On-site water sample micro-plastic multi-dimensional information integrated detection device and method

Abstract

The invention provides an on-site water sample micro-plastic multi-dimensional information integrated detection device and method, and relates to the technical field of micro-plastic pollution monitoring, and the device comprises a microscopic image identification and analysis module, a sample conveying module, a sample suction filtration module, a gas path transmission module, an electromagnetic thermal cracking module, a filtration purification module and a mass spectrometry detection module, the sample conveying module, the sample suction filtration module and the gas path transmission module are respectively communicated with the electromagnetic thermal cracking module, the filtration and purification module comprises a solid filtration and purification module and a gas filtration and purification module, and the sample conveying module, the electromagnetic thermal cracking module, the solid filtration and purification module and the sample suction filtration module sequentially form a sample liquid phase communication path. The microscopic image recognition and analysis module obtains a sample image at the sample conveying module. The particle size distribution and number information borne by the image and the type and mass concentration information borne by the thermal cracking mass spectrum are synchronously obtained, and the method has the advantages that the needed sample amount is small, information is not crossed, and pollution in the asynchronous information obtaining process is avoided.

Description

Technical Field

[0001] This application relates to the technical field of microplastic pollution monitoring. More specifically, it relates to a device and method for integrated detection of multi-dimensional information of microplastics in on-site water samples. Background Art

[0002] Among global ecological environment issues, microplastic pollution has become a focus. Plastic fragments, fibers or particles with a size ≤ 5 mm are collectively referred to as microplastics, which are also known as "PM2.5 in the ocean" and are listed as major global environmental problems together with global climate change, ozone depletion and ocean acidification. They cause serious harm to the marine environment and ecosystem. Microplastics suspended in seawater can affect the photosynthesis of marine algae; they are easily ingested by some marine organisms and are difficult to digest in the gastrointestinal tract, causing malnutrition and even death of marine organisms. Some studies have found that microplastics can also affect the spawning and reproductive ability of some marine organisms such as fish; in addition, microplastics themselves contain some toxic plastic additives, and their surfaces are also prone to enrichment of organic pollutants and heavy metals, etc., which will have a toxic effect on surrounding organisms. The migration and sedimentation mechanism of microplastics in the environment is controlled by multi-dimensional attribute parameters such as their quantity, particle size distribution characteristics, polymer type and quality, which directly determine the distribution law and ecological risk level of pollutants among water-sediment-organism phases. In-depth study of the multi-dimensional parameter characteristics of microplastics in water bodies is of great significance for revealing their ecological risks, formulating pollution prevention and control strategies, protecting aquatic ecosystems and human health.

[0003] Currently, microplastic detection mainly relies on three technical systems: visual counting method, spectroscopy method and thermal analysis-mass spectrometry method, which are respectively used to obtain key parameters such as particle quantity, species characteristics and mass concentration. However, although the visual method and spectroscopy method can reflect the particle-related information (quantity, particle size distribution, etc.) and species information of microplastics, their mass concentration information is missing. Although pyrolysis-mass spectrometry can achieve qualitative and quantitative analysis of microplastics in complex matrices, it sacrifices the physical form information of particles in a destructive detection method. Due to the widespread presence of microplastics in various environmental media, the risk of secondary pollution during sample collection, transportation and pretreatment processes has led to a systematic overestimation of the concentration and quantity of current water body microplastics. As a complex particle system with multi-attribute coupling, this fragmentation of the detection of multi-dimensional parameters (quantity-particle size-species-mass) of microplastic pollutants makes the traditional single-dimensional detection technology lack the technical support for multi-parameter collaborative analysis when quantifying the migration and transformation law of microplastics in the water environment.

