Tube for sampling volatile and semi-volatile compounds and sampling method

Abstract

A sampling system equipped with tubes with mixed class hydrophobic adsorbent elements for passive or active sampling of volatile and semi-volatile compounds for environmental pollution investigation or exploration of various forms of natural resource sources, such as petroleum, and methods of sampling thereof.

Description

[0001] The present invention is in the field of environmental chemistry and relates to an apparatus and a sampling method for sampling and analyzing air in adsorbent material to determine the chemical composition of the collected sample, in particular to a tube with a hydrophobic adsorbent element of the mixed active and passive class, for sampling volatile and semi-volatile compounds in environmental pollution surveys or for prospecting various forms of natural resource sources such as petroleum.

[0002] The management of contaminated areas is a field that has been around for more than 30 years, during which various tools have been created to assist the investigations required for management. Despite this, there is still a serious lack of economically viable and technically appropriate tools for the environmental pollution assessment in a scanning mode of pollutants. The tools for environmental surveys in a scanning mode need to have versatility in the list of compounds and applications, performance in different environmental conditions (for example in very humid environments, even in the presence of water that can affect the collection process) and lower costs compared to other technologies.

[0003] The present inventors' in-depth analysis of the state of the art shows that there is a lack of samplers for volatile and semi-volatile compounds for mixed active or passive sampling and that allow quantitative analysis and solvent sample extraction, such as the Waterloo Membrane Sampler (WMS), which is a sampling device, a glass container with a lid and a vapor / gas permeable membrane containing an adsorbent element, which is only used for quantitative assessment of volatile organic compounds through passive sampling. The analysis is performed by solvent sample preparation or by thermal desorption, followed by gas chromatography analysis.

[0004] In addition, the US EPA TO-17 method discloses an analysis and sampling method for volatile organic compound analysis disclosed by the US EPA, which is only quantitatively assessed through active sampling. Sampling is performed in a tube containing one or more adsorbent elements. Extraction is performed only by thermal desorption of the tube method, followed by gas chromatography analysis.

[0005] In addition, the USEPA TO-3C method is an analytical and sampling method for semi-volatile organic compounds analysis published by the US EPA, which is quantitatively evaluated only by active sampling. Sampling is performed in a tube containing adsorbent elements with a polyurethane filter. Preparation is completed by extraction using solvents and the Soxhlet process. Analysis is performed by gas chromatography.

[0006] Finally, the NIOSH method is an analytical method for occupational and sampling evaluation described by NIOSH for the analysis of a limited catalog of volatile organic compounds. Sampling is active and uses a glass tube containing coconut shell activated carbon. There is a major limitation in this case, since coconut shell activated carbon does not have hydrophobicity, and can be interfered by moisture when applied to soil air sampling, which usually has a high moisture content.

[0007] In view of the gaps in the prior art, the proposed invention is a sampling system equipped with a tube (1) with passive or active hybrid category adsorbent material mixtures for sampling volatile and semi-volatile compounds for environmental pollution investigation or exploration of various forms of natural resource sources such as oil.

[0008] The invention is a tube (1) made of metallic, glassy or polymeric material, with rigidity and inert to the substances or compounds to be sampled and analyzed. On the outer surface of the tube there are arrows (3) indicating the sampling flow and the tube serial number (4) for traceability.

[0009] The tube has two polyethylene caps (5) for closure.

[0010] Its interior comprises a mixture of hydrophobic activated carbon spheres (2) of different sizes (0.4 to 0.8 mm) and surface area of 1000 to 1300 m 2 / g, fixed with metallic or glassy fabric or other material (6) inert to the substances or compounds to be sampled and analyzed. The set also has two stainless steel retainer springs (7) to prevent the internal elements from moving inside the tube during active sampling.

[0011] The invention can be better understood with the help of the attached drawings.

[0012] Figure 1 A front view of the sampler tube (1) is shown.

[0013] Figure 2 A side view of the sampler tube (1) without caps is shown.

[0014] Figure 3The internal components of the tube (1) are shown.

[0015] Figure 4 An enlarged view of the tube (1) and its internal components is shown. For active sampling, in addition to the sampler tube (1), a syringe (8) is used coupled with a check valve system (9).

[0016] Figure 5 The syringe (8) and check valve system (9) are shown.

[0017] To perform active sampling, the sampling tube (1), the syringe (8) and the check valve system (9) are used. The system makes the sampling process easier as errors are avoided due to the fact that the connection of the sampler tube to the system is not broken during the sampling process.

