Preparation of adsorbent filters prelabeled with standards for evaluating the sampling of contaminants in liquid and gaseous matrices.

Abstract

A filtration and adsorption sampling and concentration system is described, which includes a stationary phase consisting of activated carbon fiber felt with a micro- and mesoporous structure and a specific surface area of ​​approximately 1500 m / g enclosed in a sealed enclosure, and a sample collection and / or concentration standard, a method for making the same, and an associated method for the analysis of organic and inorganic analytes using the system.

Description

[Technical Field]

[0001] The present invention relates to the field of environmental sampling of pollutants, more particularly to the field of environmental sampling of analytes dispersed in fluid matrices, and in particular to a filtration and adsorption system pre-loaded with standards and its use for the simultaneous sampling of organic and inorganic compounds in liquid and gas matrices. [Background technology]

[0002] Air sampling of semivolatile organic compounds is performed by placing a sampling standard on a filter or on an absorbent / adsorbent material capable of retaining the vapor fraction of the analyte not retained by the filter. Such a sampling system may, for example, consist of a 102 mm diameter quartz fiber filter followed by a 0.022 g / cm density filter. 3 The sampler may consist of an air sampler equipped with an absorbent made from polyurethane foam (PUF) 50 mm thick. The sampling time may range from a few hours to a total of approximately 2200 m, depending on whether the sampling is done indoors or outdoors. 3 The sampling time can range from 1 minute to 2 hours, with weekly sampling performed at a flow rate of 225 L / min for 1000 sq ft of air.

[0003] Table 1 below compares the U.S. Environmental Protection Agency (EPA) and International Organization for Standardization (ISO) outdoor and indoor sampling methods for dibenzofurans and polychlorinated dibenzo-p-dioxins (PCDD / Fs), polybrominated dibenzo-p-dioxins (PBDD / Fs), and brominated or chlorinated pesticides, and polychlorinated biphenyls (PCBs). All of the methods in Table 1 use the same collection and sampling systems.

[0004] [Table 1]

[0005] The use of sampling standards is defined as mandatory by ISO 16000 13A and 14A and EPA TO9A regulations. In fact, a sample is only valid for quantification if the recovery of its standard falls within a defined range. Although EPA TO4A does not require labeling, the validity of the sampling for these analytes (the same as those evaluated in ISO 16000 13 and 14) can only be guaranteed by this step.

[0006] The collection medium to which the sampling standards are added may be of various types, such as polyurethane foam (PUF) according to ISO 16000 Method 13, or EPA TO-9A (EPA TO-9A, "Method TO-9A: Determination of Polychlorinated, Polybrominated, and Brominated / Chlorinated Dibenzo-p-Dioxins and Dibenzofurans in Ambient Air," EPA Methods, January, pp. 1-94, 1999). EPA TO-4A (Method TO-4A: Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air Second Edition Compendium Method TO-4A Determination of Pesticides and Polychlorinated Biphenyls in Ambient Air Using High Volume Polyurethane Foam (PUF), EPA Methods, January, p. 1-53, 1999), or I.16000-14 ("ISO / DIS 16000-14-Indoor air-Part 14: Determination of total(gas and particle-phase) polychlorinated dioxin-like biphenyls (PCBs) and polychlorinated dibenzodioxins / dibenzofurans (PCDDs / PCDFs)-Extraction, clean-up and analysis by high resolution ga", 2007) The filter may be as described in

[0007] In all of the above methods, the filters and PUFs must also be labeled with an extraction standard, which is used to calculate the recovery of the sampling standard. The filtration and adsorption collection media are extracted together in a Soxhlet extractor for a time and solvent that can vary depending on the method. The extract is then purified and the analytes are separated into classes, usually using preparative chromatography techniques. The purified and separated fractions are concentrated to a few microliters, and a third standard is added before instrumental analysis. This third standard, also called a syringe standard, is a known amount of analyte or mixture with 100% recovery.

[0008] For sampling of organic micropollutants from industrial emissions, even for long-term sampling, regulations (e.g., EN 1948-1, 4, 5 EPA TO 23) require a sampling system consisting of three separate compartments: a filtration system, an adsorption / absorption system, and a condensation system. The filtration system can be omitted, in which case particulate collection occurs directly on the adsorption / absorption system. However, in both cases, a sampling standard is available, and labeling can be performed on-site (at the measurement site) or in advance in the laboratory. In the second case, there is an additional uncertainty in the measurement due to possible losses of the standard during the time elapsed between labeling in the laboratory and sampling on-site. These losses are even more pronounced when the standard is added to the filter rather than the adsorption / absorption system. Adding a sampling standard to each of the three collection systems and then comparing the same analytes across these systems can introduce additional errors. In fact, loss of the standard due to decomposition or volatilization does not occur equally in the three systems, resulting in variable comparison results. For example, method EN 1948 Part 1-2-3-4-5, which is dedicated to the sampling of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzo-p-furans (PCDFs) and polychlorinated biphenyls (PCBs), provides for the labelling of various media according to the expected concentrations.

[0009] Adding standards directly at the sampling site reduces errors due to decomposition and volatilization of standards during transportation. However, automating the actual process of adding standards remains difficult, and the uncertainties that clearly affect this parameter the most include the stability of the standards, the reproducibility between operators and the subjective performance of labeling from one operator to another, and the atmospheric and environmental conditions under which the procedure is performed. In emissions sampling, the environment is often dusty and contaminated with the analytes being measured. Labeling in such an environment increases the risk of overestimating contaminants in the emissions due to contamination of the sampling filters during environmental exposure in the labeling procedure.

[0010] On-site marking also significantly increases the time required to set up a series of measurements. This is even more evident with continuous sampling systems, where on-site marking makes the process slow, difficult and error prone, and exposes the operator and the surrounding environment to contamination.

[0011] For liquid matrices, sampling or concentration can be achieved using filters or sorbents. Supports consisting of filters dispersed with octadecyl- or octyl-derivatized silica microparticles (ENVI-Disk™, Sigma-Aldrich) are commonly used for solid-phase extraction of organic compounds from aqueous samples, i.e., analytes dispersed in aqueous matrices, and are known in the art (EG Amvrazi and TA Albanis, "Multiresidue method for determination of 35 pesticides in virgin olive oil by using liquid-liquid extraction techniques coupled with solid-phase extraction cleanup and gas chromatography with nitrogen phosphorus detection and electron capture detection," J. Agric. Food Chem., Vol. 54, No. 26, pp. 9642-9651, 2006, doi:10.1021 / jf061375s).

