阅读说明：本技术 一种复合纳米纤维在线微固相萃取柱及其制备方法 (Composite nanofiber online micro solid-phase extraction column and preparation method thereof ) 是由 徐晖 陈丹 田馨梦 胡嘉嘉 陈延妍 于 2019-09-29 设计创作，主要内容包括：本发明属于固相萃取领域,具体涉及一种PS/SiO<Sub>2</Sub>@PDA复合纳米纤维在线微固相萃取柱及其制备方法。所述在线微固相萃取柱包括预柱柱套、填充有吸附剂材料的预柱柱芯和手动六通阀,所述吸附剂材料为PS/SiO<Sub>2</Sub>@PDA复合纳米纤维,所述PS/SiO<Sub>2</Sub>@PDA复合纳米纤维是通过制备PS/SiO<Sub>2</Sub>静电纺丝材料,并将PS/SiO<Sub>2</Sub>静电纺丝材料置于多巴胺盐溶液中使多巴胺在PS/SiO<Sub>2</Sub>静电纺丝材料表面自聚合形成PS/SiO<Sub>2</Sub>@PDA复合纳米纤维。本发明将PS/SiO<Sub>2</Sub>@PDA复合纳米纤维微固相萃取柱与在线萃取技术联用,自动化程度高,操作简便,误差来源少,灵敏度高,适用于复杂基质中的痕量分析物的样品前处理。(The invention belongs to the field of solid phase extraction, and particularly relates to PS/SiO 2 An on-line micro solid phase extraction column of @ PDA composite nanofiber and a preparation method thereof. The on-line micro solid phase extraction column comprises a pre-column sleeve, a pre-column core filled with adsorbent material and a manual six-way valve, wherein the adsorbent material is PS/SiO 2 @ PDA composite nanofiber, the PS/SiO 2 The @ PDA composite nano-fiber is prepared by preparing PS/SiO 2 Electrospinning the material and mixing the PS/SiO 2 Placing the electrostatic spinning material in dopamine salt solution to make dopamine in PS/SiO 2 Surface self-polymerization of electrostatic spinning material to form PS/SiO 2 @ PDA composite nanofiber. The invention uses PS/SiO 2 The @ PDA composite nanofiber micro solid-phase extraction column is combined with an online extraction technology, so that the automation degree is high, the operation is simple and convenient, the error source is few, the sensitivity is high, and the method is suitable for sample pretreatment of trace analytes in complex matrixes.)

1. PS/SiO₂The @ PDA composite nanofiber online micro solid-phase extraction column is characterized by comprising a pre-column sleeve, a pre-column core filled with adsorbent material and a manual six-way valve, wherein the adsorbent material is PS/SiO₂@ PDA composite nanofiber, the PS/SiO₂The @ PDA composite nano-fiber is prepared by preparing PS/SiO₂Electrospinning the material and mixing the PS/SiO₂Placing the electrostatic spinning material in dopamine salt solution to make dopamine in PS/SiO₂Surface self-polymerization of electrostatic spinning material to form PS/SiO₂@ PDA composite nanofiber.

2. PS/SiO according to claim 1₂The @ PDA composite nanofiber on-line micro solid-phase extraction column is characterized in that the PS/SiO₂The @ PDA composite nanofiber is in a core-shell type yo-yo shape and has a three-dimensional network structure, the average diameter of the PS nanofiber is 0.8 micrometer, the composite nanofiber presents the core-shell structure after the PDA is modified, the thickness of an outer PDA layer is 0.03 ~ 0.04.04 micrometer, the particle size of silicon dioxide particles is 5 ~ 8 micrometers, and the silicon dioxide particles are entangled by the PS nanofiber to form the yo-yo shape.

3. PS/SiO according to claim 1₂The @ PDA composite nanofiber online micro solid-phase extraction column is characterized in that the diameter of the pre-column core is 4.6 ~ 5 mm, the length of the pre-column core is 10 ~ 12 mm, and the filling amount of the adsorbent material is 4 ~ 8 mg.

