Method for concentrating at least one anthropogenic target substance in a sample liquid

Abstract

The invention relates to a concentration of at least one anthropogenic target substance in a sample liquid, which anthropogenic target substance consists of particles and / or particulates with an average particle or particulate size in the nanometre range, comprising: - adding a superabsorber (2) to an initial volume of liquid (1) of the sample liquid or adding the volume of liquid (1) to the superabsorber (2), - incubating, over a first period (t1), the mixture obtained by mixing the superabsorber (2) and the volume of liquid (1), and - removing a first sample (4) of the liquid portion (3) of the mixture present after incubation.

Description

[0001] Method for concentrating at least one anthropogenic target substance in a sample liquid

[0002] The invention relates to a method for concentrating at least one anthropogenic target substance in a sample liquid, which anthropogenic target substance consists of particles and / or particles with an average particle size in the nanometer range.

[0003] Nanoparticles and nanoparticles are playing an increasingly important role in our lives. This applies, for example, to the use and, in this context, also the production of these particles and particles for a wide variety of applications in the pharmaceutical industry (for example, in connection with encapsulated mRNA active ingredients), food technology, and the electrical engineering and electronics industries (for example, in connection with quantum dots).

[0004] Due to their small size and the associated changes in their physical characteristics, nanoparticles can be used to transport drugs to desired organs, as they can penetrate the blood-brain barrier (e.g., suitable for pharmaceutical applications) and the skin (e.g., suitable for the cosmetics industry). Nanoparticles are also used for diagnostic applications, such as color detection in rapid tests based on colloidal gold. They also stabilize food, thus ensuring longer shelf lives.

[0005] Nanoparticles are almost exclusively anthropogenic substances. This means that they have been produced by humans through industrial, commercial, and municipal processes, and not, for example, by biological organisms. Another aspect of nanoparticles is the pollution of our planet, as they are often difficult to biodegrade. For example, nanoparticles are formed from waste from the plastics industry or from the partial decomposition of plastic waste in nature (so-called secondary nanoplastics). The worldwide pollution of the environment with waste from the plastics industry is a global problem. Nanoplastic waste with particle orParticle sizes smaller than 1 pm enter the ecosystem unhindered and are often not stopped by sewage treatment plants. The damage caused by micro- and nanoplastics includes the accumulation of particles in the tissue of aquatic organisms. They also reach humans through polluted water and via the food chain. The accumulation of hydrophobic persistent organic pollutants (POPs) in the environment means an increasing additional burden on marine organisms and humans. Nanoparticles, or nanoparticles made of plastic, are particularly dangerous because they can pass through the cell membrane and influence cellular metabolic processes. The collection and detection methods currently used are only suitable for macro- and microplastics, but not for nanoplastics. To assess environmental pollution, plastic waste is collected from surface water, for example. This makes use of the fact that approx.98% of plastic particles are less dense than water. The plastic particles are collected using large nets with a mesh size of approximately 0.3 mm, which are dragged across the water surface by a boat. The collected sediment is separated by sieving. The plastic particles are then suspended and filtered by size. Other approaches are based on the filtration of large volumes of water or air. The concentration of plastic particles in different bodies of water is estimated at approximately 1.5 x 10-5 to 0.11 g / m3.

[0006] However, in all these approaches, the plastic components <0.33 mm (i.e. parts of the nanoparticles and nanoparticles in the micrometer range and all nanoparticles and nanoparticles in the nanometer range) are either lost or remain in the filter flow.

[0007] The detection of microplastic and nanoplastic waste is carried out using spectroscopic methods (e.g., Raman or infrared spectroscopy), thermoanalytical methods (e.g., differential scanning calorimetry (DSC)), gas chromatography / mass spectrometry (GC / MS), microscopy (optical, fluorescence-based), or fluorescence-based flow cytometry. This reveals the problem that detection is very complicated due to the low concentration of nanoplastics. A novel and simple concentration method would also be desirable for these applications.