[0012] Alternatively, solid-phase extraction of organic compounds from aqueous matrices can be performed using the Empore™ system manufactured by 3M Company, which consists of adsorbent particles (e.g., silica or carbon spheres derivatized with divinylbenzene or octadecyl or octyl groups) embedded within a polytetrafluoroethylene lattice. Empore™ disks are commonly used for solid-phase extraction of organic compounds from liquid matrices (W.M.G. Van Loon, F.G. Wijnker, M.E. Verwoerd, and J.L.M. Hermens, "Quantitative Determination of Total Molar Concentrations of Bioaccumulatable Organic Micropollutants in Water Using C18 Empore Disk and Molar Detection Techniques," Anal. Chem., Vol. 68, No. 17, pp. 2916-2926, 1996, doi:10.1021 / ac951136w), and as passive samplers or concentration systems, such as in the case of groundwater or wastewater monitoring (L. Pinasseau et al., "Calibration and field application of an innovative passive sampler for monitoring groundwater"). quality”, Talanta, Vol. 208, June 2019, pp. 120307, ​​2019, doi:10.1016 / j.talanta.2019.120307, ​​L. Mutzner et al., “Passive samplers to quantify micropollutants in sewer overflows: accumulation behavior and field validation for short pollution events”, Water Res., Vol. 160, pp. 350-360, 2019, doi:10.1016 / j.watres.2019.04.012), and have been used as passive samplers for suspended organic micropollutants (C. Sanchez, H. Carlsson, A. Colmsjo, C. Crescenzi and R.Batlle, "Determination of nitroaromatic compounds in air samples at femtogram level using C18 membrane sampling and on-line extraction with LC-MS", Anal.Chem., Vol. 75, No. 17, pp. 4639 - 4645, 2003, doi:10.1021 / ac034278w, J. Tollback, D. Tamburro, C. Crescenzi and H. Carlsson, "Air sampling with Empore solid phase extraction membranes and online single-channel desorption / liquid chromatography / mass spectrometry analysis: Determination of volatile and semi-volatile organophosphate esters", J.Chromatogr.A, Vol. 1129, No. 1, pp. 1 - 8, 2006, doi:10.1016 / j.chroma.2006.05.086).

[0013] "Sandwich" filters, such as the Atlantic SPE disk™ (Horizon Technologies), in which a sorbent material is placed between two layers of quartz or paper, are also known. The sorbent material can be, for example, silica microspheres derivatized with octadecyl, styrene / divinylbenzene, or a combination of N-vinylpyrrolidone and divinylbenzene, which are used for solid-phase extraction of organic compounds from aqueous matrices (C.C. Leandro, D.A. Bishop, R.J. Fussell, F.D. Smith, and B.J. Keely, "Semiautomated determination of pesticides in water using solid phase extraction disks and gas chromatography-mass spectrometry," J. Agric. Food Chem., Vol. 54, No. 3, pp. 645-649, 2006, doi:10.1021 / jf051874d).

[0014] US Patent No. 3,002,823 discloses a silica gel chromatography method for separating compounds of different molecular weights in an aqueous phase. This method uses a filler-free, granular gel consisting of three-dimensional molecular clusters, bound with aliphatic groups (3 to 10 carbon atoms), whose -OH group content is at least 12% of the dry weight of the gel. The latter is obtained by polymerization of an organic substance (filler-free and containing -OH groups) with an organic substance containing halide or epoxy groups.

[0015] US Pat. No. 4,118,316 discloses a gel chromatography method for separating compounds of different molecular weights using a porous silanized silica support functionalized with quaternary ammonium groups.

[0016] US Pat. No. 4,539,399 discloses silica gels that are functionalized by attaching cyclodextrins to the silanols and that can be used in thin layer chromatography.

[0017] All supports known in the art and described above can be pre-labeled with a sampling standard, which can be the same analyte as the one being sampled or the same analyte to be sampled, but with a labeling atom, i.e., an analyte that is isotopically different from that found in the sample.

[0018] European Patent Application No. 13801779.3 discloses a filter made of quartz or glass fiber or sintered silica silanized with (Si-O)n-Si-Rm groups, where (Si-O)- is the functionalized surface fraction, R is a functional group adapted to retain analytes present in liquid and gas matrices, n and m are integers, n+m=4, n>0, m>0, the filter having a dust retention rate of more than 80% for diameters greater than 0.3 μm, a thickness of 0.01-50 mm and an area of ​​0.1-2500 cm2.

[0019] Italian Patent Publication No. 102015000041855, corresponding to International Patent Application PCT / IB2016 / 054644, discloses a stationary phase for use in the analysis of organic and inorganic compounds, gases, and vapors. These include, inter alia, volatile organic compounds (VOCs), semivolatile organic compounds (VOCs), and mercury vapor. The stationary phase consists of carbon fibers, both activated and inactivated, optionally functionalized or coated, which may be entangled, twisted, woven, parallel-spun, or woven in the form of a bundle of carbon fibers, or entangled in the form of a tube, woven, or woven in the form of a disk, or entangled in the form of a tube, or entangled in the form of a disk. Furthermore, a process for analyzing the analyte is described, including capturing the analyte on the stationary phase, recovering the analyte by desorption, and quantifying the analyte.

[0020] Italian Patent No. 102015000041855, corresponding to International Patent Application PCT / IB2016 / 054644, fails to address three issues. The first is the defibration of the material. This can lead to loss of adsorbent material, making it difficult to create a stable, effective, and reproducible adsorbent substrate using activated carbon fibers (ACF). Furthermore, due to their size and the potential presence of toxic compounds, the released fibers could be harmful to the operator if inhaled or ingested after sample collection. The second is the characterization of the activated carbon fibers (ACF) used. This is because not all ACFs guarantee good analytical performance, and some activated carbon fibers can be more difficult to handle and process than others. The final issue is the distribution of standards in a uniform, automated, reproducible, and accurate manner. This issue is crucial for successful sampling and reliable data, especially when the distribution must be carried out over large surfaces.

