DE4439433A1 - Analysis of air pollutant present in both aerosol and gaseous form - Google Patents

Abstract

Quantitative analysis of a cpd. (I), present in air in both particle-bound (aerosol) and gaseous form, comprises drawing a known quantity of air through a filter assembly, having a filter for retention of aerosols and a second filter for retention of gaseous (I). Both filters are of material inert for (I) and the second is capable of sorptive uptake of gaseous (I). The improvement is that after collection, both filters are placed together in a solvent bath able to dissolve both particle-bound and sorptively-bound (I), then the content of (I) in the bath is measured by (I)-specific immunoassay. Also claimed is a sampler for use in the method.

Description

The invention relates to a method for quantitative analysis of an air constituent (analyte) that is particle-bound (Aeroso le) and in gaseous form, whereby a defin te amount of air is drawn through a filter arrangement that little least a first filter for the absorption of aerosols and one has a second filter for taking up gaseous analyte, with filter mate in the first filter and in the second filter rial made of inert material for the analyte, where the second filter for sorptive absorption of the gaseous analyte is appropriately designed.

Chemically, natural, dry air is a gas mixture. Air pollution caused by a variety of substances the composition of this "gas" is sometimes considerable. In this context, chemical ver bindings as gases and in solid form, for example to on / on Coarse or fine dust sorptively bound by natural pro or into the air through human activity Those environmental chemicals are of great importance lien that as "pollutant pollution" in the exterior and interior air from humans and animals occur increasingly (i.e. Environmental pollutants, e.g. B. allergens, pesticides, etc.). So it changes the composition of the natural air in any way it is usually necessary to check what or which substance the Ursa  che for this change. Humans do approx. 26,000 breaths. From this you can see the meaning of the Has air pollution for him. As a technical aid for the air analysis, the gas measurement technology is required because with the Smell not all fabrics are noticeable and a concent tration estimation is not possible without measuring instruments. The Measuring the concentration of a gas as air pollution necessary to along with the exposure time and others Parameters to be able to estimate whether the respective air pollution is dangerous or not. Even dusts or aerosols with particles smaller than 5 µm in size are respirable pose significant health risks. You can get in accumulate the alveoli or pass into the blood, penetrate Cells in the body and damage their metabolic enzymes Allergies or poisoning from and the like. Come several environmental noxes in the air at the same time, so syn ergistic effects possible.

The particles contained in aerosols cover a range of sizes ranging from 10 ^-3 µm to approx. 10² µm. This range can be explained by the large number of possibilities for its formation and the different physicochemical composition of air-polluting particles. The particle size is directly related to the parameters that determine the biological effect: length of stay in the air, chemical activity and lung deposition. The deposition of particles in humans affects a size range of 0.03 to 20 µm particle diameter. The amount of fine dust (<10 µm) in the so-called house dust only makes up approx. 20% of the total dust mass, but can contain up to 90% of the allergenic or toxic substances. In addition, particles of this size are constantly suspended in the air because they are carried as a result of the molecular motion - Brownian motion.

To avoid health hazards, for example at work close, are due to a corresponding legislation (Che  Mikaliengesetz) certain limit values have been enacted. Is this Occurrence of a dangerous substance in the air at the workplace not sure to rule out, the workplace is on the Falling below the limit values (maximum workplace concentration tion: MAK; technical target concentration: TAK; more biological Workplace tolerance value: BAT) to be monitored.

Today there is an extensive range of measurement methods for quantitative quick analysis of gases, vapors and aerosols len, for example using test tubes ("Determi nation of aerosols by means of detector tubes ", K. Leichnitz and J. Walten, Ann. Occup. Hyg., Vol. 24, No. 1, pp. 43-53, 1981). The tips are broken off from the test tube for the measurement the test tube into the corresponding gas detection pump leads and with this the prescribed gas or air volume sucked through the reaction layer. Most test tubes are so-called scale tubes, in which the display layer in a length dependent on the analyte concentration discolored. There are also test tubes with a color comparison layer known about a color comparison after the reaction takes place. The basis of most test tubes are pure chemical reactions of the gas or aerosol to be measured the chemicals of the tube filling layer / s. Contrary to that so-called collecting tubes of coconut shell charcoal, various Types of silica gel or molecular sieves. Because of their pure collection Behavior without a change in color, these tubes can also be used as Test tubes are described without direct display, to their An analytical determination method (e.g. HPLC: High Pressure Liquid Chromatography, GC: Gas Chromatogra phie, GC-MS: GC-Mass-Spectrometry) connects (Dräger tubes Manual, 1994).