[0008] The object of the invention is to provide a simple, rapid and universally applicable method for concentrating at least one anthropogenic target substance in a sample liquid.

[0009] This object is achieved in a surprisingly simple and universally applicable manner by means of the method defined in claim 1, the use according to claim 21, and the kit according to claim 24. Advantageous embodiments are specified in the dependent claims.

[0010] The solution is based on the use of so-called superabsorbents, with which any aqueous sample liquid can be processed in order to concentrate the nanoparticles contained in the sample liquid.

[0011] Superabsorbent polymers (SAPs) are plastics capable of absorbing many times their own weight in polar liquids. These are primarily water or aqueous solutions. When absorbing the liquid, the superabsorbent swells and forms a hydrogel. Hydrogels can be formed from any cross-linked polar polymer (e.g., polyacrylamide, polyvinylpyrrolidone, amylopectin, gelatin, cellulose). However, a copolymer of acrylic acid (propenoic acid, H2C=CH-COOH) or sodium acrylate (sodium salt of acrylic acid, H2C=CH-COONa) and acrylamide is most commonly used, although the ratio of the two monomers can vary. Additionally, a core cross-linker (CXL) is added to the monomer solution, which connects the formed long-chain polymer molecules to one another through chemical bridges, also known as cross-linking. These bridges make the polymer insoluble in water.This so-called base polymer may be subjected to a process called surface cross-linking (SXL). This involves applying another chemical to the surface of the particles, which, when heated, creates a second network only on the outer layer of the grain. This shell supports the swollen gel, ensuring it stays together even under external stress (movement, pressure).

[0012] The product is conventionally used as white granules with particle sizes ranging from 100 to 1000 μm. It is mainly used in baby diapers, sanitary pads, incontinence care, in bandages, and in small quantities in cable sheathing for deep-sea cables. Other applications include so-called gel beds, gel-forming extinguishing agents in firefighting, as a mechanical stabilizer for cut flowers in vases, or as an additive for potting soil to permanently store water. However, in these cases, potassium hydroxide-neutralized acrylic acid is used due to its better environmental compatibility. In the form of spherical particles, the use of superabsorbents as toys is known under names such as "water beads," "aqua beads," or "water beads." These are superabsorbents that are commercially available in the form of spheres of variable size (submillimeters to centimeters).

[0013] The invention was based on the following unexpected observation: A water sample was mixed with fluorescent nanoparticles with an average particle size of 30 nm. After adding commercially available water beads and an incubation period during which the beads swelled to several times their original volume, it was found that the nanoparticles were not absorbed by the superabsorbents but were concentrated in the remaining liquid.

[0014] This observation demonstrates that by using superabsorbents, especially superabsorbents commercially available in the form of so-called water beads, a wide variety of nanoparticles can be easily and quickly concentrated in a liquid sample. The concentrated particles are then easier to detect, as the concentration results in a higher target concentration.

[0015] The method and agent according to the invention thus make it possible to efficiently, easily, and quickly concentrate nanoparticles of various compositions for detection reactions. Based on this observation, the problem underlying the invention was solved.

[0016] The method according to the invention for concentrating at least one anthropogenic target substance in a sample liquid comprises:

[0017] - adding a superabsorbent to an initial liquid volume of the sample liquid or adding the liquid volume to the superabsorbent,

[0018] - incubating the mixture formed from the superabsorbent and the liquid volume for a first period of time, and

[0019] - Taking a first sample of the liquid portion of the mixture after incubation.

[0020] "Anthropogenic substances" are defined as substances that are not created by nature but by humans, for example, through industrial, commercial, or municipal processes. These include, for example, plastics, but also pesticides, pharmaceuticals, personal care products, and industrial chemicals, as well as their degradation products and metabolites. Biomolecules produced by microorganisms (e.g., enzymes, DNA / RNA fragments, etc.) and having similar sizes in the nanometer range are not considered to be particles or anthropogenic substances mentioned in this application.