[0021] A scientific publication by Cerasa et al. (2020 "Validation studies on activated carbon fiber passive sampler for PCDD / Fs and PCBs in water", Chemosphere, January, Vol. 239, No. 124666, doi:10.1016 / j.chemosphere.2019.124666. Epub 25 Aug. 2019) describes the use of a pre-labeled carbon fiber adsorbent membrane in an aqueous matrix and demonstrates the possibility of using activated carbon fiber (ACF) adsorbents in this matrix as well as in air. No isotopically labeled standards and / or sampling standards have been added to this material. The properties of the activated carbon fiber (ACF) are shown in the following table:

[0022] [Table 2]

[0023] In particular, Cerasa et al. (2020) reported validation data for activated carbon fiber (ACF) membranes for quantitative adsorption and desorption of PCDD / Fs and PCBs in water as an alternative to standard liquid-liquid extraction techniques. Validation was performed according to the requirements of standard methods EPA 1613 and EPA 1668, which assume liquid-liquid extraction techniques. The adsorption and desorption results for each contaminant class from the activated carbon fiber (ACF) were then compared with those of liquid-liquid extraction techniques using standards spiked in water. In Cerasa et al. (2020), this method does not involve the addition of isotopically labeled congener standards to the adsorption membrane prior to extraction or concentration. Quantitative results were obtained using isotopically labeled water standards, and then the sampling was replicated using the labeled congeners. Indeed, the use of original congener standards inevitably entails the possibility of results being altered by existing interfering substances in the water. Summary of the Invention [Problem to be solved by the invention]

[0024] The function of a sampling standard is to assess possible losses of analytes during the same sample run. These losses can result from breakthrough of the filtration / adsorption system, reactions with substances present in the sampled matrix, or evaporation or decomposition processes that may occur during the time elapsed between sample run and subsequent chemical analysis. Analyte sampling can be both passive and active. In the first case, the analyte reaches the concentration system by diffusion, and in the second case, by the use of a pump. When the analyte is highly dilute, it is necessary to sample a large amount of matrix to be able to exceed the limit of quantitation (LOQ). In these cases, resorting to active sampling with a concentration system, also known as a collection system, is virtually essential to achieve sampling within a reasonably short time, i.e., 24 to 300 hours. An ideal collection system would completely retain the analyte and allow the remainder of the matrix to pass through. A practical collection system would retain a significant proportion of the analyte, along with other compounds (interfering substances) present in the matrix. High sample volumes can lead to breakthrough of the collection system, while high levels of interfering substances can lead to analyte degradation. The addition of sampling standards helps to assess such aberrations. The efficiency of a concentration system is defined as the ratio of the amount of analyte collected to the total amount of analyte passing through it. The capacity of a concentration system is defined as the maximum amount of analyte it can hold before it becomes saturated and loses / changes its efficiency.

[0025] The resulting sample thus consists of a concentration system containing the analyte, interfering substances, and a sampling standard that defines the quality of the sample. Each sampling is associated with a volume sampled. The analyte is extracted from the sample using a mixture of solvents selected to extract the maximum amount of analyte and the minimum amount of interfering substances. The sampling standard is selected to have similar chemical / physical behavior to the analyte, and in the case of isotopically labeled compounds, is extracted in a similar manner due to its equivalent chemical / physical behavior. Further purification of the extract may be necessary before proceeding with the analysis. An alternative to solvent extraction is thermal desorption, which is used when the analytes interact weakly, are volatile at the operating temperature, the desorption enthalpy is smaller than the energy required to decompose the analyte, and the volatility of interfering substances is low or absent.

[0026] Thus, the analyte sampling procedure contemplates the introduction of a sampling standard, possibly isotopically labeled and a compound similar to the analyte being sampled, or the isotopically labeled analyte itself, at a known concentration onto the collection system prior to sampling, in a step known as sample labeling.

[0027] The labeling step can be performed before the sampling system is transported to the measurement site, or can be performed in situ at the time of sampling.

[0028] Unfortunately, sampling devices known in the art are subject to loss of sampling standards, which can alter the accuracy of the sampling itself. Losses can occur due to evaporation processes that occur during the time that passes between standard preparation, sampling, and subsequent chemical analysis. Loss of sampling standards can also occur if the system is handled in an improper location, with potential danger to the operator.

[0029] The choice of sorbent is also important for proper sampling of the analytes present in the matrix. An insufficient sorbent will not guarantee a homogeneous and representative sample, a characteristic essential for providing accurate analytical data. Therefore, the selected material must have the ability to quantitatively adsorb the analytes present in the sample without environmental interference or significant sample loss, with the percentage criteria defined by the method used.

[0030] The same inventors have themselves demonstrated that the device described in patent no. 102015000041855 can be implemented in such a way that a reference standard can be pre-dosed without the drawbacks of devices known in the art, by using materials that are made less susceptible to defibration by encapsulation / encapsulation.

[0031] The proposed technical solution makes it possible to overcome the problems of devices known in the art, facilitates the sampling operation in a series of measurements, avoids handling chemicals in inappropriate places (to ensure operator safety and the integrity of standards handled outside a controlled environment such as a chemical laboratory), and reduces the loss of both reference analytes and analytical artifacts.

[0032] Therefore, the inventors have devised a filtration / sorption system capable of retaining semivolatile organic and inorganic standard compounds, which reliably assesses analyte sampling / concentration from a fluid matrix in the presence or absence of particulate matter. This system, pre-loaded with sampling standards, has a high ability to quantitatively retain the standards unchanged from the time they are added to the system until they are used. This allows for higher recoveries of the sampling standards to be achieved, thereby reducing measurement uncertainty and increasing the precision and accuracy of the method.

[0033] Another technical problem solved by the present invention is that of delamination / fibrillation.

