore volume (ml/g) and specific surface area (m ² /g) values obtained from the above-mentioned measurements, assuming that the pores were cylindrical.

The physical properties of the adsorbent activated carbon of each prototype are shown in Table 1. From top to bottom in Table 1, they are the surface oxide amount (meq/g), BET specific surface area (m ² /g), average pore diameter (nm), and average fiber diameter (μm).

[Measurement of collection efficiency of atmospheric per- and polyfluoroalkyl compounds 1]
Experiments were conducted to collect atmospheric particle-adsorbent per- and polyfluoroalkyl compounds in a particle-adsorbent compound collection area, as well as semi-volatile per- and polyfluoroalkyl compounds in a semi-volatile compound collection area and volatile per- and polyfluoroalkyl compounds in a volatile compound collection area.

[Experiment 1 for the collection of particle-adsorbed per- and polyfluoroalkyl compounds]
A sampler consisting of the particle-adsorbent collection area described in the Examples was installed outdoors, and aeration was performed for 48 hours at a rate of 20 L/min, and the amount of fine particles collected on the collection filter paper in each stage of the particle-adsorbent collection area was measured. Table 2 shows the month of measurement and the amount of collected particles (μg/ ^m3 ) for each particle size (each stage).

After calculating the amount of fine particles, the amount of PFOS and PFOA attached to the fine particles collected in November 2017 was quantitatively evaluated using the following procedure.

After aeration, the collection filter paper of each stage was thoroughly stirred and contacted with 15 ml of a mixed solvent mainly composed of dichloromethane and ethyl acetate, then centrifuged to separate the solid and liquid, and the extract was collected.

The extract was quantitatively measured in MRM mode using a GC-MS/MS (Waters QuatrimicroGC) to confirm the collection performance.

The recovery amounts (pg/m ³ ) of PFOS and PFOA attached to fine particles for each particle size (each row) are shown in Table 3. The quantitative measurement was carried out four times.

[Results and discussion of particle-adsorbed per- and polyfluoroalkyl compound collection experiments 1]
As shown in Tables 2 and 3, the particle-adsorbing compound collection area was confirmed to have the ability to collect fine particles in the air, and it was also confirmed that it was possible to quantify the PFOS and PFOA adsorbed to the fine particles.

[Experiment 1 for the collection of semi-volatile per- and polyfluoroalkyl compounds and experiment 1 for the collection of volatile per- and polyfluoroalkyl compounds]
Using the above-mentioned semi-volatile compound collection area and a volatile compound collection area equipped with a filter section made of activated carbon of each prototype example, collection experiments were conducted on semi-volatile per- and polyfluoroalkyl compounds and volatile per- and polyfluoroalkyl compounds.

As per- and polyfluoroalkyl compounds, this time, FTOHs and ethyl perfluorooctanesulfamide (IUPAC name: N-ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctane-1-sulfamide) (hereinafter referred to as "N-EtFOSA") were used for the evaluation. The substance name of FTOHs varies depending on the number of carbon atoms. For example, C ₈ F ₁₇ CH ₂ CH ₂ OH is named 8:2FTOH (IUPAC name: 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decanol). N-EtFOSA is a substance represented by the following chemical formula (vii).

Each standard substance (4:2FTOH (IUPAC name: 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanol), 6:2FTOH (IUPAC name: 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol), 8:2FTOH, 10:2FTOH (IUPAC name: 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluoro-1-dodecanol), N-EtFOSA and N-EtFOSE) was diluted with methanol to 100 ppb and 100 μl was added to the urethane foam filter section of the semi-volatile compound collection area. Next, air at 22-24°C was ventilated at a rate of 20 l/min into the semi-volatile compound collection area and the volatile compound collection area for 48 hours.

After aeration, the urethane foam filter part and the filter part made of activated carbon from each prototype were removed and thoroughly stirred in 15 ml of a mixed solvent mainly composed of dichloromethane and ethyl acetate, then centrifuged to separate the solid and liquid, and the extract was collected.

The extract was quantitatively measured in MRM mode using a GC-MS/MS (Waters QuatrimicroGC) to confirm the collection performance.

Table 4 shows the recovery rate (%) for each target substance in the urethane foam filter. Quantitative measurements were performed four times. In the table, "ND" indicates that the value was below the lower limit of quantification.

Table 5 shows the recovery rate (%) of each target substance in the filter part made of activated carbon for each prototype. Quantitative measurements were performed four times.

In the table, "ND" indicates that the value is below the lower limit of quantification. In addition, there were cases where the recovery rate was 150% or more due to the phenomenon of coelution, in which mass numbers affect the same fragment.