[0021] In the above-described method according to the invention, the first sample taken from the liquid portion of the mixture of liquid and superabsorbent present after incubation can be the entire remaining liquid portion. However, it is also possible to take only a partial volume of the liquid portion present as the first sample.

[0022] The first sample can be used directly for subsequent analysis, e.g., using a spectroscopic method. It can also be further concentrated in a cascading process in one or more additional steps, e.g., by re-adding a superabsorbent or re-adding it to a superabsorbent and reincubating it, or by using a conventional method for concentrating target substances, e.g., one of the methods mentioned above. If only a portion of the liquid portion is taken as the first sample, the target substance in the liquid portion of the mixture remaining after sampling can be further concentrated by reincubating it for a second period. Both variants of the process can be repeated several times, resulting in a higher concentration of the target substance at each step of the cascaded concentration.

[0023] It is advantageous to reduce the initial sample volume in a first step by means of the method according to the invention using a superabsorbent, and to carry out a further concentration of the target substance in a subsequent second step using a conventional concentration technique, e.g., filtration, ultrafiltration, precipitation reaction, ultracentrifugation, or enrichment using the method described in EP 2283026 B1. These known techniques can be used significantly more efficiently in already reduced sample volumes than in more diluted solutions. Thus, the method according to the invention is suitable for significantly simplifying known methods for concentrating nanoparticles, or nanoparticles for large-volume sample liquids and / or sample liquids containing the target substance only in low concentrations.

[0024] As mentioned, in an advantageous embodiment, the method may comprise a further concentration of the target substance in the first sample taken after the first sample has been taken.

[0025] The further concentration of the target substance in the first sample taken can be carried out using a filtration, ultrafiltration or precipitation reaction technique.

[0026] Alternatively, the further concentration of the target substance in the first sample taken can also be carried out again - and optionally repeated in cascade one or more times - by carrying out the following process steps:

[0027] - adding a superabsorbent to the first sample or adding the first sample to the superabsorbent,

[0028] - incubating the mixture formed from the superabsorbent (5) and the first sample for a second period of time, and

[0029] - Taking a concentrated first sample of the liquid portion of the mixture present after incubation.

[0030] Similar to the procedure described above for the first stage of the cascade, the concentrated first sample taken from the liquid portion remaining after incubation can comprise the entire volume of the liquid portion. Alternatively, the concentrated first sample can be a partial volume of the remaining liquid portion.

[0031] The target substance can be further concentrated in the concentrated first sample or in a further concentrated first sample obtained by further concentration, in particular by means of a superabsorbent, by means of a filtration, ultrafiltration, or precipitation reaction. This is advantageous if the volume of the concentrated first sample corresponds to only a few milliliters, e.g., 1 to 10 ml.

[0032] As already mentioned, the method according to the invention for concentrating the target substance in the liquid portion of the mixture remaining after taking the first sample from the liquid portion of the mixture of the originally used liquid volume and the superabsorbent can comprise the following further steps: reconcentrating the target substance in the liquid portion of the mixture remaining after taking the first sample - and optionally repeating this cascadingly one or more times - by - re-incubating the mixture remaining after taking the first sample from the liquid portion and the superabsorbent over a third period of time; and

[0033] - Taking a second sample of the liquid portion of the mixture after further incubation.

[0034] By incubating again, the volume of the liquid portion is further reduced and the target substance in the liquid portion is further concentrated. The concentration of the target substance is determined, among other things, by the preset duration of the third period and the conditions prevailing during incubation.

[0035] In the process according to the invention, the initially used liquid volume can contain a polar liquid, in particular as the main component. In an advantageous embodiment of the process according to the invention, the liquid volume can contain a polar solvent, in particular as the main component. For example, the liquid volume can consist of a polar solvent to a mass fraction of at least 50%. The polar liquid or polar solvent can be water, for example.

[0036] The target substance is a nanoparticle. Such a nanoparticle consists of an anthropogenic substance, in particular at least one natural polymer, at least one biocompatible synthetic polymer, an inorganic material, or an organic material.