[0034] In fact, in systems known in the art that apply activated carbon fibers (ACF) for analytical purposes, fiber aggregates are lost from the material itself during handling, resulting in unquantifiable loss of adsorbent material. This physical characteristic severely limits the use of such activated carbon fiber filters (ACF) as sampling systems, since their structural integrity cannot be guaranteed. In fact, the release of fibers of various sizes into the washing solvent can already be observed during the membrane cleaning process prior to sampling, which is usually performed in the same way as extraction. Unclear fibers can also be seen with the naked eye when handling the filter itself, releasing material onto the support on which the filter is placed or onto the gloves used by the operator. The released fibers have the same adsorption properties as the original material. This event can cause an irreproducible and unquantifiable loss of the sampling standard added to the membrane at time t = 0, negatively impacting workplace safety and potentially causing an irreproducible and unquantifiable loss of sample. Unquantifiable ACF unclearness is dependent on subjective handling, and therefore the recovery of the sampling standard is highly variable. Fibers released from activated carbon fibers (ACF) can adversely affect the portion of the material spiked with a sampling standard. Because the recovery of this standard is essential for verifying quantitative analyses, being adversely affected by a completely uncontrollable variable can render properly performed sampling useless. Handling can involve the simple packaging of pre-labeled membranes or their transport and use. The defibration of filters after sampling or simply spiked with standards can also pose an occupational health issue. These fibers, concentrated with potentially toxic analytes, can easily be dispersed in the air and thus inhaled or involuntarily ingested by operators during all filter handling procedures.

[0035] Fiber loss (also known as delamination) can occur not only during filter handling but also during sampling or extraction steps. In the first case, fiber loss can lead to unquantifiable loss of sample and absolute loss of adsorption medium capacity, in addition to the potential underestimation of sampling standards. In the second case, extraction efficiency can become so low that it becomes completely uncontrollable. Each fiber from the filter has practically the exact same adsorption capacity as the original membrane, and even small amounts present in the extract tend to passively adsorb the original compounds and standards. This occurs in any type of liquid extraction and can lead to inaccurate evaluation of sampling and extraction standards and the target analytes themselves. The aforementioned problem arises whenever activated carbon fibers (ACFs) are used directly in analytical applications. It should be emphasized that this drawback cannot be simply solved by ultracentrifugation and subsequent extraction of the sedimented fibers. This is because the dimensions of the fibers themselves are such that they are always suspended, making it impossible to separate specific particles. Furthermore, even if separation of the extractables and residual fiber impurities is successful, the kinetics of analyte partitioning between the filtered fiber and the extraction solvent are unknown, and the recoveries of analytes and sampling standards may vary from case to case.

[0036] In the present invention, this technical problem is solved by encapsulating and / or sealing the adsorbent membrane, avoiding the loss of activated carbon fiber (ACF) fractions. Unlike other types of encapsulation, where the adsorbent is placed between two filters (sandwich system) or dispersed in a separate device, the membrane is sealed and / or sealed by protecting it on all sides. In fact, the latter two types of systems do not guarantee that released fibers will not disperse during filter handling. Therefore, the proposed solution envisions encapsulating / encapsulating the activated carbon fiber (ACF) membrane, and includes all solutions that have the following characteristics: they do not significantly increase impedance or reduce the adsorption capacity of the material itself, thus not interfering with sampling; they are compatible with the matrix being sampled; they are not competitors of the analyte and do not produce sampling artifacts; and they are compatible with laboratory extraction or handling techniques (i.e., they are not thermally unstable or degradable by the action of pressure or solvents). Furthermore, their shape, thickness, and orientation are designed to fit the sampling equipment.

[0037] Therefore, the sealing / encapsulation avoids leakage or loss of micro / macro-sized parts of the activated carbon fiber (ACF) membrane, and also ensures that there is no loss of the sampling standard and that the quantitative analysis of the actual sample is accurate. Furthermore, it ensures easy handling of the activated carbon fiber (ACF) membrane. The sealing procedure ensures excellent airtightness and resistance to chemical and physical stresses and does not interfere with the sampling system.

[0038] Another advantage is the fact that it can work on a micro-scale without adversely affecting the materials inside the enclosure. The containment system is achieved without altering the stability of pre-added standards, and guarantees that standards can be added after encapsulation without competing with the activated carbon fibers (ACF).

[0039] Depending on the application and extraction system, the encapsulating material may be pre-cleaned with a solvent.

[0040] Another factor considered in the following invention is the selection of the type of ACF, whose chemical and physical properties vary based on the degree of activation, i.e., the industrial procedure to which they are subjected. The higher the degree of activation, the more stringent the non-analytical technical procedures have become, and the higher the specific surface area, the adsorption capacity, and the purity of the adsorbent, but also the more fragile it becomes. This results in a material with less agglomeration and facilitates its defibration. [Means for solving the problem]

[0041] The aforementioned technical problems were solved by the use of a micro- and mesoporous structure and a specific surface area of ​​approximately 1500 m, enclosed in a sealed enclosure. 2 This is solved by a filtration and adsorption sampling and concentration system that includes a stationary phase consisting of a felt cloth of activated carbon fibers having 0.1% saturation / g and a sampling and / or concentration standard.

[0042] A further object of the present invention is to provide a method for producing a polymeric nanoparticle with a micro- and mesoporous structure and a specific surface area of ​​approximately 1500 m², enclosed in a sealed enclosure. 2 A method for preparing a filtration and adsorption sampling and concentration system comprising a stationary phase consisting of a felt-type cloth of activated carbon fibers having a % saturation of 0.1% by mass per 1000 kJ / g, and a sampling and / or concentration standard.

[0043] A further object of the present invention is to provide a method for producing a polymeric nanoparticle with a micro- and mesoporous structure and a specific surface area of ​​approximately 1500 m², enclosed in a sealed enclosure. 2 A method for the analysis of organic and inorganic analytes by using a filtration and adsorption sampling and concentration system comprising a stationary phase consisting of a felt-type cloth of activated carbon fibers having a solubility of 1000 s / g and a sampling and / or concentration standard.

