A diamond-like carbon film chromatographic column, its preparation method and use

Abstract

The present invention provides a diamond-like carbon film chromatographic column, a preparation method thereof and uses thereof. The preparation method of the diamond-like carbon film chromatographic column is as follows: a ternary nano-composite coating formed by a metal element, an N element and a C element is formed on the inner wall of the chromatographic column by using a micro-arc ion plating technique. The chromatographic column of the present invention can effectively reduce the non-specific adsorption of target analytes sensitive to metals, obtain stable, effective and ideal analysis results, and at the same time does not affect the durability and convenience of the chromatographic column.

Description

Technical Field

[0001] The present invention relates to the technical field of chromatographic analysis, and particularly to a diamond-like carbon film chromatographic column, a preparation method thereof and uses thereof. Background Art

[0002] Diamond-like carbon film, having performance characteristics similar to those of diamond film, is a new type of thin film material with high hardness, low friction coefficient, high chemical stability, high resistivity and high infrared transmittance. Since an unusual hardness and good chemical properties of a chemically vapor deposited (CVD) carbon form of thin film appeared by accident in 1963, many foreign research institutions began to study the deposition process of diamond thin film. In 1971, Aisenberg, Chabot and others used the ion beam evaporation method, with graphite as the thin film material, and decomposed and ionized graphite by argon arc discharge to generate carbon ions. The carbon ions were focused into a beam by a magnetic field and deposited on a substrate at room temperature in a low-pressure deposition chamber under relatively high vacuum conditions to form a hard carbon film. This hard carbon film has some characteristics similar to diamond - such as high transparency, high impedance and high hardness. At that time, this film was called i-form carbon. It was not until 1976 that Spencer and others explored the structure of this hard carbon film, and it was confirmed that there were several carbon-based crystals such as diamond in the film, and then it was called diamond-like carbon film. In the same year, Derjaguin and others synthesized diamond thin film by the chemical conversion method. Since then, the low-pressure CVD diamond thin film process has attracted people's attention. In the mid-1970s, some scholars demonstrated the practical CVD diamond thin film technology, and then the Japanese imitated and developed this technology. Currently, diamond and diamond-like carbon thin films are mainly prepared by the low-pressure chemical vapor deposition (CVD) technology. The low-pressure CVD technology includes the hot filament CVD method, the plasma CVD method, the ion beam evaporation method, the photo / laser CVD method, the additional active hydrogen laser CVD method, etc.

[0003] Liquid chromatography is a class of separation and analysis techniques, characterized by using a liquid as the mobile phase, and the stationary phase can have various forms, such as paper, thin plates, and packed beds, etc. During the development of chromatography techniques, in order to distinguish various methods, respective nomenclatures were generated according to the form of the stationary phase, such as paper chromatography, thin-layer chromatography, and column liquid chromatography. In classical liquid chromatography, the mobile phase slowly flows through the chromatographic column by gravity, so the particle size of the stationary phase cannot be too small (about 100 μm - 150 μm). The separated samples are analyzed after being collected separately, making classical liquid chromatography not only have low separation efficiency, slow analysis speed, but also relatively complex operation. It wasn't until the 1960s that highly efficient stationary phases with particle sizes less than 10 μm were developed, and high-pressure infusion pumps and automatically recorded detectors were used, overcoming the shortcomings of classical liquid chromatography and developing into high-performance liquid chromatography, also known as high-pressure liquid chromatography. However, in the analysis of metal-sensitive compounds as target compounds, the non-specific adsorption generated by the chromatographic column is an inevitable problem, which will lead to a large relative standard deviation (RSD) in the chromatographic results and a large number of overlapping chromatographic peaks, affecting the accurate results obtained from chromatographic analysis. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a diamond-like carbon film chromatographic column, its preparation method and uses, for solving the problem of how to better improve the reliability, consistency, etc. of chromatographic analysis results when using small-particle-size silica gel fillers in the prior art.

