Cationic polythiophene derivative and method for detecting and removing perfluorinated compounds

Abstract

The invention relates to the field of persistent pollutant detection and repair, in particular to a cationic polythiophene derivative for detecting and removing perfluorinated compounds and a method thereof, the provided cationic polythiophene derivative has good water solubility, shows obvious specificity in detection, can sensitively detect the perfluorinated compounds, and can be used for detecting and removing the perfluorinated compounds. Conformations and aggregation states of the compounds with the structures as shown in the formula (I) and the formula (II) in a solution show different states to external stimulation, so that the optical characteristics of the compounds are changed. The types of the detected and removed perfluorinated compounds comprise short-chain perfluoroalkyl carboxylic acid (perfluorobutyric acid PFBA and perfluorohexanoic acid PFHxA), long-chain perfluoroalkyl carboxylic acid (perfluorocaprylic acid PFOA and perfluorododecanoic acid PFDoA), short-chain perfluoroalkyl sulfonic acid (trifluoromethanesulfonic acid TFMS, perfluorobutyl sulfonic acid PFBS and perfluorohexyl sulfonic acid PFHxS) and long-chain perfluoroalkyl sulfonic acid (perfluorooctyl sulfonic acid PFOS).

Description

Technical Field

[0001] The present invention relates to the technical field of persistent pollutant detection and remediation, and in particular to a cationic polythiophene derivative and a method for detecting and removing perfluorinated compounds. Background Art

[0002] Over the past decade, global research on the environmental and health risks of perfluorinated compounds (PFCs) has intensified. PFCs are a class of synthetic chemicals widely used in industries such as pesticide synthesis, food production, electroplating, textile finishing, and polymer production. Studies have shown that PFCs are contaminated in environmental media worldwide, as well as in wildlife and humans (blood, breast milk, and liver), causing adverse effects on humans, including liver damage, thyroid disease, immunotoxicity, and cancer.

[0003] Therefore, efficient and sensitive detection of perfluorinated compounds is of great significance. Currently established methods for detecting perfluorinated compounds primarily include liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, and enzyme-linked immunosorbent assay (ELISA). While these methods often rely on large-scale instrumentation, while offering high sensitivity, they are expensive, require long testing cycles, and require time-consuming and labor-intensive sample pretreatment. Furthermore, they require specialized testing personnel, making them inadequate for large-scale sample and on-site testing.

[0004] Methods that utilize the photochemical properties of materials to detect perfluorinated compounds have garnered widespread attention due to their rapidity and high sensitivity. Currently, most optical methods for detecting perfluorinated compounds rely on the interaction of fluorescent probes with the compounds, resulting in changes in fluorescence emission before and after the interaction. Our research group has designed metal polypyridine complexes (Chinese Patent: CN118638157A) as fluorescent probes, enabling highly sensitive quantitative detection and removal of perfluorinated pollutants. However, fluorescence sensing requires specialized optical detection systems and suffers from strong background interference, limiting its application.

[0005] Colorimetric sensing technology is a simple analytical method that can be used as a pre-screening tool for on-site testing. When connected to a smartphone application, it can provide convenient color reading, offering unique rapid response and cost-effectiveness. Gold nanoparticles (AuNPs) are commonly used to develop colorimetric sensors. Takayose et al. (Anal. Lett. 2012, 45, 2856) proposed a method for detecting perfluorinated compounds using gold nanoparticles. Perfluorinated compound-modified gold nanoparticles aggregate through fluorine-fluorine interactions. Finally, the color of the solution changes from red to purple. Although simple, the sensitivity is insufficient, and the minimum measurable concentration is only 103 ppm (250 μM). Niu et al. (Anal. Chem. 2014, 86, 4170) also developed a sensor based on gold nanoparticles for detecting perfluorinated compounds. In this method, gold nanoparticles are modified with two different functional groups. Once perfluorinated compounds are adsorbed on the surface of the gold nanoparticles, they begin to aggregate and precipitate. Quantitative detection of perfluorinated compounds is performed by measuring the absorbance in the supernatant. Therefore, the reaction solution must be incubated at room temperature for 0.5 hours before detection, and the precipitate must be removed from the reaction solution by centrifugation. This is a complex and time-consuming operation. Therefore, the development of rapid, convenient, and highly sensitive technologies for the detection and removal of perfluorinated compounds is urgently needed. Summary of the Invention

[0006] The object of the present invention is to provide a cationic polythiophene derivative and a method for detecting and removing perfluorinated compounds, so as to solve the problems existing in the above-mentioned prior art.

