A flat membrane electro-membrane extraction device, its use method and application

Abstract

A flat membrane electro-membrane extraction device, its usage method and application. The device includes a sample bottle, a receiving bottle, a working electrode, a counter electrode, a flat microporous fiber membrane, a power supply device, and a magnetic stirring device. The side of the sample bottle is provided with an upward extension tube, and the outlet of the extension tube is higher than the top of the sample bottle. The receiving bottle has an inverted T structure and is composed of two parts: an upper vertical cavity and a bottom flat cavity that are interconnected. The diameter of the flat cavity is exactly the same as the diameter of the top of the sample bottle, the height of the flat cavity is much smaller than the height of the sample bottle, and the diameter of the vertical cavity is much smaller than the diameter of the flat cavity. The flat microporous fiber membrane is clamped between the sample bottle and the bottom of the receiving bottle. With the present invention, rapid separation of target substances can be achieved under the assistance of electricity. The selectivity of the flat microporous fiber membrane and the extraction solvent loaded on the membrane enables the device to have stronger purification ability. The inverted T-shaped receiving bottle endows the device with an extremely large enrichment multiple, and it has high application value in the fields of sample pretreatment and analytical detection.

Description

Technical Field

[0001] The present invention relates to the field of sample pretreatment, and particularly relates to a flat membrane electro-membrane extraction device, its use method and application. Background Art

[0002] Compared with the rapidly developing analytical instruments, matrix purification pretreatment has become a bottleneck problem restricting the development of analytical chemistry. Since the compounds to be analyzed and determined are often trace or even ultra-trace components in the sample, the complex matrix in the sample poses a great challenge to their accurate quantitative detection. Therefore, developing simple, rapid, green and efficient sample pretreatment techniques for the extraction of compounds in complex matrices is of great significance for removing matrix interference and improving the sensitivity and accuracy of analytical methods.

[0003] Electro-membrane extraction technology is a new type of sample pretreatment technology proposed by Pedersen-Bjergaard et al. in 2006. Its separation principle is that under the action of an electric field, charged analytes move towards the electrode with the opposite electric charge and pass through the supported liquid membrane into the receiving liquid. During the electro-membrane extraction process, the mass transfer process of analytes is mainly dominated by electro-migration, which greatly shortens the extraction time; at the same time, due to the selectivity of the supported liquid membrane, the electro-membrane extraction technology has a stronger purification ability, which has enabled it to develop rapidly in the field of sample pretreatment. In practical applications, hollow fiber membrane electro-membrane extraction has gradually evolved into a more convenient and flexible flat membrane electro-membrane extraction. However, at present, the enrichment ability of this technology for analytes to be measured is still limited by the lag in the development of flat membrane electro-membrane extraction devices. Huang et al. fabricated a flat membrane electro-membrane extraction device using a 10 - 1000 μL pipette tip and a 2.0 ml centrifuge tube. In the experiment, the volumes of both the sample phase and the receiving phase were 600 μL, and the enrichment of analytes to be measured could not be achieved (Journal of Chromatography A, 2014, 1326: 7 - 12). The utility model patent with the application number 201921883701.9 discloses an electro-membrane extraction device for separating or enriching metal ions. Since the feed solution reservoir is 2 - 10 times that of the analytical solution reservoir and the volume of the feed liquid pool is 1 - 2 times that of the analytical pool, the maximum enrichment factor of this device is only 10. Although the enrichment factor can be further increased by continuously replacing the feed liquid phase solution, this will increase the operation complexity of the device and be time-consuming and laborious.

