A continuous field-amplification liquid-liquid electroextraction device and its application

Abstract

This invention relates to a continuous field amplification-liquid-liquid electro-extraction device and its application, belonging to the field of chemical analysis technology. The device includes: an extraction assembly comprising an electrolyte replenishment device, a rinsing device, and an electrolyte electrode wire; the electrolyte replenishment device contains an electrolyte solution, the rinsing device contains a rinsing solution, one end of the electrolyte electrode wire is immersed in the electrolyte solution, and the other end is grounded; and a sample assembly comprising a sample container, a receiving tube, and a sample electrode wire; the sample container contains the extractable substance, one end of the receiving tube is immersed in the extractable substance, and the other end is connected to both the electrolyte replenishment device and the rinsing device; one end of the sample electrode wire is connected to a power source, and the other end is immersed in the extractable substance. This device continuously replenishes the receiving tube with electrolyte through the electrolyte replenishment device, maintaining or increasing the conductivity of the solution in the receiving tube, thereby achieving the purpose of continuously amplifying the electric field strength.

Description

Technical Field

[0001] This invention relates to the field of chemical analysis technology, and in particular to a continuous field amplification-liquid-liquid electro-extraction device and its application. Background Technology

[0002] Electric field-assisted sample pretreatment technology, using an electric field as the driving force, has significantly improved the extraction efficiency and selectivity of trace analytes, becoming a focal point of field-assisted technology research. This technology has been widely applied in many important fields such as food, medicine, environment, and biology, and continues to demonstrate its superior performance and broad applicability. Liquid-liquid electro-extraction technology, as a membrane-free electric field-assisted preparation technology, is convenient to operate and easily integrated with various detection technologies, exhibiting multiple advantages such as fast analysis speed, high sensitivity, strong selectivity, and environmental friendliness and energy saving, possessing broad and promising application prospects.

[0003] Recent research indicates that in liquid-liquid electroextraction, both the current and the migration rate of the analyte in the receiving phase exhibit an exponential decreasing trend over time. In other words, during electroextraction, the electromigration rate of the analyte from the donor phase to the receiver phase rapidly declines. If electroextraction is not completed within a certain time window, subsequent processes become extremely slow, essentially "aborting" the electroextraction process and severely hindering the improvement of electroextraction efficiency. The causes and mechanisms of this rapid decline in electroextraction rate are currently unclear and have not been reported.

[0004] Existing liquid-liquid electroextraction technology struggles to maintain a high extraction rate throughout the entire electroextraction time window. This results in analytes with relatively low electrophoretic mobility being forced to "stop" before complete extraction (at a very, very low rate) after a certain extraction time, severely limiting the technology's widespread application. Therefore, overcoming this technical bottleneck and developing a faster and more efficient liquid-liquid electroextraction technology and apparatus is of great significance. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a continuous field amplification-liquid-liquid electro-extraction device. This device continuously replenishes the receiving tube with electrolyte through an electrolyte replenishment device, maintaining or increasing the conductivity of the solution in the receiving tube, thereby achieving the purpose of continuously amplifying the electric field strength.

[0006] To achieve the above objectives, the present invention provides a continuous field amplification-liquid-electrohydride extraction device, comprising: An extraction assembly includes an electrolyte replenishment device, a rinsing device, and an electrolyte electrode wire. The electrolyte replenishment device contains an electrolyte solution, the rinsing device contains a rinsing solution, one end of the electrolyte electrode wire is immersed in the electrolyte solution, and the other end of the electrolyte electrode wire is grounded. The sample assembly includes a sample container, a receiving tube, and a sample electrode wire. The sample container is used to hold the extractant. One end of the receiving tube is used to immerse the extractant, and the other end of the receiving tube is connected to the electrolyte replenishment device and the rinsing device, respectively. One end of the sample electrode wire is used to connect to a power source, and the other end of the sample electrode wire is used to immerse the extractant.

[0007] In their research addressing the aforementioned technical problems, the inventors discovered that in electroextraction, the target analyte rapidly migrates from a larger donor phase to a smaller receiver phase under the influence of an electric field, achieving high enrichment. However, due to the small volume of the receiver phase, the amount of electrolyte it can hold is limited, leading to rapid electrolyte depletion during electroextraction. This causes a significant increase in the resistance of the receiver phase, concentrating the electric field on the receiver phase rather than the donor phase. Consequently, the electric field distribution on the donor phase becomes weak, resulting in insufficient electric field force and a sharp decrease in the analyte migration rate to the donor phase, hindering or even halting the extraction process. Therefore, the inventors hypothesized that adding an appropriate amount of electrolyte during electroextraction could reduce the resistance of the receiver phase, allowing a sustained high electric field distribution on the donor phase (i.e., sustained field amplification), maintaining a high migration rate for the analyte in this region, thereby improving electroextraction efficiency. Therefore, the inventors proposed the aforementioned sustained field amplification-liquid-liquid electroextraction device, which continuously replenishes the receiver tube with electrolyte through an electrolyte replenishment device, maintaining or increasing the conductivity of the solution in the receiver tube, thereby achieving the purpose of continuously amplifying the electric field strength. This device can introduce a dynamic electrolyte replenishment mechanism in the receiving phase during the electroextraction process, effectively solving the problem of the difficulty in maintaining a stable electric field strength in traditional liquid-liquid electroextraction.

[0008] In one embodiment, the electrolyte replenishment device includes an electrolyte injector and an injection pump, with the electrolyte injector fixed to the injection pump.