[Results and considerations of collection experiments for semi-volatile per- and polyfluoroalkyl compounds and volatile per- and polyfluoroalkyl compounds 1]
As shown in Table 4, N-EtFOSE was specifically captured in the urethane foam filter of the semivolatile compound collection area, and the recovery rate was approximately 100% in all prototype samplers. In addition, all fluorotelomer alcohols were below the detection limit in the urethane foam filter, demonstrating that the semivolatile compound collection area and the volatile compound collection area are capable of selectively capturing compounds according to their physical properties.

As shown in Table 5, Prototypes 3 to 5 showed good results in terms of the collection rate of all FTOHs. In Prototype 1, 4:2FTOH and 10:2FTOH were below the detection limit, meaning that adsorption was not possible. In addition, the collection rates for 6:2FTOH and 8:2FTOH were both less than 10%, indicating that the adsorption performance was insufficient. In Prototype 2, the collection performance for 10:2FTOH was sufficient, but the collection performance for 4:2FTOH, 6:2FTOH, and 8:2FTOH was less than 50%, indicating that the adsorption performance was insufficient.

It is believed that Prototype 1 did not have the necessary pores and specific surface area to capture the target substances, and therefore did not fully demonstrate its capture performance. As for Prototype 2, although the specific surface area may have been sufficient, it is believed that the various hydrophilic FTOHs were not fully captured because the surface was hydrophobic.

For prototypes 3 to 5, the collection rates of 4:2FTOH, 6:2FTOH, 8:2FTOH, and 10:2FTOH were all 50% or more, demonstrating excellent collection performance. These were all test examples in which the surface of the activated carbon was oxidized, and it is believed that the presence or absence of the oxidation treatment, i.e., the large amount of oxide on the surface of the activated carbon, was the factor that resulted in high collection performance.

Among them, prototype 4 had a high collection rate of over 70% for all of 4:2FTOH, 6:2FTOH, 8:2FTOH, and 10:2FTOH, confirming the best collection performance.

Regarding the collection rate of N-EtFOSA, it was found that prototype 1 had a collection rate below 50% and did not have sufficient collection performance. Although prototype 2 exceeded 50%, it still could not be said to have sufficient collection performance.

In all of Prototypes 3 to 5, the capture rate of N-EtFOSA exceeded 100%, demonstrating sufficient capture performance. Prototype 4, which has the same specific surface area as Prototype 2, suggests that the capture performance is significantly improved by oxidizing the activated carbon surface. In other words, for N-EtFOSA, the specific surface area of Prototype 3 is necessary, and the increased acidic groups on the activated carbon surface make it possible to provide sufficient capture performance.

Looking at each prototype overall, prototype 1 does not have sufficient collection performance for 4:2FTOH, 6:2FTOH, 8:2FTOH, or 10:2FTOH, and is not suitable as a collection material. Prototype 2 has excellent collection performance for 10:2FTOH, and may be used as a collection material exclusively for 10:2FTOH. However, from the perspective of capturing 4:2FTOH, 6:2FTOH, 8:2FTOH, 10:2FTOH, and N-EtFOSA in a balanced manner, prototypes 3 to 5 have excellent collection performance for per- and polyfluoroalkyl compounds.

As described above, N-EtFOSA, a semivolatile per- and polyfluoroalkyl compound, was efficiently captured in the semivolatile compound capture area, and the recovery rate of the compound was nearly 100%. Furthermore, since the compound was not detected in the filter portion of the volatile compound capture area, it was found that semivolatile per- and polyfluoroalkyl compounds and volatile per- and polyfluoroalkyl compounds can be separated and efficiently captured in each capture area.

By separating and collecting semi-volatile per- and polyfluoroalkyl compounds in the semi-volatile compound collection area located in front of the volatile compound collection area, clogging of the micropores in the adsorbent activated carbon in the filter section of the volatile compound collection area is prevented, and deterioration of adsorption performance is expected to be reduced. In addition, by separating and collecting the compounds, it is possible to prevent co-elution during measurement, reduce analytical errors in the measurement device, and improve measurement accuracy.

In this way, by collecting per- and polyfluoroalkyl compounds adsorbed to particles, semi-volatile per- and polyfluoroalkyl compounds, and volatile per- and polyfluoroalkyl compounds in different collection areas, it became possible to separate and collect each compound, and it was found that all forms of per- and polyfluoroalkyl compounds could be measured satisfactorily.

