Field of the Invention

The present invention relates to an inorganic (N0 ₂ , S0 ₂ and 0 ₃ ) passive sampler that can be used in air pollution sampling studies such as indoor, outdoor and personal exposure measurements.

Background of the Invention

Passive samplers are pieces of equipment which are capable of collecting gas samples from the atmosphere at a rate controlled by molecular diffusion without the need for any active air movement. The passive sampling method to which the invention relates is expressed by the Fick’s lst. Law based on molecular diffusion. Within the scope of the national air pollution sampling studies, passive samplers are used for different purposes such as indoor, outdoor, and personal exposure samplings for N0 ₂ , S0 ₂ and 0 ₃ pollutants.

Passive samplers provide more convenience and advantage in air quality measurement studies compared to active and automatic sampling methods thanks to the facts that they are simple, easy to carry and inexpensive and that they enable sampling at multiple points simultaneously without requiring electrical power. Therefore, in recent years, the use of passive samplers has become widespread in domestic and international air pollution sampling studies (indoor, outdoor and personal exposure measurements).

Nitrogen dioxide (N0 ₂ ), sulfur dioxide (S0 ₂ ) and ozone (0 ₃ ) are among the most common inorganic air pollutant components in the atmosphere. There are different sources that can cause high levels of these components in indoor environments as well outdoor environments. Personal exposure to high concentrations of these components results in significant health effects. Therefore, determination of the levels of these components becomes even more important.

Passive samplers are available in two forms, namely radial and axial, depending on the direction of the diffusion process. In radial passive samplers, diffusion direction is parallel to the sampler’s diameter. The sorbent cartridge is located in a cylindrical, porous and polymeric diffusive membrane body. In axial passive samplers, the diffusion path is perpendicular to the sampler section. Axial passive samplers are classified in two ways, namely badge and tube, based on the sampler geometry. When the diffusion path length / sampler cross-sectional area (L/A) ratio is greater than 1, it is referred to as the tube type sampler, and when the ratio is smaller than 1 it is referred to as the badge type sampler. The sampling surface areas of the radial passive samplers are larger than those of the axial samplers and the length of the diffusion path is shorter. Therefore, they are suitable for shorter sampling periods since the sampling rates are higher than those of the axial samplers.

In passive samplers; absorbent materials coated with chemicals specific to the components are used as the retaining means. Depending on the retaining means used, generally ion chromatographic and spectrophotometric analyzes are performed. Optimum sampling times that the passive samplers can be used effectively vary according to the geometries of the passive samplers and thus their sampling rates. Passive samplers with high sampling rates are used for shorter duration (e.g. 8 hours, 1 day) studies, while passive samplers with low sampling rates are used for longer duration studies (e.g. 1 week, 1 month).

The invention disclosed in the state of the art international patent document numbered WO2016141443A1 is a kit comprising passive samplers which sample gas concentrations such as sulphur dioxide, nitrogen dioxide and ozone in the air simultaneously. A separate passive sampler is used for each pollutant. Each passive sampler in the kit is cylindrical and all of them are placed into a rectangular box.

The Chinese patent document numbered CN 102221592 in the state of the art discloses a method for detecting the ozone concentration in the air by using a passive sampler. It does not include N0 ₂ and S0 ₂ . This method is preferred because it is simple, easy, has high sensitivity, low detection limit, and extremely high practical application values.

The United States patent document numbered US20080259341 in the state of the art discloses a system and detection method for measuring a gas concentration in the air including a light source, a passive sampler and a detector.

The costs of the commercial passive samplers used in the art and obtained from abroad are rather high and most of them do not provide post-sampling analysis service. In addition, many passive samplers are disposable and are not reusable after cleaning and pre-treatment. This requires buying new passive samplers for each sampling study. In our country, high costs are imposed when commercially purchased samplers are used in passive sampling studies conducted for the inorganic components discussed in the scope of the present invention, and this limits the possibility of sampling at multiple points. Furthermore, a separate passive sampler is required to be used for each component in most of the commercial passive samplers.

In addition, in the passive samplers used in the art, N0 ₂ and S0 ₂ pollutants are generally collected in separate samplers instead of a single sampler. In this case, there is a need to prepare three separate passive samplers if three components are sampled simultaneously. With the present sampler that is developed, unlike the other passive samplers, the concentrations of 3 components are determined simultaneously and it is possible to re-use the sampler after cleaning. In most sampling studies, blank samplers are prepared for each component for reliability of the results. This increases the number of samplers to be prepared even more. Moreover, this is not practical.

Summary of the Invention

The objective of the present invention is to provide a passive sampler which allows simultaneous sampling at multiple points.

Another objective of the present invention is to provide a passive sampler which is not disposable, is reusable after cleaning and pretreatment, and enables to determine the concentrations of three components simultaneously.

Detailed Description of the Invention

An“inorganic passive sampler” developed to fulfill the objectives of the present invention is illustrated in the accompanying figures, in which:

Figure 1 is a view of the closed cover on top of the inorganic passive sampler. Figure 2 is a view of the barrier cover on top of the inorganic passive sampler. Figure 3 is a view of the fixing apparatus and grip used for fixing the retaining means to the inorganic passive sampler.