[0009] By precisely controlling the injection speed of the aforementioned syringe pump, not only can trace target substances be efficiently concentrated and enriched in the receiving tube, but the compression state of the analyte enrichment zone can also be flexibly controlled, thereby significantly improving the overall efficiency and accuracy of electroextraction and providing a more advanced and controllable solution for the extraction of trace analytes.

[0010] In one embodiment, one end of the electrolyte electrode wire is inserted into the tail of the piston rod of the electrolyte injector and exposed at the head of the piston rod; The flushing device includes a flushing fluid injector.

[0011] In one embodiment, the receiving tube is connected to the electrolyte replenishment device and the flushing device via a three-way pipe.

[0012] This invention also provides a continuous field amplification-liquid-liquid electro-extraction analysis method, comprising the following steps: preparing a sample to be extracted, preparing a standard, performing electro-extraction using the aforementioned continuous field amplification-liquid-liquid electro-extraction device to obtain the sample to be tested and the standard sample, and detecting and analyzing the sample to be tested and the standard sample.

[0013] The above-described analytical method, during electroextraction, continuously introduces a high-concentration electrolyte solution into the receiving phase at a low flow rate, while expelling the old solution from the receiving phase. This prevents a decrease in the resistivity of the receiving phase, maintaining a consistently high electric field strength in the donor phase (continuous field amplification), thereby sustaining a rapid migration rate of the analyte within the donor phase. This further enhances the speed and capacity of electroextraction, achieving more efficient enrichment. The pumping conditions and electroextraction system conditions are well-matched, preventing the enriched analyte from being pushed back into the donor phase. Furthermore, the compression of the analyte enrichment zone within the receiving phase can be adjusted by regulating the supplemental pumping rate. This technique is characterized by ease of operation, low cost, and excellent enrichment effect.

[0014] In one embodiment, the sample to be tested is enriched in the receiving tube; The electro-extraction includes: rinsing the receiving tube with a rinsing solution, and after the voltage is increased to the electro-extraction voltage, continuously injecting the electrolyte solution into the receiving tube using an electrolyte replenishment device.

[0015] Electroextraction is performed using the aforementioned continuous field amplification-liquid-liquid electroextraction device, which creates an analyte enrichment zone in the receiving tube. This zone is located at a certain distance from the tube opening, which prevents the target analyte from back osmosis into the sample tube when collecting the solution in the receiving tube. Furthermore, the compression state of the analyte enrichment zone can be adjusted by regulating the pumping speed of the replenishing electrolyte solution during the electroextraction process.

[0016] In one embodiment, the electroextraction voltage is -30~30kV, the electroextraction time is 1~30 min, and the electrolyte solution injection rate is 0.1μL / min to 50μL / min.

[0017] Adding electrolytes to the receiving phase during liquid-liquid electroextraction can lead to several adverse consequences. First, during the dynamic mass transfer process of electroextraction, pumping electrolyte solution into a trace amount of the receiving phase inevitably results in some electrolyte solution being pumped out from the other end, potentially pushing the analyte that has just been enriched in the receiving phase back into it, thus reducing extraction efficiency. Second, replenishing electrolyte solution to a small amount of the receiving phase during dynamic electroextraction can cause a significant change in the conductivity of the receiving phase and a sudden increase in current, thereby overloading the power supply and interrupting the electroextraction process; this is especially true when analyzing samples with complex matrices, where the background current is already very high, increasing the risk of power overload. Therefore, based on a continuous field amplification-liquid-liquid electroextraction device, the inventors conducted a visual pre-experiment (under power failure) by pushing electrolytes into a 50 cm microliter receiving tube (0.37 mm in diameter). Even a small amount of dynamic pushing caused the target pigment to be pushed back into the donor phase bottle. Considering that using a larger diameter receiving tube allows for higher concentrations of electrolyte solution and faster electrolyte solution injection rates, the inventors proposed the above-mentioned pumping conditions based on commonly available receiving tube sizes. This prevents the analyte from being pushed back out of the tube. Above the aforementioned speed range, the sample tube shows a darkening of color, indicating that the sample is beginning to be ejected. Furthermore, the low-speed pumping conditions prevent power overload and resolve the issue of sudden current spikes observed during experiments. Based on this, combined with suitable electroextraction conditions, the adverse consequences of adding electrolyte to the receiving phase during electroextraction are addressed, truly achieving "continuous field amplification" and improved electroextraction efficiency.

[0018] In one embodiment, the electrolyte solution is injected at a rate of 1.07 μL / min to 10.20 μL / min.

[0019] In one embodiment, the electroextraction voltage is -30 to -5 kV.

[0020] In one embodiment, the electroextraction voltage is -18 to -5 kV.

[0021] In one embodiment, the electroextraction time is 1 to 20 minutes.

[0022] In one embodiment, the electrolyte solution includes an electrolyte, and the concentration of the electrolyte in the electrolyte solution is 0.1~1000 mmol / L; The rinsing solution includes an electrolyte, and the concentration of the electrolyte in the rinsing solution is 0.1~1000 mmol / L.

[0023] Considering that when selecting different power supply models, the range of electroextraction parameters, reagent concentration range, and receiver tube diameter range will need to be adjusted accordingly based on the differences in power supply load capacity, the concentrations of the electrolyte solution and rinsing solution mentioned above can be well adapted to different power supply models.

[0024] In one embodiment, the electrolyte solution includes an electrolyte, and the concentration of the electrolyte in the electrolyte solution is 1~60 mmol / L; The rinsing solution includes an electrolyte, and the concentration of the electrolyte in the rinsing solution is 1~30 mmol / L.