[Study on collection performance of volatile per- and polyfluoroalkyl compounds 2]
Next, the inventors used the following activated carbon prototypes 6 to 21 to reexamine the optimal transition and collision energy of the MRM mode of GC-MS/MS ("GCMS-TQ8050", manufactured by Shimadzu Corporation), and conducted Experiment 2 on the collection of per- and polyfluoroalkyl compounds in air samples under more accurate analytical conditions.

[Activated carbon treatment 2]
<Prototype Example 6>
10 g of fibrous activated carbon "CF" (C1) manufactured by Futamura Chemical Co., Ltd. was used as the activated carbon of Prototype Example 6.

<Prototype Example 7>
10 g of fibrous activated carbon "CF" (C1) manufactured by Futamura Chemical was immersed in 500 ml of a 4.2% hydrogen peroxide solution, left to stand for 220 hours, then removed and dried to obtain the activated carbon of Prototype Example 7.

<Prototype Example 8>
10 g of fibrous activated carbon "FE3010" (C2) manufactured by Futamura Chemical Co., Ltd. was used as the activated carbon of Prototype Example 8.

<Prototype Example 9>
10 g of fibrous activated carbon "FE3010" (C2) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 4.2% hydrogen peroxide solution, left to stand for 150 hours, then taken out and dried to obtain the activated carbon of Prototype Example 9.

<Prototype Example 10>
10 g of fibrous activated carbon "FE3012" (C3) manufactured by Futamura Chemical was used as the activated carbon of Prototype Example 10.

<Prototype Example 11>
10 g of fibrous activated carbon "FE3012" (C3) manufactured by Futamura Chemical was immersed in 500 ml of a 4.2% hydrogen peroxide solution, left to stand for 100 hours, then removed and dried to obtain activated carbon of prototype 11.

<Prototype Example 12>
10 g of fibrous activated carbon "FE3013" (C4) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 1.5% hydrogen peroxide solution, left to stand for 70 hours, then removed and dried to obtain activated carbon of prototype 12.

<Prototype Example 13>
10 g of fibrous activated carbon "FE3015" (C5) manufactured by Futamura Chemical was used as the activated carbon of Prototype Example 13.

<Prototype Example 14>
10 g of fibrous activated carbon "FE3015" (C5) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 1.5% hydrogen peroxide solution, left to stand for 40 hours, then removed and dried to obtain the activated carbon of prototype 14.

<Prototype Example 15>
10 g of fibrous activated carbon "FE3015" (C5) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 4.2% hydrogen peroxide solution, left to stand for 70 hours, then removed and dried to obtain activated carbon of prototype 15.

<Prototype Example 16>
10 g of fibrous activated carbon "FE3015" (C5) manufactured by Futamura Chemical was immersed in 500 ml of a 14.0% hydrogen peroxide solution, left to stand for 350 hours, then removed and dried to obtain the activated carbon of prototype 16.

<Prototype Example 17>
10 g of fibrous activated carbon "FE3015" (C5) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 18.9% hydrogen peroxide solution, left to stand for 480 hours, then taken out and dried to obtain the activated carbon of Prototype Example 17.

<Prototype Example 18>
10 g of fibrous activated carbon "FE3018" (C6) manufactured by Futamura Chemical was used as the activated carbon of Prototype Example 18.

<Prototype Example 19>
10 g of fibrous activated carbon "FE3018" (C6) manufactured by Futamura Chemical Co., Ltd. was immersed in 500 ml of a 4.2% hydrogen peroxide solution, left to stand for 50 hours, then taken out and dried to obtain the activated carbon of prototype 19.

<Prototype Example 20>
10 g of coconut shell activated carbon "CW480SZ" (C7) manufactured by Futamura Chemical was immersed in 500 ml of a 4.2% hydrogen peroxide solution, left to stand for 70 hours, then removed and dried to obtain the activated carbon of prototype 20.

<Prototype Example 21>
10 g of phenolic resin activated carbon "QW250" (C8) manufactured by Futamura Chemical was immersed in 500 ml of a 4.2% hydrogen peroxide solution, left to stand for 70 hours, then removed and dried to obtain the activated carbon of Prototype Example 21.

[Measurement of adsorbent activated carbon 2]
The surface oxide, specific surface area and average pore diameter of each of the prototypes 6 to 21 were determined in the same manner as in "Measurement of adsorbent activated carbon 1" above.