[0007] In order to achieve the purpose of the present invention, the following technical solutions are provided:

[0008] A cationic polythiophene derivative for detecting and removing perfluorinated compounds, the structures of which are shown in formula (I) and formula (II):

[0009]

[0010] Formula (I) is a homopolymer structure, R1 is H or CH3; R2 is O or CH2; R3 is an alkyl group with an integer number of carbon atoms between 1 and 6 and its isomers: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; m is an integer between 0 and 15; M is Cl or Br; n is a positive integer, and the weight average molecular weight of the polythiophene derivative is between 3,000 and 50,000.

[0011] Formula (II) is composed of thiophene units connected through the 2 and 5 positions to form a conjugated main chain, and its structural formula is shown below:

[0012]

[0013] Formula (II) is a copolymer structure, R1 is H or CH3; R2 is O or CH2; m is an integer between 0 and 15; M is Cl or Br; R 1# ,R 2# ,R 3# ,R 4# , selected from R in the above formula (Ⅰ) # Substituents, wherein R3 is an alkyl group with an integer carbon number between 1 and 6 and its isomers: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; and satisfies R 1# ≠R 2# ≠R 3# ≠R 4# ; n1, n2, n3, n4 are integers between 1 and 500, and make the average molecular weight of the polythiophene derivative be between 3,000 and 100,000.

[0014] Furthermore, the types of perfluorinated compounds detected and removed include short-chain perfluoroalkyl carboxylic acids: perfluorobutyric acid PFBA, perfluorohexanoic acid PFHxA, long-chain perfluoroalkyl carboxylic acids: perfluorooctanoic acid PFOA, perfluorododecanoic acid PFDoA, short-chain perfluoroalkyl sulfonic acids: trifluoromethanesulfonic acid TFMS, perfluorobutanesulfonic acid PFBS, perfluorohexanesulfonic acid PFHxS, and long-chain perfluoroalkyl sulfonic acid: perfluorooctane sulfonic acid PFOS.

[0015] A method for detecting perfluorinated compounds using the cationic polythiophene derivative comprises the following steps:

[0016] (1) dissolving the cationic polythiophene derivatives represented by formula (I) and formula (II) in water to prepare probe molecules;

[0017] (2) adding the probe molecule obtained in step (1) into a quartz cuvette to obtain a detection reagent;

[0018] (3) gradually adding the perfluorinated compound standard solution into the cuvette and measuring the changes in its UV-visible absorption spectrum and fluorescence spectrum;

[0019] (4) Analyze the relationship between the absorbance ratio and the concentration of the specific perfluorinated compound and the relationship between the fluorescence intensity and the concentration of the specific perfluorinated compound, and perform quantitative and specific detection of the specific perfluorinated compound in the solution.

[0020] Furthermore, the concentration of the cationic polythiophene derivative in the detection system is 0.1-100 μM, the reaction volume is 200-3000 μL, the reaction pH is 4-14, the reaction temperature is 4-40° C., and the reaction system is ultrapure water and HEPES buffer solution.

[0021] A method for removing perfluorinated compounds using the cationic polythiophene derivative comprises the following steps:

[0022] (1) dissolving the cationic polythiophene derivative represented by formula (I) / formula (II) in ultrapure water to obtain a probe molecule solution;

[0023] (2) adding the probe molecule prepared in step (1) into water containing a perfluorinated compound to react;

[0024] (3) After the reaction is completed, the solution is added to a removal system for separation and removal, and the sample after removal is analyzed to obtain the efficiency of the probe molecule in removing the specific perfluorinated compound.

[0025] Furthermore, the perfluorinated compound is separated and removed by precipitation when the concentration is 20-200 μM.

[0026] Furthermore, when the concentration of the perfluorinated compound is 0.1-20 μM, an ultrafiltration system is used for separation and removal, and the pore size of the ultrafiltration system includes but is not limited to: 3-300 kDa.

[0027] The beneficial effects of the present invention are embodied in:

[0028] The present invention provides a probe molecule for visual dual-mode detection of perfluorinated compounds, made from a cationic polythiophene derivative. The probe can be used for rapid, quantitative, and specific detection of perfluorinated compounds. The perfluorinated compounds are detected by utilizing the color and fluorescence intensity changes in the solution caused by the reaction of polythiophene with the perfluorinated compound. The polythiophene derivative-perfluorinated compound complex is then removed by a removal system. The detection method of the present invention has high specificity and sensitivity, supports visual detection, and has a wide range of applications, enabling simultaneous dual-mode detection and removal of perfluorinated compounds in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Figure 1 is a diagram showing the effect of the probe molecule of formula (I) with different R1 substituents in Example 1 of the present invention on detecting PFOS. A) shows the structural differences of different PT names and different R1 substituents; B) shows a schematic diagram of colorimetry and absorption spectrum sensing; C) shows a schematic diagram of fluorescence colorimetry and fluorescence spectrum sensing.