4. PS/SiO according to claim 1 ~ 3₂The preparation method of the @ PDA composite nanofiber on-line micro solid-phase extraction column is characterized by comprising the following steps of:

（1）PS/SiO₂preparing the nano-fibers: mixing silicon dioxide (SiO)₂) Adding the particles into N, N-Dimethylformamide (DMF) solvent, and performing ultrasonic dispersion to obtain a dispersion solution; then adding polystyrene into the dispersion solution, stirring and mixing uniformly to obtain an electrostatic spinning solution, adding the electrostatic spinning solution into an injector for electrostatic spinning, and obtaining PS/SiO₂Drying the nanofiber membrane in an oven;

（2）PS/SiO₂preparation of @ PDA composite nanofiber: the PS/SiO obtained in the step (1)₂The nanofiber membrane is completely immersed in dopamine hydrochloride solution, and dopamine is in PS/SiO at room temperature₂Self-polymerizing the surface of the nanofiber membrane to obtain PS/SiO₂The @ PDA composite nano-fiber is cleaned by ultrapure water and dried in vacuum;

(3) pre-treating a pre-column core: ultrasonically cleaning the pre-column core by using methanol and ultrapure water in sequence, and drying;

(4) assembling an on-line micro solid phase extraction column: mixing PS/SiO₂Filling @ PDA composite nano-fibers into the pre-column core pretreated in the step (3), assembling the pre-column core with a stainless steel sieve plate and a Teflon sealing piece at the top of the column, then loading the pre-column core into a matched pre-column sleeve, and assembling to obtain a micro-solid phase extraction column; and (3) installing a six-way valve between the liquid chromatographic column and the automatic sample injector, and replacing the quantitative ring of the six-way valve with the extraction column to construct and finish the on-line micro-solid phase extraction column.

5. The method according to claim 4, wherein the mass ratio of silica to polystyrene in step (1) is 74: 1 ~ 76: 1, the concentration of silica in the electrospinning solution is 1.5 ~ 2.5.5 mg/ml, and the concentration of polystyrene is 1.4 ~ 1.6.6 g/ml.

6. The preparation method according to claim 4, wherein the electrospinning in step (1) is carried out by transferring the electrospinning solution into a plastic syringe and fixing the syringe on a constant current injection pump, using an aluminum foil wrapped with filter paper as an electrospinning collector, applying a DC voltage of 18 ~ 20 kV, connecting a positive electrode to a stainless steel needle tip, connecting the electrospinning collector to a negative electrode, wherein the distance between the positive electrode and the negative electrode is 15 ~ 20 cm, the flow rate of the constant current injection pump is 0.8 ~ 1 ml/hr, and the duration of the electrospinning is 4 ~ 8 hours.

7. The method according to claim 4, wherein the dopamine hydrochloride solution in step (2) is prepared from a mixed solvent of Tris buffer and methanol, and the concentration of dopamine is 2 ~ 3 mg/ml.

8. The method according to claim 4, wherein the Tris buffer has a concentration of 10mM, a pH of 8.5, and a volume ratio of the Tris buffer to the methanol of 1:1 ~ 1: 1.2.

Technical Field

The invention belongs to the field of solid phase extraction, and particularly relates to PS/SiO₂An on-line micro solid phase extraction column of @ PDA composite nanofiber and a preparation method thereof.

Background

Solid Phase Extraction (SPE) technology was proposed in the 70's of the 20 th century and is currently the most common sample pretreatment technology. SPE is based on liquid phase column chromatographic separation, solid phase adsorbent is used as a stationary phase, when liquid sample solution passes through, an analyte is retained by the solid phase adsorbent, and then a proper solvent is selected to elute the analyte, so that the purposes of purification, separation and enrichment are achieved. The technology can be used together with an instrument on line, and can process specific trace substances in different complex matrix samples in a green, efficient and rapid manner. Therefore, SPE is widely used in various fields such as clinical, pharmaceutical, food and environmental sciences.

The micro solid phase extraction (μ -SPE) technology was developed in 2006 and was assembled into μ -SPE devices by packing very small amounts of adsorbent (typically less than 500mg) in capillary columns or mini-columns. Compared with the traditional solid phase extraction, the mu-SPE requires less adsorbent, has high enrichment efficiency and lower solvent consumption. The mu-SPE technology is combined with the on-line technology, and a series of rapid, convenient and economic analysis methods are developed.

The core of the micro solid phase extraction technology is the selection of an adsorbent in an extraction column, and the preparation and selection of the adsorbent influence the extraction selectivity, the extraction effect, the service life, the detection sensitivity, the reproducibility, the application range and the like.