[Micropore volume]
The pore volume was measured by nitrogen adsorption using an automatic specific surface area/pore distribution measuring device ("BELSORP-miniII", manufactured by Microtrack-Bell Co., Ltd.). The sum of the micropore volumes (V _mic ) (cm ³ /g), which is the pore volume of pores with diameters of 1 nm or less in Prototype Examples 6 to 21, was determined by analyzing the dV/dD value in the pore diameter range of 1 nm or less from the t-plot of the nitrogen gas adsorption isotherm using the MP method.

[Mesopore volume]
The dV/dD value in the pore diameter range of 2 to 60 nm was analyzed by the DH method from the nitrogen gas adsorption isotherm. The diameter range of pore diameters of 2 to 60 nm in the analysis software is 2.43 to 59.72 nm. From the analysis results, the sum of mesopore volumes (V _met ) (cm ³ /g), which is the pore volume of Prototype Examples 6 to 21 in the pore diameter range of 2 to 60 nm, was calculated.

[Volume difference]
The volume difference (V _s ) of Examples 6 to 21 is the value obtained by subtracting the sum of the mesopore volumes (V _met ) (cm ³ /g) from the sum of the micropore volumes (V _mic ) (cm ³ /g), and was calculated using the above formula (i).

The physical properties of the activated carbons of Prototype Examples 6 to 21 are shown in Tables 6 to 8. From top to bottom in Table 6, the properties are the surface oxide amount (meq/g), BET specific surface area (m ² /g), average pore diameter (nm), micropore volume (V _mic ) (cm ³ /g), mesopore volume (V _met ) (cm ³ /g), and volume difference (V _s ) (cm ³ /g).

[Volatile per- and polyfluoroalkyl compound collection experiment 2]
As in the above-mentioned Collection Experiment 1, FTOHs was used as the per- and polyfluoroalkyl compound, and evaluation was carried out for Prototype Examples 6 to 21.

Each standard substance was diluted with methanol to 100 ng/ml (100 ppb) and 100 μl was added to a flexible polyurethane foam (PUF) and placed in the first stage. Next, the second stage was filled with the prototype activated carbon so that the thickness of the filled case was approximately 2 mm when filled in a 47 mm diameter case, and air at 22-24°C was passed through the PUF in the first stage and the adsorbent activated carbon in the second stage at a rate of 20 l/min for 48 hours.

After aeration, the prototype activated carbon was transferred to a PP centrifuge tube (volume 15 ml) and 10 ml of a mixed solvent mainly composed of dichloromethane and ethyl acetate was added. The centrifuge tube was shaken at 225 rpm for 10 minutes, and the extract was collected. This extraction process was repeated twice in succession, and a total of 30 ml of extract was collected.

The collected extract was concentrated to 1 ml using a nitrogen blowing concentrator, and the extract was then quantitatively measured in MRM mode using a GC-MS/MS (GCMS-TQ8050, Shimadzu Corporation) to confirm the collection performance.

Tables 9 to 11 show the recovery rate (%) of fluorotelomer alcohols (FTOHs) for each target substance for the activated carbons of prototypes 6 to 21. The target substances are 4:2 FTOH (IUPAC name: 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexanol), 6:2 FTOH (IUPAC name: 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol), 8:2 FTOH, and 10:2 FTOH (IUPAC name: 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluoro-1-dodecanol).

In the table, "ND" indicates that the value is below the lower limit of quantification. Compared to collection experiment 1, the variation in the mass spectrometry measurement values was reduced.

[Results and considerations of the collection experiment of volatile per- and polyfluoroalkyl compounds 2]
In the prototypes 6 to 9, the recovery rate was below the lower limit of quantification for all FTOHs, and the adsorption of the target substances was insufficient. It is presumed that the adsorption performance was not exhibited because the FTOH did not have the pores or specific surface area required for the adsorption of the target substances.

Prototype Examples 10 to 21 were able to recover all of the FTOH. It was shown that the target substance can be adsorbed when the BET specific surface area is 900 m ² /g or more. It is presumed that the specific surface area parameter of the activated carbon has a certain effect on the adsorption performance of each FTOH. Furthermore, Prototype Examples 10 to 19, which are fibrous activated carbon, showed particularly good results with a recovery rate of 50% or more for all of the FTOH. From the viewpoint of the contact efficiency between the target substance and activated carbon, it is believed that fibrous activated carbon allows for more efficient adsorption of FTOH.

It was also shown that activated carbon with developed micropores and mesopores exhibits higher adsorption performance for any FTOH. In prototypes 6 and 7, neither the micropores nor the mesopores were developed, and it is believed that no FTOH was adsorbed. In prototypes 8 and 9, the micropores were developed but the mesopores were not developed, and therefore there were few mesopores on the entrance side of the activated carbon pores, and it is believed that the FTOH molecules were not smoothly introduced into the micropores, resulting in no adsorption.