[0030] Figure 2 Schematic diagram of the detection effect of PFOS by the probe molecule of formula (I) with different carbon chain lengths m in Example 1 of the present invention. A) lists the names of different PTs and the differences in carbon chain lengths m; B) is a schematic diagram of colorimetry and absorption spectrum sensing; C) is a schematic diagram of fluorescence colorimetry and fluorescence spectrum sensing.

[0031] Figure 3 In Example 1 of the present invention, different R #The effect diagram of the probe molecule of formula (I) for detecting PFOS, A) is listed as different PT names and different R # Structural differences of substituents; B) is a schematic diagram of colorimetry and absorption spectrum sensing; C) is a schematic diagram of fluorescence colorimetry and fluorescence spectrum sensing.

[0032] Figure 4 Schematic diagram of the detection of PFOS using probes of different structures using formula (II) in Example 1 of the present invention. A) shows the difference between different PT names and different monomer and polymerization ratios; B) shows a schematic diagram of colorimetry and absorption spectrum sensing; C) shows a schematic diagram of fluorescence colorimetry and fluorescence spectrum sensing.

[0033] Figure 5 Figure 2 is a diagram showing the colorimetric sensing effect of the probe molecule and PFOS in Example 2 of the present invention, wherein A) is a diagram showing the relationship between PFOS concentration and the change in the PT absorption spectrum; B) is a diagram showing the relationship between PFOS concentration and the change in the PT absorbance ratio; the inset shows the linear relationship between the absorbance ratio and PFOS concentration; C) is a colorimetric visualization diagram of the probe molecule and different PFOS concentrations; D) is a diagram showing the change in the R / (G+B) value of the probe molecule and different PFOS concentrations.

[0034] Figure 6 The colorimetric effect diagram of the probe molecule specifically recognizing perfluorinated compounds in Example 2 of the present invention, A) UV absorption spectra after the reaction of different ions with the probe molecule; B) absorbance ratio A after the reaction of different ions with PT 505nm / A 405nm Change diagram (serial number in the figure: 1PT, 2SO4 2- 、3CO3 2- 、4HCO3 - 、5Cl - 、6PO4 3- 7NO2 - 、8BrO3 - 9F - , 10K + 、11Ca 2+ , 12SDS, 13Tween-20, 14CTAB, 15PFOS, 16PFOA, the same below); C) Color change diagram after the reaction of different ions with PT.

[0035] Figure 7 The effect diagram of the probe molecule and PFOS fluorescence sensing in Example 3 of the present invention is shown in Figure 3. A) is the relationship between the change of PFOS concentration and the change of PT fluorescence emission spectrum; B) is the ratio of PFOS concentration to fluorescence intensity FI 600nm / FI 535nmC) Fluorescence visualization of the probe molecule and different concentrations of PFOS under blue light irradiation; D) R / (G+B) value change diagram of different concentrations of PFOS and probe molecules under blue light irradiation.

[0036] Figure 8 Figure 3 is a diagram showing the fluorescence effect of the probe molecule in Example 3 of the present invention on the specific recognition of perfluorinated compounds, A) fluorescence spectra after the reaction of different ions with the probe molecule; B) changes in fluorescence quenching rate after the reaction of different ions with PT (sequence numbers in the figure: 1PT, 2SO42-, 3CO32-, 4HCO3-, 5Cl-, 6PO43-, 7NO2-, 8BrO3-, 9F-, 10K+, 11Ca2+, 12SDS, 13Tween-20, 14CTAB, 15PFOS, 16PFOA, the same below); C) fluorescence intensity ratio FI after the reaction of different ions with PT 575nm / FI 535nm (D) Fluorescence color change diagram of different ions reacting with PT under 420nm blue light excitation

[0037] Figure 9 The effect diagram of the probe molecule detecting different perfluorinated compounds in Example 4 of the present invention, A) is the ultraviolet absorption spectrum of different perfluorinated compounds after reaction with the probe molecule; B) is the absorbance ratio A after reaction of different perfluorinated compounds with the probe molecule 525nm / A 405nm Change diagram (serial numbers in the diagram: 1PT, 2PFBA, 3PFHxA, 4PFOA, 5PFDoA, 6PFMS, 7PFBS, 8PFHxS, 9PFOS).