[0025] In one embodiment, the concentration of the electrolyte in the electrolyte solution is 3 to 60 mmol / L.

[0026] In one embodiment, the concentration of electrolyte in the rinsing solution is 2-30 mmol / L.

[0027] In one embodiment, the electrolyte comprises malonic acid and / or triethylamine.

[0028] In one embodiment, the electrolyte solution comprises a methanol-acetonitrile solution with a volume ratio of 50:50, the rinsing solution comprises a methanol-acetonitrile solution with a volume ratio of 50:50, and the power supply is a switchable 0~30kV power supply.

[0029] This invention also provides the application of the continuous field amplification-liquid-liquid electro-extraction analysis method in cosmetic testing.

[0030] The present invention also provides a method for detecting perfluorinated and polyfluoroalkyl substances in cosmetics, using the continuous field amplification-liquid-liquid electro-extraction analysis method described above.

[0031] Compared with the prior art, the present invention has the following beneficial effects: The present invention relates to a continuous field amplification liquid-liquid electro-extraction device, method, and application. The device continuously replenishes the receiving tube with electrolyte through an electrolyte replenishment device, thereby maintaining or increasing the conductivity of the solution in the receiving tube, thereby achieving the purpose of continuously amplifying the electric field strength. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the continuous field amplification-liquid-liquid electro-extraction device in Example 1; wherein, 10 is a high-voltage power supply, 20 is a precision injection pump, 30 is an electrolyte injector, 31 is a high-concentration electrolyte solution, 40 is a rinsing solution injector, 41 is a low-concentration organic electrolyte solution, 50 is a three-way tube, 60 is a stainless steel electrode wire, 70 is a platinum electrode wire, 80 is a receiving tube, 90 is a sample tube, and 91 is the substance to be extracted; Figure 2 This is a schematic diagram of the state during the electroextraction process of the continuous field amplification electroextraction device in Example 1; wherein, 20 is a precision injection pump, 30 is an electrolyte injector, 31 is a high-concentration electrolyte solution, 40 is a rinsing liquid injector, 41 is a low-concentration organic electrolyte solution, 70 is a platinum electrode wire, 80 is a receiving tube, 90 is a sample tube, 91 is the analyte to be extracted, and 92 is the target analyte enrichment zone. Figure 3 This is a schematic diagram illustrating the extraction of Allura Red in the sample tube and receiving tube in Example 2. Figure 3 (1) The condition of Allura Red in the sample tube before and 10 min after electroextraction. Figure 3 (2) To show the analyte enrichment zone after 10 min of extraction with red ion, B0, B1, B2, B3, B4, B5, and B6 correspond to the supplementary pump linear velocities of 0 mm / min, 10 mm / min, 20 mm / min, 30 mm / min, 40 mm / min, 50 mm / min, and 60 mm / min, respectively. Figure 4 This is a graph showing the changes in extraction rate using different concentrations of supplemented electrolyte solution in Example 3. Figure 5 The graph shows the extraction rate variation curves using different pumping speeds in Example 3; Figure 6 This is a graph showing the changes in extraction rate for different methyl tert-butyl ether contents in the sample vials in Example 3. Detailed Implementation

[0033] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0034] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] source: Unless otherwise specified, all reagents, materials, and equipment used in this embodiment are commercially available; unless otherwise specified, all test methods are conventional test methods in this field.

[0037] Example 1 A continuous field amplification-liquid-liquid electro-extraction device.

[0038] I. A schematic diagram of the device is shown below. Figure 1 As shown.

[0039] The continuous field amplification-liquid-liquid electro-extraction device includes an extraction component and a sample component.

[0040] The extraction assembly includes an electrolyte replenishment device, a rinsing device, and electrolyte electrode wires.

[0041] In this embodiment, the electrolyte replenishment device consists of an electrolyte injector 30 and a precision injection pump 20. The electrolyte injector is fixed to the precision injection pump and is used to contain the electrolyte solution. In this embodiment, the electrolyte solution is a high-concentration organic electrolyte solution. The electrolyte electrode wire is a stainless steel electrode wire 60, one end of which is inserted into the piston rod of the electrolyte injector and passes through the rubber head on the piston rod to contact the high-concentration electrolyte solution 31, while the other end is grounded. The rinsing device is a rinsing liquid injector 40, which is used to contain the rinsing liquid. In this embodiment, the rinsing liquid is a low-concentration organic electrolyte solution 41, which is manually injected before each electroextraction to rinse the receiving tube 80 and refresh the solution in the tube.

[0042] The sample assembly includes a sample container, a receiving tube, and a sample electrode wire.

[0043] In this embodiment, the sample container is a sample tube 90, which is used to hold the extractant 91; one end of the receiving tube is connected to the electrolyte syringe and the rinsing solution syringe respectively through a three-way tube 50, and the other end is used to immerse the extractant; the sample electrode wire is a platinum electrode wire 70, one end of which is used to connect to the power supply, and the other end is used to immerse the extractant.

[0044] II. The continuous field amplification-liquid-liquid electro-extraction device is assembled according to the following steps.

[0045] 1. Insert the stainless steel electrode wire 60 into the piston rod of the electrolyte injector 30 and pass it through the rubber head on the piston rod to form a "syringe electrode" structure. One end of the stainless steel electrode wire 60 contacts the high-concentration electrolyte solution 31, and the other end is connected to an electric wire and grounded.