[0004] Smoking is harmful to health, and the health risks caused by tobacco production and consumption have attracted increasing attention. However, as a personal consumption preference, smoking is difficult to completely disappear in the short term. To reduce the possible health risks of consumers, it is crucial to develop and produce low-harm tobacco products and establish a scientific risk assessment method for tobacco products. Cigarette smoke is extremely complex, with more than 5,000 components. Objectively and effectively evaluating the exposure risk of cigarette smoke and the level of smoke intake has become the focus of research. Biomarkers, as an indicator reflecting the changes caused by the interaction between biological systems and the environment, have been applied to evaluate the exposure risk of cigarette smoke. Since cigarette smoke biomarkers are metabolites or certain changes in smokers' bodies, measuring their content can more truly reflect the actual exposure amount of smokers to smoke components and the degree of exposure risk. Currently, the methods for detecting cigarette smoke and its biomarkers mainly include gas chromatography, gas chromatography-mass spectrometry, high-performance liquid chromatography, and liquid chromatography-mass spectrometry. However, the content of some smoke biomarkers is extremely low, and the complex matrix poses a great challenge to the accurate detection of these trace or even ultra-trace smoke biomarkers. Summary of the Invention

[0005] The object of the present invention is to provide a flat membrane electro-membrane extraction device, its use method and application for the above existing problems, which can achieve the rapid separation of target substances under the assistance of electricity, and then realize the simultaneous separation, purification and enrichment of trace or even ultra-trace compounds in complex matrices, and has high application value in the fields of sample pretreatment and analysis and detection.

[0006] To achieve the above object, the technical solution of the flat membrane electro-membrane extraction device provided by the present invention is as follows:

[0007] A flat membrane electro-membrane extraction device includes a sample bottle, a receiving bottle, a working electrode, a counter electrode, a flat microporous fiber membrane, a power supply device, and a magnetic stirring device. An upward extension tube is provided on the side of the sample bottle, and the outlet of the extension tube is higher than the top of the sample bottle. The receiving bottle has an inverted T structure and is composed of two parts: an upper vertical cavity and a bottom flat cavity that are interconnected. The diameter of the bottom flat cavity is exactly the same as the diameter of the top of the sample bottle, the height of the bottom flat cavity is much smaller than the height of the sample bottle, and the diameter of the upper vertical cavity is much smaller than the diameter of the bottom flat cavity. The flat microporous fiber membrane is clamped between the sample bottle and the bottom of the receiving bottle. One end of the working electrode passes through the extension tube and extends into the sample bottle, and the other end is connected to the power supply device through a wire. One end of the counter electrode extends into the receiving bottle through the top opening of the upper vertical cavity, and the other end is connected to the power supply device.

[0008] The height of the above bottom flat cavity is 1 / 20 - 1 / 500 of the height of the sample bottle.

[0009] The diameter of the upper vertical cavity is 1 / 5 - 1 / 30 of the diameter of the bottom flat cavity.

[0010] The sample bottle is placed on a magnetic stirrer, and the rotor of the magnetic stirrer is arranged in the sample bottle.

[0011] The flat microporous fiber membrane is a flat polypropylene microporous fiber membrane with a pore diameter of 0.2 μm and a thickness of 100 μm to 200 μm.

[0012] Both the working electrode and the counter electrode are platinum wires with a diameter of 0.3 mm.

[0013] The power supply device is a power supply for an electrophoresis instrument, and the voltage applied by the power supply device is 1 V to 100 V.

[0014] The present invention provides a method for using the flat membrane type electro-membrane extraction device described in the above technical solution, including the following steps:

[0015] Step S001: Adjust the pH of the sample solution with an acid or a base, transfer the sample solution to the sample bottle, add a rotor to the sample bottle, and place the sample bottle on a magnetic stirrer;

[0016] Step S002: Place a flat microporous fiber membrane on the top of the sample bottle, coat the extraction solvent on the surface of the flat microporous fiber membrane, then place the bottom of the receiving bottle on the flat microporous fiber membrane, and clamp and fix it with a clamping plate;

[0017] Step S003: Inject the receiving phase into the receiving bottle through the upper vertical cavity of the receiving bottle, insert the working electrode into the sample solution through the extension tube, insert the counter electrode into the receiving phase through the opening of the upper vertical cavity, and then connect the working electrode and the counter electrode to the power supply device through wires respectively;

[0018] Step S004: Turn on the magnetic stirrer and the power supply device, start the extraction process, and after extracting for a certain time (1 min to 30 min), turn off the power supply device and the magnetic stirrer;

[0019] Step S005: Withdraw the counter electrode from the receiving phase, and use a microsyringe to take a certain amount of the extract from the receiving bottle for analysis and detection.