[0038] Figure 10 The diagram shows the effect of the probe molecule on PFOS removal in Example 5 of the present invention, AB represents precipitation removal (Figure A: flow chart, Figure B: effect diagram of PFOS removal by precipitation); CD represents ultrafiltration removal of PFOS (Figure C: flow chart, Figure D: effect diagram of PFOS removal by ultrafiltration). DETAILED DESCRIPTION

[0039] In order to deepen the understanding of the present invention, the following embodiments are further described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, rather than to limit the present invention.

[0040] First, the structure of the cationic polythiophene derivative provided by the present invention is shown in the figure:

[0041]

[0042] Formula (I) is a homopolymer structure, R1 is H or CH3; R2 is O or CH2; R3 is an alkyl group with an integer carbon number between 1 and 6 and its isomers (methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl); R4 is H or CH3; m is an integer between 0 and 15; M is Cl or Br; n is a positive integer, and the weight average molecular weight of the polythiophene derivative is between 3,000 and 50,000.

[0043] Formula (II) can be formed by connecting the thiophene units through the 2 and 5 positions to form a conjugated main chain, and its structural formula is shown below:

[0044]

[0045] Formula (II) is a copolymer structure, R1 is H or CH3; R2 is O or CH2; m is an integer between 0 and 15; M is Cl or Br; R1#, R2#, R3#, R4# are selected from the R# substituent in formula (I) above, wherein R3 is an alkyl group with an integer between 1 and 6 carbon atoms and its isomers (methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl); R4 is H or CH3; and satisfies R1#≠R2#≠R3#≠R4#; n1, n2, n3, n4 are integers between 1 and 500, and the weight-average molecular weight of the polythiophene derivative is between 3,000 and 100,000.

[0046] The cationic polythiophene derivatives of formula (I) and formula (II) have good water solubility and exhibit significant specificity in detection, enabling sensitive detection of perfluorinated compounds. The conformational and aggregation states of the compounds of formula (I) and formula (II) in solution exhibit different states in response to external stimuli, which in turn causes changes in their optical properties.

[0047] Second, the present invention provides a probe molecule for visual dual-mode detection of perfluorinated compounds, which can be used for rapid, quantitative and specific detection of perfluorinated compounds;

[0048] The types of perfluorinated compounds detected and removed include but are not limited to short-chain perfluoroalkyl carboxylic acids (perfluorobutyric acid PFBA, perfluorohexanoic acid PFHxA), long-chain perfluoroalkyl carboxylic acids (perfluorooctanoic acid PFOA, perfluorododecanoic acid PFDoA), short-chain perfluoroalkyl sulfonic acids (trifluoromethanesulfonic acid TFMS, perfluorobutanesulfonic acid PFBS, perfluorohexanesulfonic acid PFHxS), and long-chain perfluoroalkyl sulfonic acids (perfluorooctane sulfonic acid PFOS).

[0049] In order to achieve the purpose of detecting perfluorinated compounds;

[0050] The steps of the probe molecule of the present invention for rapid detection of perfluorinated compounds are as follows (taking PFOS as an example):

[0051] (1) dissolving the cationic polythiophene derivative in water to prepare a probe molecule;

[0052] (2) adding the probe molecule obtained in step (1) into a quartz cuvette to obtain a detection reagent;

[0053] (3) Gradually add PFOS standard solution dropwise into the cuvette and measure the changes in its UV-visible absorption spectrum and fluorescence spectrum;

[0054] (4) The relationship between the absorbance ratio and the change of PFOS concentration and the relationship between the fluorescence intensity ratio and the change of PFOS concentration were analyzed to perform quantitative and specific detection of PFOS in the solution.

[0055] The probe molecule of the present invention can detect PFOS in a concentration range of 0.1-5×10 5 The concentration of the probe molecule is in the range of 0.1-100 μM, preferably 50 μM.

[0056] The reaction conditions include: (1) the volume of the reaction system is 200-3000 μL, preferably 2000 μL; (2) the reaction temperature of the reaction system is 4-40°C, preferably 25°C; (3) the pH value of the reaction system is 4-12, preferably pH=7; (4) the concentration of the polythiophene derivative is 10-150 μM, preferably 50 μM; (5) the mixing reaction time is 1-10 min, preferably 5 min.