[0005] To achieve the above object and other related objects, the present invention is realized by including the following technical solutions.

[0006] The present invention first provides a preparation method of a diamond-like carbon film chromatographic column, which forms a ternary nano-composite coating composed of metal elements, N elements, and C elements on the inner wall of the chromatographic column by using micro-arc ion plating technology.

[0007] Preferably, the chromatographic column is made of metal or glass. More preferably, the chromatographic column is made of metal.

[0008] Preferably, the metal element is selected from one or more of Cr, Al, Cr, Ti, and Fe.

[0009] Preferably, in the micro-arc ion plating technology, three C targets and one metal elemental target are used, and a negative bias pulse power supply is adopted.

[0010] Preferably, the thickness of the ternary nano-composite coating is 0.10 - 0.15 μm.

[0011] Preferably, a Cr underlayer with a thickness of 0.01 - 0.05 μm is first formed; then the ternary nano-composite coating is formed.

[0012] More preferably, first clean the column tube of the chromatographic column to remove impurities, and then deposit a Cr underlayer on the inner wall of the chromatographic column; then supply nitrogen, adjust the two target materials to work simultaneously to form a deposition transition layer, and until the power densities of the two targets are adjusted to the set values, maintain the respective parameter conditions and deposit the working layer.

[0013] Preferably, cleaning the column tube of the chromatographic column includes atmospheric pressure plasma cleaning.

[0014] Preferably, when depositing the underlayer of metal elements, turn off the power supply of the C target, and gradually increase the power density of the elemental metal target to 0.2 - 3.2 W / cm 2 , such as 1.0 W / cm 2 , 1.5 W / cm 2 , 2.0 W / cm 2 , 2.5 W / cm 2 or 3.0 W / cm 2 .

[0015] More preferably, when depositing the underlayer of metal elements, the electrical parameters are -150 V, 250 KHz, 500 ns.

[0016] Preferably, during the process of depositing the transition layer, from the start of the C target working to adjusting the power density of the C target to 40 - 50 W / cm 2 , simultaneously adjust the nitrogen pressure to 10 - 18 MPa, and at the same time adjust the power density of the elemental metal target to 0.2 - 0.8 W / cm 2 .

[0017] In a more specific embodiment, when depositing the filter layer, the electrical parameters are -60 V, 50 KHz, 1500 ns.

[0018] Preferably, when depositing the transition layer, the deposition time is 10 - 15 min.

[0019] Preferably, when depositing the working layer, the deposition time is 50 - 100 min.

[0020] Preferably, use a negative bias pulse power supply to perform plasma cleaning on the column tube of the chromatographic column; the power density of the C target is 5 - 8.5 W / cm 2 ; the power density of the elemental metal target is 0.1 - 0.4 W / cm 2 . More preferably, during the plasma cleaning, the electrical parameters are -400 V, 250 KHz, 500 ns.

[0021] The present invention also provides a diamond-like carbon film chromatographic column formed by using the preparation method as described above.

[0022] Preferably, in the ternary nano-composite coating, the content of C atoms existing in the form of sp3 hybrid bonds is higher than that of C atoms existing in the form of sp2 hybrid bonds.

[0023] Use of the diamond-like film chromatographic column as described above as a liquid chromatographic column, a gas chromatographic column or a supercritical chromatographic column.

[0024] Use of the diamond-like film chromatographic column as described above as a chromatographic column in the field of chromatographic analysis for treating metal-sensitive target analytes.

[0025] According to the use as described above, it is characterized in that the metal-sensitive target analyte is selected from one or more of organic acids, organophosphates, oligonucleotides, phosphopeptides, acidic free oligosaccharides and phospholipids, polypeptides and bovine serum albumin.

[0026] Preferably, the organophosphates are specifically such as sodium dexamethasone phosphate.

