CN103611511B - A kind of preparation method of grapheme open-tube electric chromatographic column - Google Patents

Abstract

The invention relates to a preparation method of a graphene open-tube electrochromatographic column, relating to a preparation method of a novel capillary electrochromatographic column with conductive polymer polyaniline assisted-polydopamine bonded graphene oxide as a stationary phase, and a conductive polymer polyaniline bond Combined with the inner wall of the capillary as a bottom material, it not only improves the specific surface area of the capillary, but also significantly shortens the modification time and times of dopamine, improves the degree of modification of polydopamine, and is more conducive to the reaction of graphene oxide. The invention is easy to operate , low cost, the whole preparation process is carried out in aqueous solution, no organic solvents or toxic reagents are used, no pollution to the environment, various coatings prepared have good stability, and the capillary column has a long service life. Compared with the polydopamine-bonded graphene oxide open-tubular column, the tube electrochromatographic column significantly improves the chromatographic performance of the graphene open-tubular column, and has a better separation effect on benzene homologues.

Description

A kind of preparation method of graphene open-tube electrochromatographic column

technical field

The invention relates to the technical field of chromatography, in particular to a preparation method of a graphene open-tube electrochromatographic column.

Background technique

Capillary electrochromatography is a new type of micro-separation technology with high efficiency, rapidity and high selectivity. It is developed by combining the advantages of high efficiency of capillary electrophoresis and high selectivity of high performance liquid chromatography, and has the advantages of fast analysis speed, high column efficiency, and less consumption of samples and solvents. The preparation of electrochromatographic column is the core of capillary electrochromatographic separation and analysis. The performance of chromatographic columns such as column efficiency, column reproducibility, and column life are the evaluation indicators for the practical application of chromatographic columns. Therefore, the preparation of electrochromatographic columns with good separation performance is the focus of research in the field of chromatography.

Graphene is a monoatomic layer network formed by sp ² hybridized carbon atoms. Due to its very large specific surface area and highly delocalized π-electron system, it can form strong adsorption and π-π stacking effects with hydrophobic and π-electron-containing compounds, so it has gradually been developed for chromatographic separation.

 The method of using polydopamine to bond graphene oxide can fix graphene oxide on the inner wall of capillary, and then use it for electrochromatographic separation. Dopamine can be polymerized on the surface of various organic or inorganic materials to form polydopamine, but the modification of polydopamine on the inner wall of capillary requires repeated coating, and the modification takes a long time.

Contents of the invention

For overcoming the problems existing in the background technology, the invention provides a kind of preparation method of graphene electrochromatographic column, and concrete technical scheme is as follows:

A preparation method of a graphene open-tube electrochromatographic column, comprising the steps of:

(1) Pretreatment of the capillary: the capillary is washed with 1M NaOH for 2 hours in turn, washed with pure water for half an hour, and dried with nitrogen;

(2) Prepare N-phenyl-3-aminopropyltrimethoxysilane-ethanol solution, pass it into the capillary obtained in step (1) for silanization reaction, react at 60°C for 12~24h, and then use pure ethanol washing, drying with nitrogen;

(3) Separately configure 0.2M aniline hydrochloric acid solution and 0.05M ammonium persulfate hydrochloric acid solution, mix the above two solutions in equal volumes and quickly pass them into the capillary obtained in step (2), react overnight, and wash with pure water , and then treated at 120°C for 3 hours to obtain a capillary bonded with polyaniline;

(4) Prepare a 10 mM Tris-HCl buffer solution (pH=8.5) with a dopamine concentration of 2 mg/mL, shake it for 10 min to pre-oxidize it; pass the pre-oxidized dopamine solution through a syringe pump at a flow rate of 0.05 mL/h continuously Pass through the capillary obtained in the previous step for 8h to 16h, wash with pure water, and blow dry with nitrogen to obtain a capillary with a polydopamine-coated inner wall;

(5) Pass an aqueous solution of graphene oxide with a concentration of 1 mg/mL into the capillary obtained in step (4), seal both ends, put it in a 60°C water bath for 12-24 hours, wash with pure water to obtain graphene electrochromatography column.

As a preference:

The capillary is a quartz capillary.

The volume percentage of N-phenyl-3-aminopropyltrimethoxysilane in the N-phenyl-3-aminopropyltrimethoxysilane-ethanol solution in the step (2) is 20-50%.

There is a step (3') between the step (3) and the step (4), and the step (3') repeats the process of the step (3) for one time or more to obtain a multilayer polyaniline-modified capillary.

In the above method, the preparation methods of N-phenyl-3-aminopropyltrimethoxysilane ethanol solution, aniline hydrochloric acid solution and ammonium persulfate hydrochloric acid solution are all prior art.