[0044] Further features of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings and examples. [Brief explanation of the drawings]

[0045] [Figure 1]A comparison of the mean recoveries of a mixture of 13C PCB congeners added to QFF (quartz fiber filter) and ACF (activated carbon fiber) filters after 24 hours of exposure at a temperature of 35°C is shown in the graph, with the Y-axis representing R% (recovery) and the X-axis representing 13C-labeled PCB congeners (L, labeled). [Figure 2] A comparison of the mean recoveries of a 13C PCDD / F congener mixture added to QFF (quartz fiber filter) and ACF (activated carbon fiber) filters after 24 hours of exposure at a temperature of 35°C is shown in the graph, with the Y-axis representing R% (recovery) and the X-axis representing 13C-labeled PCDD / F congeners. [Figure 3] A comparison of the mean recoveries of 13C PCB congener sampling standards added to aluminum-wrapped and sealed QFF (quartz fiber filter) and ACF (activated carbon fiber) filters after 15 days of exposure to an average temperature of 23.5°C and relative humidity of 55.9% is shown in the graph, with R% (recovery) on the Y-axis and 13C-labeled PCB congeners (L, labeled) on the X-axis. [Figure 4] A comparison of the mean recoveries of 13C PCDD / F congener sampling standards added to aluminum-wrapped and sealed QFF (quartz fiber filter) and ACF (activated carbon fiber) filters after 15 days of exposure to an average temperature of 23.5°C and relative humidity of 55.9% is shown in the graph, with R% (recovery) on the Y-axis and 13C-labeled PCDD / F congeners on the X-axis. [Figure 5] A comparison of the average recoveries of 13C PCDD / F congener sampling standards spiked into aluminum-encased, wrapped, and sealed ACF (activated carbon fiber) ACN 15 type after 7 days, 30 days (1 month), and 90 days (3 months) at an ambient temperature of approximately 20°C and a refrigerator temperature of approximately 4°C is shown in the graph, where the Y-axis is R% (recovery) and the X-axis is the 13C-labeled PCDD / F congener used as the sampling standard. [Figure 6]A comparison of the average recoveries of 13C PCB congener sampling standards spiked into aluminum-encased, wrapped, and sealed ACF (activated carbon fiber) ACN Type 15 after 7 days, 30 days (1 month), and 90 days (3 months) at an ambient temperature of approximately 20°C and a refrigerator temperature of approximately 4°C is shown in the graph, where the Y-axis is R% (recovery) and the X-axis is the 13C-labeled PCB congener (L, label) used as the sampling standard. [Figure 7] 1 shows a schematic of the fabrication of an ACF filter type ACN 15 encapsulated with an aluminum edge. DETAILED DESCRIPTION OF THE INVENTION

[0046] definition In the sense of the present invention, carbon fiber (CF) refers to a material consisting of fibers with a diameter of approximately 5 to 10 microns and composed mainly of carbon atoms.

[0047] In the sense of the present invention, activated carbon fibers (FCA) are fibrous carbonaceous adsorbents obtained by carbonization and activation of polymer fibers, preferably of the phenol-aldehyde or poly(acrylonitrile) (PAN) type, as described, for example, in Italian Patent Application No. 102015000041855, which is incorporated by reference.

[0048] In the sense of the present invention, sampled organic and inorganic compounds are all classes of compounds that are of interest to analytical chemistry. Purely by way of example, they may be polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-para-dioxins and polychlorinated dibenzofurans, chlorobenzenes, alkylbenzenes, alkanes, phthalates, polybrominated diphenyl ethers, perfluoroalkylated drugs, active ingredients, perfluoroalkylated substances (PFAS-PFOA), metabolites, mercury in elemental and bound form, semivolatile metal halides.

[0049] In the sense of the present invention, a sampling standard refers to any compound equivalent or similar to the analyte to be sampled, or the isotopically labeled analyte itself, that is added to the sampling system to reduce aberrations and measurement errors and to assess the accuracy of the measurement.

[0050] The object of the present invention is to develop a nano-sized ... 2 A filtration and adsorption sampling and concentration system comprising a stationary phase consisting of a felt-type cloth of activated carbon fibers having a % saturation of 0.1% by mass per 1000 saturates / g, and a sampling and / or concentration standard.

[0051] If desired, the activated carbon fibers can be functionalized or coated.

[0052] Preferably, the activated carbon fibers are coated with a coating agent selected from the group consisting of squalene, methyl silicone OV-1, methyl silicone SE-30, methyl-phenyl-silicone (20% phenyl) OV-7, methyl-phenyl-silicone (50% phenyl) OV-17, cyanopropyl-methyl-phenyl-silicone OV-225, Carbowax 20M (polyethylene glycol), nitroterephthalic acid ester of PEG (FFAP), diethylene glycol succinate (DEGS).

[0053] Preferably, the felt is a woven or nonwoven fabric.

[0054] Preferably the felt is of the ACN 15 type.

[0055] The term ACN 15 refers to a concentration of 1500 m 2 / g, mfibres 3.3dtex, 80% uncrimped and 20% crimped, Kynol type nonwoven felt for large capacity.

[0056] The membranes of the present invention can be used for in situ analyte sampling by active or passive methods, and can also be used to concentrate samples from previously collected gas or liquid matrices.

[0057] In the latter case, it is also possible to concentrate the analytes present in the laboratory if required by the method, or if it is desired to lower the limit of quantification of already collected samples, or if it was not possible to use ACF in the sampling step.

[0058] A further object of the present invention is to provide a method for manufacturing a semiconductor device having a specific surface area of ​​approximately 1500 m², enclosed in a sealed enclosure. 2 1. A method for preparing a filtration and adsorption sampling and concentration system comprising a stationary phase made of a felt nonwoven fabric of activated carbon fibers having a micro- or mesoporous structure of 1 / g and a sample collection and / or concentration standard, the method comprising: (a) a step of purifying the stationary phase from organic or inorganic impurities; (b) a drying step of the stationary phase obtained at the end of step (a); (c) adding a sampling standard; (d) a process of encapsulating and sealing the enclosure without using adhesives and / or glues; Includes.

[0059] Preferably, in step (a), purification is carried out by solvent extraction or by treatment with an acid and an oxidizing agent followed by washing with water, most preferably MilliQ™ water.

[0060] Preferably, in step (b), drying of the stationary phase is carried out under vacuum if the purification in step (a) was carried out with a solvent, or by thermal dehydration if the purification in step (a) was carried out with an acid and oxidizing agent treatment.

[0061] In step (c), the loading of the sampling standards onto the membrane is carried out in a uniform, reproducible and accurate manner.

[0062] Preferably, in step (c), the deposition of the sampling standards onto the stationary phase is performed at n predetermined positions. Preferably, in step (c), the deposition of the sampling standards onto the stationary phase is performed by an automated multi-tip dispensing device that is able to dispense the sampling standards onto the membrane at different speeds in a fully repeatable and automatic manner.

[0063] In automated dispensing devices, the stationary phase is placed on a rotating or vibrating plate with an adjustable and constant speed. The sampling standards are dispensed simultaneously with the movement of the membrane, thus ensuring equal distribution over the entire surface.