[0037] As mentioned, in an advantageous embodiment, the superabsorbent can be a plastic or comprise a plastic that absorbs a portion of the liquid volume, e.g., a polar solvent such as water contained in the liquid volume, to form a gel or hydrogel. Advantageously, the plastic is selected such that it absorbs essentially no nanoparticles. This is the case, for example, with the aforementioned superabsorbents made from the aforementioned polymer or copolymer materials, e.g., with commercially available water beads, water pearls, etc.

[0038] The superabsorbent can be used in the form of particles, e.g., as a powder, as granules, or in the form of geometric bodies, especially spheres (spherical particles). It can thus be added to the liquid volume or the first sample in the form of such particles, or the liquid volume or the first sample can be added to the superabsorbent in this form. The particles or spheres can have a diameter between 100 and 5000 pm.

[0039] Advantageously, the superabsorbent is commercially available superabsorbent spheres, for example, superabsorbent spheres sold under the names "Aquabeads," "Water Beads," "Water Pearls," "Aqua Beads," "Hydrospheres," or "Gel Beads." In an advantageous embodiment of the method, the volume of the liquid portion remaining after the incubation step, and thus the concentration of the target substance in the remaining liquid portion, can be controlled by the length of the incubation period(s), the size and number of superabsorbent particles or spheres added to the initial volume of the sample liquid or the first sample, and / or the temperature prevailing during incubation.

[0040] The sample liquid may be a filtrate or a centrifugation supernatant. This means that one or more separation steps are performed before concentration to remove further components from the sample.

[0041] One embodiment of the method provides for the sample liquid to be an environmental sample. An environmental sample is taken from the environment, for example, from bodies of water such as lakes or rivers. Sediment or gas samples, for example, which are subsequently mixed with a liquid, are also referred to as environmental samples.

[0042] The invention further comprises a method for detecting an anthropogenic target substance in a sample liquid, comprising:

[0043] - Concentrating the sample liquid by means of the concentration method according to the invention using the superabsorbents, and

[0044] - Carrying out a physical detection procedure for the qualitative and / or quantitative determination of the anthropogenic target substance.

[0045] The physical detection method is used to determine whether certain nanoparticles or nanoparticles are present in the concentrated sample, and what their concentration is. In the initial liquid volume, these would not be detectable using the physical detection method, as their concentration is too low. A microscope is used for qualitative and / or quantitative determination. Here, for example, the nanoparticles or nanoparticles are counted in a section of a defined size. Alternatively, a fluorescence measurement method or a spectroscopic measurement method is used. For this, the nanoparticles or nanoparticles must

[0046] Nanoparticles contain a fluorescent dye, which is added in particular before concentration.

[0047] The invention further encompasses the use of a superabsorbent for the single or multiple cascading concentration of the anthropogenic target substance in a liquid sample. The liquid sample may contain a polar liquid, in particular water, wherein the superabsorbent is configured to absorb the polar liquid, e.g., water, or at least a portion of the polar liquid, to form a hydrogel. The superabsorbent may be formed from the materials described above and, in the previously described embodiments, may be used as granules or, particularly preferably, in the form of spheres, in particular commercially available water beads, water beads, or aqua beads.

[0048] The cascaded concentration can comprise multiple stages. After each stage, a sample can be taken for analysis and the concentration process can be continued, or the sample, or a portion of the sample, concentrated in at least one stage after incubation with the superabsorbent can be further concentrated using other known methods.

[0049] The invention also includes a kit for carrying out the method described above. The kit can, for example, comprise one or more containers pre-filled with superabsorbent, into which a user can then add an initial volume of liquid for concentration or a sample already concentrated in a first stage.

