Carbon nanotube fiber ionization device and application

Abstract

The invention discloses a carbon nanotube ionization device which comprises an injector and a mass spectrometer (6), the injector comprises an injector body (1) and a needle (7) connected to the front end of the injector body (1), a microfiltration membrane (2) is arranged between the injector body (1) and the needle (7), the needle (7) is connected with a plastic tube (3) and the mass spectrometer (6), the plastic tube (3) is connected with a peek head (4), and the peek head (4) is connected with the mass spectrometer (6). The rear end of the carbon nano tube fiber bundle (5) is embedded into the plastic tube (3), and the front end of the carbon nano tube fiber bundle (5) is arranged in front of a sample inlet of the mass spectrometer (6). According to the method for detecting the hazardous substances in the children's products by using the carbon nanotube fiber ionization device, carbon nanotube fiber ionization is adopted as an ion source, and a small portable mass spectrometer is combined, so that an on-site rapid qualitative and quantitative method for the hazardous substances in the children's products is established; technical support can be provided for quality safety on-site analysis and detection and supervision and law enforcement of children products.

Description

Technical Field

[0001] The present invention relates to an open ionization device and its application, in particular to a carbon nanotube fiber ionization device and an analysis method for its combination with a small portable mass spectrometer. Background Art

[0002] In-situ ionization technology is an atmospheric pressure open ionization technology that has developed rapidly in recent years. Since Professor Cooks of Purdue University proposed desorption electrospray ionization (DESI), dozens of in-situ ionization technologies such as direct analysis in real time (DART), dielectric barrier discharge ionization (DBDI), and paper spray ionization (PSI) have been developed, and the development of new in-situ ionization technologies remains a research hotspot. At the same time, the development and application of small portable mass spectrometers with advantages such as light weight and small size have also been continuously deepened. The proposal and application of in-situ ionization small portable mass spectrometry combined technology have revolutionized traditional mass spectrometry analysis technology. It does not require bringing the sample back to the laboratory for cumbersome sample pretreatment and mass spectrometry analysis, realizing rapid and direct on-site analysis of the sample, and opening up a new field of mass spectrometry analysis. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a carbon nanotube fiber ionization device and an analysis method for its combination with a small mass spectrometer to detect harmful substances in children's products.

[0004] The carbon nanotube ionization device of the present invention includes a syringe and a mass spectrometer. The syringe includes a syringe body and a needle connected to its front end. A microporous filter membrane is provided between the syringe body and the needle. The needle is connected to a plastic tube and the mass spectrometer respectively. The plastic tube is connected to a peek head. The rear end of the carbon nanotube fiber bundle is embedded in the plastic tube, and the front end is arranged in front of the sample inlet of the mass spectrometer.

[0005] In the carbon nanotube ionization device of the present invention, the carbon nanotube fiber bundle contains 50 carbon nanotube fibers, and the diameter of each carbon nanotube fiber is 60 - 80 μm.

[0006] For the carbon nanotube ionization device of the present invention, the rear end of the plastic tube is connected to the needle, and the front end is inserted into the peek head and flush with its tip. The length of the carbon nanotube fiber is 1 cm, and the latter half is embedded inside the front end of the plastic tube. The front end of the carbon nanotube fiber is arranged at a position 0.5 cm in front of the inlet of the mass spectrometer.

[0007] For the carbon nanotube ionization device of the present invention, the mass spectrometer is a Miniβ small portable mass spectrometer.

[0008] The carbon nanotube ionization device of the present invention further includes an injection pump, which is connected to the syringe.

[0009] For the carbon nanotube ionization device of the present invention, the volume of the syringe is 2 mL, the needle is a stainless steel needle, and is connected to the high-voltage source of the Miniβ small portable mass spectrometer through a metal wire; the microporous filter membrane is an organic microporous filter membrane with a pore size of 0.45 μm.

[0010] An analysis method for detecting harmful substances in children's products using the carbon nanotube ionization device described above, which is characterized in that it includes the following steps:

[0011] Take 0.1 g of children's product sample, add it to the inside of the syringe body, install the syringe plunger rod and the needle, suck 1 ml of extraction solvent, turn the needle upward, repeatedly pull the plunger rod for extraction, then install the microporous filter membrane between the syringe body and the needle, place the syringe body on the injection pump, apply an ionization voltage, and perform analysis using a mass spectrometer.

[0012] For the method of the present invention, the children's products include crayon toys, finger paints, and children's toothpaste; when the children's product is a crayon toy, the harmful substances are solvent yellow 1, basic red 9, disperse blue 106, and solvent yellow 3; when the children's product is finger paint, the harmful substances are aniline, 2-naphthylamine, 4-aminobiphenyl, and 4-chloro-2-methylaniline; when the children's product is children's toothpaste, the harmful substance is salicylic acid.