[0046] 2. One end of the three-way tube 50 is connected to the electrolyte syringe 30 via a Luer connector, and the other end of the three-way tube is connected to the flushing solution syringe 40 via a Teflon tube. Its end is connected to the receiving tube 80.

[0047] 3. Inject a high-concentration electrolyte solution 31 (i.e., electrolyte solution) into the electrolyte syringe 30, and then fix the electrolyte syringe 30 onto the precision injection pump 20; in this embodiment, the high-concentration electrolyte solution 31 is a methanol-acetonitrile solution with a volume fraction of 50:50, which contains a certain concentration of organic electrolyte; the organic electrolyte is 30 mmol / L malonic acid and 30 mmol / L triethylamine.

[0048] 4. Inject a low-concentration organic electrolyte solution 41 (i.e., flushing solution) into the flushing solution syringe 40. The low-concentration organic electrolyte solution 41 is a 50:50 methanol-acetonitrile solution, and the organic electrolyte consists of 3 mmol / L malonic acid and 3 mmol / L triethylamine. Before each electroextraction, flush the receiving tube 80 by manually injecting the flushing solution syringe 40, and replace the receiving phase solution in the tube.

[0049] 5. Immerse the other end of the receiving tube 80 and the platinum electrode wire 70 connected to the high voltage power supply 10 into the sample tube 90 containing the extract 91.

[0050] Compared to existing liquid-liquid electroextraction technology, the continuous field amplification-liquid-liquid electroextraction device of this invention for enriching trace analytes amplifies the electric field intensity during electroextraction, further improving the speed and capacity of liquid-liquid electroextraction. It is simple to operate, low in cost, and provides excellent enrichment results.

[0051] This electroextraction device, during the electroextraction process, activates a precision injection pump 20, which drives an electrolyte injector 30 to slowly replenish the receiving tube 80 with a high-concentration electrolyte solution 31. This maintains or increases the conductivity of the solution in the receiving tube 80, continuously amplifying the electric field strength and improving the electroextraction efficiency. Using this device, the injection rate of the high-concentration electrolyte solution can be adjusted by controlling the precision injection pump, thereby regulating the compression state of the analyte enrichment zone.

[0052] The receiving tube 80 can be made of PEEK or Teflon insulating material. In this embodiment, it is connected to the end of the tee tube 50, and both are 50 cm long. The inner diameter of the PEEK tube is 0.37 mm, and the inner diameter of the Teflon tube is 0.38 mm. The sample tube 90 is a 10 mL polypropylene EP tube. The tee tube is made of polypropylene, Y-shaped, 12.6 mm long, 8.6 mm wide, with an outer diameter of 1.7 mm and an inner diameter of 1.0 mm.

[0053] In this embodiment, the high-voltage power supply 10 is a switchable positive and negative 0~30 kV power supply; the stainless steel electrode wire 60 has a diameter of 1 mm; and the platinum electrode wire has a diameter of 0.5 mm. The precision syringe pump 20 provides a supplemental infusion flow rate of 1.07 μL / min to 10.20 μL / min, and a collection flow rate of 540 μL / s. An electrolyte syringe 30, fixed to the precision syringe pump 20, injects a high-concentration electrolyte solution 31 with a capacity of 10 mL, and a flushing solution syringe 40, injecting a low-concentration electrolyte solution 41, has a capacity of 5 mL.

[0054] III. A continuous field amplification-liquid-liquid electro-extraction analysis method.

[0055] See Figure 2 This is a schematic diagram illustrating the state during electroextraction using the continuous field amplification electroextraction device of the present invention. The method for enriching trace analytes using the aforementioned electroextraction device includes the following steps: S1: Prepare the sample solution to be tested; weigh approximately 20 mg of the sample to be tested into a sample vial; extract the sample to be tested in the sample vial using a methanol-acetonitrile solution and methyl tert-butyl ether with a volume ratio of 50:50 (methanol-acetonitrile solution to methyl tert-butyl ether, volume ratio of methanol-acetonitrile solution to methyl tert-butyl ether is 0.25:1 ~ 0.43:1). The specific operation is as follows: vortex for 3 min, sonicate in a water bath for 30 min, and then centrifuge at 10000 rpm for 5 min. S2: Prepare a series of standard sample solutions; prepare samples of known concentrations by adding standard solutions to blank samples; extract the target analytes from the samples using equal volumes of methanol-acetonitrile solution and methyl tert-butyl ether, specifically by vortexing for 3 min, sonicating in a water bath for 30 min, and then centrifuging at 10,000 rpm for 5 min. S3: Assemble the above-described continuous field amplification-liquid-liquid electro-extraction device, and extract the test sample solution and the standard series sample solutions respectively; before electro-extraction, flush the receiving tube 80 with the injection syringe 40 containing a low-concentration electrolyte solution, and fill it with the low-concentration electrolyte solution 41, such as... Figure 2 As shown in state a.

[0056] S4: Adjust the voltage range of the high-voltage power supply 10 to -18~-5 kV (i.e., the electroextraction voltage). During electroextraction, immerse the receiving tube 80 and the platinum electrode wire 70 in the sample solution. At this time, the initial state of the sample solution is as follows: Figure 2 As shown in state b. Turn on the power, and after 10-20 seconds of high voltage boosting, immediately turn on the precision injection pump 20 to continuously inject the high-concentration electrolyte solution into the electrolyte injector 30. The injection rate is 1.07 μL / min to 10.20 μL / min (i.e., the rate of electrolyte solution injection). At this time, the sample solution is as follows: Figure 2As shown in state c, the electroextraction duration is 1–20 min (i.e., the electroextraction time). At the end of electroextraction, simultaneously turn off the power supply and the precision syringe pump. The sample solution at the end of extraction should resemble... Figure 2 As shown in state d, the solution in the sample tube changes from a red solution in the initial state to a colorless and transparent solution, while the target enrichment zone 92 is formed, which is the color of the target.