[0050] The liquid concentrated according to the described method or according to the described use, i.e. the liquid portion remaining after incubation, or a sample taken from the concentrated liquid can be fed manually or automatically to a laboratory device for further treatment or analysis. In one possible embodiment of the method or use, such a liquid or sample of the liquid can be introduced into a cartridge, in particular a microfluidic cartridge, of an automatic analysis device for the automated detection of the target substance using a physical detection method for the qualitative and / or quantitative determination of the anthropogenic target substance. This can be done manually or automatically.

[0051] The invention is explained in more detail below with reference to the figures and some exemplary embodiments. These examples do not represent a limitation of the means and methods according to the invention.

[0052] Fig. 1 shows a schematic representation of the cascading concentration of a target substance in a liquid: a) Liquid before adding a superabsorbent; b) Liquid after adding a superabsorbent and incubating the mixture; c) First sample taken from the mixture after adding another superabsorbent and incubating the mixture; d) Remaining mixture of liquid and superabsorbent, if applicable, after taking the first sample and after further incubation.

[0053] Fig. 2 shows a representation of samples and blank samples, some of which were obtained by the concentration according to the invention and exposed to UV light; and Fig. 3 shows evaluations of the measured data: a) a graphical representation of the mean values ​​of the measured values ​​in a bar chart; b) a correlation between the degree of concentration and the increase in fluorescence of the samples.

[0054] The use of superabsorbents to concentrate a target substance, especially nanoparticles, in a polar liquid as a solvent, such as water, is very simple and universally applicable. A suitable method is briefly described as follows using Fig. 1 a and b:

[0055] 1. Addition of a superabsorbent 2 to a volume of a, in particular aqueous, liquid 1, or alternatively: addition of the liquid 1 to a superabsorbent 2 provided;

[0056] 2. Incubation of the mixture of the liquid 1 and the superabsorbent 2 over a first period t1 to reduce the volume of the liquid portion 3 of the mixture; and subsequently

[0057] 3. Transfer at least a first sample 4 of the liquid portion 3 of the mixture into a new container as a sample for further processing.

[0058] Further processing may, for example, involve quantitative and / or qualitative detection of the target substance present in the liquid. Detection is carried out using, for example, a spectroscopic or microscopic method.

[0059] The degree of concentration and the speed of this process can be controlled very precisely by the type of superabsorbent used, by its amount used, or by the incubation time and / or the incubation temperature.

[0060] The method thus provides a simple solution to the problem of processing low-concentration samples for further processing of the target substances of interest, in particular nanoparticles, or their detection. The method shown in Fig. 1 a and b does not require equipment such as ultracentrifuges, expensive ultrafiltration membranes, complex processes such as PEG precipitation or general precipitation reactions for concentrating nucleic acids, etc. Furthermore, the method is universally applicable with regard to the type of nanoparticles. A further advantage is that the superabsorbents are non-toxic and harmless and often also biodegradable. The method according to the invention can therefore greatly simplify the investigation of low-concentration nanoparticles.

[0061] For large-volume and / or highly diluted liquids containing the nanoparticles, or nanoparticles in a very low concentration, a cascading concentration of the target substance is an option. For example, in a first stage, the described method with the above-mentioned steps 1-3 can be used to concentrate the target substance. In a second stage, the first sample 4 can be reduced in volume to further concentrate the target substance. This can be done either by means of a conventional filtration or precipitation process or other conventional methods. Alternatively, the further concentration of the target substance in the first sample 4 can also be achieved, as shown in Fig. 1 c, by adding fresh superabsorbent 5 to the first sample 4 or by transferring the first sample 4 to a new superabsorbent 5 and incubating it again for a second period t2.Additionally or alternatively, the liquid portion 6 remaining in the mixture with the superabsorbent 2 after the first sample 4 has been taken can be further reduced by incubating the mixture for a third period t3, as shown in Fig. 1d. This leads to further swelling and volume expansion of the spheres consisting of the superabsorbent 2 and to a further volume reduction of the liquid portion 6, which is accompanied by an increase in the concentration of the target substance in the liquid portion 6.