[0020] The liquid level of the sample solution in the sample bottle is close to (or just touches) the surface of the flat microporous fiber membrane. "Close" can be understood as being able to touch during the stirring process.

[0021] The liquid level of the receiving phase is at 1 / 3 to 4 / 5 of the height of the upper vertical cavity.

[0022] The extraction solvent can be a single 2-nitrophenyl octyl ether, or a mixed solution of bis(2-ethylhexyl) phosphate and 2-nitrophenyl octyl ether. In the mixed solution, the volume percentage of bis(2-ethylhexyl) phosphate is 1% to 20%, preferably 5%.

[0023] The receiving phase is an aqueous solution with a specific pH. The description of the specific pH is as follows: for different flue gas components and their biomarkers, the pH requirements for the receiving phase solution are different. For example, for nicotine, cotinine, and hydroxycotinine, the pH of the receiving phase can be 1 - 3, but for 3 - hydroxybenzo[a]pyrene and S - phenylmercapturic acid, the pH of the receiving phase needs to be 11 - 13.

[0024] The present invention also provides the application of the flat - membrane electro - membrane extraction device described in the above technical solution in the detection of flue gas components and their biomarkers.

[0025] The flue gas components and their biomarkers are nicotine, cotinine, hydroxycotinine, 3 - hydroxybenzo[a]pyrene, and S - phenylmercapturic acid.

[0026] The matrix of the flue gas components and their biomarkers is urine, blood, saliva, tissue, and hair.

[0027] The detection techniques are high - performance liquid chromatography and liquid chromatography - mass spectrometry.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] (1) The present invention provides a flat - membrane electro - membrane extraction device, a usage method, and an application. The device is simple to operate, has less reagent consumption, low cost, and is green and efficient; it can achieve rapid separation of flue gas biomarkers under the assistance of electricity. The selectivity of the flat microporous fiber membrane and the extraction solvent loaded on the membrane endows the device with stronger purification ability, and the inverted - T - shaped receiving bottle gives the device an ultra - large enrichment factor; the device integrates the steps of separation, purification, and enrichment, without intermediate transfer and drying and re - dissolution, shortening the pretreatment time, effectively preventing sample loss during the phase - transfer process, and improving the accuracy and precision of flue gas biomarker detection.

[0030] (2) By adjusting the pH of the sample phase solution, the present invention enables all the flue gas biomarkers to be detected to exist in the form of single - charge ions, which is beneficial for their extraction and separation under the action of electric - field migration.

[0031] (3) When extracting flue gas components and their biomarkers, the present invention uses a solution with a specific pH as the receiving phase. The purpose is based on the fact that the electric - field migration effect is the main mass - transfer driving force in the electro - assisted liquid - membrane extraction technology. The solvent with a specific pH can make all the flue gas components and their biomarkers to be detected exist in the form of single - charge ions, which is beneficial for their extraction into the receiving phase under the action of electric - field migration.

[0032] (4) The present invention loads the extraction solvent on the porous polypropylene membrane. The amount of the extraction solvent used is small, only 60 μL, avoiding the problems of large consumption of organic solvents and environmental harm in traditional extraction technologies.

[0033] (5) The present invention is suitable for the separation, purification, enrichment and detection of trace and even ultra-trace flue gas components and their biomarkers in different matrices, and has high application value in the field of sample pretreatment and analysis and detection. DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic structural diagram of the flat membrane electro-membrane extraction device in Embodiment 1 of the present invention.

[0035] In the figure: 1. Power supply device, 2. Wire a, 3. Wire b, 4. Counter electrode, 5. Working electrode, 6. Upper vertical cavity, 7. Bottom flat cavity, 8. Flat microporous fiber membrane, 9. Sample bottle, 10. Extension tube, 11. Magnetic stirrer, 12. Rotor.

[0036] Figure 2 It is a schematic principle diagram of the flat membrane electro-membrane extraction in Embodiment 2 of the present invention.

[0037] Figure 3 It is a chromatogram before and after separation, purification and enrichment in Embodiment 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] The following further describes the specific embodiments of the present invention in conjunction with the drawings, but not limited thereto.