[0057] S5: After extraction, set the precision syringe pump infusion rate to 540 μL / min. Figure 2 As shown in state e, start the precision injection pump and directly perform online analysis and detection, or collect 90 μL of the sample solution or standard solution in the receiving tube for analysis and detection.

[0058] S6: Compare the liquid chromatogram of the enriched sample solution with the liquid chromatograms or mass spectra of a series of enriched standard solutions of known concentrations. During the comparison, if the retention time of a specific component in the liquid chromatogram of the enriched standard solution matches the retention time of a characteristic peak in the sample solution, then that characteristic peak will be considered a characteristic marker produced by the same substance as the corresponding component in the standard solution. Based on the peak area of ​​this characteristic marker, the content of the target compound in the sample can be accurately calculated using the established accompanying standard curve.

[0059] Example 2 I. The instruments used in this embodiment include the continuous field amplification-liquid-liquid electro-extraction device and micropipette described in Example 1 for enriching trace analytes. The reagents used are: methanol, acetonitrile, triethylamine (chromatographic grade); malonic acid, methyl tert-butyl ether (analytical grade).

[0060] The conductivity solution for the electroextraction device was prepared in advance. During the electroextraction process, different concentrations of conductivity solution were used to replenish the solution in the receiving tube. After comparing the extraction results, a methanol-acetonitrile solution containing 30.0 mmol / L malonic acid and triethylamine was selected as the replenishing conductivity solution. Using the conductivity solution with this composition ratio, the Allura Red substance in the sample vial was completely extracted after electroextraction, and the solution in the sample vial was clear and transparent. The steps for preparing this conductivity solution are as follows: Weigh 0.312 g of malonic acid using a 1 / 10000 electronic balance and place it in a 100 mL volumetric flask. Dissolve it in a small amount of a 50:50 methanol-acetonitrile solution, then add 420 μL of triethylamine. Dilute to the mark with a 50:50 methanol-acetonitrile solution and shake well before use. A methanol-acetonitrile solution containing 3.0 mmol / L malonic acid and 3.0 mmol / L triethylamine was selected as the receiving phase solution. The receiving tube was rinsed and the low-concentration conductivity solution was replaced before electroextraction. Using this conductivity solution ratio avoids the problem of bubble generation due to Joule heating caused by current overload during electroextraction. The steps for preparing this conductivity solution are as follows: Weigh 0.0312 g of malonic acid using a 1 / 10000 electronic balance and place it in a 100 mL volumetric flask. Dissolve it in a small amount of a 50:50 methanol-acetonitrile solution, then add 42 μL of triethylamine. Dilute to the mark with a 50:50 methanol-acetonitrile solution and shake well.

[0061] II. Sample to be tested in this embodiment: Methyl tert-butyl ether suspected of being contaminated with Allura Red; Standard: Allura Red, analytical grade, purchased from Shanghai Maclean's Biochemical Technology Co., Ltd., batch number CAS: 25956-17-6. Weigh 5 mg of Allura Red into a 10 mL volumetric flask, dilute to the mark with a 50:50 methanol-acetonitrile solution, and shake well to prepare a 500 μg / mL Allura Red standard solution.

[0062] The electroextraction enrichment of allura red in methyl tert-butyl ether using the continuous field amplification-liquid-liquid electroextraction apparatus for enriching trace analytes as described in Example 1 includes the following steps: 1. Prepare the sample to be tested.

[0063] Assemble the electroextraction apparatus. Add 2.0 mL of the methyl tert-butyl ether to be tested and 1.0 mL of a 50:50 methanol-acetonitrile solution to the sample tube, shake well, and the sample solution to be tested is prepared.

[0064] 2. Set the electroextraction parameters.

[0065] Transparent Teflon tubes were used as receiving tubes to observe the analyte enrichment zones. Before electroextraction, the solution in the receiving tube was manually replenished by injecting a syringe containing a low concentration of conductivity solution (malonic acid:triethylamine = 3.0 mmol / L: 3.0 mmol / L). The high-voltage power supply was set to -15 kV. At the start of electroextraction, the platinum electrode wire and receiving tube of the electroextraction device were immersed in the sample solution. The power was turned on, and after 10 seconds of voltage rise, the precision syringe pump was started, and a syringe containing a high concentration of conductivity solution (malonic acid:triethylamine = 30.0 mmol / L: 30.0 mmol / L) was injected to replenish the electrolyte solution in the receiving tube. After 10 minutes of electroextraction, the high-voltage power supply and the precision syringe pump were simultaneously turned off. The state of the sample tube and receiving tube before and after electroextraction was photographed with a mobile phone. The precision syringe pump is set to 1.13 μL / min to 6.80 μL / min, which translates to a linear velocity of 10 mm / min, 20 mm / min, 30 mm / min, 40 mm / min, 50 mm / min, and 60 mm / min in the receiving tube.

[0066] 3. Analysis of electroextraction results: The extraction of allura red in methyl tert-butyl ether was assessed by the amount of red remaining in the sample tube after electro-extraction; the band compression was assessed by the amount of red enrichment in the receiving tube.

