阅读说明：本技术 一种基于等离子体电离质谱技术的微塑料原位检测方法 (Micro-plastic in-situ detection method based on plasma ionization mass spectrometry technology ) 是由 贾滨 程平 刘吉星 徐丽 黄玉梁 董俊国 谢春光 赵高升 于 2021-07-14 设计创作，主要内容包括：本发明公开一种基于等离子体电离质谱技术的微塑料原位检测方法,包括如下步骤：S1、建立数据库,采集常见微塑料降解产物的种类和数量,建立微塑料降解反应的指纹谱图库；S2、样品提供,将样品通过样品承载组件放置于等离子体炬管和离子传输管之间并且调整好等离子体炬管、样品承载组件以及离子传输管之间的距离；S3、通入载气,开启等离子体电离源,激发产生等离子体,令等离子体炬管产生等离子体焰炬,使得微塑料进行降解；S4、微塑料降解后的产物被等离子体电离,产生产物的离子,产物的离子经离子传输管的入口进入质谱仪；S5、打开质谱仪进行检测,通过采集到的产物的离子与指纹谱图库进行对比。本发明可以对样品中的微塑料进行定性定量分析。(The invention discloses a micro-plastic in-situ detection method based on a plasma ionization mass spectrometry technology, which comprises the following steps: s1, establishing a database, collecting the types and the number of common micro-plastic degradation products, and establishing a fingerprint spectrum library of the micro-plastic degradation reaction; s2, providing a sample, placing the sample between the plasma torch tube and the ion transmission tube through the sample carrying assembly, and adjusting the distance between the plasma torch tube, the sample carrying assembly and the ion transmission tube; s3, introducing carrier gas, starting a plasma ionization source, exciting to generate plasma, and enabling a plasma torch tube to generate a plasma torch so as to degrade the micro plastic; s4, ionizing the product after the micro plastic is degraded by plasma to generate the ion of the product, and enabling the ion of the product to enter a mass spectrometer through an inlet of an ion transmission tube; and S5, opening the mass spectrometer for detection, and comparing the collected ions of the product with the fingerprint spectrogram library. The invention can carry out qualitative and quantitative analysis on the micro-plastic in the sample.)

1. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology comprises a plasma torch tube (1) and a sample carrying assembly (2), wherein the sample carrying assembly (2) is arranged at an inlet of an ion transmission tube (4) of a mass spectrometer (3), the ion transmission tube (4) is horizontally arranged, the plasma torch tube (1) is obliquely arranged on a vertical plane where the ion transmission tube (4) is arranged, an open end of the plasma torch tube (1) faces downwards and faces an inlet of the ion transmission tube (4), so that product ions obtained by degradation and ionization of a sample (6) on the sample carrying assembly (2) by a plasma torch (5) can smoothly enter the inlet of the ion transmission tube (4), and the method is characterized by comprising the following steps:

s1, establishing a database, collecting the types and the number of common micro-plastic degradation products, and establishing a fingerprint spectrum library of the micro-plastic degradation reaction;

s2, providing a sample, placing the sample between the plasma torch tube and the ion transmission tube through the sample carrying assembly, and adjusting the distance between the plasma torch tube, the sample carrying assembly and the ion transmission tube;

s3, introducing carrier gas, starting a plasma ionization source, exciting to generate plasma, and enabling a plasma torch tube to generate a plasma torch so as to degrade the micro plastic;

s4, ionizing the product after the micro plastic is degraded by plasma to generate the ion of the product, and enabling the ion of the product to enter a mass spectrometer through an inlet of an ion transmission tube;

and S5, opening a mass spectrometer for detection, and comparing the collected ions of the product with a fingerprint spectrogram library to judge how many kinds of micro plastics exist in the sample.

2. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology of claim 1, wherein the method comprises the following steps: the plasma ionization source is a microwave plasma ionization source or a low-temperature plasma ionization source.

3. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology of claim 1, wherein the method comprises the following steps: the carrier gas for exciting the plasma ionization source to generate plasma is inert gas.

4. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology as claimed in claim 3, wherein: the inert gas is argon or helium.

5. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology of claim 1, wherein the method comprises the following steps: the carrier gas for exciting the plasma ionization source to generate plasma is nitrogen, oxygen or air.

6. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology of claim 1, wherein the method comprises the following steps: the sample is a solid sample or a liquid sample.

7. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology as claimed in claim 6, wherein: the sample bearing component is an objective table, and the solid sample or the liquid sample is placed on the surface of the objective table.

8. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology of claim 1, wherein the method comprises the following steps: the sample is a gaseous sample or an aerosol sample.