[0039] Embodiment 1: Flat Membrane Electro-Membrane Extraction Device

[0040] A specific embodiment of the flat membrane electro-membrane extraction device provided by the present invention is as Figure 1 shown. The flat membrane electro-membrane extraction device includes a sample bottle 9, a receiving bottle, a working electrode 5, a counter electrode 4, a flat microporous fiber membrane 8, a power supply device 1, and a stirring device. The sample bottle 9 is provided with an extension tube 10, and the outlet of the extension tube is higher than the top of the sample bottle. The receiving bottle is of an inverted T structure and is composed of two parts: an upper vertical cavity 6 and a bottom flat cavity 7 that are interconnected. The diameter of the bottom flat cavity 7 is exactly the same as the diameter of the top of the sample bottle 9, and the height of the bottom flat cavity 7 is much smaller than the height of the sample bottle 9. The diameter of the upper vertical cavity 6 is much smaller than the diameter of the bottom flat cavity 7. The flat microporous fiber membrane 8 is clamped between the sample bottle 9 and the bottom flat cavity 7 through a splint. One end of the working electrode passes through the extension tube and extends into the sample bottle 9, and the other end is connected to the power supply device 1 through wire b 3. One end of the counter electrode 4 extends into the receiving bottle through the top opening of the upper vertical cavity 6, and the other end is connected to the power supply device 1 through wire a 2. The sample bottle 9 is placed on a magnetic stirrer 11, and the rotor 12 of the magnetic stirrer is arranged in the sample bottle 9.

[0041] When the wire b3 is connected to the positive electrode of the power supply device 1, the wire a2 is connected to the negative electrode of the power supply device 1; conversely, the wire b3 and the wire a2 are respectively connected to the negative electrode and the positive electrode of the power supply device 1. The positive or negative connection is determined according to the flue gas components and their biomarkers.

[0042] Example 2: Method for using a flat membrane electro-membrane extraction device

[0043] The schematic diagram of the flat membrane electro-membrane extraction device provided by the present invention is as Figure 2 shown, and its using method includes the following steps:

[0044] Step S001: Adjust the pH of the sample solution with an acid or a base (the pH of the sample solution is different for different flue gas components and their biomarkers), transfer the sample solution to the sample bottle 9, add a rotor 12 to the sample bottle 9, and place the sample bottle 9 on the magnetic stirrer 11;

[0045] Step S002: Place a flat microporous fiber membrane 8 on the top of the sample bottle 9, and coat the extraction solvent on the surface of the flat microporous fiber membrane. The extraction solvent is a mixed solution of bis(2-ethylhexyl) phosphate and 2-nitrophenyloctyl ether, and the volume percentage of bis(2-ethylhexyl) phosphate in the mixed solution is 5%. Then place the bottom flat cavity 7 of the receiving bottle on the flat microporous fiber membrane 8 and fix it by clamping with a splint. The flat microporous fiber membrane 8 is a flat polypropylene microporous fiber membrane with a pore diameter of 0.2 μm and a thickness of 100 μm - 200 μm.

[0046] Step S003: Inject an aqueous solution with a specific pH (here it is a hydrochloric acid aqueous solution with pH = 2) as the receiving phase into the receiving bottle through the top of the upper vertical cavity 6. The liquid level of the receiving phase is at 1 / 3 - 4 / 5 of the height of the upper vertical cavity 6. The working electrode 5 passes through the extension tube 10 and inserts into the sample solution, and the counter electrode 4 passes through the opening of the upper vertical cavity 6 and inserts into the receiving phase. Then connect the working electrode 5 and the counter electrode 4 to the power supply device 1 through the wires b3 and a2 respectively; the working electrode 5 and the counter electrode 4 are platinum wires with a diameter of 0.3 mm.

[0047] Step S004: Turn on the magnetic stirrer 11 and the power supply device 1 to start the extraction process. After 20 minutes of extraction, turn off the power supply device 1 and the magnetic stirrer 11; the power supply device 1 is an electrophoresis power supply, and the applied voltage is 60V.

[0048] Step S005: Withdraw the counter electrode 4 from the receiving phase, and use a micro-syringe to take a certain amount of the extraction solution from the receiving bottle for analysis and detection.