[0027] As described above, the diamond-like film chromatographic column of the present invention, its preparation method and use have the following beneficial effects:

[0028] This application provides an innovative high-performance chromatographic column with a diamond-like thin film coated on the surface, which can effectively reduce non-specific adsorption caused by the interaction between metal and metal-sensitive compounds without using complex mobile phases or cumbersome methods. By eliminating the secondary interaction with metal through the coating, in chromatographic analysis, the adoption of this chromatographic column can enable metal-sensitive compounds to obtain sharper chromatographic peak shapes, achieve faster, more reproducible and accurate data integration; at the same time, the system aging step can be omitted, shortening the time from injection to obtaining results. Description of the Drawings

[0029] Figure 1 SEM images showing the surface morphology of the coatings of the diamond-like film chromatographic columns prepared in Examples 1 to 4.

[0030] Figure 2 SEM images showing the surface morphology of the coatings of the diamond-like film chromatographic columns prepared in Comparative Example 3.

[0031] Figure 3 SEM images showing the surface morphology of the coatings of the diamond-like film chromatographic columns prepared in Comparative Examples 4 to 6.

[0032] Figure 4 Comparison diagrams of XPS spectra of the diamond-like film chromatographic columns prepared in Examples 1 to 3 and the coated chromatographic columns in the prior art.

[0033] Figure 5 Diagrams showing the column efficiency test results of the coated chromatographic columns prepared in Examples 1 to 3 and Comparative Examples 1 to 3.

[0034] Figure 6 shows the test effect diagrams of successively injecting 5 needles continuously using the diamond-like carbon film chromatographic column prepared in Example 1.

[0035] Figure 7 It shows the test effect diagrams of successively injecting 6 needles continuously using the diamond-like carbon film chromatographic column prepared in Example 2.

[0036] Figure 8 It shows the test effect diagrams of successively injecting 6 needles continuously using the diamond-like carbon film chromatographic column prepared in Example 3.

[0037] Figure 9 It shows the test effect diagrams of successively injecting 6 needles continuously using the coated chromatographic column prepared in Comparative Example 1.

[0038] Figure 10 It shows the test effect diagrams of successively injecting 6 needles continuously using the coated chromatographic column prepared in Comparative Example 2.

[0039] Figure 11 It shows the test effect diagrams of successively injecting 6 needles continuously using the coated chromatographic column prepared in Comparative Example 3.

[0040] Figure 12 It shows the comparison diagram of the liquid chromatography-mass spectrometry test results of the chromatographic column before and after coating in Example 1 for bovine serum albumin. Detailed implementation manners

[0041] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0042] Before further describing the specific implementation manners of the present invention, it should be understood that the protection scope of the present invention is not limited to the specific specific implementation manners described below; it should also be understood that the terms used in the embodiments of the present invention are used to describe specific specific implementation manners, rather than to limit the protection scope of the present invention; in the specification and claims of the present invention, unless otherwise clearly specified in the text, the singular forms "a", "an" and "the" include the plural forms.

[0043] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art of this technology. In addition to the specific methods, devices, and materials used in the embodiments, according to the knowledge of those skilled in the art of this technology and the description of the present invention, any methods, devices, and materials of the prior art similar or equivalent to those described in the embodiments of the present invention can also be used to implement the present invention.

[0044] As described above, the above are only the preferred embodiments of the present invention, and there is no limitation in any form and essence to the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. Those skilled in the art, without departing from the spirit and scope of the present invention, when making some equivalent changes, modifications, and evolutions using the technical content disclosed above, are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

[0045] In this application, the applicant provides an innovative chromatographic column, which forms a ternary nano-composite coating composed of metal elements, N elements, and C elements on the inner wall of the chromatographic column by using micro-arc ion plating technology.

[0046] Based on considerations of the application effect of the chromatographic column and factors such as the application of the chromatographic column, the thickness of the ternary nano-composite coating is 0.10 - 0.15 μm.