[0004] Therefore, there is an urgent need to develop an on-site, short-process and highly integrated water body microplastic detection device to realize the synchronous analysis of the four-dimensional characteristics of "quantity-particle size-species-mass" of water body microplastics. Summary of the Invention

[0005] To solve the above problems, the technical solution adopted in this application is a multi-dimensional information integration detection device for microplastics in on-site water samples, which includes a microscopic image recognition and analysis module, a sample delivery module, a sample suction filtration module, an air path transmission module, an electromagnetic thermal cracking module, a filtration and purification module, and a mass spectrometry detection module. The sample delivery module, the sample suction filtration module, and the air path transmission module are respectively connected to the electromagnetic thermal cracking module. The filtration and purification module includes a solid filtration and purification module and a gas filtration and purification module, which are respectively arranged at the through openings of the sample suction filtration module and the mass spectrometry detection module in the electromagnetic thermal cracking module. The sample delivery module, the electromagnetic thermal cracking module, the solid filtration and purification module, and the sample suction filtration module form a sample liquid phase path in sequence, and the microscopic image recognition and analysis module obtains the sample image at the sample delivery module.

[0006] Optionally, the sample delivery module includes a liquid pump, a transmission pipeline, and a sample pool, and the sample outlet of the transmission pipeline extends to directly above the solid filtration and purification module inside the electromagnetic thermal cracking module.

[0007] Optionally, the solid filtration and purification module sequentially includes a water inlet cup, a quartz fiber filter membrane, a porous tungsten sheet, and a filtered water collection cup according to the flowing order of the sample liquid phase. The gas filtration and purification module includes quartz fiber and a metal filter.

[0008] Optionally, the air path transmission module includes a dry carrier gas source and a thermal cracking carrier gas source, and the dry carrier gas source and the thermal cracking carrier gas source are respectively connected to the electromagnetic thermal cracking module through control valves.

[0009] Optionally, the electromagnetic thermal cracking module includes a quartz thermal cracking cavity with an electromagnetic induction coil tightly wound around the outer wall. Both ends of the electromagnetic induction coil are connected to a temperature rise controller, and the temperature rise controller is connected to a thermal sensor arranged at the solid filtration and purification module.

[0010] Optionally, the microscopic image recognition and analysis module includes a microscope, a camera, and an image processing device. The camera obtains the sample image information at the sample pool through the microscope and transmits it to the image processing device.

[0011] Optionally, the suction filtration module includes a suction filtration path, and the suction filtration path is connected to a vacuum pump through a suction filtration sump.

[0012] This application also provides a multi-dimensional information integration detection method for microplastics in on-site water samples, which uses the multi-dimensional information integration detection device for microplastics in on-site water samples as described in any of the foregoing, and includes the following steps: S1: Collect the water body microplastic sample through the sample delivery module and transport it to the electromagnetic thermal cracking module, and obtain the sample image information through the microscopic image recognition and analysis module during the transportation process; S2: The sample in the electromagnetic thermal cracking module is filtered by the sample suction filtration module through the solid filtration and purification module. After filtration, the sample is dried by the drying carrier gas through the gas path transmission module. Then, the gas path transmission module provides a vacuum environment and a thermal cracking carrier gas for the electromagnetic thermal cracking module. S3: The electromagnetic thermal cracking module heats the sample to decompose it into thermal cracking gas. The thermal cracking gas is carried by the thermal cracking carrier gas and enters the mass spectrometry detection module for detection and analysis after being filtered by the gas filtration and purification module.

[0013] Optionally, after suction filtration, anhydrous ethanol is transported through the sample delivery module to clean the pipeline and remove the moisture in the solid filtration and purification module. Then, the drying carrier gas at 90 - 120 °C is transported through the gas path transmission module for drying for 3 - 10 minutes.

[0014] Optionally, before the electromagnetic thermal cracking module heats the sample, the gas path transmission module uses high-purity argon as the thermal cracking carrier gas, controls the gas flow rate and introduces it into the electromagnetic thermal cracking module. At the same time, the shunt air extraction pump is turned on to remove the impurity gas in the electromagnetic thermal cracking module and maintain the vacuum state.