[0067] After analyzing the remaining color in the sample vials, in this embodiment, when the precision syringe pump was set to a replenishment pump rate of 2.27 μL / min to 5.67 μL / min (corresponding to a replenishment pump linear velocity of 20 mm / min to 50 mm / min in the receiving tube), Allura Red was well extracted after 10 minutes of electroextraction. The solution in the sample tube was transparent, and the target analyte was enriched in the receiving tube. See details. Figure 3 (1). Based on the analysis of the enrichment of Allura Red in the receiving tube, in this embodiment, when the supplementary injection rate of the precision injection pump was set from 1.13 μL / min to 6.80 μL / min (corresponding to a supplementary injection linear velocity of 10 mm / min to 60 mm / min in the receiving tube), the analyte band was gradually compressed as the supplementary injection rate increased. See details below. Figure 3 (2), where the target enrichment zone of B0 (corresponding to a supplementary pump injection linear velocity of 0 mm / min) appears red, but the corresponding Figure 3 (1) In the test tube without replenishment of electrolyte solution after 10 minutes of electro-extraction (i.e., the second test tube from the left), it can be seen that without replenishment of electrolyte solution, the 10-minute electro-extraction cannot complete the depletion extraction, and the solution in the test tube still has residual color after electro-extraction. However, under the same electro-extraction conditions, when replenishment of electrolyte solution is started with low-speed pumping, Figure 3(1) The residual color of the solution in the test tube becomes significantly lighter or even colorless, indicating that exhaustion extraction has been achieved, reflecting the continuous field amplification effect.

[0068] Example 3 Perfluorinated and polyfluoroalkyl substances in cosmetics were enriched using a continuous field amplification-liquid-liquid electro-extraction method.

[0069] The instruments used in this embodiment include the liquid-liquid electro-extraction device for continuous field amplification enrichment of trace analytes described in Example 1; a 1 / 10000 electronic balance; micropipette; a Vortex-Genie adjustable vortex mixer; a CT15RT benchtop centrifuge; an LC-20A high-performance liquid chromatograph and a 4000 Q TRAP triple quadrupole mass spectrometer; and an Accucore C18 column (100 × 4.6 mm, 2.6 μm, Thermo Fisher Scientific). The reagents used include: methanol, acetonitrile, triethylamine, methyl tert-butyl ether (chromatographic grade); ammonium acetate, and malonic acid (analytical grade).

[0070] A high-concentration conductive solution was pre-prepared and injected into a syringe fixed to a precision infusion pump. The electrolytes, malonic acid and triethylamine, were used in a 1:1 ratio, and concentrations of 3.0 mmol / L, 6.0 mmol / L, 10.0 mmol / L, 30.0 mmol / L, and 60.0 mmol / L were tested. Figure 4 (See Table 1 for data) The extraction results of perfluorinated and polyfluoroalkyl substances in sunscreen at different electrolyte concentrations show that the extraction rates of perfluorinated and polyfluoroalkyl substances in sunscreen are higher when the concentrations of malonic acid and triethylamine are 30.0 mmol / L and 60.0 mmol / L. Therefore, a methanol-acetonitrile solution with concentrations of 30.0 mmol / L for malonic acid and 30.0 mmol / L for triethylamine was selected as the optimal high-concentration conductivity solution. The steps for preparing this conductivity solution are as follows: Weigh 0.312 g of malonic acid using a 1 / 10000 electronic balance and place it in a 100 mL volumetric flask. Dissolve it in a small amount of a 50:50 methanol-acetonitrile solution, then add 420 μL of triethylamine. Dilute to the mark with a 50:50 methanol-acetonitrile solution and shake well before use. The low-concentration conductivity solution in the receiving tube is a methanol-acetonitrile solution containing 3.0 mmol / L malonic acid and 3.0 mmol / L triethylamine. The steps for preparing this conductivity solution are as follows: Weigh 0.0312 g of malonic acid using a 1 / 10000 electronic balance and place it in a 100 mL volumetric flask. Dissolve it in a small amount of a 50:50 methanol-acetonitrile solution. Add 42 μL of triethylamine and dilute to the mark with a 50:50 methanol-acetonitrile solution. Shake well and set aside.

[0071] Table 1. Electroextraction recovery rate (%) with different supplemental conductivity concentrations (n=3)

[0072] Note: During the experiment to optimize the concentration of the supplemental conductivity solution, the sunscreen was extracted using 2.0 mL of methyl tert-butyl ether and 1.0 mL of a 50:50 methanol-acetonitrile solution, with a pump flow rate of 20 mm / min.

[0073] Select the high-concentration conductive solution to supplement the pump injection rate, refer to [reference needed]. Figure 5 (See Table 2 for specific data). As can be seen from the figure, the optimal range for the supplemental injection rate of the precision syringe pump is 2.15 μL / min to 4.30 μL / min, corresponding to a supplemental injection linear velocity of 20 mm / min to 40 mm / min in the receiving tube. The optimal supplemental injection linear velocity for the high-concentration conductive solution was selected as 20 mm / min.

[0074] Table 2. Electroextraction recovery rate (%) at different replenishment pump linear velocities (n=3)

[0075] For the selected ratio of methanol acetonitrile to methyl tert-butyl ether, please refer to [link / reference]. Figure 6 (See Table 3 for specific data). As can be seen from the figure, the extraction effect is very good when the ratio of methanol to acetonitrile to methyl tert-butyl ether is 0.25:1 to 0.43:1, corresponding to a methyl tert-butyl ether content of 70% to 80% in the figure. The optimal feed phase was selected with a methyl tert-butyl ether content of 73.3%, i.e., 2.2 ml of methyl tert-butyl ether and 0.8 ml of methanol to acetonitrile.