In prototypes 10 to 21, the pore volumes of both the micropores and mesopores are large, and it is believed that both types of pores are sufficiently developed, so it can be inferred that FTOH molecules were smoothly introduced into the pores of the activated carbon, demonstrating excellent adsorption performance. Prototypes 12 to 19 demonstrated particularly excellent FTOH recovery performance. Prototypes 12 to 19 are all characterized by a large micropore volume and the fact that, although the mesopores are well developed, the mesopore volumes are not particularly large. After the FTOH molecules are adsorbed into the micropores, they are easily desorbed out of the pores during the extraction operation, which is thought to be why a particularly good recovery rate was demonstrated.

In contrast, since the pore volumes of both micropores and mesopores are large in Prototypes 20 and 21, it can be said that these are activated carbons having pores that have developed in a complex manner, ranging from large pores to small pores. It is presumed that the FTOH molecules adsorbed in the complexly developed pores are less likely to be smoothly desorbed during the extraction operation, resulting in a slightly lower FTOH recovery rate than Prototypes 12 to 19. In view of these results, it can be seen that the sum of the pore volumes of the micropores (V _mic ), the sum of the pore volumes of the mesopores (V _met ), and the volume difference (V _s ), which is the difference between these, affect the FTOH recovery rate.

In addition to the pore conditions of the activated carbon, we also investigated whether the adsorption performance of FTOH could be improved by improving the affinity with FTOH, which has hydrophilic groups, by improving the amount of surface oxide. When comparing prototype 13 and prototypes 14 to 17, which use the same activated carbon raw material, prototypes 14 to 17, which have an increased amount of surface oxide, showed better adsorption performance. Similarly, in prototypes 18 and 19, prototype 19, which has a larger amount of surface oxide, showed better adsorption performance. Therefore, it is understood that it is possible to further improve the adsorption performance of FTOH by increasing the amount of surface oxide on the activated carbon.

As shown in the above volatile per- and polyfluoroalkyl compound capture experiments 1 and 2, it was understood that the adsorption performance of volatile per- and polyfluoroalkyl compounds can be greatly improved by setting the BET specific surface area, pore conditions, and surface oxide amount of the adsorbent activated carbon to a certain level or higher. This allows the adsorption of volatile per- and polyfluoroalkyl compounds by the adsorbent activated carbon in the filter section of the volatile compound capture area to be effectively performed, and therefore it was shown that the accuracy of comprehensive quantitative analysis of all forms of per- and polyfluoroalkyl compounds can be further improved.

[Study on collection performance of atmospheric per- and polyfluoroalkyl compounds 2]
The above experiments showed that it was possible to collect all forms of per- and polyfluoroalkyl compounds in the atmosphere, and therefore the inventors conducted a quantitative evaluation experiment of per- and polyfluoroalkyl compounds in an actual environment.

[Creating a sampler 2]
In order to prepare a sampler for collecting per- and polyfluoroalkyl compounds, the inventors prepared a sampler using polypropylene resin with the following composition.

Intake section: Intake hole: Inner diameter 11.0 mm
Particle-adsorbent compound collection area 1st stage: Particle-adsorbent compound collection area for collecting fine particles of 10 μm or more Clearance section: Inner diameter 40 mm
Collection filter paper: Quartz fiber filter, diameter 25 mm
Impactor plate: Shape of FIG. 4(a), diameter 47 mm
Connection hole: Inner diameter 4.3 mm
Second stage: Particle-adsorbent compound collection area for collecting fine particles of 2.5 to 10 μm Clearance section: Inner diameter 40 mm
Collection filter paper: Quartz fiber filter, diameter 25 mm
Impactor plate: Shape of FIG. 4(a), diameter 47 mm
Connection hole: Inner diameter (diameter) 2.2mm
3rd stage: Particle-adsorbing compound collection area for collecting fine particles of 1.0 to 2.5 μm Clearance section: Inner diameter 40 mm
Collection filter paper: Quartz fiber filter, diameter 25 mm
Impactor plate: Shape of FIG. 4(a), diameter 47 mm
Connection hole: Inner diameter (diameter) 40mm

Quartz fiber filters manufactured by Shibata Scientific Co., Ltd. were used as collection filters for each particle-adsorbing compound collection area.

Semi-volatile compound collection area Urethane foam filter part: polyurethane foam (manufactured by Shibata Scientific Co., Ltd.), diameter 47 mm, height 50 mm

Volatile Compound Area A circular sheet (diameter 47 mm, thickness 2 mm) was prepared using Prototype 10 of adsorbent activated carbon, and two sheets were placed on top of each other to form a filter section.