[0047] In a specific embodiment, the metal element is selected from one or more of Cr, Al, Cr, Ti, and Fe. Considering the use effect of the coating formed by micro-arc ion plating technology in the field of chromatographic analysis, the applicant found that the Cr target is the most suitable.

[0048] In a specific embodiment, when using micro-arc ion plating technology, a Cr underlayer with a thickness of 0.01 - 0.05 μm is first formed; then the ternary nano-composite coating is formed. Thus, the bonding force between the ternary nano-composite coating and the column tube of the chromatographic column is enhanced. In this application, the material of the column tube of the chromatographic column is a metal material or a glass material. More specifically, a metal material, namely stainless steel material, is selected, and it is stainless steel material in both the embodiments and comparative examples of this application.

[0049] In micro-arc ion plating technology, three C targets and a metal elemental target are used, and a negative bias pulse power supply is adopted.

[0050] In a more specific embodiment, first clean the chromatographic column tube to remove impurities, and then deposit a Cr underlayer on the inner wall of the chromatographic column; then provide nitrogen, adjust the two target materials to work simultaneously and deposit the transition layer. Until the power densities of the two targets are adjusted to the set values, maintain the parameter conditions and deposit the working layer.

[0051] The means for cleaning the chromatographic column tube to remove impurities can be those in the prior art, mainly to remove organic substances, adsorbed substances or pollutants on the surface of the chromatographic column, such as one or more of alkali washing, water washing, organic solvent cleaning, oil and ester removal agent cleaning. In this application, isobaric plasma cleaning is specifically used. The main purpose is to remove the adsorbed substances and pollutants on the surface of the target and the chromatographic column tube, and at the same time increase the bonding ability of the surface of the chromatographic column tube.

[0052] In a more specific embodiment, a negative bias pulse power supply is used to perform plasma cleaning on the chromatographic column tube. In the following specific embodiments and comparative examples, the parameters of the plasma cleaning are: electrical parameters: -400V, 250KHz, 500ns; the power density of the C target is 8.5W / cm 2 ; the power density of the elemental metal target is 0.4W / cm 2 .

[0053] For the diamond-like carbon film chromatographic column formed by the method in this application, in the ternary nano-composite coating, the content of C atoms existing in the form of sp3 bond hybridization is higher than that of C atoms existing in the form of sp2 bond hybridization.

[0054] The chromatographic columns used in the following more specific embodiments and comparative examples of this application all undergo the following cleaning treatment process before coating: 1); First, pre-grind the chromatographic column tube with water sandpaper in the order of sandpaper particle size from coarse to fine: 280, 400, 500, 1000, 1200, 1500; 2) Then slowly rinse the wall with 0.1mol / L sodium hydroxide 5 times. 3) The oil and grease removal process is to perform ultrasonic cleaning in an oil and grease removal agent water bath for 30 minutes, the water bath temperature is 40°C, then wash 4 times with deionized water to remove the residual oil and grease removal agent, and finally perform ultrasonic cleaning in a cold water bath with absolute ethanol for 10 minutes. In the following more specific embodiments and comparative examples, the chromatographic column used for coating is a stainless steel chromatographic column.

[0055] Example 1

[0056] This embodiment provides a diamond-like carbon film chromatographic column, which is prepared by the following steps:

[0057] First, perform atmospheric pressure plasma cleaning on the chromatographic column tube. The plasma cleaning is as follows: Turn on the negative bias pulse power supply to perform ion cleaning on the chromatographic column tube for 10 minutes. The electrical parameters are -400V, 250KHz, 500ns, and the power densities of the C target and Cr target are 8.5W / cm 2 and 0.4W / cm 2 ;

[0058] Then deposit a Cr underlayer: Gradually adjust the bias voltage to -150V, turn off the C target power supply, and gradually increase the Cr target power density to 3.2W / cm 2 , and the deposition time is 15 minutes;

[0059] After that, deposit a transition layer: Turn on the three C target power supplies, gradually adjust the C target power density to 40W / cm 2 , adjust the Cr target power density to 0.2W / cm 2 , and at the same time gradually increase the N2 gas flow rate, deposit the transition layer for 15 minutes, and the electrical parameters are -60V, 50KHz, 1500ns;

[0060] Finally, deposit the working layer: Fix the power densities of the C target and Cr target, keep the electrical parameters unchanged, and deposit the working layer for 90 minutes.