The solid phase adsorbent which is commercialized at present is generally alumina, activated carbon, silica, C8, C18 and other materials. However, the commercial solid phase extraction column has the following problems: the commercialized solid phase adsorbent has the defects of limited types, poor extraction selectivity, low extraction efficiency and the like, and is mostly disposable and expensive. These shortcomings limit the further development and application of micro solid phase extraction technology, and thus the development and preparation of novel adsorbent materials are urgently needed.

Polystyrene is a common high polymer for electrostatic spinning, and is easy to form superfine fiber hydrophobic polymer, and the electrostatic spinning material has a highly crosslinked three-dimensional network structure and high specific surface area. Silicon dioxide (SiO)₂) Is an inorganic oxide and has the characteristics of stable structure, large aperture, biocompatibility and the like. Dopamine is a substance researched and researched by inspired by marine mussel bioadhesive behavior, is easy to self-polymerize in an alkaline aerobic environment to form polydopamine, and the polydopamine coated material has good hydrophilicity, biocompatibility and biodegradability in an aqueous solution.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide PS/SiO₂An on-line micro solid phase extraction column of @ PDA composite nanofiber and a preparation method thereof.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:

PS/SiO₂The @ PDA composite nanofiber online micro solid-phase extraction column comprises a pre-column sleeve, a pre-column core filled with adsorbent material and a manual six-way valve, wherein the adsorbent material is PS/SiO₂@ PDA composite nanofiber, the PS/SiO₂The @ PDA composite nano-fiber is prepared by preparing PS/SiO₂Electrospinning the material and mixing the PS/SiO₂Placing the electrostatic spinning material in dopamine salt solution to make dopamine in PS/SiO₂Surface self-polymerization of electrostatic spinning material to form PS/SiO₂@ PDA composite nanofiber.

In the above-mentioned scheme, the first step of the method,the PS/SiO₂The @ PDA composite nanofiber presents a core-shell type yo-yo shape and has a three-dimensional net structure, the average diameter of the inner-layer PS nanofiber is 0.8 micrometer, the composite nanofiber presents the core-shell structure after the PDA is modified, the thickness of the outer-layer PDA layer is 0.03-0.04 micrometer, the particle size of silicon dioxide particles is 5-8 micrometers, and the silicon dioxide particles are entangled by the PS nanofiber to form the yo-yo shape.

In the scheme, the diameter of the pre-column core is 4.6-5 mm, the length of the pre-column core is 10-12 mm, and the filling amount of the adsorbent material is 4-8 mg.

The above PS/SiO₂The preparation method of the @ PDA composite nanofiber on-line micro solid-phase extraction column comprises the following steps:

(1)PS/SiO₂preparing the nano-fibers: mixing silicon dioxide (SiO)₂) Adding the particles into N, N-Dimethylformamide (DMF) solvent, and performing ultrasonic dispersion to obtain a dispersion solution; then adding polystyrene into the dispersion solution, stirring and mixing uniformly to obtain an electrostatic spinning solution, adding the electrostatic spinning solution into an injector for electrostatic spinning, and obtaining PS/SiO₂Drying the nanofiber membrane in an oven;

(2)PS/SiO₂preparation of @ PDA composite nanofiber: the PS/SiO obtained in the step (1)₂The nanofiber membrane is completely immersed in dopamine hydrochloride solution, and dopamine is in PS/SiO at room temperature₂Self-polymerizing the surface of the nanofiber membrane to obtain PS/SiO₂The @ PDA composite nano-fiber is cleaned by ultrapure water and dried in vacuum;

(3) pre-treating a pre-column core: ultrasonically cleaning the pre-column core by using methanol and ultrapure water in sequence, and drying;

(4) assembling an on-line micro solid phase extraction column: mixing PS/SiO₂Filling @ PDA composite nano-fibers into the pre-column core pretreated in the step (3), assembling the pre-column core with a stainless steel sieve plate and a Teflon sealing piece at the top of the column, then loading the pre-column core into a matched pre-column sleeve, and assembling to obtain a micro-solid phase extraction column; a six-way valve is arranged between the liquid chromatographic column and the automatic sample injector, and the micro-solid phase extraction column is used for replacing a quantitative ring of the six-way valve to construct and complete the on-line micro-solid phaseAnd (4) an extraction column.