[0013] For the method of the present invention, the mass spectrometry analysis conditions are: injection time: 30 ms; the collision gas is air, and the collision time is 150 ms;

[0014] Table 1 Small portable mass spectrometry analysis parameters of 9 harmful substances

[0015]

[0016] The ionization modes, ionization voltages, parent ions, daughter ions, and collision energies of 9 harmful substances are shown in Table 1.

[0017] The method of the present invention, wherein the sampling amount is 0.1 g. When sampling, the crayon toy is cut into small particles with scissors and then added into the syringe, and the finger paint and children's toothpaste are directly dipped with a glass rod and transferred into the syringe;

[0018] The extraction solvent is methanol with a volume of 1 ml; the flow rate of the injection pump is 50 μl / min.

[0019] The carbon nanotube ionization device of the present invention is different from the prior art in that:

[0020] The method for detecting harmful substances in children's products by the carbon nanotube fiber ionization device of the present invention uses carbon nanotube fiber ionization as the ion source, combines with a small portable mass spectrometer, and establishes a rapid on-site qualitative and quantitative method for harmful substances in children's products, which can provide technical support for on-site analysis, detection, supervision and law enforcement of the quality and safety of children's products.

[0021] The method of the present invention only requires a simple sample pretreatment process. The sample extraction is completed in the syringe, the ionization voltage is applied, and the ionization process of the target substance is realized by the carbon nanotube fiber bundle. Combining with a small portable mass spectrometer, a rapid on-site analysis method for harmful substances in children's products is established. The detection limit is between 10 and 20 μg / kg, the quantification limit is between 20 and 50 μg / kg, and the analysis period is less than 1 min. This method is simple, rapid, real-time and efficient, and is suitable for the rapid on-site analysis of harmful substances in children's products.

[0022] The following further describes the carbon nanotube ionization device of the present invention and its application with reference to the accompanying drawings. Description of the Drawings

[0023] Figure 1 It is the experimental flow chart of the carbon nanotube fiber ionization device and its application in the present invention;

[0024] Figure 2 It is the physical diagram of the carbon fiber bundle of the carbon nanotube fiber ionization device in the present invention;

[0025] Figure 3 It is the electron microscope image of the carbon nanotube fiber of the carbon nanotube fiber ionization device in the present invention, where a - magnified 500 times, b - magnified 8000 times;

[0026] Figure 4 It is the secondary mass spectrum diagram of 4 kinds of prohibited colorants in the crayon toy of the present invention, where: a - Solvent Yellow 1, b - Basic Red 9, c - Disperse Blue 106, d - Solvent Yellow 3;

[0027] Figure 5The secondary mass spectra of 4 prohibited primary aromatic amines in the finger paints of the present invention, where: a - aniline, b - 2 - naphthylamine, c - 4 - chloro - 2 - methylaniline, d - 4 - aminobiphenyl;

[0028] Figure 6 The secondary mass spectrum of the prohibited salicylic acid product in the children's toothpaste of the present invention;

[0029] The translations of all the English words that appear in the attached drawings of the present invention are as follows:

[0030] Relative abundance: Relative abundance; Solvent yellow 1: Solvent yellow 1; Basic red 9: Basic red 9; Disperse blue 106: Disperse blue 106; Solvent yellow 3: Solvent yellow 3; Benzidine: Aniline; 2 - Naphtylamine: 2 - naphthylamine; 4 - Chloro - 2 - methylamiline: 4 - chloro - 2 - methylaniline; 4 - Aminobiphenyl: 4 - aminobiphenyl; m / z: Mass - to - charge ratio. Detailed implementation manners

[0031] 1. Experimental part

[0032] 1.1 Main instruments and devices

[0033] Miniβ small portable mass spectrometry analysis system (length 55 cm, width 24 cm, height 31 cm, weight 20 kg, power ≤ 100 W): Beijing Qingpu Technology Co., Ltd.; S - 4800 type scanning electron microscope: Hitachi, Ltd., Japan; Carbon nanotube fibers (diameter 60 - 80 μm): Jiangsu Xianfeng Nano Materials Technology Co., Ltd. TGD01 type syringe pump: Baoding Leifu Fluid Technology Co., Ltd. ML503 type analytical balance: Mettler Toledo Technology (China) Co., Ltd. Peek head (inner diameter 1.6 mm) and plastic tube (made of fluorinated ethylene propylene copolymer, outer diameter 1.6 mm, inner diameter 0.8 mm): Agilent Technologies (China) Co., Ltd. The Peek head is used to firmly hold the plastic tube, so that the plastic tube can tightly hold the carbon nanotube fiber bundle inside it, making the entire carbon nanotube fiber ion source device more stable and firm.