[0061] Example 2

[0062] This example provides a diamond-like carbon film chromatographic column, which is prepared by the following method:

[0063] Clean the chromatographic column tube by atmospheric pressure plasma cleaning technology. The plasma cleaning is as follows: Turn on the negative bias pulse power supply to perform ion cleaning on the chromatographic column tube for 10 minutes. The electrical parameters are -400V, 250KHz, 500ns, and the power densities of the C target and Cr target are 8.5W / cm 2 and 0.4W / cm 2 ;

[0064] Then deposit a Cr underlayer: Gradually adjust the bias voltage to -150V, turn off the C target power supply, and gradually increase the Cr target power density to 3.2W / cm 2 , and the deposition time is 15 minutes;

[0065] After that, deposit a transition layer: Turn on the three C target power supplies, gradually adjust the C target power density to 45W / cm 2 , adjust the Cr target power density to 0.25W / cm 2 , and at the same time gradually increase the N2 gas flow rate, deposit the transition layer for 15 minutes, and the electrical parameters are -60V, 50KHz, 1500ns;

[0066] Final deposition of the working layer: Fix the power densities of the C target and the Cr target, keep the electrical parameters unchanged, and deposit the working layer for 60 minutes.

[0067] Example 3

[0068] This example provides a diamond-like carbon film chromatographic column, which is prepared by the following steps:

[0069] Clean the chromatographic column tube using the atmospheric pressure plasma cleaning technique. Plasma cleaning is to turn on the negative bias pulse power supply to perform ion cleaning on the chromatographic column tube for 10 minutes. The electrical parameters are -400 V, 250 kHz, 500 ns, and the power densities of the C target and the Cr target are 8.5 W / cm 2 and 0.4 W / cm 2 ;

[0070] Subsequently deposit a Cr underlayer: Gradually adjust the bias voltage to -150 V, turn off the C target power supply, and gradually increase the power density of the Cr target to 3.2 W / cm 2 , and the deposition time is 15 minutes;

[0071] Then deposit a transition layer: Turn on the power supplies of three C targets, gradually adjust the power density of the C target to 48 W / cm 2 , adjust the power density of the Cr target to 0.35 W / cm 2 , and at the same time gradually increase the N2 gas flow rate, deposit the transition layer for 15 minutes, and the electrical parameters are -60 V, 50 kHz, 1500 ns;

[0072] Final deposition of the working layer: Fix the power densities of the C target and the Cr target, keep the electrical parameters unchanged, and deposit the working layer for 100 minutes.

[0073] Example 4

[0074] This example provides a diamond-like carbon film chromatographic column, which is prepared by the following steps:

[0075] Clean the chromatographic column tube using the atmospheric pressure plasma cleaning technique. Plasma cleaning is to turn on the negative bias pulse power supply to perform ion cleaning on the chromatographic column tube for 10 minutes. The electrical parameters are -400 V, 250 kHz, 500 ns, and the power densities of the C target and the Cr target are 8.5 W / cm 2 and 0.4 W / cm 2 ;

[0076] Subsequently deposit a Cr underlayer: Gradually adjust the bias voltage to -150 V, turn off the C target power supply, and gradually increase the power density of the Cr target to 3.2 W / cm 2 , and the deposition time is 15 minutes;

[0077] Deposit the transition layer afterwards; turn on the power supplies of three C targets, and gradually adjust the C target power density to 50 W / cm 2 , adjust the Cr target power density to 0.5 W / cm 2 , meanwhile, gradually increase the N2 gas flow rate, deposit the transition layer for 15 min, and the electrical parameters are -60 V, 50 KHz, 1500 ns;

[0078] Finally, deposit the working layer: fix the C target and Cr target power densities, keep the electrical parameters unchanged, and deposit the working layer for 60 min.