In the above scheme, the silica in step (1): the mass ratio of polystyrene is 74: 1-76: 1; the concentration of silicon dioxide in the electrostatic spinning solution is 1.5-2.5 mg/ml, and the concentration of polystyrene is 1.4-1.6 g/ml

In the scheme, the specific operation of electrostatic spinning in the step (1) is as follows: transferring the electrostatic spinning solution into a plastic injector, fixing the plastic injector on a constant-current injection pump, applying 18-20 kV of direct-current voltage by using an aluminum foil wrapped by filter paper as an electrostatic spinning collector, connecting a stainless steel needle tip with a positive electrode, connecting the electrostatic spinning collector with a negative electrode, wherein the distance between the positive electrode and the negative electrode is 15-20 cm, the flow rate of the constant-current injection pump is 0.8-1 ml/h, and the duration of electrostatic spinning is 4-8 h.

In the scheme, the dopamine hydrochloride solution in the step (2) is prepared by a mixed solvent of Tris buffer solution and methanol, and the concentration of dopamine is 2-3 mg/ml.

In the above scheme, the concentration of the Tris buffer is 10mM, the pH is 8.5, and the volume ratio of the Tris buffer to methanol is 1: 1-1: 1.2.

in the present invention, the PS/SiO₂The application method of the @ PDA composite nanofiber on-line micro solid-phase extraction column comprises the following steps: firstly, an extraction process is carried out, wherein a certain volume of sample solution is extracted at a Loading position at a certain flow rate; after extraction is finished, a certain volume of deionized water is taken to quickly drip wash the online micro solid-phase extraction column, and residual sample solution is removed; after the leaching is finished, the valve of the six-way valve is quickly turned to the Injection position to carry out the desorption process, the mobile phase in the liquid chromatogram starts to carry out dynamic reverse desorption, the desorption flow rate of the target object is the flow rate of the mobile phase in the liquid chromatogram, the desorption time is consistent with the operation time of the liquid chromatogram method, and all the desorbed target object is introduced into the chromatographic column to enter a subsequent detector for analysis and detection.

The invention has the beneficial effects that:

(1) the invention provides a micro solid phase extraction column, which uses PS/SiO with hydrophobic inner layer and hydrophilic outer layer₂@PDAThe composite nano fiber is used as a micro solid phase extraction adsorbent, the adsorbent material has a three-dimensional network structure, high porosity, large specific surface area and good physical and chemical stability, and is similar to pure PS/SiO₂Compared with electrostatic spinning materials, the adsorbent material PS/SiO of the invention₂The @ PDA has the advantages of higher enrichment effect, stronger matrix interference resistance, good biocompatibility, low preparation cost, economy and environmental protection;

(2) the invention uses PS/SiO₂The @ PDA composite nanofiber micro solid-phase extraction column is combined with an online extraction technology, so that the automation degree is high, the operation is simple and convenient, the error source of detection is reduced, the sensitivity of an instrument is increased, and the method is suitable for sample pretreatment of trace analytes in a complex matrix;

(3) the on-line micro solid phase extraction column is utilized for analysis and detection, not only has low detection limit and good reproducibility, but also has low cost and long service life compared with the existing one-time commercial solid phase extraction column.

Drawings

FIG. 1 is PS/SiO₂The preparation flow chart of the @ PDA composite nanofiber.

FIG. 2 is PS/SiO₂An experimental flow chart of the on-line combination of the @ PDA micro solid phase extraction column and the liquid phase-mass spectrum.

FIG. 3 is a topographical view of a material: FIGS. 3A and 3B are PS, PS/SiO, respectively₂8000 times of magnified scanning electron microscope images; FIG. 3C and the interpolated FIG. 3C-1 are PS/SiO, respectively₂Scanning electron micrographs of @ PDA fiber at 5000 and 15,000 times magnification; FIG. 3D is PS/SiO₂@ PDA is a transmission electron micrograph at 20,000 times magnification; FIGS. 3E, 3F and 3G are PS, PS/SiO, respectively₂And PS/SiO₂Contact angle plot of @ PDA material.

FIG. 4 is PS/SiO₂The service life of the on-line micro solid phase extraction column of @ PDA.

FIG. 5A is PS/SiO₂@ PDA extraction column and self-made PS/SiO₂Comparing the enrichment effect of the extraction column; FIG. 5B is a graph comparing the enrichment effect of three different detection modes (autosampler, offline and online).

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.