[0064] The distribution of the sampling standards on the stationary phase can be carried out in concentric circles (n circles) in the case of a rotating plate, or in n lines (continuous or interrupted, crossed or non-crossed) in the case of an oscillating plate or non-rotating motion.

[0065] Preferably, the dispensing of the sampling standards is performed with a quantitative precision equal to 10 μl±0.20 μl and a standard deviation of 0.1%.

[0066] Optionally, in step (c), a stabilizer is added to the sampling standards.

[0067] This procedure avoids the loss of the sampling standards before measurements are made and therefore during their storage and / or transport.

[0068] For example, for PCDD / Fs and PCBs, 4% tetradecane is added to the nonane solution containing the sampling standards.

[0069] The sampling system is enclosed in a sealed enclosure, where enclosure is understood as a method of sealing it on all sides using a continuous material of a mesh size such that no fibres are released to the outside.

[0070] Preferably, the housing material is selected from the group consisting of natural or synthetic polymers, cellulose or silica based sheets, wire mesh or combinations thereof.

[0071] More preferably, the material of the housing is selected from the group consisting of quartz fiber, polypropylene, nylon fiber, aldehyde fiber, phenolic fiber, amino fiber, vinyl fiber filter, cellulose fiber, cellulose derivatives and metal screens and combinations thereof.

[0072] The housing is sealed by a technique selected from the group consisting of sewing, heat welding, chemical welding, electric welding, air pressure welding, ultrasonic welding, bonding, melting, bending, punching, riveting, sealing with an external seal or sealing with an adhesive solvent, and the housing is not sealed by a technique involving the addition of any type of adhesive or pressure sensitive adhesive.

[0073] The filter thus obtained differs from an enclosed filter sandwiched between two filters.

[0074] Adsorbent filters pre-labeled with dilute sampling standards can be stored at temperatures between 4 and 30°C.

[0075] In one embodiment of the invention, the adsorption filter has a diameter of 102 millimeters, a thickness of 2 millimeters, and a surface area of ​​approximately 1500 m 2 / g ACF filter.

[0076] Other embodiments may provide, for example, rectangular (high volume filters) or other shapes depending on the needs of the application, or other diameters, for example 47 mm.

[0077] A method for analyzing organic and inorganic analytes by using a filtration and sorptive sampling and concentration system comprising a stationary phase consisting of activated carbon fiber and a sampling and / or concentration standard provides for the step of analyte collection on the filtration and sorptive sampling and concentration system, followed by the steps of analyte extraction and quantification.

[0078] The analytes can be extracted from the filter using common extraction techniques.

[0079] Filtration and adsorption sampling and concentration systems comprising a stationary phase of activated carbon fiber and a sampling and / or concentration standard can be used for active or passive sampling of fluid, gaseous and liquid matrices. [Example]

[0080] [Example 1] A comparison of ISO 16000 13 and 14 with EPA TO 4A and 9A, known from the prior art and reported in Table 1, shows that sampling standards are added to quartz fiber filters (QFF). In this study, the ability to maintain the sampling standards and PCDD / F and PCB congeners unchanged over time on the quartz fiber filters was compared with that of the encapsulated ACF filter, type ACN-15.

[0081] Approximately 1500 ml of SSA pre-washed in toluene 2 Five 102 mm felt-type ACF filters with a diameter of 1 / g and a thickness of 2 mm were prepared. Of these, three QFF and three ACF filters were 13 C 12 Sampling standards containing known amounts of PCDD / Fs and PCBs were pre-labeled and subsequently sealed.

[0082] Because the sampling standards contain only a few congeners, a more complete standard mixture was used to assess the effect on the remaining compounds. 13 C 12 It was decided to use the same temperature as the sampled compounds. Hypothetically, this could be related to the procedures that the compounds undergo during transport to the laboratory once sampled. For this reason, of the remaining pre-cleaned filters, two QFF and two ACF filters were labeled with a known amount of a standard mixture. The ACF filters were then sealed. It was decided to evaluate the most influential variable regarding compound volatilization, namely temperature.

[0083] For the ACF filter type ACN-15, the porosity and its distribution were evaluated by BET analysis and Langmuir equation, and a predominantly microporous distribution with a small amount of mesoporosity was identified as the preferred type of ACF.

[0084] The types of ACF used are derived from the carbonization (activation) of phenolic fibers (novoloids) in an inert atmosphere and are traditionally designated by terms correlated with the BET number. Specifically, ACF-15 is the activity grade of choice. As the surface area increases, a higher proportion of analytes are adsorbed to the material, which can be explained by the increase in the absolute volume of the material and the enlarged pore size. Higher porosity alters the energy distribution of analytes adsorbed to the material. The internal structure of ACF is irregular, and the distance between the various pores significantly influences the force with which the adsorbate interacts with the substrate. ACFs with smaller surface areas and narrower porous structures ensure a more homogeneous substrate capable of distributing analytes with greater binding forces (high-energy pores) than occurs with ACF-20 and ACF-25. In the latter case, in fact, contact with the substrate generates a layer of analytes, resulting in a significant reduction in the interaction force between the analytes furthest from the surface and the adsorbent itself.

[0085] A suitable adsorbent for sampling must be able to function even under potentially adverse environmental conditions. Therefore, it is also important to evaluate the adsorption isotherm of the analyte at various temperatures. ACF-15 exhibits slightly variable behavior from 25°C to 150°C, ensuring reproducible performance even under extreme conditions and at low concentrations.

[0086] Therefore, ACF-15 appears to be the best candidate, as it has a good surface area to quantitatively sample all concentrations of the analytes present in the matrix. Also, from a macroscopic point of view, as the degree of activation increases, so does the degree of defibration, which is a negative characteristic of this type of adsorbent.

[0087] Filters spiked with standard 13C12 PCDD / F and PCB mixtures The two filters, ACF and QFF, were exposed to a constant temperature of 35°C for 24 hours.

[0088] The data obtained are shown in Figures 1 and 2.

[0089] Filters spiked with sampling standards Six filters (three QFF and three ACF) were sampled with 1000 pg of PCDD / F and PCB sampling standards. 13 C 12 They were then packaged in the same way, i.e., wrapped in aluminum pre-washed with DCM and sealed in an airtight package. The filters were placed at an average temperature of 23.5°C (maximum 37.4°C, minimum 9.8°C) and an average relative humidity of 55.9% (maximum 89.3%, minimum 30.7%) for 15 days. Summer transport of the pre-labeled filters was assumed, but the temperatures considered were in any case underestimated. After exposure, six filters were extracted separately to assess the recoveries of the standards. Figures 3 and 4 show the average recoveries of PCDD / Fs and PCBs.