[0079] Comparative Example 1

[0080] Comparative 1 is the comparative example of Example 1. During the coating process of the chromatographic column tube, when depositing the working layer, the deposition time is replaced from 90 min in Example 1 to 20 min, and the rest remains unchanged.

[0081] Comparative Example 2

[0082] Comparative 2 is the comparative example of Example 1. During the coating process of the chromatographic column tube, when depositing the working layer, the Cr target power density is changed from 0.5 W / cm 2 to 0.05 W / cm 2 , and the rest remains unchanged.

[0083] Comparative Example 3

[0084] Comparative 3 is the comparative example of Example 1. During the coating process of the chromatographic column tube, when depositing the working layer, the C target power density is adjusted from 40 W / cm 2 to 10 W / cm 2 , and the rest remains unchanged.

[0085] Comparative Example 4

[0086] Comparative Example 5 is the comparative example of Example 1. During the coating process of the chromatographic column tube, the metal target is changed to a Ti target.

[0087] Comparative Example 5

[0088] Comparative Example 5 is the comparative example of Example 1. During the coating process of the chromatographic column tube, the metal target is changed to an Al target.

[0089] Comparative Example 6

[0090] Comparative 4 is the comparative example of Example 1. During the coating process of the chromatographic column tube, the metal target is changed to an Fe target.

[0091] Performance result test part

[0092] A) SEM test result analysis:

[0093] Figure 1Shown are SEM images of the coating surface morphologies of the diamond-like carbon film chromatographic columns prepared in Examples 1 to 4. As Figure 1 shown, it can be seen that the coatings formed in Examples 1 to 4 have a flat, delicate and uniform surface, completely covering the chromatographic column substrate.

[0094] Figure 2 Shown are SEM images of the coating surface morphologies of the diamond-like carbon film chromatographic columns prepared in Comparative Example 3. As Figure 2 shown, it can be seen that compared with Examples 1 to 4, the flatness of the coating surface decreases, and some of the chromatographic column substrate is exposed.

[0095] Figure 3 Shown are SEM images of the coating surface morphologies of the diamond-like carbon film chromatographic columns prepared in Comparative Examples 4 to 6. As Figure 3 shown, the coating formed by the Cr target has fine particle size and a flatter surface; while the coatings formed by the Ti, Al, and Fe targets all show a cluster phenomenon of particle aggregation, with obvious gaps between the clusters, making it difficult to control their uniform distribution on the surface of the chromatographic column substrate, resulting in a decrease in the flatness of the coating surface, and due to aggregation, some of the substrate is easily exposed.

[0096] B) X-ray photoelectron spectroscopy (XPS) test.

[0097] The spectra of the coated chromatographic columns in Examples 1 to 4 are as Figure 4 shown. By comparison, it is found that the main peak positions in the spectra of Examples 1 to 4 are all between 284.4 - 285.2 eV, closer to 285.2 eV; indicating that in the C atoms of the coating in this application, there are both sp2 and sp3 hybridization forms, and the sp3 hybridization form is the main one.

[0098] C) Liquid chromatography test (column efficiency):

[0099] Chromatographic packing: XB-C18 5μm; Chromatographic column specification: 4.6 * 250 mm;

[0100] Mobile phase: methanol - water = 75 - 25; Flow rate: 1 ml / min; Column temperature: 25 °C; Detection wavelength: 254 nm Injection volume: 10 μl;

[0101] Sample (UIT): Uracil 5 μg / ml, Phenol 200 μg / ml, 4-Chloronitrobenzene 25 μg / ml, Toluene 850 μg / ml, dissolved in the mobile phase.