[0034] As Figure 1 shown, the carbon nanotube ionization device of the present invention includes a syringe and a mass spectrometer 6. The syringe includes a syringe body 1 and a needle 7 connected to its front end. A microporous filter membrane 2 is provided between the syringe body 1 and the needle 7. The needle 7 is connected to the plastic tube 3 and the mass spectrometer 6 respectively. The plastic tube 3 is connected to the Peek head 4. The rear end of the carbon nanotube fiber bundle 5 is embedded in the plastic tube 3, and the front end is arranged in front of the sample inlet of the mass spectrometer 6.

[0035] The carbon nanotube fibers contained in the carbon nanotube fiber bundle 5 are 50 in number. The diameter of each carbon nanotube fiber is 60 - 80 μm. The rear end of the plastic tube 3 is connected to the needle 7, and the front end is inserted into the peek head 4 and is flush with its tip. The length of the carbon nanotube fiber is 1 cm, and the latter half is embedded inside the front end of the plastic tube 3. The front end of the carbon nanotube fiber is set at 0.5 cm in front of the inlet of the mass spectrometer 6. In this embodiment, the length of the carbon nanotube fiber bundle 5 embedded in the plastic tube 3 is about 0.5 cm, and the length extending outside the plastic tube 3 is about 0.5 cm.

[0036] The mass spectrometer 6 is a Miniβ small portable mass spectrometer. The device of the present invention further includes an injection pump, which is connected to a syringe. The volume of the syringe is 2 mL. The needle 7 is a stainless steel needle and is connected to the high-voltage source of the Miniβ small portable mass spectrometer through a metal wire; the microporous filter membrane 2 is an organic microporous filter membrane with a pore diameter of 0.45 μm.

[0037] 1.2 Main materials and reagents

[0038] Standard substances: Solvent Yellow 1, Basic Red 9, Disperse Blue 106, Solvent Yellow 3, aniline, 2-naphthylamine, 4-chloro-2-methylaniline, 4-aminobiphenyl, and salicylic acid standard substances are purchased from Dr. Ehrenstrorfer Company in Germany, and their purities are all greater than 96%. All standard substances are dissolved in methanol and diluted to the required concentration. Children's product samples are purchased from local markets and e-commerce platforms.

[0039] 1.3 Experimental procedures

[0040] Take 0.1 g of children's product samples. When sampling, crayon toys are cut into small particles with scissors and added to the syringe, and finger paints and children's toothpaste are directly dipped with a glass rod and transferred to the syringe;

[0041] Install the syringe plunger rod and the stainless-steel needle, draw 1 ml of extraction methanol, hold the stainless-steel needle upward, and repeatedly pull and push the plunger rod for dispersion extraction. Then install the microporous filter membrane between the syringe and the stainless-steel needle, place the syringe on the syringe pump, and set the flow rate to 50 μl / min. Place the carbon nanotube fiber ion device 0.5 cm in front of the inlet of the small portable mass spectrometer. Connect the high-voltage source of the small portable mass spectrometer to the stainless-steel tube needle through a metal wire and apply high voltage. Under the thrust of the syringe pump, the solution in the syringe is roughly separated through the microporous filter membrane. Macromolecular substances insoluble in methanol in the sample are intercepted, and the solution containing the target substance is transmitted through the needle and the plastic tube to the carbon nanotube fiber bundle. The loose carbon nanotube fiber bundle will automatically gather under the action of the surface tension of the solution. After applying the high voltage of the ion source, the high voltage is transmitted to the carbon nanotube fiber bundle through the tip of the needle and the solution. An electrospray is formed at the tip of the carbon nanotube fiber bundle by the solution. Along with the desolvation process, the target substance is ionized. Then, under the negative pressure of the inlet of the small portable mass spectrometer, it enters the instrument, thus completing the entire detection process.

[0042] The schematic diagram of the experimental procedure is as Figure 1 shown, and the physical diagram of the carbon nanotube fiber bundle is as Figure 2 shown.

[0043] 1.4 Small portable mass spectrometry analysis conditions

[0044] Sampling time: 30 ms; the collision gas is air, and the collision time is 150 ms. The ionization mode, ionization voltage, parent ion, daughter ion, and collision energy of 9 target compounds are shown in Table 1.