[0057] Third, the present invention provides a method for removing perfluorinated compounds in water, in order to achieve the purpose of removing perfluorinated compounds;

[0058] The steps of removing perfluorinated compounds by the probe molecules of the present invention are as follows (taking PFOS as an example):

[0059] (1) dissolving Formula I / Formula II in ultrapure water to obtain a probe molecule solution;

[0060] (2) adding the probe molecule prepared in step (1) to water containing PFOS for reaction;

[0061] (3) After the reaction is completed, the solution is added to the removal system for separation and removal, and the sample after removal is analyzed to obtain the efficiency of the probe molecule in removing PFOS;

[0062] The removal reaction of the present invention can be separated and removed using different systems:

[0063] (1) Precipitation removal, preferably the molar ratio of probe molecule to PFOS is 1:1; PFOS concentration is 20-200 μM and separation and removal is performed by precipitation;

[0064] (2) Ultrafiltration removal, preferably using an ultrafiltration system to separate and remove PFOS at a concentration of 0.1-20 μM; the pore size of the ultrafiltration system includes but is not limited to: 3-300 kDa;

[0065] Fourth, the types of perfluorinated compounds detected and removed include but are not limited to short-chain perfluoroalkyl carboxylic acids (perfluorobutyric acid PFBA, perfluorohexanoic acid PFHxA), long-chain perfluoroalkyl carboxylic acids (perfluorooctanoic acid PFOA, perfluorododecanoic acid PFDoA), short-chain perfluoroalkyl sulfonic acids (trifluoromethanesulfonic acid TFMS, perfluorobutanesulfonic acid PFBS, perfluorohexanesulfonic acid PFHxS), and long-chain perfluoroalkyl sulfonic acids (perfluorooctane sulfonic acid PFOS).

[0066] Example 1: Structural Characteristics of Cationic Polythiophene Probes for Recognizing Perfluorinated Compounds

[0067] Homopolymers PT1-PT17 and PT29, and copolymers PT18-PT20 and PTC-PTF were synthesized with reference to the literature (Chinese patent: CN118480172A).

[0068] The prepared probe molecules with different structures (Formula I and Formula II) were added into cuvettes respectively to obtain detection reagents for detecting perfluorinated compounds (taking PFOS as an example);

[0069] The PFOS standard solution was added into the cuvette to measure the changes in UV-visible absorption spectrum, fluorescence spectrum, visual color and fluorescence color.

[0070] like Figure 1 As shown, after adjusting the structure of the R1 substituent in the molecule of formula (I), the probe molecule has a signal output response to PFOS, which is specifically manifested as: UV-visible absorption spectrum and color change, fluorescence quenching of the fluorescence spectrum accompanied by a change in fluorescence color, indicating that the synthesized probe molecule formula (I) can be used for UV / fluorescence dual-mode detection of PFOS when the R1 structure at position 4 of thiophene is CH3 or H.

[0071] like Figure 2 As shown, after adjusting the carbon chain length of m in the molecule of formula (I), the probe molecules all have a good signal output response to PFOS, indicating that the synthesized probe molecules of formula (I) with carbon chain length of m of 1-15 can be used for UV / fluorescence dual-mode detection of PFOS.

[0072] like Figure 3 As shown, in the molecule of formula (I), R # After the structure of the substituent group, the probe molecules all had good signal output response to PFOS, indicating that the synthesized probe molecule formula (I) R #Substituents such as quaternary ammonium salt substituents (methyl, ethyl, propyl, butyl, hexyl), 1-methylimidazole, and 1,2-dimethylimidazole structures can all be used for UV / fluorescence dual-mode detection of PFOS.

[0073] like Figure 4 As shown, after adjusting the structure and polymerization ratio of the monomers in the molecule of formula (II), the probe molecules all have good signal output responses to PFOS, indicating that the synthesized probe molecule formula (II) can be used for UV / fluorescence dual-mode detection of PFOS after adjusting the structure and polymerization ratio of the monomers.

[0074] Example 2: Cationic polythiophene probes for colorimetric and ultraviolet absorption spectroscopy sensing of perfluorinated compounds

[0075] 1. Quantitative detection of perfluorinated compounds by colorimetry and UV-visible absorption spectroscopy

[0076] The probe mother solution was dissolved in ultrapure water to obtain a probe molecule solution. 2 mL of the obtained probe molecule solution was added to a cuvette of uniform volume as a reagent for detecting PFOS.