[0049] The liquid level of the sample solution in the sample bottle 9 just touches the surface of the fiber membrane flat microporous fiber membrane 8.

[0050] Example 3: Application of flat membrane electro-membrane extraction device in the detection of nicotine in urine.

[0051] (1) Preparation of urine sample containing nicotine:

[0052] Take nicotine standard, using 10 mmol / L phosphate buffer solution with pH 5.6 as solvent, prepare a standard solution containing 1000 mg / L nicotine. Dilute the nicotine standard solution with a concentration of 1000 mg / L with urine to obtain a urine sample containing 1 mg / L nicotine.

[0053] (2) Flat membrane electro-membrane extraction:

[0054] Use the urine sample containing 1 mg / L nicotine obtained in step (1) as the sample phase, and extract nicotine in the sample phase using a flat membrane electro-membrane extraction device. The specific operation of flat membrane electro-membrane extraction is as follows:

[0055] a) Take 16 mL of sample solution into sample bottle 9, add rotor 12 to sample bottle 9, and place sample bottle 9 on magnetic stirrer 11.

[0056] b) Place a flat microporous fiber membrane 8 on the top of sample bottle 9, coat 60 μL of extraction solvent on the surface of flat microporous fiber membrane 8. The extraction solvent is a mixed solution of bis(2-ethylhexyl) phosphate and 2-nitrophenyl octyl ether. The volume percentage of bis(2-ethylhexyl) phosphate in the mixed solution is 5%. Then place the receiving bottle on flat microporous fiber membrane 8 and fix it with a splint.

[0057] c) Inject 0.2 mL of receiving phase into the receiving bottle through the top of the upper vertical cavity 6. The receiving phase is hydrochloric acid aqueous solution with pH = 2. Insert the working electrode 5 into the sample solution through the extension tube 10, insert the counter electrode into the receiving phase through the opening of the upper vertical cavity 6, and then connect the working electrode 5 and the counter electrode 4 to the positive and negative poles of the power supply device 1 through wires respectively.

[0058] d) Turn on magnetic stirrer 11 and power supply device 1 to start the extraction process. After extracting for a certain time, turn off power supply device 1 and magnetic stirrer 11. Among them, the voltage of the power supply device is 80 V, and the extraction time is 20 min.

[0059] e) Withdraw the counter electrode 4 from the receiving phase, use a micro-syringe to take a certain amount of extract from the receiving bottle, which is the purified and enriched nicotine extract, for analysis and detection.

[0060] Example 4: Purification effect of flat membrane electro-membrane extraction technology.

[0061] The chromatograms of the urine sample containing 1 mg / L nicotine and the nicotine extract after purification and enrichment in Example 3 were determined by a high performance liquid chromatography-mass spectrometer to evaluate the purification and enrichment effect of the flat membrane electro-membrane extraction technology provided by the present invention. The detection conditions of the high performance liquid chromatography-mass spectrometer were as follows: the chromatographic column was an Xtimate C18 column with a specification of 4.6×150 mm and a particle size of 3.0 μm. The mobile phase was 40% 10 mmol / L pH=6.5 phosphate buffer (containing 0.1% triethylamine)-60% methanol, the flow rate was 1.0 mL / min, the injection volume was 5.0 μL, and the detection wavelength was 259 nm. The results are as Figure 3 shown. It can be seen from Figure 3 that the flat membrane electro-membrane extraction technology provided by the present invention not only has outstanding purification ability for the matrix in urine, but also has great enrichment ability for nicotine in urine, and the maximum enrichment multiple of a single enrichment can reach 80.