[0102] Figure 5 Shown are the column efficiency test result graphs of the coated chromatographic columns prepared in Examples 1 to 3 and Comparative Examples 1 to 3. Among them, Figure 5 in the upper row, from left to right in sequence are Examples 1 to 3; Figure 5In the lower middle row, from left to right are Comparative Examples 1 to 3 in sequence.

[0103] It can be seen from Figure 5 above that the column efficiencies of Examples 1 to 3 are all above 20,000, while the column efficiencies of Comparative Examples 1 to 3 are around 10,000. The column efficiency of the examples is better than that of the comparative examples, and there is partial tailing in the comparative examples.

[0104] D) Application of liquid chromatography - mass spectrometry test: Determination of sodium dexamethasone phosphate

[0105] Instrument model: AB Sciex TRIPLE QUAD 4500

[0106] Liquid chromatography conditions: Mobile phase: A: 5 mmol / L ammonium formate solution; B: acetonitrile - methanol (1:1) Flow rate: 0.2 mL / min Column temperature: 30 °C Injection volume: 2 μL.

[0107] Gradient elution program

[0108] Time / min Phase A / % Phase B / % 0.00 85 15 1.50 55 45 2.50 5 95 5.00 5 95 5.10 85 15 8.00 85 15

[0109] Figure 6a It shows the test effect diagrams of successively injecting 5 needles continuously using the diamond - like carbon film chromatographic column prepared in Example 1.

[0110] Figure 6b It shows the test effect diagram of the 20th needle using the diamond - like carbon film chromatographic column prepared in Example 1.

[0111] Figure 7 It shows the test effect diagrams of successively injecting 6 needles continuously using the diamond - like carbon film chromatographic column prepared in Example 2.

[0112] Figure 8 It shows the test effect diagrams of successively injecting 6 needles continuously using the diamond - like carbon film chromatographic column prepared in Example 3.

[0113] It can be seen from Figures 6 - 8 that the diamond - like carbon film chromatographic columns prepared in Examples 1 to 3 have good analysis effects on sodium dexamethasone phosphate, high sensitivity, good durability, and good batch reproducibility. Figure 6b It can be seen that the diamond - like carbon film chromatographic column prepared in Example 1 still has good sensitivity and column efficiency after 20 needles.

[0114] Figure 9 It shows the test effect diagrams of successively injecting 6 needles continuously using the coated chromatographic column prepared in Comparative Example 1. It can be seen that the durability of the final coating becomes poor, which is reflected in the weakening of the peak height after 4 needles.

[0115] Figure 10Shown is the test effect diagram of successively injecting 6 needles continuously using the coated chromatographic column prepared in Comparative Example 2. The final coating is unevenly distributed, with some chromatographic column substrates exposed, resulting in non-specific adsorption with the target substance; it is manifested that the peak height decreases and the noise increases significantly starting from the first needle.

[0116] Figure 11 Shown is the test effect diagram of successively injecting 6 needles continuously using the coated chromatographic column prepared in Comparative Example 3. The coating produced in Comparative Example 3 causes the substrate to be exposed, resulting in non-specific adsorption with the target substance; it is manifested that the peak height decreases and the noise increases significantly starting from the first needle.

[0117] E) Liquid chromatography - mass spectrometry test application: Determination of bovine serum albumin

[0118] Chromatographic packing: SEC - 300, 5 μm; Chromatographic column specification: 4.6 * 250 mm; Mobile phase: 8.99 g of anhydrous sodium dihydrogen phosphate + 10.65 g of anhydrous disodium hydrogen phosphate in 1000 ml of water, adjust pH = 6.80; Flow rate: 0.35 ml / min Column temperature: 30 °C Detection wavelength: 215 nm Injection volume: 5 μl; Sample: Weigh an appropriate amount of BSA precisely, dissolve and dilute it with the mobile phase to obtain a sample solution containing 0.1 mg per 1 ml.