In addition to the described test tubes for gases and aero there are a wide variety of different ways for the sampling of airborne dust or aerosol. In the event of by so-called individual samplers, for example  to be carried by individuals to remove the dust / aerosol to which these people are exposed is in DE 35 35 538 A1 a filter-carrying device in the form of a cassette described. The cassette as a sampler is assembled and fastened, for example, in a user's buttonhole, and then a pump via a gas suction pipe on the sampler attached. At the end of a certain sampling time, the Disassembled and weighed the filter cassette, so that the total amount of the total inside the filter cartridge dust is determined. This type of sampling is on limited particulate and fibrous material, and allowed no specification or differentiation according to individual damage types of fabric.

US Pat. No. 4,961,916 is a sampler known of an arrangement of several consecutive Contains filters in a cassette. Different by the choice porosities of the successive filter layers used separator between aerosols, Dust and gaseous components reached. The second The filter layer is chemically pretreated so that the gaseous Components react on / on this layer, d. H. derivatized will and remain bound. After sampling is done the individual filters are analyzed separately by looking at the First filter layer collected components chemically derivatized be worked up, worked up and eluted. The one on the second Components bound to the filter layer are also chemical worked up further. Then the actual Ana takes place lysis of the collected substances using the already mentioned HPLC, GC, GC-MS methods. This remains limited However, procedures on such air constituents, for example are listed in tabular form in the publication for which namely a selective chemical derivatization and thus a immobilization on a filter layer is possible.  

DE 41 21 493 A1 describes an analysis device for the quantitative ven determination of air contents based on immunochemi known reactions. Are in medical analytics so-called immunoassays are known (see, for example, "Principle and Prac tise of Immunoassay ", by C.P. Price and D.J. Newman, Macmillan Publishers Ltd., 1991), which is a highly sensitive and highly spec fish Detection of a given substance based on Allow antibody reactions. In the known device are on a first layer facing the outside air for the immobilized specific antibodies. Further marked analyte (tracer) is kept ready, which is in bankruptcy reacts with the analyte with the antibodies, whereby from the amount of unresponsive tracer to the amount of con curing analyte can be concluded. Not more responsive Tracer diffuses through a diffusion to the first layer sionskontakt subsequent middle reaction layer to a Detection layer where the tracer triggers a color reaction so that a conclusion on the analyte from the resulting discoloration air content is possible. For airborne substances that both It is gaseous and in the form of aerosols However, the method is not suitable, as it is prone to aerosol components table is not sensitive.

From the article "Polychlorinated dibenzodioxins and furans Workplaces by Reinhard Stockmann et al. (in "Dust - Pure keeping the air "53 (1993, pages 389 to 393) is a procedure ren with the features of the preamble of claim 1 known. The known method deals with the simultaneous and separate detection of vaporous and particulate PCDD and PCDF for emission measurements e.g. B. in waste incineration Investments. For the separation of particulate and particle-bound PCDD / PCDF a binder-free glass fiber filter is used. Vapor-shaped PCDD / PCDF are cleaned in the downstream Polyurethane foam deposited. After a long time The two filters are separated after sampling from each other and with chemical derivatization according to usual  Process analyzed. Such an analysis is definitely very expensive because it is not immediate and in place can be made.

It is an object of the present invention, a method of to create the type mentioned at the beginning, with the air constituents, which are gaseous and particle-bound, with an exact and easily executable procedures can be demonstrated.

The method with the features is used to solve this task of claim 1. Advantageous embodiments of the Ver driving are listed in the subclaims.

In a further aspect, it is an object of the invention to provide a Sampling device for use in the invention Method. The sampler serves to solve this task direction with the features of claim 5.

It could be shown that with the method according to the invention ren and the sampling device according to the invention a ge more accurate and efficient pollutant analysis of substances that due to their physico-chemical properties at the same time gaseous and particle-bound in the air, possible is. It is essential that both the aerosols are collected are also taken up as the gaseous component of the analyte without derivatization or any chemical cal reaction of the analyte takes place, so that the recorded Air pollutants then together an analysis process can be subjected to being brought together in solution and an immunoassay is performed. Through the common Solution of all analyte components and quantitative analysis firstly, immonoassay simplifies the Process because of any chemical derivatizations and processing steps can be dispensed with, and secondly, because the joint analysis of all components in a solution generally a simplification of the procedure  interprets and no longer several separate analyzes for Aero Brine and gaseous components are required.