[0018] i. The cap of the sampler tube section (1) is removed as indicated by the arrow (3);

[0019] ii. The sampler tube (1) is connected to the syringe (8) as shown; Figure 6

[0020] iii. The cap (5) is removed from the sampler tube (1) and connected to the sampling point;

[0021] iv. The plunger of the syringe is pushed and pulled according to the volume to be sampled. The check valve system (9) only allows the flow of air as shown when pulling the plunger and as shown when pushing the plunger; Figure 7 Figure 8 v. The sampler tube (1) is disconnected;

[0022] vi. The cap (5) is reattached.

[0023]

[0024] Figure 6 The tube (1) connected to the syringe (8) and valve system (9) is shown.

[0025] Figure 7 The flow of air from the sampling point through the sampler when pulling the plunger of the syringe is shown.

[0026] Figure 8 The flow of air through the side check valve when pushing the plunger of the syringe is shown.

[0027] ​​​For passive sampling, only a specific sampling cap (10) is used. It is a cap with a silicone tubing section (11), a rigid metal or polymer support (12) and a hydrophobic and oleophobic membrane (13), made of polytetrafluoroethylene (PTFE) or acrylic copolymer, which allows the free passage of the compounds and / or substances of interest and prevents the formation of a barrier in the collection area of ​​the compounds and / or substances of interest due to the presence of liquid water. In addition, the membrane significantly reduces the passage of water in the form of vapor, which can cause analytical problems such as low sensitivity.

[0028] Figure 9 A sampling cap kit (10) for use with a passive sampling method is shown.

[0029] For passive sampling, a sampler tube (1) and a sampling cap (10) are used.

[0030] A. Remove the cap from the paired sampler tube section (1) to the point indicated by the flow arrow (3);

[0031] B. Connecting the sampler tube (1) to the sampling cap kit (10);

[0032] C. Positioning the sampler at the location to be sampled, for example, within a building for indoor air assessment or buried underground for soil air assessment;

[0033] D. After the sampling period, remove the sampler;

[0034] E. Reinstall the cap (5).

[0035] Figure 10 The internal components of the assembled pipeline for passive sampling are shown.

[0036] Figure 11 Shown is a front view of the installed sampler tube for passive sampling.

[0037] In summary, the new system and method are the only sampler designed for active or passive sampling. With this type of sampler, volatile compounds can be analyzed by solvent extraction. Furthermore, the extraction can be performed using different solvents, thus enabling the inclusion of analysis of semivolatile compounds and multiple analyses (including dilutions not suitable for thermal desorption methods), and the adsorbent elements are made of different sizes (0.4 to 0.8 mm) and have surface areas ranging from 1000 to 1300 m 2 The adsorbent element is composed of a mixture of hydrophobic activated carbon balls (2) of 1000 g / g and is selected to be suitable for sampling a variety of organic compounds. The hydrophobicity of the adsorbent element suppresses water interference caused by saturation, thus preventing false negative results.

[0038] The application is not limited to the details or representation set forth in the foregoing description or illustrated in the drawings. Many modifications and other representations of the application will come to mind to one skilled in the art with the benefit of the teachings presented in the foregoing description and the associated drawings. Moreover, it will be apparent that modifications and other embodiments can be practiced, which depart from the specifics of the disclosed forms. Accordingly, the application is not limited to the disclosed forms but is intended to cover all modifications and other forms falling within the scope of the appended claims.

[0039] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A sampler tube, characterized by Its components: a tube (1) made of metallic, glassy or polymeric material, with rigidity and inertness, with an external surface engraved with an arrow (3) and a tube serial number (4); two caps, preferably polyethylene caps (5), with a hydrophobic and oleophobic film (13) consisting of polytetrafluoroethylene (PTFE) or acrylic copolymer; consisting of a mixture of hydrophobic activated carbon spheres (2) of different sizes from 0.4 to 0.8 mm and surface area from 1000 to 1300 m 2 / g, said mixture being fixed in metallic and glassy fabric (6); two retainer springs (7).

2. A method characterized by Its steps: i. removing the cap of the sampler tube portion (1) to the point indicated by the arrow (3); ii. connecting the sampler tube (1) to a syringe (8); iii. removing the cap (5) still on the sampler tube (1) from the sampler tube and connecting it to the sampling point; iv. pushing and pulling the plunger of the syringe according to the volume to be sampled; v. disconnecting the sampler tube (1); vi. reattaching the cap (5).

3. A method characterized by Its steps: A. removing the cap from the paired sampler tube portion (1) to the point indicated by the flow arrow (3); B. connecting the sampler tube (1) to the sampling cap kit (10); C. positioning the sampler at the point to be sampled; D. after the sampling period, removing the sampler; E. reattaching the cap (5).

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