[0076] Table 3. Electroextraction recovery rates (%) for different methyl tert-butyl ether contents (n=3)

[0077] The cosmetic sample to be tested in this embodiment is: Cosmetic samples to be tested: Cosmetics suspected of being contaminated with perfluorinated and polyfluorinated alkyl substances, including sunscreen, moisturizer, foundation, lipstick, essential oil, eyeshadow, and mascara.

[0078] Blank cosmetic samples: Cosmetics that have been tested and found to be free of target perfluorinated and polyfluoroalkyl substances, including sunscreens, moisturizers, foundations, lipsticks, essential oils, eyeshadows, and mascaras.

[0079] Standards: Perfluorobutyric acid (PFBA), perfluorovalerate (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUdA), perfluorododecanoic acid (PFDoA), perfluorotridecanoic acid (PFTrDA). Perfluorotetradecanoic acid (PFTeDA), perfluorohexadecanoic acid (PFHxDA), perfluorooctadecanoic acid (PFOcDA), perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) were purchased from Amp Laboratory Technology Co., Ltd. Potassium 9-chlorohexadecfluoro-3-oxononane-1-sulfonate (9-Cl-SA), potassium 11-chloroeicosicofluoro-3-oxoundecane-1-sulfonate (11-Cl-SA), and 4,8-dioxa-3-hydro-perfluorononanoic acid (ADONA) were purchased from Wellington Laboratory, Canada; hexafluoropropylene oxide dimer acid (GenX) was purchased from AccuStandard, USA.

[0080] The continuous field amplification-liquid-liquid electro-extraction apparatus for enriching trace analytes in cosmetics, as described in Example 1, includes the following steps: (1) Preparation of the injection solution for the sample to be tested: Assemble the electroextraction apparatus. Weigh 20 mg of the cosmetic sample to be tested into a 10 mL EP tube using a 1 / 10000 electronic balance. Add 2.2 mL of methyl tert-butyl ether and 0.8 mL of a 50:50 methanol-acetonitrile solution sequentially. Vortex for 3 min, sonicate in a water bath for 30 min, and centrifuge at 10000 rpm for 5 min to obtain the sample solution. Set the high-voltage power supply to -12 kV and the precision syringe pump flow rate to 2.15 μL / min (corresponding to a linear velocity of 20 mm / min for replenishing the conductivity solution in the receiving tube). Before electroextraction, replace the solution in the receiving tube with a syringe containing a low concentration of conductivity solution (malonic acid:triethylamine = 3.0 mmol / L: 3.0 mmol / L). Immerse the platinum electrode wire and receiving tube of the electroextraction device into the sample solution. Turn on the power and wait 20 seconds for the pressure to build up. Then, start the precision syringe pump and inject a syringe containing a high-concentration conductivity solution (malonic acid:triethylamine = 30.0 mmol / L:30.0 mmol / L) to begin electroextraction. After 8.0 minutes, turn off the power and the precision syringe pump. Set the injection rate of the precision syringe pump to 540 μL / min. By pushing the syringe pump for 10 seconds, collect 90 μL of the sample solution in the receiving tube.

[0081] (2) Preparation of standard injection solution: Assemble the electroextraction apparatus. Weigh the blank cosmetic sample into a 10 mL EP tube using a 1 / 10000 electronic balance, and add standard solutions of 20 perfluorinated and polyfluoroalkyl substances to achieve a spiked concentration of 1 ng / g for the blank cosmetic sample. 1 10ng·g 1 20 ng·g 1 50ng·g 1 100ng·g 1 200ng·g 1 300ng·g 1 2.2 mL of methyl tert-butyl ether and 0.8 mL of a 50:50 methanol-acetonitrile solution were added sequentially. The mixture was vortexed for 3 min, sonicated in a water bath for 30 min, and then centrifuged at 10,000 rpm for 5 min to obtain the sample solution. Before electroextraction, the high-voltage power supply was set to -12 kV, and the precision syringe pump was set to a flow rate of 2.15 μL / min (corresponding to a replenishment flow rate of 20 mm / min in the receiving tube). After replacing the solution in the receiving tube with a low-concentration conductive liquid syringe before electroextraction, the platinum electrode wire and receiving tube of the electroextraction device were immersed in the sample solution. The power was turned on, and after 20 s of voltage boosting, the precision syringe pump was turned on to begin electroextraction. After 8.0 min, the power and precision syringe pump were turned off, and the flow rate of the precision syringe pump was set to 540 μL / min. By pushing the syringe pump for 10 s, 90 μL of solution was collected in the receiving tube to obtain a series of concentration standard injection liquids.

[0082] (3) Detection by liquid chromatography-mass spectrometry: The mobile phase consisted of methanol and a 5 mmol / L ammonium acetate aqueous solution, with a flow rate of 0.8 mL / min and an injection volume of 25 μL. A gradient elution mode was used, with the initial aqueous phase concentration at 98%, decreasing to 2% within 6.5 min, maintaining this concentration for 3.5 min, then increasing to 98% within 0.3 min and maintaining this concentration for 3.7 min to achieve equilibration. The aqueous phase (5 mmol / L ammonium acetate aqueous solution) was prepared as follows: 0.3854 g of ammonium acetate was weighed using a 1 / 10000 electronic balance and placed in a 1000 mL volumetric flask, diluted to the mark, filtered, and degassed by sonication for later use.