[0119] The diamond - like carbon film chromatographic column prepared in Example 1 and the uncoated chromatographic column in the example were tested. The test results are as Figure 12 shown, and it can be seen from Figure 12 that the column efficiency of the coated column tube of the diamond - like carbon film chromatographic column in this application is more than twice that of the uncoated column tube, the tailing factor is significantly better than that of the uncoated column tube, and the peak shape of the coated column tube is better than that of the uncoated column tube.

[0120] The above embodiments are to illustrate the implementation schemes disclosed in the present invention and should not be construed as limitations on the present invention. In addition, various modifications listed herein and changes in the methods and compositions of the invention are obvious to those skilled in the art without departing from the scope and spirit of the present invention. Although the present invention has been specifically described in conjunction with various specific preferred embodiments of the present invention, it should be understood that the present invention should not be limited to these specific embodiments. In fact, all obvious modifications to those skilled in the art as described above to obtain the invention should be included within the scope of the present invention.

Claims

1. A method for preparing a diamond-like carbon film chromatographic column, characterized in that, First, clean the chromatographic column tube to remove impurities. Using the micro-arc ion plating technology, first form a Cr underlayer with a thickness of 0.01 - 0.05 μm on the inner wall of the chromatographic column, and then form a ternary nano-composite coating composed of metal elements, N elements, and C elements; The preparation method of the ternary nano-composite coating includes: providing nitrogen, adjusting the materials of two targets to work simultaneously to form a deposition transition layer. After adjusting the power densities of both targets to the set values, maintaining each parameter condition and depositing the working layer. During the process of depositing the transition layer, start the C target to work until the power density of the C target is adjusted to 40-50 W / cm 2 , while adjusting the nitrogen pressure to 10-18 MPa, and at the same time adjusting the power density of the metal elemental target to 0.2-0.8 W / cm 2 ; When depositing the working layer, the deposition time is 50 - 100 min; In the ternary nano-composite coating, the content of C atoms existing in the form of sp3 hybrid bonds is higher than that of C atoms existing in the form of sp2 hybrid bonds; the metal element and the metal simple substance are Cr.

2. The preparation method according to claim 1, characterized in that, The chromatographic column is made of metal or glass.

3. The preparation method according to claim 1, wherein, In the micro-arc ion plating technology, three C targets and one metal simple substance target are used, and a negative bias pulse power supply is adopted.

4. The preparation method according to claim 1, characterized in that, The thickness of the ternary nano-composite coating is 0.10 - 0.15 μm.

5. The preparation method according to claim 1, characterized in that, Cleaning the chromatographic column tube includes atmospheric pressure plasma cleaning.

6. The preparation method according to claim 1, characterized in that, When depositing the Cr underlayer, turn off the power supply of the C target and gradually increase the power density of the elemental metal target to 1.0 - 3.2 W / cm 2 .

7. The preparation method according to claim 5, wherein The column tube of the chromatographic column is subjected to plasma cleaning using a negative bias pulse power supply; the power density of the C target is 5-8.5 W / cm 2 ; the power density of the metal elemental target is 0.1-0.4 W / cm 2 .

8. A diamond-like carbon film chromatographic column formed by using the preparation method according to any one of claims 1 - 7.

9. Use of the diamond-like carbon film chromatographic column according to claim 8 as a liquid chromatographic column, a gas chromatographic column, or a supercritical chromatographic column.

10. Use of the diamond-like carbon film chromatographic column according to claim 8 as a chromatographic column in the field of chromatographic analysis for treating metal-sensitive target analytes.

11. The use according to claim 10, characterized in that, The metal-sensitive target analytes are selected from one or more of organic acids, organophosphates, oligonucleotides, phosphopeptides, acidic free oligosaccharides, phospholipids, and polypeptides.

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