[Trapping experiment of per- and polyfluoroalkyl compounds in real environments]
Samplers with the above configuration were installed outdoors in Tsukuba City, Ibaraki Prefecture (April 2020) and Minokamo City, Gifu Prefecture (May 2020), and were ventilated at an airflow rate of 20 L/min for 72 hours to conduct experiments to capture per- and polyfluoroalkyl compounds in the air under real-world conditions.

First, the collection experiment in Tsukuba city, Ibaraki prefecture was conducted under conditions of temperature 2-21°C (average 11°C) and relative humidity 31-100% (average 71%), and the experimental results are shown in Tables 12-15. Next, the collection experiment in Minokamo city, Gifu prefecture was conducted under conditions of temperature 16-27°C (average 22°C) and relative humidity 43-88% (average 65%), and the experimental results are shown in Tables 16-19.

In the particle-adsorbing compound collection area, measurements were taken of perfluorocarboxylic acids (hereinafter referred to as "PFCAs") such as 6:2FTUCA (IUPAC name: 3,4,4,5,5,6,6,7,7,8,8,8-dodecafluoro-2-octenoic acid), PFBA, PFPeA, PFHxA, PFOA, PFNA, PFUnDA, PFDoDA, PFTrDA, PFTeDA, PFHxDA, 8:2diPAP, and HFPODA, as well as perfluoroacids (hereinafter referred to as "PFSAs") such as PFBS, PFOS, PFDS, and 6:2FTSA (all from ISO21675:2019).

In the semi-volatile compound collection area, in addition to the aforementioned PFCAs and PFSAs, measurements were also taken of FOSA and N-MeFOSA (from ISO21675:2019) as perfluorooctanoic acids (hereafter referred to as "FOSAs"), and N-MeFOSE and N-EtFOSE as perfluorooctanesulfonic acids (hereafter referred to as "FOSEs"). Note that recovery rates (%) were also measured using N-MeFOSE and N-EtFOSE as surrogates.

In the volatile compound collection area, 4:2FTOH, 6:2FTOH, 8:2FTOH, and 10:2FTOH were used as FTOHs, and 6:2FTI, 8:2FTI, and 10:2FTI were measured as fluorotelomer iodines (hereinafter referred to as "FTIs"). FTI is a substance represented by the following chemical formula (viii). Note that 4:2FTOH, 6:2FTOH, 8:2FTOH, and 10:2FTOH were used as surrogates, and the recovery rate (%) was also measured.

After aeration, the sampler was collected, and the collection filter paper from each stage of the particle-adsorbent compound collection area was placed in a PP test tube, 4 ml of methanol was added, and the mixture was shaken for 20 minutes. The process of transferring the permeate to another PP test tube was repeated three times to collect an extract. The extract was concentrated with nitrogen spray to a constant volume of 1 ml, and the per- and polyfluoroalkyl compounds collected in the particle-adsorbent compound collection area were quantitatively measured in MRM mode using an LC-MS/MS (LCMS-8030, Shimadzu Corporation).

The urethane foam filter part of the semi-volatile compound collection area was loaded into a PP syringe, and 18 ml of a mixed solvent of dichloromethane and ethyl acetate was passed through at a rate of 1 drop/second (1 drop/second), obtaining extract A-1 in a PP test tube. Furthermore, 15 ml of methanol was passed through at a rate of 1 drop/second (1 drop/second), obtaining extract B in a PP test tube. Extracts A-1 and B were concentrated with nitrogen spray to a constant volume of 1 ml. 300 μl of extract A-1 was taken into another PP test tube, and the solvent was replaced with methanol to obtain extract A-2. Extract A-1 was quantitatively analyzed for per- and polyfluoroalkyl compounds collected in the semi-volatile compound collection area using GS-MS/MS, and extracts A-2 and B were quantitatively analyzed in MRM mode using LC-MS/MS, and all values were added together to calculate the total.

The filter part made of adsorbent activated carbon from the volatile compound collection area was placed in a PP test tube, 10 ml of a mixed solvent of dichloromethane and ethyl acetate was added, and the mixture was shaken for 10 minutes. The process of transferring the permeate to another PP test tube was repeated twice to collect an extract. The extract was concentrated by blowing nitrogen into the solution to a constant volume of 1 ml, and the per- and polyfluoroalkyl compounds collected in the volatile compound collection area were quantitatively analyzed using GS-MS/MS in MEM mode.