[0045] Table 1 Small portable mass spectrometry analysis parameters of 9 harmful substances

[0046]

[0047] 2. Results and discussion

[0048] 2.1 Characterization of carbon nanotube fibers

[0049] Carbon nanotube fibers have strong hardness and good electrical conductivity, which play an important role in the ionization process of target substances. Observe the microstructure of a single carbon nanotube fiber, and its scanning electron microscope image is as Figure 3 shown. As can be seen from Figure 3 a), after magnifying the carbon nanotube fiber by 500 times, each carbon nanotube fiber is composed of many carbon nanotubes condensed together. After continuing to magnify the end of the carbon nanotube fiber by 8000 times, as can be seen from Figure 3 b), many loose carbon nanotubes can be observed at its end.

[0050] 2.2 Optimization of carbon nanotube fiber bundles

[0051] The carbon nanotube fiber bundle is composed of multiple carbon nanotube fibers, and the number thereof has a great influence on the influence intensity of the target substance. The numbers of carbon nanotube fibers are set to 10, 30, 50, and 70. Using Solvent Yellow 1 as a representative target substance, optimization is carried out. The results show that when the number of carbon nanotube fibers is 50, the ionic strength no longer increases. Therefore, it is selected that the carbon nanotube fiber bundle consists of 50 carbon nanotube fibers.

[0052] 2.3 Optimization of the distance from the carbon nanotube ion source to the injection port

[0053] The distance between the ion source and the mass spectrometry injection port is also an important factor affecting the response of the target substance. If the distance is too close, the desolvation effect may not be complete and the ionization efficiency is low; conversely, the number of charged ions entering the mass spectrometry decreases and the response value decreases. In the present invention, the distances between the carbon nanotube fiber bundle and the injection port of the small portable mass spectrometry are set to 0.3, 0.5, 0.7, and 1 cm. The results show that when the distance is small (less than 0.5 cm), the mass spectrometry signal intensity is weak; when the distance is greater than 0.5 cm, the mass spectrometry response signal of the target substance shows a downward trend. Therefore, in the present invention, the distance from the ion source to the injection port of the small portable mass spectrometry is set to 0.5 cm.

[0054] 2.4 On-site rapid analysis method for harmful substances in children's products based on carbon nanotube fiber ionization small portable mass spectrometry

[0055] Blank crayon toy samples determined to contain no Solvent Yellow 1, Basic Red 9, Disperse Blue 106, and Solvent Yellow 3 are selected, blank finger paint samples determined to contain no aniline, 2-naphthylamine, 4-chloro-2-methylaniline, and 4-aminobiphenyl are selected, and blank children's toothpaste samples determined to contain no salicylic acid are selected, and positive samples are respectively prepared. Analyze according to the experimental steps, and determine the parent ions of 9 prohibited harmful substances, which are Solvent Yellow 1 (m / z 198.1), Basic Red 9 (m / z 288.1), Disperse Blue 106 (m / z 336.1), Solvent Yellow 3 (m / z 226.1), aniline (m / z 185.1), 2-naphthylamine (m / z 144.1), 4-chloro-2-methylaniline (m / z 142.1), 4-aminobiphenyl (m / z 170.1), and salicylic acid (m / z 137.1).

[0056] Collision-induced dissociation is respectively carried out on the parent ions of the 9 harmful substances determined, and the secondary mass spectrometry diagrams of the four harmful dyes are as Figure 4As shown. The main fragment ions of Solvent Yellow 1 are m / z 95.2; the main fragment ions of Basic Red 9 are m / z 195.2 and m / z 271.1; the main fragment ions of Disperse Blue 106 are m / z 196.1; the main fragment ions of Solvent Yellow 3 are m / z 133.2 and m / z 91.3. The secondary mass spectra of the four hazardous primary aromatic amines are as Figure 5 shown. The main fragment ions of aniline are m / z 168.1; the main fragment ions of 2-naphthylamine are m / z 117.2 and m / z 103.2; the main fragment ions of 4-chloro-2-methylaniline are m / z 107.2 and m / z 82.1; the main fragment ions of 4-aminobiphenyl are m / z 153.1 and m / z 143.2. The secondary mass spectrum of salicylic acid is as Figure 6 shown. Its main fragment ion is m / z 93.1.

[0057] The strongest fragment ion peaks in the secondary mass spectra of each substance were selected. The detection limit of the method was estimated by 3 times the signal-to-noise ratio, and the quantification limit of the method was estimated by 10 times the signal-to-noise ratio. The detection limits of the 9 hazardous substances were measured to be 10 - 20 μg / kg, and the quantification limits were 20 - 50 μg / kg. A good linear relationship was presented in their respective linear ranges (r > 0.99). In the low, medium, and high level addition ranges, their average recoveries were between 86.7 - 112.5%, and the relative standard deviations were 3.8 - 10.5%. The results of the methodology experiment showed that the method of the present invention was accurate and reliable.