[0083] Mass spectrometry detection conditions: negative ion MRM mode. Curtain gas: 15.0; Collision gas: medium; Ionization voltage: -4200 V; Nebulization temperature: 650 °C; Nebulizing gas: 55.0; Auxiliary gas: 60.0; Inlet voltage: -10.0 V; Outlet voltage: -15 V. The chromatographic retention time, precursor ion, daughter ion, declustering voltage, and collision energy of the target analyte are shown in Table 4. Table 4. Chromatographic retention time, precursor ion, daughter ion, declustering voltage, and collision energy parameters of the target analyte.

[0084] (4) Data processing: After the system is balanced, the sample solution to be tested and a series of standard solutions of different concentrations are injected separately.

[0085] By inputting the spiked concentrations of each blank cosmetic sample into the software, the peak area-concentration standard curve equation can be obtained, and the software can calculate the results of each spiked concentration. The effectiveness and accuracy of this method for detecting the perfluorinated and polyfluoroalkyl substances were demonstrated. The limit of detection (LOD), lower limit of quantitation (LOQ), accuracy, and precision of each target analyte were evaluated according to the ICH (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use) Q2 analytical method validation guidelines. First, an analytical method was established using sunscreen samples, with a signal-to-noise ratio (SNR) of 3x and a SNR of 30x as the LOD. The LOD, LOQ, linear range, and fitting coefficients are shown in Table 5. Accuracy and precision were evaluated by calculating intra-day and inter-day recoveries and relative standard deviations (RSDs). The inter-day difference was obtained from the determination of five parallel samples of three concentrations on the same day, and the intra-day difference was obtained from the parallel determination of three parallel samples of three concentrations per day for five days. Next, the method was validated for other cosmetic samples by calculating the inter-day and intra-day differences at two concentrations. In summary, the accuracy and precision data of sunscreen and other cosmetic samples are shown in Tables 6 and 7, respectively.

[0086] Table 5. Limits of detection, limits of quantitation, linear ranges, and coefficients of fit for electroextraction of perfluorinated and polyfluoroalkyl substances.

[0087] Table 6. Accuracy and precision data of perfluorinated and polyfluoroalkyl substances in electro-extracted sunscreens

[0088] Table 7. Accuracy and precision data of electroextraction of perfluorinated and polyfluoroalkyl substances in other cosmetics

[0089] a. Recovery rate The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A continuous field amplification-liquid-liquid electro-extraction analysis method, characterized in that, Includes the following steps: Prepare the sample to be extracted and the standard. Perform electro-extraction using a continuous field amplification-liquid-liquid electro-extraction device to obtain the sample to be tested and the standard sample. Detect and analyze the sample to be tested and the standard sample. The continuous field amplification-liquid-electrohydride extraction device includes: An extraction assembly includes an electrolyte replenishment device, a rinsing device, and an electrolyte electrode wire. The electrolyte replenishment device contains an electrolyte solution, the rinsing device contains a rinsing solution, one end of the electrolyte electrode wire is immersed in the electrolyte solution, and the other end of the electrolyte electrode wire is grounded. The sample assembly includes a sample container, a receiving tube, and a sample electrode wire. The sample container is used to hold the extractant. One end of the receiving tube is used to immerse the extractant, and the other end of the receiving tube is connected to the electrolyte replenishment device and the rinsing device, respectively. One end of the sample electrode wire is used to connect to a power source, and the other end of the sample electrode wire is used to immerse the extractant. In the continuous field amplification-liquid-liquid electroextraction analysis method, the sample to be tested is enriched in the receiving tube; the electroextraction includes: rinsing the receiving tube with rinsing solution, and after the voltage is increased to the electroextraction voltage, continuously injecting electrolyte solution into the receiving tube using an electrolyte replenishment device, so that the electrophoretic migration rate of the target at the opening of the receiving tube is greater than the reverse liquid flow rate generated by the injection.

2. The continuous field amplification-liquid-liquid electro-extraction analysis method according to claim 1, characterized in that, The electrolyte replenishment device includes an electrolyte injector and an injection pump, with the electrolyte injector fixed to the injection pump.

3. The continuous field amplification-liquid-liquid electro-extraction analysis method according to claim 2, characterized in that, One end of the electrolyte electrode wire is inserted into the tail of the piston rod of the electrolyte injector and exposed at the head of the piston rod; The flushing device includes a flushing fluid injector.

4. The continuous field amplification-liquid-liquid electro-extraction analysis method according to claim 1, characterized in that, The receiving tube is connected to the electrolyte replenishment device and the rinsing device via a three-way pipe.

5. The continuous field amplification-liquid-liquid electro-extraction analysis method according to claim 1, characterized in that, The electro-extraction voltage is -30~30kV, the electro-extraction time is 1~30 min, and the electrolyte solution injection rate is 0.1μL / min to 50μL / min.

6. The continuous field amplification-liquid-liquid electro-extraction analysis method according to any one of claims 1-5, characterized in that, The electrolyte solution includes an electrolyte, and the concentration of the electrolyte in the electrolyte solution is 0.1~1000 mmol / L; The rinsing solution includes an electrolyte, and the concentration of the electrolyte in the rinsing solution is 0.1~1000 mmol / L.

7. The application of the continuous field amplification-liquid-liquid electro-extraction analysis method according to any one of claims 1-6 in cosmetic testing.

8. A method for detecting perfluorinated and polyfluoroalkyl substances in cosmetics, characterized in that, The detection was performed using the continuous field amplification-liquid-liquid electro-extraction analysis method according to any one of claims 1-6.

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