9. The method for in-situ detection of the micro plastic based on the plasma ionization mass spectrometry technology of claim 8, wherein the method comprises the following steps: the sample bearing component is a gaseous sample introducing pipe.

Technical Field

The invention relates to the technical field of micro-plastic detection, in particular to a micro-plastic in-situ detection method based on a plasma ionization mass spectrometry technology.

Background

Plastics are key materials for many industrial applications, such as construction, health care, engineering and packaging. Over the past fifty years, the global production of plastic waste has increased at a rate of 8.7% per year, with the global production reaching 91 million tons in 2017. However, plastic waste has become one of the most serious environmental problems due to the difficulty in degrading and mishandling plastics. Plastics in the environment slowly degrade into smaller pieces, influenced by factors such as sunlight, microbes or mechanical abrasion. Plastic particles with a diameter of less than 5mm are defined as Microplastics (MPs). Depending on the source, microplastics can be divided into primary (e.g.plastics production and cosmetics) microplastics and secondary (e.g.macroplastic decomposition) microplastics. As a typical new pollutant, micro plastics have stable chemical properties, can exist in the environment for a long time, cause serious environmental problems and gradually attract wide attention of scholars.

The currently available tools for identification and quantification of MPs are mainly macroscopic detection, conventional optical microscopy, application of dye staining, flow cytometric analysis, microscopic Fourier Transform Infrared (FTIR) spectroscopy, microscopic Raman (RM) spectroscopy, pyrolysis-gas chromatography-mass spectrometry (py GC-MS) and thermal degradation analysis by thermal extraction-desorption gas chromatography-mass spectrometry (TED GC-MS). The above methods each have advantages and disadvantages, but the common disadvantage is that it is difficult to perform in situ rapid in situ identification.

The conventional mass spectrometry means are: the molecules of the object to be detected attached to the surface of the sample or in the sample are ionized under the action of an ionization source to obtain ions of the molecules, and the gas-phase ions are sent into a mass spectrum for mass analysis and detection, so that a mass spectrum of the sample is obtained; for analysis of micro-plastics in soil, water and other samples, namely detection of the type and content of the micro-plastics in the samples, the micro-plastics cannot be ionized by a common mass spectrometry ionization method, and are large particles compared with molecules, so that analysis of the micro-plastics usually requires a relatively complex sample pretreatment process, is time-consuming and labor-consuming, and cannot be detected and analyzed in situ.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and adopts a plasma ionization mass spectrometry technology to carry out qualitative and quantitative analysis on micro plastic samples in environmental samples (such as soil, water, atmospheric aerosol) and the like, thereby realizing a method for rapidly detecting the components and the content of the micro plastic in the samples in situ without sample pretreatment and preseparation.

The invention is realized by the following technical scheme:

a method for in-situ detection of micro plastic based on plasma ionization mass spectrometry technology comprises a plasma torch tube and a sample carrying assembly, wherein the sample carrying assembly is arranged at an inlet of an ion transmission tube of a mass spectrometer, the ion transmission tube is horizontally arranged, the plasma torch tube is obliquely arranged on a vertical plane where the ion transmission tube is arranged, an open end of the plasma torch tube faces downwards and faces towards the inlet of the ion transmission tube, so that product ions obtained by degradation and ionization of a sample on the sample carrying assembly by a plasma torch can smoothly enter the inlet of the ion transmission tube, and the method for in-situ detection of micro plastic comprises the following steps:

s1, establishing a database, collecting the types and the number of common micro-plastic degradation products, and establishing a fingerprint spectrum library of the micro-plastic degradation reaction;

s2, providing a sample, placing the sample between the plasma torch tube and the ion transmission tube through the sample carrying assembly, and adjusting the distance between the plasma torch tube, the sample carrying assembly and the ion transmission tube;

s3, introducing carrier gas, starting a plasma ionization source, exciting to generate plasma, and enabling a plasma torch tube to generate a plasma torch so as to degrade the micro plastic;

s4, ionizing the product after the micro plastic is degraded by plasma to generate the ion of the product, and enabling the ion of the product to enter a mass spectrometer through an inlet of an ion transmission tube;

and S5, opening a mass spectrometer for detection, and comparing the collected ions of the product with a fingerprint spectrogram library to judge how many kinds of micro plastics exist in the sample.

As a preferred embodiment of the present invention: the plasma ionization source is a microwave plasma ionization source or a low-temperature plasma ionization source.

In the technical scheme, the microwave plasma ionization source has higher ionization and decomposition degrees, can maintain plasma under high air pressure, has very high ratio of electron temperature and ion temperature to neutral gas temperature, keeps proper temperature of carrier gas and has high safety factor; the low-temperature plasma ionization source is formed in a dielectric barrier discharge mode, electron energy in the low-temperature plasma generated by dielectric barrier discharge is high, the low-temperature plasma almost acts with all gas molecules, the reaction is fast, the gas velocity is not limited, the operation is simple, and the start and stop are fast.