[0062] In both alternative process paths, further concentration stages can follow in cascading fashion.

[0063] An embodiment of the invention is described in more detail below.

[0064] Example: Concentration of Rhodamine B-filled latex nanoparticles (0 25.8 nm) in a water sample

[0065] The latex nanoparticles were provided by the Fraunhofer Institute for Applied Polymer Research. The concentration of the latex particles in the stock solution was 2.02 M%. The particles were added to a 500 ml water sample, creating a 1:10,000 dilution.

[0066] Subsequently, a superabsorbent in the form of commercially available "water beads" was added to the water sample. During the concentration process by absorbing water into the water beads, samples PO, P1, and P2 were taken at different times, each corresponding to a different concentration.

[0067] The samples are divided into blank samples L0, L1, L2 for controls (without latex nanoparticles) and samples PO, P1, P2 which contain the latex nanoparticles. The samples are specifically as follows: Blank sample L0: ultrapure water without latex particles (500 ml) Blank sample L1: concentration of 500 ml ultrapure water to 40 ml ultrapure water Blank sample L2: further concentration of L1 to 1 ml ultrapure water Sample PO: 1:10,000 dilution of the latex particle stock solution in 500 ml ultrapure water Sample P1: concentration of 500 ml ultrapure water to 40 ml ultrapure water Sample P2: further concentration of P1 to 1 ml ultrapure water The particles in the respective samples were detected by measuring the fluorescence of the dye contained in the latex nanoparticles.

[0068] Fig. 1 shows a qualitative detection of latex nanoparticles. For this purpose, the respective samples PO, P1, P2 and the blank samples LO, L1, L2 were transferred in triplicate to a UV-transparent measuring plate. The measuring plate with the samples was then exposed to UV light. Exposure to UV light excites fluorescence in the samples containing latex particles. No fluorescence is visible in the blank samples LO, L1, L2, and the fluorescence of the samples PO, P1, P2, which contain the latex nanoparticles, increases with increasing concentration.

[0069] Table 1 shows a quantitative measurement of the respective samples using a fluorescence measuring device. The measurements were performed by exciting the samples PO, P1, P2 and the blank samples LO, L1, L2 (each in triplicate) at an emission of 559 nm. While the values ​​of the blank samples LO, L1, L2 remain stable and low with increasing concentration, the values ​​of the samples PO, P1, P2 containing the nanoparticles increase proportionally to the degree of concentration.

[0070] Table 1 :

[0071] Fig. 2 graphically displays and evaluates the measured values ​​listed in Table 1. Fig. 2a shows the mean values ​​of the respective measured values ​​for a sample as a bar chart. Fig. 2b shows a correlation between the degree of concentration and the increase in fluorescence of samples PO ("1"), P1 ("2"), and P2 ("3"), which contained nanoparticles.

[0072] The experimental data clearly show that the fluorescent latex nanoparticles in the sample do not diffuse into the superabsorbent (“water beads”) but remain in the external solution, thus increasing the concentration of the latex nanoparticles continuously and correspondingly to the degree of concentration.

[0073] 1 initial fluid volume

[0074] 2.5 Superabsorbent

[0075] 3, 6 liquid part of the mixture 4 first sample t1 , t2, t3 periods

[0076] L0, L1, L2 blank samples

[0077] PO, P1, P2 samples

Claims

Patent claims 1. A method for concentrating at least one anthropogenic target substance in a sample liquid, which anthropogenic target substance consists of particles and / or particles with an average particle size in the nanometer range, comprising: - adding a superabsorbent (2) to an initial liquid volume (1) of the sample liquid or adding the liquid volume (1) to the superabsorbent (2), - incubating the mixture formed from the superabsorbent (2) and the liquid volume (1) over a first period of time (t1), and - Taking a first sample (4) of the liquid portion (3) of the mixture present after incubation.

2. The method according to claim 1, further comprising further concentrating the anthropogenic target substance in the taken first sample (4).