Surprisingly, it was also found that the common Ana lysis of aerosol and gaseous component of the pollutant provides more accurate results than if the components were individually analyzed and the results are then added together.

In the method according to the invention, the analysis of the collected analytes using an analyte-specific immunoase says. Immunoassays are highly sensitive test systems for qua litative and / or quantitative determination of substances Basis of the antibody-antigen reaction. With immunoassays a distinction is made between homogeneous and heterogeneous systems. Further can be classified into so-called competitive or not competitive or sandwich tests depending on the execution mode and Components are done. These variants are known to the person skilled in the art Known in the field of biochemical laboratory analysis and in the Lite rature described ("Principle and Practice of Immunoassay", by C.P. Price and D.J. Newman, Macmillan Publishers Ltd., 1991). The use of immunoassays in the analysis of air content substances opens up the possibility of also polluting such substances capture that not directly or with the currently usual physi calico-chemical methods only by means of elaborate enrichment tion, derivatization and analysis methods are measurable. The Immunochemical processes are now in use and implementation so far simplified that it can also be carried out on site by Can not be used by non-specialists. This will make one immediate measurement and monitoring of analyte concentrations for example at the workplace, in living or indoor areas also made possible by means of the highly specific immunochemical tests light. The preferred embodiment of the method under An Using an immunoassay allows a very specific analysis without appreciable cross-sensitivity to similar air substances because the analyte-antibody reaction is very specific is. In addition, cross-reactivities can usually be in advance  true and be taken into account quantitatively. When using of an immunoassay, it has proven to be particularly important that according to the invention the collected aerosols and gaseous Components are analyzed together and simultaneously, since only such a correct overall result is determined, while at ge separate analysis of the individual components, the sum of which does not Total content of analyte in the examined air results.

For use in the method according to the invention, a Sampling device proposed in which a be per se known collection tube, as described in the Dräger Tube Manual, 9. Edition, 1994, are described in combination with a gas close upstream first sampler part is used in the one suitable for collecting aerosol, for the analyte inert filter membrane is arranged. Located in the collection tube there is an adsorption layer in which the gaseous analyte ad is sorbed. If necessary, behind the adsorption layer a post-shift layer must be present, which is separated in the laboratory can be analyzed to determine if the total amount of the analyte to be measured is adsorbed in the adsorption layer or whether its capacity was insufficient and consequently, adsorption also takes place in the post-shift layer has found. In this case, a new sample must be taken be taken as it is not certain that the entire existing amount of gas has been adsorbed.

Has been particularly suitable in connection with the a parallel sampler device according to the invention, in which two identical sampler devices according to the invention connected in parallel and used simultaneously for sampling will. In this way, par allele measurements can be carried out, the one sampler device tion can be analyzed directly on site and the second can be checked as a reference sample in the laboratory as required.  

The invention is described below using exemplary embodiments explained in more detail with reference to the drawings, in which:

Fig. 1 shows a schematic sectional view of a sampler device; and

Fig. 2 shows a schematic sectional view of a parallel sampling device.

In Fig. 1, a sampler device with a first sampler part 12 and a second sampler part 1 shows ge. The second of the sampler parts in the present exemplary embodiment is a collecting tube known per se, for example the Dräger tube silica gel type B. The ends of the collecting tube 1 are designed as breakable tips 2 , 3 . In the first place seen in the flow direction 4 , an adsorption layer is arranged in the collecting tube as the second filter 5 , followed by a secondary layer 6 . The two filter layers 5 , 6 are separated by a holding element 7 . Directly at the position of the holding element 7 there is a marking or notch 8 , at which the collecting tube is to be sawn or broken after the sample has been taken. The adsorption and downstream layers are held vibration-proof by holding elements 9 , 10 .

At the top in FIG. 1, lying at the front in the flow direction, the first sampler part 12 is shown, which has a housing with a first housing part 11 and a second housing part 13 . The upper housing part 13 is connected to the lower housing part 11 by means of four plastic screws 14 ben. An O-ring seal 15 , for example made of synthetic rubber, is embedded in the upper housing part 13 so that it seals in the assembled state of the housing with the first filter 16 and one, for example, on polyethylene sintered material. existing filter support layer 17 closes. The first sampler part 12 has a round inflow opening 18 and an outflow opening 19 . The inflow opening 18 preferably has an inner diameter of approximately 15 to 30 mm if a conventional pump is used, which is able to operate at a flow rate of 0.5 to 3 l / min. The Ausströmöff opening 19 is designed so that a gas-tight connection with the second sampler part is possible, the collecting tube shown directly, sealed in the air outlet 19 is a plug, or alternatively a connector 22 , for example a flexible hose, for gas-tight connection of the first sampler part 12 is used with the second sampler part 1 .