As a preferred embodiment of the present invention: the carrier gas for exciting the plasma ionization source to generate plasma is inert gas.

As a preferred embodiment of the present invention: the inert gas is argon or helium.

As a preferred embodiment of the present invention: the carrier gas for exciting the plasma ionization source to generate plasma is nitrogen, oxygen or air.

As a preferred embodiment of the present invention: the sample is a solid sample or a liquid sample.

As a preferred embodiment of the present invention: the sample bearing component is an objective table, and the solid sample or the liquid sample is placed on the surface of the objective table.

As a preferred embodiment of the present invention: the sample is a gaseous sample or an aerosol sample.

As a preferred embodiment of the present invention: the sample bearing component is a gaseous sample introducing pipe.

The invention discloses a method for in-situ detection of micro-plastic based on plasma ionization mass spectrometry technology, which has the following advantages compared with the prior art:

1. the measured sample is not required to be pretreated, mass spectrometry is directly carried out after the sample is ionized by a plasma ionization source, micro plastic particles can be cracked in plasma to generate substances such as ketones, alcohols, organic acids, lipids and the like, the components of cracked products are related to the types of the micro plastic and related to the gas generating the plasma, a mass spectrometer is used for analyzing the types of product ions, comparing data and the like, qualitative and quantitative analysis on the types and the content of the micro plastic in the complex sample can be realized, the sample data acquisition process can be completed within seconds, and repeated times can be realized;

2. the measured object can be in a liquid, solid or gaseous form, and the applicability is wide;

3. the plasma ionization source can adopt a microwave plasma ionization source or a low-temperature plasma ionization source formed by dielectric barrier discharge and the like, and has strong selectivity;

4. the carrier gas can be inert gases such as argon, helium and the like, and can also be directly excited by nitrogen, oxygen or air, so that the method is very convenient;

5. the technical scheme has high analysis speed and simple operation steps, can improve the sample detection flux, or can carry out direct real-time analysis on site, and is favorable for screening and researching a large number of environmental samples in a large area range.

Drawings

Fig. 1 is a schematic structural diagram of a first embodiment of the present invention, which is used for representing in-situ detection of a solid sample or a liquid sample.

Fig. 2 is a schematic structural diagram of a second embodiment of the present invention, which is used for representing in-situ detection of a gaseous sample.

The corresponding part names indicated by the numbers and letters in the drawings:

wherein: 1. a plasma torch tube; 2. a sample support assembly; 3. a mass spectrometer; 4. an ion transfer tube; 5. a plasma torch; 6. and (3) sampling.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

Wherein the showings are for the purpose of illustration only and are shown by way of illustration only and not in actual form, and are not to be construed as limiting the present patent; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The first embodiment is as follows:

referring to fig. 1, a method for in-situ detection of micro plastic based on plasma ionization mass spectrometry includes a plasma torch tube 1 and a sample carrying assembly 2, the sample carrying assembly 2 is disposed at an inlet of an ion transmission tube 4 of a mass spectrometer 3, the ion transmission tube 4 is disposed horizontally, the plasma torch tube 1 is disposed obliquely on a vertical plane where the ion transmission tube 4 is located, an open end of the plasma torch tube 1 faces downward and toward the inlet of the ion transmission tube 4, so that product ions obtained by degradation and ionization of a sample 6 on the sample carrying assembly 2 by a plasma torch 5 can smoothly enter the inlet of the ion transmission tube 4, and the method for in-situ detection of micro plastic includes the following steps:

s1, establishing a database, collecting the types and the number of common micro-plastic degradation products, and establishing a fingerprint spectrum library of the micro-plastic degradation reaction;

s2, providing a sample, namely placing a solid sample or a liquid sample between the plasma torch tube and the ion transmission tube through the sample carrying assembly, and adjusting the distance between the plasma torch tube, the sample carrying assembly and the ion transmission tube;

s3, introducing carrier gas, starting a plasma ionization source, exciting to generate plasma, and enabling a plasma torch tube to generate a plasma torch so as to degrade the micro plastic;

s4, ionizing the product after the micro plastic is degraded by plasma to generate the ion of the product, and enabling the ion of the product to enter a mass spectrometer through an inlet of an ion transmission tube;

and S5, opening a mass spectrometer for detection, and comparing the collected ions of the product with a fingerprint spectrogram library to judge how many kinds of micro plastics exist in the sample.

It should be noted that, in the above embodiments, the sample supporting component is a stage, and the solid sample or the liquid sample is placed on the stage.