Claims

1. A flat membrane electro-membrane extraction device, characterized in that, It includes a sample bottle, a receiving bottle, a working electrode, a counter electrode, a flat microporous fiber membrane, a power supply device, and a magnetic stirring device. An upward extension tube is provided on the side of the sample bottle, and the outlet of the extension tube is higher than the top of the sample bottle. The receiving bottle has an inverted T structure and is composed of two parts: an upper vertical cavity and a bottom flat cavity that are interconnected. The diameter of the bottom flat cavity is exactly the same as the diameter of the top of the sample bottle, the height of the bottom flat cavity is much smaller than the height of the sample bottle, and the diameter of the upper vertical cavity is much smaller than the diameter of the bottom flat cavity. The flat microporous fiber membrane is clamped between the sample bottle and the bottom of the receiving bottle. One end of the working electrode passes through the extension tube and extends into the sample bottle, and the other end is connected to the power supply device through a wire. One end of the counter electrode extends into the receiving bottle through the top opening of the upper vertical cavity, and the other end is connected to the power supply device.

2. The flat membrane electro-membrane extraction device according to claim 1, characterized in that, The height of the bottom flat cavity is 1 / 20 - 1 / 500 of the height of the sample bottle.

3. The flat membrane electro-membrane extraction device according to claim 1, characterized in that, The diameter of the upper vertical cavity is 1 / 5 - 1 / 30 of the diameter of the bottom flat cavity.

4. The flat membrane electro-membrane extraction device according to claim 1, characterized in that, The flat microporous fiber membrane is a flat polypropylene microporous fiber membrane with a pore diameter of 0.2 μm and a thickness of 100 μm - 200 μm.

5. The flat membrane electro-membrane extraction device according to claim 1, characterized in that, Both the working electrode and the counter electrode are platinum wires with a diameter of 0.3 mm.

6. The flat membrane electro-membrane extraction device according to claim 1, characterized in that The power supply device is a power supply for an electrophoresis instrument, and the voltage applied by the power supply device is 1 V - 100 V.

7. A method for using a flat membrane electro-membrane extraction device according to any one of claims 1-6, characterized in that, It includes the following steps: Step S001: Adjust the pH of the sample solution with acid or base, transfer the sample solution to the sample bottle, add a rotor to the sample bottle, and place the sample bottle on a magnetic stirrer. Step S002: Place a flat microporous fiber membrane on the top of the sample bottle, coat the extraction solvent on the surface of the flat microporous fiber membrane, then place the bottom of the receiving bottle on the flat microporous fiber membrane, and fix it by clamping with a clamp. Step S003: Inject the receiving phase into the receiving bottle through the upper vertical cavity of the receiving bottle, insert the working electrode into the sample solution through the extension tube, insert the counter electrode into the receiving phase through the upper end opening of the upper vertical cavity, and then connect the working electrode and the counter electrode to the power supply device through wires respectively. Step S004: Turn on the magnetic stirrer and the power supply device to start the extraction process. After extracting for a certain time, turn off the power supply device and the magnetic stirrer. Step S005: Withdraw the counter electrode from the receiving phase, and use a microsyringe to take a certain amount of the extract from the receiving bottle for analysis and detection.

8. The usage method according to claim 7, characterized in that, The liquid level of the sample solution in the sample bottle is close to the surface of the flat microporous fiber membrane.

9. The method of use according to claim 7, characterized in that, The liquid level of the receiving phase is at 1 / 3 - 4 / 5 of the height of the upper vertical cavity.

10. The method of use according to claim 7, characterized in that, The extraction solvent is either 2-nitrophenyloctyl ether or a mixed solution of bis(2-ethylhexyl) phosphate and 2-nitrophenyloctyl ether, and the volume percentage of bis(2-ethylhexyl) phosphate in the mixed solution is 1% - 20%.

11. The usage method according to claim 7, wherein The receiving phase is an aqueous solution with a specific pH.

12. The usage method according to claim 7, characterized in that The extraction time is 1 min - 30 min.

13. Application of the flat membrane electro-membrane extraction device as described in claim 1 in the detection of flue gas components and their biomarkers.

14. The application according to claim 13, characterized in that, The flue gas components and their biomarkers are nicotine, cotinine, hydroxycotinine, 3-hydroxybenzo[a]pyrene, and S-phenylmercapturic acid.

15. The application according to claim 13, wherein The matrix of the flue gas components and their biomarkers is urine, blood, saliva, tissue, and hair.

16. The application according to claim 13, wherein The techniques for detection are high performance liquid chromatography and liquid chromatography - mass spectrometry.

Images