[0090] The data reported in Figures 1-4 show that the sorbent media (QFFs) commonly used for air sampling of PCDD / Fs and PCBs do not have the same ability to maintain the sampling standards, apart from the standard mixtures that do not change over time. Temperature, the parameter judged to be the most influential in this procedure, appears to alter the original concentration of the standards attached to the sorbent media.

[0091] Thermally stressed ACF filters maintain good average recoveries regardless of temperature, allowing them to be used as if recently spiked with sampling standards (Figures 3 and 4). Similarly, replicated sampling filters demonstrated no change with temperature (Figures 1 and 2). The same is not true for quartz fiber filters treated in exactly the same way as ACF filters, which show good recoveries only for the higher molecular weight classes.

[0092] This demonstrates that quartz fiber filters are prone to errors and underestimation when pre-labeled, which can result in a large loss of sampled analyte.

[0093] [Example 2] When used in ISO16000 Method 13A, the felt-type ACF fiber filter ACN 15 is cut to a diameter of 102 mm and a thickness of 2 mm, and its SSA is approximately 1500 m 2 / g. This method is intended for sampling PCDD / Fs and PCBs, so tetradecane is added to a nonane solution containing the sampling standards.

[0094] The optimal conditions were identified and PCDD / F and PCB sampling standards were placed on an ACN15 type ACF membrane and subsequently sealed in. The collection system was then placed in an aluminum sheet pre-cleaned with dichloromethane (DCM) and sealed in an airtight bag.

[0095] The packaged membranes were allowed to stand while two of the factors that affect the system's ability to keep the standards unchanged were evaluated: temperature and time.

[0096] Exposures were evaluated for 7 days, 1 month, and 6 months. Each test was performed at two temperatures: ambient temperature of 22°C and refrigerator temperature of 4°C. All tests were performed in triplicate to ensure reproducibility of results.

[0097] The results are shown in Figures 5 and 6.

[0098] The data reported so far show that ACF has the ability to maintain the concentration of added standards for up to 6 months without change over time, which allows the assumption that several filters can be made and used at long intervals.

[0099] [Example 3] Studies carried out on activated carbon fibre as a concentration or sampling medium in water (Cerasa et al., 2020 "Validation studies on activated carbon fibre passive sampler for PCDD / Fs and PCBs in water", Chemosphere, January, Vol. 239, No. 124666, doi:10.1016 / j.chemosphere.2019.124666. Epub 25 August 2019) indicate that this filter can also be used in aqueous matrices. Indeed, in "Validation studies on activated carbon fibre passive sampler for PCDD / Fs and PCBs in water", this material was evaluated as suitable according to the requirements of methods ISO 1613B and 1668B (for PCDD / Fs and PCBs, respectively).

[0100] The purpose of this invention does not exclude its use in aqueous matrices, and although its use in this example concerns the trace pollutants PCDD / F and PCB, it does not exclude the possibility of extending its use to other trace pollutants in general. Given the possibility of passive systems such as POCIS (Polar Organic Chemical Integrator Sampler), the ACF filter (encapsulated) is perfectly suitable for passive sampling in waterways. Furthermore, its use as an active concentration system can be evaluated when inserted into an SPE cartridge through which a water sample is pumped, as in the case of "Innovative fast SPE for the extraction of PCDD / Fs and dl-PCBs in aqueous samples D preliminary assessment."

[0101] Therefore, pre-spiked ACF sampling standards can streamline the field procedure by simply inserting the filter into the housing made for the adsorption media. The presence of the standards allows for correction of errors due to losses associated with the amount of water sampled and any breakthrough. Results show that ACF filters pre-packaged in one of the potential ways of spiked with sampling standards, in the presented examples PCDD / Fs and PCBs, can retain these compounds unchanged for up to six months. Estimated recoveries from replicates allow filters with pre-spiked standards to be considered usable.

[0102] [Example 4] To assess the significance of the delamination phenomenon, the quantitative results of the three encapsulated ACF filters were compared with three ACF filters used as is.

[0103] The encapsulation was performed by placing the ACF between two quartz filters surrounded by two aluminum rings, all of which had a diameter of 102 mm and an SSA of 1500 v.1 m. 2 / g.

[0104] Sampling standards for PCDD / Fs and PCBs in tetradecane-stabilized nonane are added to all membranes of the ACF (encapsulated before sealing).

[0105] The membranes packaged in this manner were processed by replicating ambient air sampling. All membranes were stored in aluminum sheets for a short period (less than 1 hour), transported to the ambient air monitoring site, attached to a high-volume sampler (Echo Hi-Vol Tecora), and the sampler was activated at a flow rate of 200 L / min for only 5 minutes. The membranes were then placed in the aluminum sheets and transported to the laboratory. This experiment was used to evaluate potential losses due to ACF fiber detachment. During the experiment, unsealed membranes were visually observed for residual fibers on the aluminum sheets used for transportation and storage, as well as fibers on the filter holder grid of the high-volume sampler. All membranes were extracted with a Soxhlet filter using a quartz filter thimble. When unsealed ACF membranes were inserted into the thimble, additional fiber loss was observed in the air and outside the thimble. Samples were analyzed for PCDD / Fs and PCBs. 13 C 12 A tagged extraction standard was added. After 36 hours of hot extraction in toluene, the extract was concentrated, and the samples for the unsealed membranes with quartz filters and aluminum rings showed some residual fibers in the test tube. Therefore, it became necessary to filter the samples; although the solution from the sealed ACF samples did not require filtration, this was also filtered to avoid any discrepancies in the experimental methodology. Filtration was performed using a 47 mm quartz filter, after which the residue was eluted with a further 5 ml of toluene.

[0106] The reported data indicate that the sampling standards found on unsealed sorbents averaged approximately 10% less for both PCBs and PCDD / Fs.

[0107] [Table 3]

[0108] [Table 4]

[0109] A more significant difference is observed in the recovery of the extracted standards. This difference (approximately 20% for PCDD / Fs and also 30% for PCBs) can be precisely attributed to the adsorption effect of fibers carried by the toluene during the Soxhlet extraction step. These free fibers present on the extract adsorbed the standards, and filtration after elution / washing with 5 ml of toluene was not sufficient to recover the analytes.