In the present invention, a layer of conductive polymer polyaniline is covalently bonded to the inner wall of the capillary, and the polyaniline-modified capillary can accelerate the oxidation-reduction reaction of dopamine due to the excellent electrical conductivity of polyaniline, significantly shorten the modification time and number of modifications, and accelerate The formation of polydopamine, at the same time, the specific surface area of the capillary modified by polyaniline is significantly increased, and the modification amount of polydopamine is also significantly increased, thereby increasing the amount of covalently bonded graphene oxide, making graphene oxide easier to bond It is used for electrochromatographic separation on the inner wall of capillary.

The conductive polymer polyaniline is bonded to the inner wall of the capillary as a bottom material, which not only increases the specific surface area of the capillary, but also significantly shortens the modification time and times of dopamine, improves the modification degree of polydopamine, and is more conducive to the synthesis of graphene oxide. reaction.

Beneficial effects of the present invention:

1) The chromatographic separation performance of the open-tubular column prepared by the present invention is significantly improved compared with the polydopamine-bonded graphene oxide open-tubular column without polyaniline. The preparation process of the method is simple, easy to operate, and low in cost. The entire preparation process is carried out in aqueous solution without using organic solvents or toxic reagents, and has no pollution to the environment. At the same time, the coating obtained through layer-by-layer covalent self-assembly has relatively high good stability.

2) Compared with the polydopamine-bonded graphene oxide open-tubular column, the polyaniline-assisted-polydopamine-bonded graphene oxide open-tubular column prepared by the present invention significantly improves the chromatographic performance of the graphene open-tubular column, and the benzene Homologues have a good separation effect.

Description of drawings

Figure 1 is a schematic diagram of the preparation process of the new graphene open-tube electrochromatographic column.

Figure 2 is a scanning electron microscope image of the novel graphene open-tube electrochromatographic column. A(×1500), B(×5000), C(×50000).

Fig. 3 is an electrochromatographic separation diagram of five kinds of substituted benzenes separated by a graphene open-tube electrochromatographic column prepared in Example 1 of the present invention. Among them, peak 1 is benzene, peak 2 is toluene, peak 3 is ethylbenzene, peak 4 is n-propylbenzene, and peak 5 is n-butylbenzene.

Detailed ways

The present invention is further illustrated by the following non-limiting examples, which are not intended to limit the scope of the present invention.

Example 1

(1) Take a 60cm long quartz capillary (50 μm i.d. × 375 μm o.d.), wash it with 1M NaOH for 2 hours, rinse it with pure water for half an hour, and dry it with nitrogen; (2) Prepare N-phenyl-3-aminopropyl trimethyl Oxysilane ethanol solution (20%, v/v), put it into the pretreated capillary for silanization reaction, react at 60°C for 12h, wash with pure ethanol after the reaction, and blow dry with nitrogen; (3) Separately configure 0.2M aniline hydrochloric acid solution and 0.05M ammonium persulfate hydrochloric acid solution, the above two solutions were mixed in equal volumes and then quickly passed into the silanized capillary tube, reacted overnight, washed with pure water, and treated at 120 ° C for 3 hours, Obtain a capillary bonded with polyaniline; (4) Weigh 10 mg of dopamine and dissolve it in 5 mL of 10 mM Tris buffer, adjust the pH value to 8.5, shake the prepared dopamine solution for 10 minutes, and then dissolve it at a flow rate of 0.05 mL/h Continuously pass into the pretreated capillary for 8 hours, wash with pure water, and blow dry with nitrogen to obtain a polyaniline-bonded capillary with a polydopamine coating on the inner wall; (5) Graphene oxide with a concentration of 1 mg/mL The aqueous solution of the above-mentioned solution was passed into the capillary obtained above, both ends were sealed, put into a 60° C. water bath for 24 hours, and washed with pure water to obtain a graphene open-tube column.

The capillary column prepared in Example 1 was installed on a capillary electrophoresis apparatus for capillary electrochromatographic separation, and five kinds of substituted benzenes were successfully separated, and the obtained electrochromatogram is shown in FIG. 3 .