FIG. 2 shows a parallel sampling device in which two identical sampling devices as in FIG. 1 are built next to one another on an adapter 21 . The adapter 21 can be connected to a pump in order to suck air simultaneously through the parallel sampling devices. One sampler device can then be analyzed directly on site using the method according to the invention, while the second is brought to the laboratory for control measurement.

Example: Sampling and analysis of pentachlorophenol (PCP) in the air

In the following example, the method according to the invention for the detection of airborne pollutants which occur simultaneously as gases and aerosols is carried out using an immunochemical analysis step and with the sampling device from FIG. 1.

PCP air mixture

To produce a suitable sample air, an aqueous PCP suspension and air at 3.5 bar are sprayed in a defined sample chamber using a two-component nozzle. The PCP-Sus pension consists of Aerosil 380, which has been coated with a monomolecular layer of PCP, and ultrapure water. The compressed air used is dried and heated as required. The volume flow of the compressed air is 1280 L / h and that of the PCP suspension is 15.4 ml / h. The sample chamber is designed so that the air generated simulates indoor conditions. In the Probenkam mer the sampler device is arranged so that the air inlet 18 is oriented perpendicular to the flow direction of the simulated room air. For the sampling, ambient conditions of 55-65% relative air humidity and 21-23 ° C were set. Due to its chemical characteristics, PCP occurs both as a gas and as a particle-bound aerosol under these conditions.

PCP sampling and analysis

The tips 2 , 3 on the glass test tube 1 are "smoothly" broken off with a known additional device. The first sampler part 12 is then assembled and gas-tightly connected to the collecting tube at its proximal end, as seen in the flow direction, by means of a suitable connecting piece 22 . The distal end of the collecting tube 1 is then inserted into a gas detection pump. Then, for example, 10- 150 liters of test air in the flow direction 4 are sucked through the receiver device. During this air sampling, the dust / aerosol present in the sample air is collected / enriched on the first filter 16 and the gaseous pollutant content is adsorbed on the second filter 5 in the collecting tube. The pollutants collected by both sampler parts 1 , 12 can then be examined together. For this purpose, the collecting tube is broken at the mark 8 and the tube contents 9 , 5 , 7 , 6 , 10 , but at least the components 5 , 6 , 7 are transferred into an extraction vessel with solvent. Furthermore, the first filter 16 is removed from the first sampler part and also transferred into the extraction vessel. The choice of solvent depends on the solubility behavior of the analyte. A possible impairment of the subsequent immunoassay by the solvent must also be taken into account. It has been found that, for example, methanol is very suitable for the desorption of collected penta chlorophenol (PCP) without impairing the subsequent immunoassay.

The extraction vessel consists, for example, of a ver screwable plastic bottle in which there are some steel balls are located. The container with the filters is used for extraction shaken for about a minute. To be disruptive after extraction Aerosol, dust or filter parts can then be removed ßend the supernatant solution over a Filtrier- or Filtra tion unit can be filtered. The filtrate can then the PCP concentration directly or after dilution with water Be determined using an immunoassay. A comparison of the Results of the method according to the invention differ air heavily contaminated with PCP with the results of conventional standard laboratory procedures for determining the pollutant level Air generation is shown in Table 1.

In Table I there are both the measurement results with a gas chroma graphical method (GC) as well as the results of an Immu noassays listed, although in the present case a simplified The immunoassay was carried out that does not contain any absolute values of the Provides concentration, but only the classification of the sample in allows predetermined ranges of concentration in this Example in the ranges <33.3 µg / m³, 33.3 to 333.3 µg / m³ and <333.3 µ / m³.