3. The method according to claim 2, wherein the further concentration of the target substance in the taken first sample (4) is carried out by means of a filtration, ultrafiltration or precipitation reaction technique.

4. The method according to claim 2, wherein the further concentration of the target substance in the first sample (4) taken is carried out again by: - adding a superabsorbent (5) to the first sample or adding the first sample to the superabsorbent (5), - incubating the mixture formed from the superabsorbent (5) and the first sample for a second period of time (t2), and - Taking a concentrated first sample of the liquid portion of the mixture present after incubation.

5. The method according to claim 4, wherein the target substance is present in the concentrated first sample or in a further Concentration, in particular by means of a superabsorbent (5), further concentrated first sample obtained is further concentrated by means of a filtration, ultrafiltration or precipitation reaction.

6. The method according to any one of claims 1 to 5, further comprising: reconcentrating the target substance in the liquid portion of the mixture remaining after taking the first sample by - re-incubating the mixture of the remaining liquid portion and the superabsorbent (2) remaining after the first sample has been taken for a third period (t3); and - Taking a second sample of the liquid portion of the mixture after further incubation.

7. Method according to one of claims 1 to 6, wherein the liquid volume (1) contains a polar liquid, for example water.

8. The method according to claim 7, wherein the particles of the anthropogenic target substance consist of at least one natural polymer, of at least one biocompatible synthetic polymer, of an inorganic material or of an organic material.

9. Method according to one of claims 1 to 8, wherein the superabsorbent (2, 5) comprises a plastic which absorbs a portion of the liquid volume, water, to form a hydrogel.

10. The method according to claim 8 and 9, wherein the plastic absorbs substantially no particles contained in the anthropogenic target substance.

11. Method according to one of claims 1 to 10, wherein the superabsorbent (2, 5) is used in the form of particles, e.g. as a powder, as granules or in the form of geometric bodies, in particular spheres.

12. Method according to one of claims 1 to 11, wherein the superabsorbent (2, 5) is used in the form of, in particular commercially available, water beads, hydrospheres, aqua pearls, aquabeads, waterbeads, or gel beads.

13. The method according to any one of claims 1 to 12, wherein the volume of the liquid portion (3) remaining after incubation is controlled by the length of the period or periods (t1, t2, t3) of incubation and / or by the type and / or amount of superabsorbent (2, 5) and / or by the temperature of the mixture prevailing during incubation.

14. The method according to claim 13, wherein the superabsorbent (2, 5) is used in the form of particles, e.g. as a powder, as granules or in the form of geometric bodies, in particular spheres, and wherein the volume of the liquid portion remaining after incubation is controlled by the size and / or number of the particles.

15. Method according to one of the preceding claims, wherein the sample liquid is a filtrate or a centrifugation supernatant 16. The method according to any one of claims 1 to 15, wherein the sample fluid is an environmental sample.

17. A method for detecting an anthropogenic target substance in a sample liquid, comprising: - Concentrating the sample liquid by means of a method according to one of claims 1 to 14, - Carrying out a physical detection procedure for the qualitative and / or quantitative determination of the anthropogenic target substance.

18. The method according to claim 17, wherein the determination takes place under a microscope.

19. The method according to claim 17, wherein the physical detection method is a fluorescence measurement method or a spectroscopic measurement method.

20. The method according to claim 19, wherein when using a UV or fluorescence method, a fluorescent dye is added to the sample liquid before concentration.

21. Use of a superabsorbent (2, 5) for the single or multiple cascading concentration of at least one target substance in a liquid sample.

22. Use according to claim 21, wherein the particles of the anthropogenic target substance consist of at least one natural polymer, of at least one biocompatible synthetic polymer, of an inorganic material or of an organic material.

23. Use according to claim 21 or 22, wherein the liquid sample contains a polar liquid, in particular water, and wherein the superabsorbent (2, 5) is adapted to absorb the polar liquid to form a hydrogel.

24. Kit for carrying out the method according to any one of claims 1 to 20.

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