[0015] The beneficial effects of the high-throughput microplastic mass spectrometry detection device and method for multi-dimensional feature synchronous detection provided by this application are as follows: The device integrates the functions of microplastic image information and on-line analysis of mass concentration, can synchronously obtain four-dimensional information of the particle size, quantity, type and mass of microplastics in the sample, and has the advantages of simple operation, fast speed and comprehensiveness; highly integrated microscopic-thermal cracking-small mass spectrometry analysis and testing functions for on-site detection. After the sample passes through the sample delivery module and obtains the sample image through the microscopic image recognition and analysis module, it enters the electromagnetic thermal cracking module for thermal cracking. The whole system is closed, overcoming the problem of sample contamination in off-line and asynchronous sampling, and improving the detection accuracy; the particle size distribution and number information carried by the image are synchronously obtained with the type and mass concentration information carried by the electromagnetic thermal cracking mass spectrometry, with the advantages of less required sample volume, no information cross, and avoiding contamination in the process of asynchronous information acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for description in the embodiments or the prior art.

[0017] Figure 1 It is a schematic structural diagram of the on-site water sample microplastic multi-dimensional information integration detection device provided by the embodiment of this application.

[0018] Figure 2 It is a cross-sectional view of the solid filtration and purification module provided by the embodiment of this application; Figure 3 It is a top view of the solid filtration and purification module provided by the embodiment of this application.

[0019] Explanation of the reference numerals: 1. sample bottle; 2. glass tube; 3. micro gear pump; 4. stage; 5. quartz sample cell; 6. camera; 7. quartz thermal cracking chamber; 8. solid filtration purification module; 81. ground glass water inlet cup; 82-quartz fiber filter membrane; 83-porous tungsten sheet; 84-ground glass filtered water collection cup; 85-ground glass surface; 9. vacuum pump; 10. filtration water collection tank; 11. dry carrier gas inlet; 12. thermal cracking carrier gas inlet; 13. electromagnetic induction coil; 14. quadrupole mass spectrometer; 15-microscope; 16-quartz tube; 17-micro vacuum pump. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] Example 1 The purpose of the present invention is to address the technical problem that the existing technology is difficult to simultaneously obtain the multi-dimensional characteristics of microplastics such as the quantity, type, particle size, and quality on site, and to provide an on-site, short-process, and highly integrated water microplastic detection device to achieve accurate analysis of the four-dimensional characteristics of water microplastics: "quantity-particle size-type-quality".

[0022] like Figure 1 As shown, an on-site water sample microplastic multi-dimensional information integrated detection device includes a microscopic image recognition and analysis module, a sample conveying module, a sample filtration module, a gas transmission module, an electromagnetic thermal cracking module, a filtration purification module and a mass spectrometry detection module. The sample conveying module, the sample filtration module and the gas transmission module are respectively connected to the electromagnetic thermal cracking module. The filtration purification module includes a solid filtration purification module 8 and a gas filtration purification module, which are respectively arranged at the openings of the sample filtration module and the mass spectrometry detection module in the electromagnetic thermal cracking module; the sample conveying module, the electromagnetic thermal cracking module, the solid filtration purification module 8 and the sample filtration module form a sample liquid phase passage in sequence, and the microscopic image recognition and analysis module obtains a sample image at the sample conveying module.

[0023] In another embodiment of the present application, the sample delivery module includes a liquid pump, a transfer pipeline, and a sample cell. The sample outlet of the transfer pipeline extends directly above the solid filtration and purification module 8 inside the electromagnetic thermal cracking module. In this embodiment, a glass tube 2 is used as the external transfer pipeline of the sample delivery module, and a quartz tube 16 is integrally formed in the electromagnetic thermal cracking module as the internal transfer pipeline. This internal transfer pipeline extends outside the electromagnetic thermal cracking module and is hermetically connected to the external transfer pipeline. A micro gear pump 3 is used as the liquid pump to pump the liquid of the microplastic sample to be measured. The transfer pipeline extends into the electromagnetic thermal cracking module to deliver the sample to the solid filtration and purification module within the quartz thermal cracking chamber 7.