[0077] Scan the UV-visible absorption spectrum of the probe molecule, then gradually add a certain concentration of PFOS standard solution into the colorimetric cell, mix well, measure its UV-visible absorption spectrum, and read the peaks at 400nm and 505nm; the results are as follows Figure 5 show, Figure 5 A shows that the absorbance of the aforementioned probe molecule at 400 nm gradually decreases with the addition of PFOS, while the absorbance at 505 nm gradually increases. Figure 5 B shows the relationship between the absorbance ratio and the change of PFOS concentration. As the PFOS concentration increases, the absorbance ratio A 505nm / A 400nm Gradually increasing, quantitative detection can be achieved between 0-35μM with good linear relationship (R 2 =0.99712). According to the detection limit calculation method, the detection limit of the probe molecule for PFOS is 75.93 nmol / L.

[0078] PFOS standard solutions of different concentrations were added to vials, mixed well, and photographed under natural light indoors. The RGB value of each vial was extracted using the Color Grab software. Figure 5 The results showed that the color of the probe solution gradually changed from yellow to red with the increase of PFOS concentration. The visible detection limit was 2.5 μmol / L. The R value / (G+B) value obtained by the software was linearly related to the PFOS concentration. The correlation coefficient R 2 The detection limit was 0.98977 and 2.49 μmol / L.

[0079] 2. Specificity of colorimetric and UV spectroscopy sensing for detection of perfluorinated compounds

[0080] Select common ions in water (SO4 2- 、CO3 2- 、HCO3 - 、Cl - PO4 3- 、NO2 - BrO3 - 、F - , K + , Ca 2+ ) and surfactants (SDS, Tween-20, CTAB) as interfering substances in the detection of perfluorinated compounds (PFOS, PFOA). UV-visible absorption spectroscopy was performed under the same test conditions. The absorbance ratio of the probe before and after the addition of the interfering substances was used as a parameter to measure the degree of influence of the probe on the analyte.

[0081] like Figure 6 As shown in the figure, the results show that when different ions are added to the probe molecules, only after adding perfluorinated compounds (PFOS, PFOA), the color of the solution changes to orange or red, and the absorbance ratio A 505nm / A 405nm It is significantly higher than other ions, so the probe molecule can specifically detect perfluorinated compounds.

[0082] Example 3: Cationic polythiophene probes for fluorescence colorimetry and fluorescence spectroscopy sensing of perfluorinated compounds

[0083] 1. Quantitative detection of perfluorinated compounds by fluorescence colorimetry and fluorescence spectroscopy

[0084] The probe mother solution was dissolved in ultrapure water to obtain a probe molecule solution. 2 mL of the obtained probe molecule solution was added to a colorimetric cell of uniform volume as a reagent for detecting PFOS.

[0085] Add PFOS, mix and measure the fluorescence spectrum respectively. The results are as follows Figure 7 As shown in A, the probe molecule has an emission peak at 535nm under 420nm excitation. With the addition of PFOS, the emission peak of the probe molecule gradually decreases, and the peak at 600nm increases. Figure 7 As shown in B, the addition of PFOS makes the fluorescence intensity ratio FI 600nm / FI 535nm According to the detection limit calculation method, the detection limit of the probe molecule for PFOS is 13.69nmol / L.

[0086] Add PFOS standard solutions of different concentrations into vials, mix well, take photos under blue light excitation, and use Color Grab software to extract the RGB value of each vial. Figure 7 The results showed that the fluorescence color of the probe solution gradually turned red with the increase of PFOS concentration. The detection limit was 5 μmol / L. The R / (G+B) value obtained by the software was linearly related to the PFOS concentration. The correlation coefficient R 2 =0.99166, detection limit 0.41 μmol / L.

[0087] 2. Specificity of fluorescence colorimetry and fluorescence spectroscopy in detecting perfluorinated compounds

[0088] Select common ions in water (SO4 2- 、CO3 2- 、HCO3 - 、Cl - PO4 3- 、NO2 - BrO3 - 、F - , K + , Ca 2+ ) and surfactants (SDS, Tween-20, CTAB) as interfering substances in the detection of perfluorinated compounds (PFOS, PFOA), and the fluorescence spectrum test was carried out under the same test conditions. The fluorescence quenching rate ((I0-I) / I0) and fluorescence intensity ratio FI of the probe before and after the addition of the interfering substance were calculated. 575nm / FI 535nm It is a parameter used to measure the influence of the probe on the analyte.

[0089] like Figure 8 As shown in D, the probe molecule exhibits yellow fluorescence under 420nm blue light irradiation. After the addition of perfluorinated compounds, significant fluorescence quenching occurs and the fluorescence color gradually changes from yellow to red. This result can be observed with the naked eye. After the addition of other ions, the fluorescence of the probe molecule does not undergo obvious quenching or color change.