Example 2

(1) Take a 60cm long quartz capillary (50 μm i.d. × 375 μm o.d.), wash it with 1M NaOH for 2 hours, rinse it with pure water for half an hour, and dry it with nitrogen; (2) Prepare N-phenyl-3-aminopropyl trimethyl Oxysilane ethanol solution (20%, v/v), put it into the pretreated capillary for silanization reaction, react at 60°C for 24h, wash with pure ethanol after the reaction, and blow dry with nitrogen; (3) Separately configure 0.2M aniline hydrochloric acid solution and 0.05M ammonium persulfate hydrochloric acid solution, the above two solutions were mixed in equal volumes and then quickly passed into the silanized capillary tube, reacted overnight, washed with pure water, and treated at 120 ° C for 3 hours, A capillary bonded with polyaniline is obtained; (3′) repeating the polyaniline modification step once to obtain a double-layer polyaniline modified capillary. (4) Weigh 10 mg of dopamine and dissolve it in 5 mL of 10 mM Tris buffer, adjust the pH value to 8.5, shake the prepared dopamine solution for 10 minutes, and then continuously pass it into the pretreated capillary at a flow rate of 0.05 mL/h 8h, wash with pure water, blow dry with nitrogen gas, and obtain the polyaniline-bonded capillary with polydopamine coating on the inner wall; (5) pass an aqueous solution with a concentration of 1 mg/mL graphene oxide into the capillary obtained above , sealed at both ends, placed in a 60° C. water bath for 24 hours of reaction, washed with water to obtain a graphene open-tube column.

The above step (3') can be repeated many times.

Example 3

(1) Take a 60cm long quartz capillary (50 μm i.d. × 375 μm o.d.), wash it with 1M NaOH for 2 hours, rinse it with pure water for half an hour, and dry it with nitrogen; (2) Prepare N-phenyl-3-aminopropyl trimethyl Oxysilane ethanol solution (50%, v/v), put it into the pretreated capillary for silanization reaction, react at 60°C for 12h, wash with pure ethanol after the reaction, and blow dry with nitrogen; (3) Separately configure 0.2M aniline hydrochloric acid solution and 0.05M ammonium persulfate hydrochloric acid solution, the above two solutions were mixed in equal volumes and then quickly passed into the silanized capillary tube, reacted overnight, washed with pure water, and treated at 120 ° C for 3 hours, Obtain a capillary bonded with polyaniline; (4) Weigh 10 mg of dopamine and dissolve it in 5 mL of 10 mM Tris buffer, adjust the pH value to 8.5, shake the prepared dopamine solution for 10 minutes, and then dissolve it at a flow rate of 0.05 mL/h Continuously pass through the pretreated capillary for 16 hours, wash with pure water, and blow dry with nitrogen to obtain a polyaniline-bonded capillary with a polydopamine coating on the inner wall; (5) Graphene oxide with a concentration of 1 mg/mL The aqueous solution was passed into the capillary obtained above, both ends were sealed, put into a 60° C. water bath for 12 h, and washed with water to obtain a graphene open-tube column.

Claims (4)

1. a preparation method of graphene open-tube electrochromatographic column, is characterized in that, comprises the steps: (1) Pretreatment of the capillary: the capillary was washed with 1M NaOH for 2 hours in turn, washed with pure water for half an hour, and dried with nitrogen; (2) Prepare N-phenyl-3-aminopropyltrimethoxysilane-ethanol solution, pass it into the capillary obtained in step (1) for silanization reaction, react at 60°C for 12~24h, and then use pure ethanol washing, drying with nitrogen; (3) Prepare 0.2M aniline hydrochloric acid solution and 0.05M ammonium persulfate hydrochloric acid solution respectively, mix the above two solutions in equal volumes and quickly pass them into the capillary obtained in step (2), react overnight, and wash with pure water , and then treated at 120°C for 3 hours to obtain a capillary bonded with polyaniline; (4) Prepare a 10 mM Tris-HCl buffer solution with a dopamine concentration of 2 mg/mL and a pH value of 8.5, and shake it for 10 min to make it pre-oxidized; the pre-oxidized dopamine solution is continuously injected at a flow rate of 0.05 mL/h through a syringe pump. Pass through the capillary obtained in the previous step for 8h to 16h, wash with pure water, and blow dry with nitrogen to obtain a capillary with a polydopamine-coated inner wall; (5) Pass an aqueous solution with a concentration of 1 mg/mL graphene oxide into the capillary obtained in step (4), seal both ends, put it in a 60°C water bath for 12-24 hours, wash with pure water to obtain graphene electrochromatography column. 2. the preparation method of graphene open-tube electrochromatographic column as claimed in claim 1, is characterized in that, described capillary is quartz capillary. 3. the preparation method of graphene open-tube electrochromatographic column as claimed in claim 1, is characterized in that, in described step (2), in N-phenyl-3-aminopropyltrimethoxysilane-ethanol solution -The volume percentage of phenyl-3-aminopropyltrimethoxysilane is 20~50%. 4. the preparation method of graphene open-tube electrochromatographic column as claimed in claim 1, is characterized in that, there is step (3 ') between described step (3) and step (4), and step (3 ') repeats The process of step (3) is repeated once or more to obtain a multilayer polyaniline-modified capillary.