Different filters and filter combinations were used. With sample no. 1 was only a collection tube with Silica gel used for collection and analyzed at Pro no. 3 exclusively a PTFE filter and at sample no. 2nd the filters connected in series for the Aerosol component (PTFE filter) and filter for the gaseous  Component (silica gel) used and analyzed together. It It should first be noted that the gas chromato graphic laboratory analysis quite precisely determined PCB concentration tions show that the separate collection and analysis of the gaseous component (sample no. 1) and the aerosol component (Sample No. 3) an overall lower result is observed than in the combined collection and joint analysis (Pro no. 2), which indicates that in the separate measurement PCP components are not captured, so the sum of both Single measurements overall a significantly smaller result than the combined collection and analysis provides. A similar The result is shown in sample no. 4, here an air sample was prepared with a significantly higher PCP aerosol content. Also in this case shows the separate analysis of fiber optic filters and In total, silica gel filters have a significantly lower result than the combined analysis under sample no. 5. With that shown that with the method according to the invention more accurate Ge overall results can be determined.

Table I also shows that the results of the immunoassay are correctly correlated with those of classic laboratory analysis. This is also shown in Table II, where the results of a Series of sampling with gas chromatographic methods and Immunoassay are compared. It was again an immunoassay is used that does not show absolute values, but the Classification of the sample in predetermined intervals provides, where here the intervals <0.2 µ / ml, 0.2 to 2 µ / ml, 2 to 20 µ / ml and <20 µ / ml were used. The comparison with the Laboratory analytical control measurement shows, with the exception of the samples 1 and 6, a very good correlation between the simple Immu noassay and the laboratory control analysis. The two samples 1 and 6 represent so-called "false positive" findings. The Tatsa che that occasionally false positive results in immunoassays occur in the field of immunochemical reaction as disadvantageous property, known from immunoassays. In contrast the occurrence of "false negative" results is almost  excluded, so the procedure from a security perspective score as hypersensitive and therefore rather positive is.

The immunoassay results shown in Table II can be obtained in a very simple way, so that the Method using an immunoassay good for direct Field tests or on-site tests are suitable, the test also for Layman is easily executable.  

Table I

PCP air concentration determination using a sampling system and subsequent laboratory or immunochemical analysis

Table II

Comparison of results of the pentachlorophenol determination between immunoassay¹ and standard analysis methods²

Claims (10)

1. A method for the quantitative analysis of an air constituent (analyte) which is particle-bound (aerosols) and gaseous, a defined amount of air being drawn through a filter arrangement for sampling, which has at least a first filter for receiving aerosols and a second filter for receiving gaseous Analyte, wherein in the first filter ( 16 ) and in the second filter ( 5 ) filter material made of material inert to the analyte is used, the second filter ( 5 ) being suitably designed for sorptive absorption of the gaseous analyte, characterized in that
that after sampling, the first and the second filter ( 16 , 5 ) are fed together to a solvent bath in which both particle-bound and sorptively bound analyte from the filters is brought into solution, and
that the analyte content of the solvent bath is determined quantitatively using an analyte-specific immunoassay. 2. The method according to claim 1, characterized in that before Perform the immunoassay, filter the solvent bath and the immunoassay is performed on the filtrate. 3. The method according to any one of the preceding claims, characterized in that a single filter membrane made of PTFE, glass fabric or treated cellulose senitrate is used for the first filter ( 16 ). 4. The method according to any one of the preceding claims, characterized in that a layer of silica gel is used for the second filter ( 5 ). 5. Sampling device for use in a method for the quantitative analysis of an air content according to claim 1, with
a first sampler part ( 12 ) in which the first filter ( 16 ) is arranged as a filter membrane for receiving aerosols and which has an inflow ( 18 ) and an outflow opening ( 19 ),
a second sampler part ( 1 ), which is formed by a collecting tube known per se with a filter ( 5 , 6 ) located therein,
the tip of the collecting tube being gas-tightly connectable to the outflow opening of the first sampler part ( 12 ). 6. The device according to claim 5, wherein the first sampler ( 12 ) has a plate-shaped housing with an air passage, wherein the filter membrane ( 16 ) fills the cross section of the air passage between the inflow and outflow opening. 7. The device according to claim 6, wherein the filter membrane ( 16 ) is held on one side by an O-ring seal ( 15 ) and on the other side by a filter support layer ( 17 ) in the housing. 8. Device according to one of claims 6 or 7, wherein the first sampler part transverse to the air passage in two hous seteile ( 11 , 13 ) is divided, which are detachable from each other, so that the filter membrane ( 16 ) clamped by the two housing parts can be removed. 9. Device according to one of claims 5 to 8, wherein the first filter ( 16 ) consists of PTFE, glass fabric or treated cellulose nitrate. 10. The device according to claim 7, wherein the filter support layer ( 17 ) consists of polyethylene sintered material.