[0058] Table 2 Results of Methodology Investigation

[0059]

[0060] 2.5 Detection of Actual Samples

[0061] Using the screening method established by the present invention, 23 children's products purchased from the local market and e-commerce platforms were detected and analyzed, including 9 crayon toy samples, 9 finger paint samples, and 5 children's toothpaste samples. After screening, none of the above-mentioned hazardous substances were detected in the samples measured.

[0062] 3. Conclusion

[0063] The present invention adopts carbon fiber ionization combined with small portable mass spectrometry technology to establish a rapid on-site analysis method for hazardous substances in children's products. The method is simple and efficient, and can complete the rapid analysis of samples within 1 min, effectively solving the disadvantages of the traditional detection method such as cumbersome operation and long time consumption, and has good application prospects and practical value.

[0064] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A carbon nanotube ionization device, characterized in that: It includes a syringe and a mass spectrometer (6). The syringe includes a syringe body (1) and a needle (7) connected to its front end. A microporous filter membrane (2) is provided between the syringe body (1) and the needle (7). The needle (7) is connected to a plastic tube (3) and the mass spectrometer (6) respectively. The plastic tube (3) is connected to a peek head (4). The rear end of the carbon nanotube fiber bundle (5) is embedded in the plastic tube (3), and the front end is arranged in front of the inlet of the mass spectrometer (6).

2. The carbon nanotube ionization device according to claim 1, characterized in that: The carbon nanotube fiber bundle (5) contains 50 carbon nanotube fibers, and the diameter of each carbon nanotube fiber is 60 - 80 μm.

3. The carbon nanotube ionization device according to claim 2, wherein: The rear end of the plastic tube (3) is connected to the needle (7), and the front end is inserted into the peek head (4) and is flush with its tip. The length of the carbon nanotube fiber is 1 cm, and the rear half is embedded in the front end inside of the plastic tube (3). The front end of the carbon nanotube fiber is arranged 0.5 cm in front of the inlet of the mass spectrometer (6).

4. The carbon nanotube ionization device according to claim 3, wherein: The mass spectrometer (6) is a Miniβ small portable mass spectrometer.

5. The carbon nanotube ionization device according to claim 4, wherein: It further includes an injection pump, which is connected to the syringe.

6. The carbon nanotube ionization device according to claim 5, wherein: The volume of the syringe is 2 mL. The needle (7) is a stainless - steel needle and is connected to the high - voltage source of the Miniβ small portable mass spectrometer through a metal wire. The microporous filter membrane (2) is an organic microporous filter membrane with a pore size of 0.45 μm.

7. An analytical method for detecting harmful substances in children's products using the carbon nanotube ionization device according to any one of claims 1 to 6, characterized in that: It includes the following steps: Take 0.1 g of children's product sample, add it into the syringe body (1), install the syringe plunger rod and the needle (7), suck 1 ml of extraction solvent, turn the needle (7) upward, repeatedly pull and push the plunger rod for extraction, then install the microporous filter membrane (2) between the syringe body (1) and the needle (7), place the syringe body (1) on the injection pump, apply ionization voltage, and analyze it using a mass spectrometer.

8. The method according to claim 7, wherein: The children's products include crayon toys, finger paints, and children's toothpaste. When the children's product is a crayon toy, the hazardous substances are solvent yellow 1, basic red 9, disperse blue 106, and solvent yellow 3. When the children's product is finger paint, the hazardous substances are aniline, 2 - naphthylamine, 4 - aminobiphenyl, and 4 - chloro - 2 - methylaniline. When the children's product is children's toothpaste, the hazardous substance is salicylic acid.

9. The method according to claim 8, characterized in that: The mass spectrometry analysis conditions are: injection time: 30 ms; the collision gas is air, and the collision time is 150 ms; Table 1 Small portable mass spectrometry analysis parameters of 9 hazardous substances The ionization mode, ionization voltage, parent ion, daughter ion, and collision energy of 9 hazardous substances are shown in Table 1.

10. The method according to claim 9, wherein: The sampling amount is 0.1 g. When sampling, the crayon toy is cut into small particles with scissors and then added into the syringe. The finger paint and children's toothpaste are directly dipped with a glass rod and transferred into the syringe. The extraction solvent is methanol with a volume of 1 ml. The flow rate of the injection pump is 50 μl / min.

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