Tables 12 and 16 show the concentrations (pg/ ^m3 ) of per- and polyfluoroalkyl compounds in sample air in the particle adsorbent compound collection area, Tables 13 and 17 show the amount of particles collected (mg), particle concentration (μg/ ^m3 ), and per- and polyfluoroalkyl compound concentration (μg/g) in the particles collected in the particle adsorbent compound collection area, Tables 14 and 18 show the concentrations (pg/ ^m3 ) of per- and polyfluoroalkyl compounds in sample air in the semi-volatile compound collection area, and Tables 15 and 19 show the concentrations (pg/ ^m3 ) of volatile per- and polyfluoroalkyl compounds in sample air in the volatile compound collection area.

[Concentration of per- and polyfluoroalkyl compounds in sample air]
Tables 12, 14 to 16, 18 and 19 show the concentrations (pg/m ³ ) of per- and polyfluoroalkyl compounds in the sample air. The concentrations of per- and polyfluoroalkyl compounds are values obtained by dividing the amount (pg) of per- and polyfluoroalkyl compounds (target substances) collected in each collection area by the cumulative flow rate (m ³ ) of the sampler, and were calculated using the following formula (ix). In the tables, "BLANK" indicates a value detected by performing similar measurements on the collection filter paper, urethane foam filter section and filter section before the experiment, and "LOQ" indicates the lower limit at which each substance can be quantitatively measured by the measurement device. "-" indicates that the value is below the lower limit of quantification.

[Collection amount]
Tables 13 and 17 show the particles and particle-adsorbent per- and polyfluoroalkyl compounds collected in the particle-adsorbent compound collection area. The amount of particles collected (mg) was calculated as the difference between the filter weight after the experiment and the filter weight before the collection experiment. The weight of the filter was measured to the nearest 1 μg using a precision balance (micro electronic balance "BM-20" manufactured by A&D Co., Ltd.) in a space adjusted to a temperature of 25±1°C and a humidity of 35-40%.

[Particle concentration]
The particle concentration (μg/m ³ ) is a value obtained by dividing the above-mentioned collected amount (mg) by the cumulative flow rate (m ³ ) through the sampler, and was calculated from the following formula (x).

[Concentration of per- and polyfluoroalkyl compounds in collected particles]
The concentration of per- and polyfluoroalkyl compounds adhering to the collected particles is referred to as PFAS concentration in Tables 13 and 17. PFAS concentration (μg/g) is a value indicating the ratio of detected per- and polyfluoroalkyl compounds (PFAS) to the amount of collected particles. It is a value obtained by dividing the sum of the concentrations of per- and polyfluoroalkyl compounds (pg/m ³ ) in the particle-adsorbing compound collection area by the particle concentration (μg/m ³ ), and was calculated using the following formula (xi).

[Results and discussion of collection experiments of per- and polyfluoroalkyl compounds in real environments]
As shown in Figures 12 to 19, even in collection experiments conducted in actual environments in different regions, it was shown that per- and polyfluoroalkyl compounds in the target forms could be successfully collected in each collection area.

In the particle-adsorbent compound collection areas shown in Tables 12, 13, 16, and 17, particle-adsorbent per- and polyfluoroalkyl compounds were detected, and it can be said that good collection was achieved. In addition, although the types of particle-adsorbent per- and polyfluoroalkyl compounds detected tended to be similar in each area, differences were found, such as different types of particle-adsorbent per- and polyfluoroalkyl compounds being collected, the particle sizes of the particles to which the per- and polyfluoroalkyl compounds were attached being different, and characteristics in the concentration and amount of the per- and polyfluoroalkyl compounds. This demonstrates the significance of the sampler as a sampler used for quantitative measurement of particle-adsorbent per- and polyfluoroalkyl compounds.

It can also be said that semivolatile per- and polyfluoroalkyl compounds were successfully captured in the semivolatile compound capture areas shown in Tables 14 and 18. Since particle-adsorbent per- and polyfluoroalkyl compounds were detected in the semivolatile compound capture areas in each region, it is believed that the accuracy of capture of per- and polyfluoroalkyl compounds by form can be further improved by setting a particle-adsorbent compound capture area capable of capturing particles with smaller particle diameters in the particle-adsorbent compound capture area.

As with the particle-adsorbent compound collection areas, there were differences in the types and amounts of semi-volatile per- and polyfluoroalkyl compounds detected in each region, demonstrating the significance of the sampler for use in quantitatively measuring semi-volatile per- and polyfluoroalkyl compounds. In addition, the good measurement of N-MeFOSE and N-EtFose used as surrogates also demonstrates the high accuracy of the sampler for semi-volatile per- and polyfluoroalkyl compounds.