[0024] A valve is provided between the glass tube 2 of the external transfer pipeline and the quartz tube 16 of the internal transfer pipeline. This valve is closed after the ethanol filtration is completed to prevent subsequent thermal cracking gases from entering the pipeline and causing contamination, and to ensure the maintenance of the vacuum state during the mass spectrometry detection process.

[0025] As Figures 1 to 3 shown, in another embodiment of the present application, the solid filtration and purification module sequentially includes a water inlet cup, a quartz fiber filter membrane 82, a porous tungsten sheet 83, and a filtered water collection cup in the order of the sample liquid phase flowing through; The gas filtration and purification module includes quartz fiber and a metal filter. When the thermal cracking gas of the microplastic sample passes through the gas filtration and purification module, first, the carbon particles and un-cracked polymer fragments in the plastic thermal cracking gas are filtered by the metal filter, and the grid structure of the metal material is used for physical interception to prevent particulate matter from entering the interior of the mass spectrometer. Then, the quartz fiber filters impurities (such as high molecular weight hydrocarbon fragments) that may have a molecular weight close to the target in the gas, preventing mass spectrometry peak overlap or misjudgment, and avoiding false positive / false negative results. At the same time, the quartz fiber can efficiently adsorb sub-micron particles, reduce non-target interference peaks in the mass spectrometry signal, and improve the signal-to-noise ratio.

[0026] In this embodiment, the solid filtration and purification module 8 is composed of a ground glass filtered water collection cup 84 and a ground glass water inlet cup 81. A porous tungsten sheet 83 and a 5μm quartz fiber filter membrane 82 are sandwiched between the two cups to filter the solution entering from the outside of the quartz thermal cracking chamber 7.

[0027] The target gas produced by thermal cracking is purified through the quartz fiber and the metal filter. After being split by the micro vacuum pump 17 to maintain the mass spectrometry vacuum state, it is delivered to the quadrupole mass spectrometer 14 through a capillary for rapid analysis. The mass spectrometry detection module 14 is a portable or bench-top quadrupole mass spectrometer 14 equipped with a mass spectrometry detection and analysis device with the ability to detect volatile gases, and can be used for on-site or laboratory detection.

[0028] In another embodiment of the present application, the gas path transmission module includes a dry carrier gas source and a pyrolysis carrier gas source. The dry carrier gas source and the pyrolysis carrier gas source are respectively connected to the electromagnetic pyrolysis module through control valves.

[0029] In another embodiment of the present application, the electromagnetic pyrolysis module includes a quartz pyrolysis chamber 7 with an electromagnetic induction coil 13 tightly wound around its outer wall. The two ends of the electromagnetic induction coil 13 are connected to a temperature increase controller, and the temperature increase controller is connected to a thermal sensor disposed at the solid filtration and purification module.

[0030] The temperature control implements dynamic PID regulation, achieving a response speed of 0.1 s level within the range of ±5°C of the target temperature. Among them, a thermocouple temperature sensor is used as the thermal sensor for temperature measurement, and the sensor probe is in close contact with the porous tungsten piece 83 below the porous tungsten piece 83.

[0031] In another embodiment of the present application, the microscopic image recognition and analysis module includes a microscope 15, a camera 6, and an image processing device. The camera 6 obtains sample image information at the sample cell through the microscope 15 and transmits it to the image processing device.

[0032] In this embodiment, the microscopic image recognition and analysis module consists of a high-resolution microscope, a fast CCD camera (frame rate 600 fps), and an image processing device loaded with image processing software ImageJ, and can identify the number and particle size of microplastics collected. The specific working process is as follows: The micro gear pump 3 controls the sample flow rate to be 1 ml / min. When the liquid flows through the transparent quartz sample cell 5, the image is quickly captured by the microscope. When the cross-sectional area of the glass tube 2 and the flow rate of the microplastic sample in the water body in the glass tube 2 are known, the number of microplastics in the quartz sample cell 5 with a known volume can be used to calculate the total number of microplastic particles, with the unit being pieces / min.