[0090] Under the same test conditions, the fluorescence spectrum test was carried out. The fluorescence quenching rate of the perfluorinated compound was significantly increased compared with other ions. The ratio of the red-shifted emission peak after the addition of ions to the emission peak of the polythiophene derivative can also be used as a parameter to measure the degree of influence of the probe on the perfluorinated compound. The results are as follows Figure 8 As shown in BC, the aforementioned probe molecules have good specificity for perfluorinated compounds after interacting with different ions.

[0091] Example 4: Detection of different perfluorinated compounds using polythiophene probes

[0092] To demonstrate the universal applicability of the PFOS detection method for perfluorinated compounds with varying perfluoroalkyl chain lengths and functional groups, the response of the aforementioned polythiophene probe to other perfluorinated compounds was investigated, and UV absorption spectra of each reaction solution were recorded under the same conditions. The selected perfluorinated compounds included the PFCA series (heptafluorobutyric acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluorododecanoic acid (PFDoA)) and the PFSA series (trifluoromethanesulfonic acid (TFMS), perfluorobutanesulfonic acid (PFBS), perfluorohexanesulfonic acid (PFHxS), and perfluorooctanesulfonic acid (PFOS)), representing carbon chain lengths ranging from C4 to C12 and C1 to C8, respectively.

[0093] The probe mother solution was dissolved in ultrapure water to obtain a probe molecule solution. 2 mL of the obtained probe molecule solution was added to a colorimetric cell of uniform volume as a reagent for detecting perfluorinated substances. Under the same conditions, a UV-visible absorption spectrum was scanned and the absorbance value at 525 nm was compared with the absorbance value at 405 nm. A 525nm / A 405nm As a parameter to measure the response of the probe molecule to the substance to be tested;

[0094] The results are as follows Figure 9 As shown, Figure 9 A shows that after adding perfluorinated compounds, the absorbance of the probe molecule at 405 nm decreases, while the absorbance at 525 nm increases. Figure 9 B shows the absorbance ratio of A 525nm / A 405nm The relationship between the PFSA series and different perfluorinated compounds was analyzed. The results confirmed the universal applicability of the detection of perfluorinated compounds containing different perfluoroalkyl chain lengths and functional groups. Furthermore, within the same perfluorinated compound series, the longer the perfluoroalkyl chain length, the better the detection effect; the PFSA series performed significantly better than the PFCA series.

[0095] Example 5: Removal of perfluorinated compounds by cationic polythiophene probe molecules

[0096] 1. Removal of perfluorinated compounds by precipitation

[0097] For water samples contaminated with perfluorinated compounds, precipitation can be used to remove them. Probe molecules are added. Since PFOS causes the probe molecules to aggregate, precipitation will occur when left to stand, and the precipitation is visible to the naked eye. The precipitate is allowed to stand for 30 minutes, then centrifuged and the supernatant is taken. The supernatant is diluted 5 times and the probe molecules are added again for UV-visible absorption spectrum scanning. The absorbance value at 505nm is read and the ratio of the absorbance value at 400nm is used as an important parameter to measure the removal effect.

[0098] The results are as follows Figure 10As shown in Figure A, with the increase of probe molecule concentration, the PFOS content in the supernatant decreased significantly. The removal rate of PFOS by the probe molecule reached 96.13% based on the absorbance ratio, and the range of PFOS removal by precipitation was 20-200 μM.

[0099] 2. Ultrafiltration to remove perfluorinated compounds

[0100] The probe molecule and a trace amount of PFOS (1 μM) were mixed and added to an ultrafiltration tube. The mixture was ultrafiltrated and centrifuged at 5000 g for 10 minutes. The permeate was evaporated and concentrated to 2 mL. After concentration, the probe molecule was added again for UV-visible absorption spectrum scanning. The absorbance value at 505 nm was read and the ratio of the absorbance value at 400 nm was used as an important parameter to measure the removal effect.

[0101] The results are as follows Figure 10 As shown in Figure B, the absorbance ratio of PFOS in the permeate decreased significantly after the probe solution (PT) was added. This method can effectively remove low-concentration PFOS in water. The range of ultrafiltration removal of PFOS is 0.1-20 μM, and the removal rate reaches 99.9%.

[0102] The above examples show that the polythiophene derivatives developed in the present invention have the characteristics of high sensitivity and good stability, and can be used as adsorbents to remove perfluorinated compounds. It can be used as a simple and fast method for the simultaneous detection and removal of perfluorinated compounds.