Volatile per- and polyfluoroalkyl compounds were also successfully captured in the volatile compound capture areas shown in Tables 15 and 19. As with the other forms of per- and polyfluoroalkyl compounds listed above, regional differences were observed in the captured per- and polyfluoroalkyl compounds, demonstrating the significance of the sampler for use in quantitative measurement of volatile per- and polyfluoroalkyl compounds. The recovery of FTOHs used as a surrogate was also good, demonstrating the high accuracy of the sampler for volatile per- and polyfluoroalkyl compounds.

As described above, by using the sampler according to the present invention, good results were obtained for the collection of per- and polyfluoroalkyl compounds by form in each collection area. In other words, it was shown that the per- and polyfluoroalkyl compound collection sampler according to the present invention can efficiently and comprehensively collect per- and polyfluoroalkyl compounds present in the air, and can also separate and collect compounds by form, as well as perform highly accurate quantitative measurement.

The per- and polyfluoroalkyl compound collection sampler of the present invention can comprehensively collect per- and polyfluoroalkyl compounds present in the atmosphere in various forms, for each form of the compound, making it possible to quantitatively measure the compounds, which was not possible with existing collection materials. In addition, by controlling the physical properties of the activated carbon used as the collection material, the adsorption performance of per- and polyfluoroalkyl compounds is improved, enabling more accurate and effective quantitative measurement. This makes it possible to contribute to the quantitative evaluation of per- and polyfluoroalkyl compounds as environmental persistent organic pollutants that may be subject to regulation.

REFERENCE SIGNS LIST 10 Sampler 20 Particle-adsorbing compound collection area 21 Inertial impactor section 22 Collection filter paper 23 Impactor plate 24 Through hole 25 Clearance section 26 Acceleration nozzle 27 Connecting hole 28 Disk-shaped object 29 Extremely small particle collection section 30 Semi-volatile compound collection area 31 Urethane foam filter section 32 Urethane foam 40 Volatile compound collection area 41 Filter section C Adsorbent activated carbon

Claims (7)

A sampler for collecting per- and polyfluoroalkyl compounds in a sample air, comprising:
an intake section for sucking in the sample air;
a particle-adsorbent compound collection area connected to the air intake and including an inertial impactor for collecting particle-adsorbent per- and polyfluoroalkyl compounds in the air;
a semi-volatile compound collection area connected to the particle-adsorbent compound collection area and including a urethane foam filter section for collecting semi-volatile per- and polyfluoroalkyl compounds in the air;
a volatile compound collection area connected to the semi-volatile compound collection area and equipped with a filter section made of adsorbent activated carbon having a BET specific surface area of 900 m ² /g or more for collecting volatile per- and polyfluoroalkyl compounds in the air;
and an exhaust section connected to the volatile compound collection area, through which the atmospheric air that has ventilated each of the areas is exhausted. The per- and polyfluoroalkyl compound collection sampler according to claim 1, wherein the particle-adsorbent compound collection area is made up of multiple layers of the inertial impactor section that sequentially collects particle-adsorbent per- and polyfluoroalkyl compounds in the atmosphere in multiple particle sizes in descending order of particle diameter. The per- and polyfluoroalkyl compound collection sampler according to claim 1 or 2, wherein the amount of surface oxide on the adsorbent activated carbon is 0.10 meq/g or more. 4. The sampler for collecting per- and polyfluoroalkyl compounds according to claim 1, wherein the sum of the micropore volumes (V _mic ) of the adsorbent activated carbon having a size of 1 nm or less is 0.35 cm ³ /g or more. 4. The sampler for collecting per- and polyfluoroalkyl compounds according to claim 1 , wherein the sum of the volumes of mesopores of 2 to 60 nm in the adsorbent activated carbon (V _met ) is 0.02 cm ³ /g or more. The sum of the mesopore volumes of 2 to 60 nm of the adsorbent activated carbon (V _Met ) is 0.02 cm ³ 5. The per- and polyfluoroalkyl compound collection sampler according to claim 4, wherein the concentration of said per- and polyfluoroalkyl compounds is 1/g or more. 7. The per- and polyfluoroalkyl compound collection sampler according to claim 6 , wherein the volume difference (Vs) between the sum of the micropore volumes ( _Vmic ) and the sum of the mesopore volumes ( _{Vmet )} of the adsorbent activated carbon defined by the following formula (i) is 0.45 or more.

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