[0033] Example: 500 microplastic particles are identified in the image, the volume of the quartz sample cell is 100 mL, the flow rate of the microplastic sample in the water body is 10 cm / s, and the cross-sectional area of the glass tube is 1 cm 2 , and it is considered that the density of the microplastic sample in the water body is 1 g / cm 3 , so it can be considered that 50 microplastic particles are introduced per second, and multiplying by the pumping time of the micro gear pump 3 is the total number of microplastics.

[0034] Its particle size distribution is analyzed by the ImageJ software after gray scale and binarization of the collected image. Since the sample is evenly dispersed, the average value of 5 images is selected.

[0035] A method for integrating multi-dimensional information detection of microplastics in on-site water samples, the working process is as follows: S1: Collect water body microplastic specimens through the sample delivery module and deliver them to the electromagnetic thermal cracking module. During the delivery process, obtain the specimen image information through the microscopic image recognition and analysis module; Load the water body of the microplastic specimen into sample bottle 1, and through glass tube 2, under the power of micro gear pump 3, deliver it to quartz sample cell 5 on microscope stage 4. In this cell, the particle size information and quantity information of the microplastics are obtained by the microscopic image recognition and analysis system 6 equipped with a CCD camera. S2: Filter the specimen in the electromagnetic thermal cracking module through the sample filtration module and the solid filtration and purification module. After filtration, dry the specimen with a drying carrier gas through the gas path transmission module. Then, the gas path transmission module provides a vacuum environment and a thermal cracking carrier gas for the electromagnetic thermal cracking module; This extraction liquid is continuously delivered to solid filtration and purification module 8 in quartz thermal cracking chamber 7 without staying here. Under the suction filtration of vacuum pump 9, the microplastics are separated. The filtrate is pumped by vacuum pump 9 through suction filtration sump 10 to the outside of thermal cracking chamber 7; After filtration is completed, continue to add 50 mL of anhydrous ethanol to sample bottle 1 for pipeline cleaning and to remove the moisture in solid filtration and purification module 8. After cleaning is completed, open drying carrier gas inlet 11, use heated gas at 90 - 120 °C as the drying carrier gas, and vacuum pump 9 continues to suction filter the drying carrier gas to dry the sample for 3 - 10 minutes; S3: The electromagnetic thermal cracking module heats the specimen to decompose it into thermal cracking gas. The thermal cracking gas is carried by the thermal cracking carrier gas, and after being filtered by the gas filtration and purification module, it enters the mass spectrometry detection module for detection and analysis.

[0036] After drying is completed, high-temperature carrier gas inlet 11, vacuum pump 9, and the inlet of quartz tube 16 are closed. Open thermal cracking carrier gas inlet 12 to introduce carrier gas, turn on the power of the electromagnetic thermal cracking device, and energize electromagnetic induction coil 13 to quickly heat the tungsten piece placed on solid filtration and purification module 8 to 600 - 800 °C. The microplastics are quickly decomposed into thermal cracking gas under the action of heat conduction and enter the mass spectrometry device for detection and analysis through the carrier gas.

[0037] Optionally, before the electromagnetic thermal cracking module heats the specimen, the gas path transmission module uses high-purity argon as the thermal cracking carrier gas, controls the gas flow rate and introduces it into the electromagnetic thermal cracking module, and simultaneously turns on the shunt air pump to remove the impurity gas in the electromagnetic thermal cracking module and maintain the vacuum state.

[0038] To ensure the high-vacuum condition of the mass spectrometry, the gas path transmission module uses high-purity argon as the carrier gas source, controls the gas flow rate at 0.15 L / min through a control valve, needs to introduce carrier gas for 1 min before the test starts, and simultaneously turns on the shunt air pump to remove the impurity gas in the system and maintain the vacuum state.

[0039] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. An on-site water sample microplastic multi-dimensional information integrated detection device, characterized in that: It includes a microscopic image recognition and analysis module, a sample delivery module, a sample suction filtration module, a gas path transmission module, an electromagnetic thermal cracking module, a filtration and purification module, and a mass spectrometry detection module. The sample delivery module, the sample suction filtration module, and the gas path transmission module are respectively connected to the electromagnetic thermal cracking module. The filtration and purification module includes a solid filtration and purification module and a gas filtration and purification module, which are respectively arranged at the through openings of the sample suction filtration module and the mass spectrometry detection module in the electromagnetic thermal cracking module. The sample delivery module, the electromagnetic thermal cracking module, the solid filtration and purification module, and the sample suction filtration module sequentially form a sample liquid phase path. The microscopic image recognition and analysis module acquires a sample image at the sample delivery module.