Example two:

referring to fig. 2, a method for in-situ detection of micro plastic based on plasma ionization mass spectrometry comprises a plasma torch tube 1 and a sample carrying assembly 2, wherein the sample carrying assembly 2 is disposed at an inlet of an ion transmission tube 4 of a mass spectrometer 3, the ion transmission tube 4 is disposed horizontally, the plasma torch tube 1 is disposed obliquely on a vertical plane where the ion transmission tube 4 is located, an open end of the plasma torch tube 1 faces downward and toward the inlet of the ion transmission tube 4, so that product ions obtained by degradation and ionization of a sample 6 on the sample carrying assembly 2 by a plasma torch 5 can smoothly enter the inlet of the ion transmission tube 4, and the method for in-situ detection of micro plastic comprises the following steps:

s1, establishing a database, collecting the types and the number of common micro-plastic degradation products, and establishing a fingerprint spectrum library of the micro-plastic degradation reaction;

s2, providing a sample, placing the gaseous sample between the plasma torch tube and the ion transmission tube through the sample carrying assembly, and adjusting the distance between the plasma torch tube, the sample carrying assembly and the ion transmission tube;

s3, introducing carrier gas, starting a plasma ionization source, exciting to generate plasma, and enabling a plasma torch tube to generate a plasma torch so as to degrade the micro plastic;

s4, ionizing the product after the micro plastic is degraded by plasma to generate the ion of the product, and enabling the ion of the product to enter a mass spectrometer through an inlet of an ion transmission tube;

and S5, opening a mass spectrometer for detection, and comparing the collected ions of the product with a fingerprint spectrogram library to judge how many kinds of micro plastics exist in the sample.

It is noted that in the above embodiments, the sample support member is a gaseous sample introduction tube, and the gaseous sample or the aerosol sample is introduced from a bottom opening of the gaseous sample introduction tube to a top opening of the gaseous sample introduction tube, so as to perform ionization.

In the first embodiment and the second embodiment, as for the establishment of the database, because different types of the micro-plastic products are different and the degradation caused by different gases exciting the plasma is also different, we need to establish a database, that is, the types and the quantity of the degradation products of all the common micro-plastics are collected in advance, and a fingerprint spectrum library of the micro-plastic degradation reaction is established.

In the first and second embodiments, the plasma degrades the micro plastic to generate the degradation product, and then ionizes the degradation product to obtain the spectrogram of the degradation product, and the spectrogram is inverted by depending on the database according to the detection result of the degradation product.

In the first and second embodiments, the plasma ionization source is a microwave plasma ionization source or a low-temperature plasma ionization source.

In the first and second embodiments, the carrier gas for exciting the plasma ionization source to generate the plasma is an inert gas, and the inert gas is preferably argon or helium.

In the first and second embodiments, the carrier gas excited by the plasma ionization source to generate plasma is nitrogen, oxygen or air.

In the second embodiment, the gaseous sample is originally a gaseous sample (such as air) or an aerosol sample obtained by headspace sampling on a solid sample and a liquid sample.

In addition, it should be noted that, as a result of research, it is found that the plasma can degrade the micro plastic to generate small molecules, and thus, the in-situ detection method of the micro plastic in the first and second embodiments is adopted, in the plasma ionization source, firstly the micro plastic is degraded, and then the degradation product is ionized by the plasma to generate the ion of the product, and the ion enters the mass spectrometer to be analyzed and detected; the micro plastic particles can be cracked in the plasma to generate substances such as ketones, alcohols, organic acids, lipids and the like, the components of cracked products are related to the types of the micro plastics and related to the gas for generating the plasma, the types of product ions are analyzed by a mass spectrometer, data comparison and other operations are carried out, qualitative and quantitative analysis on the types and the contents of the micro plastics in the complex sample can be realized, the sample data acquisition process can be completed within several seconds, and the repeated operation can be realized for many times.

Finally, the plasma torch tube, the mass spectrometer, the ion transmission tube and the plasma torch adopted by the technical scheme are all the prior art, and the plasma torch can be selected by a person skilled in the art according to actual requirements, the charged particles partially ionized in the plasma working gas for some reason (such as electric spark, etc.) move at high speed under the action of high-frequency alternating electromagnetic field, collide with gas atoms, ionize them rapidly and massively to form avalanche discharge, the ionized gas forms closed annular eddy current on the cross section vertical to the direction of the magnetic field, a secondary coil corresponding to a transformer is formed in the induction coil and coupled with the induction coil corresponding to the primary coil, the high temperature generated by the high frequency induction current heats and ionizes the gas, and forms a torch-shaped stable plasma flame moment at the nozzle.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical scope of the present invention and the equivalent alternatives or modifications according to the technical solution and the inventive concept of the present invention within the technical scope of the present invention.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.