[0110] [Table 5]

[0111] [Table 6]

[0112] [Example 5] Although experimental testing was performed on a homemade laboratory prototype, an embodiment was fabricated using an industrialized system and the product produced the same results as in Example 4.

[0113] In particular, this method involves preparing a housing material, typically in sheet form. Each sheet is cut to the required dimensions slightly exceeding those of the stationary phase, placed on two substrates (a male substrate for forming the lid and a female substrate for forming the bottom) prepared for thermoforming, and then thermoforming is performed by punching. The stationary phase is placed on the thermoformed bottom, and then a sample collection / concentration standard is added using a microdroplet diffusion system with high quantitative accuracy (quantitative accuracy 10 μl ± 0.20 μl).

[0114] After placing the coated housing inside the lid, a pre-welding step is performed under controlled atmosphere conditions with nitrogen injection to remove excess solvent, resulting in a continuous ring weld around the membrane, followed by a final welding at the circular edge around the central membrane, which provides good structural rigidity for the final product and allows for easy handling.

[0115] [Example 6] At the same time, chemical and physical characterization of ACN-15, the ACF identified as having the optimal activation degree, was carried out. In particular, the analysis of the specific surface area based on nitrogen absorption by the Brunauer-Emmett-Teller (BET) method and by application of the Langmuir equation is reported below. Prior to the measurements, the samples were degassed at 150 °C with a nitrogen flow.

[0116] The nitrogen adsorption capacity increases rapidly, and the resulting Langmuir isotherm is comparable to one of a completely microporous material of type I. The isotherm has a slight hysteresis point, which demonstrates the presence of mesoporosity.

[0117] This dual aspect is confirmed by the porous structure distribution (PSD) results, which identify mean diameters of 1.2 nm (microporous) and 22 nm (mesoporous).

[0118] Characterization of the active groups, primarily attributable to the porous voids, was also performed by Boehm titration (K.K. Beltrame, A.L. Cazetta, P.S.C. de Souza, L. Spessato, T.L. Silva, V.C. Almeida, "Adsorption of caffeine on mesoporous activated carbon fibers prepared from pineapple plant leaves," Ecotoxicol. Environ. Saf. Vol. 147 (2018) pp. 64-71, https: / / doi.org / 10.1016 / j.ecoenv.2017.08.034).

[0119] According to the literature data previously reported in Example 3, it is believed that the ACF in the table tested, type ACN-15, may have better performance. 2 / g, not only is adsorption easier at lower ACN concentrations on SSA1500, but also due to the presence of fewer acidic groups that tend to coordinate water molecules and remove active sites for pollutant adsorption.

[0120] Here, a clear distribution of basic groups is observed compared to the total acidic groups, which are mostly composed of phenolic groups.

[0121] [Table 7]

Claims

1. 1. A filtration and adsorption sampling and concentration system enclosed within a sealed enclosure, comprising: a stationary phase consisting of a felt-type cloth of activated carbon fibers having a micro-mesoporous structure and a specific surface area of ​​about 1500 m / g; a sampled and / or enriched standard; Filtration and adsorption sampling and concentration system comprising:

2. The system of claim 1 , wherein the activated carbon fibers are functionalized or coated.

3. The system of claim 1 , wherein the felt is a nonwoven fabric.

4. 10. The system of claim 1, wherein the housing is made of a material selected from the group consisting of natural or synthetic polymers, cellulose or silica-based sheets, wire mesh, or combinations thereof.

5. 5. The system of claim 4, wherein the housing is made of a material selected from the group consisting of quartz fiber, polypropylene, nylon fiber, aldehyde fiber, phenolic fiber, amino fiber, vinyl fiber filter, cellulose fiber, cellulose derivatives, and metal screen, and combinations thereof.

6. Use of the filtration and adsorption sampling and concentration system according to any one of claims 1 to 5 for active or passive sampling of fluid, gas, gaseous and liquid matrices.

7. Enclosed in a sealed enclosure, a stationary phase consisting of a felt-type cloth of activated carbon fibers having a micro-mesoporous structure and a specific surface area of ​​about 1500 m / g; 10. A method of making the filtration and adsorption sampling and concentration system of claim 1, comprising: (a) purifying said stationary phase from organic or inorganic impurities; (b) a drying step of the stationary phase obtained at the end of step (a); (c) adding a sampling standard; (d) an encapsulation and sealing process of the enclosure without the use of any kind of adhesive or glue; A method comprising:

8. 8. The method according to claim 7, wherein the purification step in step (a) is carried out by solvent extraction or by treatment with an acid and an oxidizing agent followed by washing with water.

9. 8. The method according to claim 7, wherein in step (b), the stationary phase is dried under vacuum if the purification in step (a) is carried out using a solvent, or by thermal dehydration if the purification in step (a) is carried out using an acid and oxidizing agent treatment.

10. 8. The method of claim 7, wherein in step (c), the addition of the sampling standard is performed with a quantitative precision equal to 10 μl±0.20 μl.

11. 8. The method according to claim 7, wherein in step (c), the placement of the sampling standards on the stationary phase is carried out at n predetermined positions.

12. 8. The method of claim 7, wherein in step (c), the placement of the sampling standards onto the stationary phase is performed by an automated multi-tip dispensing device.

13. 13. The method of claim 12, wherein in step (c) the stationary phase is placed on a rotating disk or alternatively a vibrating plate with an adjustable and constant speed in an automated dispensing device.

14. 13. The method of claim 12, wherein in step (c), the sampling standard is dispensed simultaneously with the movement of a membrane disposed on a rotating disk or vibrating plate.

15. 15. The method of claim 14, wherein in step (c), in the case of a rotating plate, the sampling standards are distributed concentrically.

16. 15. The method of claim 14, wherein in step (c), in the case of a vibrating plate, the sampling standards are distributed on n lines.

17. 8. The method of claim 7, wherein in step (d), the housing is sealed without adding any kind of adhesive or pressure sensitive adhesive by a technique selected from the group consisting of sewing, heat welding, chemical welding, electric welding, air pressure welding, ultrasonic welding, bonding, melting, bending, punching, riveting, sealing with an external seal, or sealing with a viscous solvent.

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