2. The on-site water sample microplastic multi-dimensional information integrated detection device according to claim 1, wherein: The sample delivery module includes a liquid pump, a transmission pipeline, and a sample cell. The sample outlet of the transmission pipeline extends to directly above the solid filtration and purification module inside the electromagnetic thermal cracking module.

3. The on-site water sample microplastic multi-dimensional information integrated detection device according to claim 1, characterized in that: The solid filtration and purification module sequentially includes a water inlet cup, a quartz fiber filter membrane, a porous tungsten sheet, and a filtered water collection cup in the order of the sample liquid phase flowing through. The gas filtration and purification module includes a quartz fiber and a metal filter.

4. The on-site water sample microplastic multi-dimensional information integrated detection device according to claim 1, characterized in that: The gas path transmission module includes a dry carrier gas source and a thermal cracking carrier gas source. The dry carrier gas source and the thermal cracking carrier gas source are respectively connected to the electromagnetic thermal cracking module through control valves.

5. The on-site water sample microplastic multi-dimensional information integrated detection device according to claim 1, characterized in that: The electromagnetic thermal cracking module includes a quartz thermal cracking cavity with an electromagnetic induction coil tightly wound around its outer wall. The two ends of the electromagnetic induction coil are connected to a temperature rising controller, and the temperature rising controller is connected to a thermal sensor arranged at the solid filtration and purification module.

6. The on-site water sample microplastic multi-dimensional information integrated detection device according to claim 2, wherein: The microscopic image recognition and analysis module includes a microscope, a camera, and an image processing device. The camera acquires sample image information at the sample cell through the microscope and transmits it to the image processing device.

7. The on-site water sample microplastic multi-dimensional information integrated detection device according to claim 2, wherein: The suction filtration module includes a suction filtration path, and the suction filtration path is connected to a vacuum pump through a suction filtration sump.

8. A multi-dimensional information integration detection method for microplastics in on-site water samples, characterized in that: Using the on-site water sample microplastic multi-dimensional information integrated detection device as described in any one of claims 1-7, it includes the following steps: S1: Collect a water body microplastic sample through the sample delivery module and deliver it to the electromagnetic thermal cracking module. During the delivery process, acquire sample image information through the microscopic image recognition and analysis module. S2: Filter the sample in the electromagnetic thermal cracking module through the solid filtration and purification module by the sample suction filtration module. After filtration, dry the sample with a dry carrier gas by the gas path transmission module. Then, the gas path transmission module provides a vacuum environment and a thermal cracking carrier gas for the electromagnetic thermal cracking module. S3: The electromagnetic thermal cracking module heats the sample to decompose it into thermal cracking gas. The thermal cracking gas is carried by the thermal cracking carrier gas, filtered by the gas filtration and purification module, and then enters the mass spectrometry detection module for detection and analysis.

9. The on-site water sample microplastic multi-dimensional information integration detection method according to claim 8, wherein: After filtration, anhydrous ethanol is delivered through the sample delivery module for pipeline cleaning and to remove the moisture in the solid filtration and purification module. Then, a dry carrier gas at 90-120°C is transmitted through the gas path transmission module for drying for 3-10 minutes.

10. The on-site water sample microplastic multi-dimensional information integration detection method according to claim 8, characterized in that: Before the electromagnetic thermal cracking module heats the sample, the gas path transmission module uses high-purity argon as the thermal cracking carrier gas, controls the gas flow rate and introduces it into the electromagnetic thermal cracking module. Synchronously, turn on the shunt suction pump to remove the impurity gas in the electromagnetic thermal cracking module and maintain a vacuum state.

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