[0103] Matters not covered by this invention are known in the art. The above embodiments are intended only to illustrate the technical concepts and features of this invention. Their purpose is to enable those skilled in the art to understand the contents of this invention and implement them accordingly. They are not intended to limit the scope of protection of this invention. Any equivalent changes or modifications made in accordance with the spirit and essence of this invention are intended to be covered by the scope of protection of this invention.

Claims

1. A cationic polythiophene derivative for detecting and removing perfluorinated compounds, characterized in that: The structures are shown in formula (I) and formula (II): Formula (I) is a homopolymer structure, R1 is H or CH3; R2 is O or CH2; R3 is an alkyl group with an integer number of carbon atoms between 1 and 6 and its isomers: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; m is an integer between 0 and 15; M is Cl or Br; n is a positive integer, and the weight average molecular weight of the polythiophene derivative is between 3,000 and 50,000. Formula (II) is composed of thiophene units connected through the 2 and 5 positions to form a conjugated main chain, and its structural formula is shown below: Formula (II) is a copolymer structure, R1 is H or CH3; R2 is O or CH2; m is an integer between 0 and 15; M is Cl or Br; R 1# ,R 2# ,R 3# ,R 4# , selected from R in the above formula (Ⅰ) # Substituents, wherein R3 is an alkyl group with an integer carbon number between 1 and 6 and its isomers: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; and satisfies R 1# ≠R 2# ≠R 3# ≠R 4# ; n1, n2, n3, n4 are integers between 1 and 500, and make the average molecular weight of the polythiophene derivative be between 3,000 and 100,000.

2. The cationic polythiophene derivative for detecting and removing perfluorinated compounds according to claim 1, characterized in that: The types of perfluorinated compounds detected and removed include short-chain perfluoroalkyl carboxylic acids: perfluorobutyric acid PFBA, perfluorohexanoic acid PFHxA, long-chain perfluoroalkyl carboxylic acids: perfluorooctanoic acid PFOA, perfluorododecanoic acid PFDoA, short-chain perfluoroalkyl sulfonic acids: trifluoromethanesulfonic acid TFMS, perfluorobutanesulfonic acid PFBS, perfluorohexanesulfonic acid PFHxS, and long-chain perfluoroalkyl sulfonic acid: perfluorooctane sulfonic acid PFOS.

3. A method for detecting perfluorinated compounds using the cationic polythiophene derivative according to claim 1, characterized in that: The following steps are involved: (1) dissolving the cationic polythiophene derivatives represented by formula (I) and formula (II) in water to prepare probe molecules; (2) adding the probe molecule obtained in step (1) into a quartz cuvette to obtain a detection reagent; (3) gradually adding the perfluorinated compound standard solution into the cuvette and measuring the changes in its UV-visible absorption spectrum and fluorescence spectrum; (4) Analyze the relationship between the absorbance ratio and the concentration of the specific perfluorinated compound and the relationship between the fluorescence intensity and the concentration of the specific perfluorinated compound, and perform quantitative and specific detection of the specific perfluorinated compound in the solution.

4. The method for detecting perfluorinated compounds using a cationic polythiophene derivative according to claim 3, wherein: The concentration of the cationic polythiophene derivative in the detection system is 0.1-100 μM, the reaction volume is 200-3000 μL, the reaction pH is 4-14, the reaction temperature is 4-40° C., and the reaction system is ultrapure water and HEPES buffer solution.

5. A method for removing perfluorinated compounds using the cationic polythiophene derivative according to claim 1, characterized in that: The following steps are involved: (1) dissolving the cationic polythiophene derivative represented by formula (I) / formula (II) in ultrapure water to obtain a probe molecule solution; (2) adding the probe molecule prepared in step (1) into water containing a perfluorinated compound to react; (3) After the reaction is completed, the solution is added to a removal system for separation and removal, and the sample after removal is analyzed to obtain the efficiency of the probe molecule in removing the specific perfluorinated compound.

6. The method for removing perfluorinated compounds using a cationic polythiophene derivative according to claim 5, characterized in that: The perfluorinated compounds were separated and removed by precipitation when the concentration was 20-200 μM.

7. The method for removing perfluorinated compounds using a cationic polythiophene derivative according to claim 5, characterized in that: When the concentration of the perfluorinated compound is 0.1-20 μM, an ultrafiltration system is used for separation and removal, and the pore size of the ultrafiltration system includes but is not limited to: 3-300 kDa.

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