Figure 4 is a view of the metal filters used as the retaining means during sampling.

Figure 5 is a view of the lugs that facilitate arrangement of two semicircular inorganic passive samplers on the substrate.

Figure 6 is a view of the ribs that will enable the barrier cover to fit onto the inorganic passive sampler.

Figure 7 is a view of the inorganic passive sampler. The components in the figures are given reference numbers as follows:

1. Inorganic passive sampler

2. Closed cover

3. Barrier cover

4. Metal filter

5. Fixing apparatus

6. Grip

7. Substrate

8. Lugs

9. Ribs

The inorganic passive sampler (1) of the present invention is used for different purposes such as indoor sampling, outdoor sampling and personal sampling for inorganic air pollutants such as N0 ₂ , S0 ₂ and 0 ₃ , and

- is produced in two semicircular pieces,

- includes a stainless steel metal filter coated with 20% TEA (triethanolamine) solution (for N0 ₂ -S0 ₂ ) and a stainless steel metal filter coated with an aqueous solution comprising 1% NaN0 ₂ , 2% Na ₂ C0 ₃ and 2% glycerol (for 0 ₃ ) as the retaining means,

- includes N0 ₂ -S0 ₂ retaining means on one of the semicircular pieces and 0 ₃ retaining means on the other,

- is converted into a single sampler form as a result of connection of the two semicircular pieces placed next to each other on a substrate.

In the present invention, the three separate air pollutants N0 ₂ , S0 ₂ and 0 ₃ will be retained by different retaining means placed in a single sampler. These retaining means are produced in a semicircular form. When forming the inorganic passive sampler, N0 ₂ and S0 ₂ will be retained in a single retaining means and 0 ₃ in a separate (second semicircle) retaining means. Thus, it will be possible to sample all three components simultaneously with a single sampler.

In the passive sampler, a stainless steel metal filter (4) coated with 20% TEA (triethanolamine) solution is used for nitrogen dioxide (N0 ₂ ) and sulphur dioxide (S0 ₂ ), and a stainless steel metal filter (4) coated with an aqueous solution comprising 1% NaN0 ₂ , 2% Na ₂ C0 ₃ and 2% glycerol is used for ozone (O3) as the retaining means. In order to increase the retaining efficiency, two metal filters (4), which are cut-out in semicircular form placed on top of each other, are covered with coating solution. Metal filters (4) used as the retaining means have a 50-100 mesh size.

In one embodiment of the invention, instead of metal filters (4); 0.5 cm thick polyurethane foam (PUF) and GF/A glass fiber filter paper are also used as alternative retaining means in passive samplers.

The metal filters (4) are placed in the semicircular samplers and fixed to the sampler base by means of a fixing apparatus (5). The fixing apparatus (5) is used to ensure that the metal filters (4), which are the retaining means, to remain fixed on the sample base and not to fall off when the sampler is inverted to be suspended at the sampling point; and it is configured so as to completely fit to the inner base of each semicircle.

On the flat side of the fixing apparatus (5) there is provided a grip (6) for convenient placement and removal thereof to/from the sampler base. Then, to form a single-piece sampler form, the semicircular samplers are connected to each other upon being placed side by side on a substrate (7) produced from the sampler material. The objective here is to provide a more compact sampler to be treated as a single sampler instead of preparing individual samplers for N0 ₂ -S0 ₂ and O3, attaching separate covers and carrying and suspending them separately at the sampling point. There are lugs (8) provided on the substrate (7) on two opposing sides which ensure proper placement of the two semicircular samplers.

A barrier cover (3) comprising a metal filter (4) is placed on the semicircular samplers that are assembled on the substrate (7) for use during sampling. The metal filters (4) used in the barrier cover (4) have a 50-100 mesh size. A fixing apparatus (5) is used for keeping the metal filter (4) fixed in the barrier cover (3). There are ribs (9) provided on the inside of the barrier cover (3) and on the outer surface of the semicircular samplers to ensure that the cover (3) fits completely. Additionally, a closed cover (2) is mounted on the barrier cover (3) while carrying the samplers. Thus, instead of changing the cover at the sampling point, the closed cover (2) can be removed from the barrier cover (3) thereby enabling to start the sampling operation immediately. This is regarded as an advantage of the sampler in terms of time saving and ergonomics.

After the sampling process is finished, the closed cover (2) is mounted back on the barrier cover (3) and the samplers are taken to the laboratory for analysis. Passive samplers can be used in different sampling studies such as indoor sampling, outdoor sampling and personal sampling. Therefore, as an alternative, samplers with long diffusion path can be designed for use in indoor outdoor sampling studies, and samplers with short diffusion path can be designed for use in personal sampling and workplace sampling studies. The height of the sampler with short diffusion path is 0.9 cm and the height of the sampler with long diffusion path is 2 cm. The sectional area of each semicircular sampler is 4.75 cm ² . The material of the sampler is polypropylene and its color is white. All sampler pieces are of the same material.