CN-121994778-A - Micro-nano plastic detection method and system

CN121994778ACN 121994778 ACN121994778 ACN 121994778ACN-121994778-A

Abstract

The application provides a method and a system for detecting micro-nano plastics, which relate to the technical field of micro-nano plastic detection, and the method comprises the steps of obtaining a sample to be detected, and determining the positions of all suspicious micro-nano plastics in the sample based on hyperspectral imaging; the method comprises the steps of utilizing laser with step power to eliminate biological matrixes on the surface of suspicious micro-nano plastic based on a photo-thermal ablation pretreatment technology, determining the step power according to the biological matrixes, collecting Raman spectrum of the suspicious micro-nano plastic after the photo-thermal ablation pretreatment, and outputting detection results according to the Raman spectrum. The positions of all suspicious micro-nano plastics in the sample are determined based on hyperspectral imaging, and the sample is detected by utilizing Raman spectrum, so that the high-efficiency positioning capability of nanoscale hyperspectral imaging is organically combined with the accurate discrimination capability of laser confocal Raman spectrum, and a photothermal ablation pretreatment technology is introduced, so that the interference of biological matrixes is effectively overcome, and the high-flux, high-resolution and high-accuracy detection of the micro-nano plastics is realized.

Inventors

CHEN XINGQI
Fang Hengyu
GAO SHIXIANG

Assignees

南京大学

Dates

Publication Date: 20260508
Application Date: 20260410

Claims (10)

1. The detection method of the micro-nano plastic is characterized by comprising the following steps of: Acquiring a sample to be detected, and determining the positions of all suspicious micro-nano plastics in the sample based on hyperspectral imaging; the method comprises the steps of eliminating biological matrixes on the surface of suspicious micro-nano plastic by using laser with stepped power based on a photothermal ablation pretreatment technology, wherein the size of the stepped power is determined according to the biological matrixes; And collecting Raman spectrum of the suspicious micro-nano plastic after photo-thermal ablation pretreatment, and outputting a detection result according to the Raman spectrum.
2. The method of claim 1, wherein determining the location of all suspected micro-nano-plastics in the sample based on hyperspectral imaging comprises: scanning the sample by utilizing a hyperspectral imaging module in an enhanced dark field illumination mode to generate hyperspectral data of the sample; And (3) performing similarity matching on the spectral characteristics of the micro-nano plastics in the hyperspectral data and the spectral characteristics of the plastics in the plastic library, and marking the micro-nano plastics with similarity larger than a set threshold value as suspicious micro-nano plastics.
3. The method of claim 1, wherein photo-thermal ablation pretreatment of suspected micro-nano plastic with a stepped power laser comprises: When the residual quantity of the biological matrix in the region where the suspicious micro-nano plastic is positioned is smaller than a set threshold value, performing preliminary detection on a sample in the region of interest by using laser with low power, and evaluating the ablation threshold value of the current biological matrix; and selectively ablating the possible micro-nano plastic surface biological matrix based on the photo-thermal effect by using the laser with medium power according to the ablation threshold value of the current biological matrix.
4. The method of claim 3, wherein the photothermal ablation pretreatment of the suspected micronano-plastic with a stepped power laser, further comprising: When the residual quantity of the biological matrix in the region where the suspicious micro-nano plastic is positioned is larger than or equal to a set threshold value, performing preliminary detection on a sample in the region of interest by using laser with low power, and evaluating the ablation threshold value of the current biological matrix; And selectively ablating the possible micro-nano plastic surface biological matrix by using the laser with high power according to the ablation threshold of the current biological matrix based on the photo-thermal effect.
5. A micro-nano plastic detection system, comprising: the nanometer hyperspectral imaging module is used for collecting hyperspectral data of a sample; the data processing module is used for determining the positions of all suspicious micro-nano plastics in the sample based on the hyperspectral data of the sample; the laser confocal Raman spectrum module is used for eliminating biological matrixes on the surface of the suspicious micro-nano plastic by utilizing laser with stepped power based on a photo-thermal ablation pretreatment technology, wherein the size of the stepped power is determined according to the biological matrixes; The shared optical path module is used for connecting the nano hyperspectral imaging module and the laser confocal Raman spectrum module to the same objective optical path through the optical path switching device.
6. The system of claim 5, wherein the nano-hyperspectral imaging module comprises: a dark field illumination unit for generating high-intensity oblique illumination light to illuminate the sample region; and the CCD camera is used for acquiring hyperspectral data of the sample.
7. The system of claim 5, wherein the laser confocal raman spectroscopy module comprises: The laser is used for emitting laser with stepped power to the sample, and the biological matrix on the surface of the suspicious micro-nano plastic is eliminated by utilizing the laser with stepped power based on the photo-thermal ablation pretreatment technology; A confocal microscope; the spectrometer and the detector are used for collecting the Raman spectrum of the suspicious micro-nano plastic after the photothermal ablation pretreatment and outputting a detection result according to the Raman spectrum.
8. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 4 when the computer program is executed.
9. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 4.
10. A computer program product comprising a computer program, characterized in that the computer program, when executed by a processor, implements the steps of the method of any of claims 1 to 4.

Description

Micro-nano plastic detection method and system Technical Field The application relates to the technical field of micro-nano plastic detection, in particular to a micro-nano plastic detection method and a micro-nano plastic detection system. Background Micro-nano plastic (plastic particles with the size smaller than 1 μm) is widely used as an emerging environmental pollutant in water bodies and organisms, and the ecological risk and health effect evaluation of the micro-nano plastic is highly dependent on an accurate detection technology. At present, detection for micro-nano plastics mainly depends on two major analysis technologies, namely a spectrum analysis technology and an imaging analysis technology, but the single technology has inherent limitations. In the spectrum analysis technology, a laser confocal Raman spectrometer is one of the gold standard methods of the current micro-nano plastic chemistry identification. The working principle is based on the Raman scattering effect, namely, a sample is irradiated by monochromatic laser, and the characteristic scattering spectrum generated by the transition of the molecular vibration energy level is detected to obtain the fingerprint structure information of the substance. The technology can perform nondestructive analysis on micron-sized plastic particles, is highly sensitive to chemical bonds such as C-C, C-H, and can effectively distinguish different polymer types (such as PE, PP, PS, and the like). After the confocal microscope is coupled, point scanning analysis can be carried out on the sample micro-area to acquire spectral information of a specific position. In the imaging analysis technology, the nano hyperspectral imaging module integrates an enhanced dark field illumination and hyperspectral imaging unit, and can realize high-resolution positioning and imaging of nano-scale particles. The working principle is that in the enhanced dark field mode, hyperspectral data of a sample in a visible light-near infrared band (400-1000 nm) are collected, and suspicious micro-nano plastics are rapidly screened through algorithms such as spectral angle matching and the like, and a two-dimensional distribution image is generated. Although the above-mentioned technology plays an important role in micro-nano plastic detection, in practical application, especially in complex environmental water samples and biological blood matrixes, a single technology has technical bottlenecks which are difficult to overcome. Limitations of confocal laser raman spectroscopy include: (1) The positioning efficiency is extremely low, and the nano-scale target particles are found in the complex matrix like a 'sea fishing needle'. The traditional micro-region Raman analysis requires an operator to manually search suspicious micro-nano plastics through an optical microscope, and has extremely low probability of finding effective particles and severely limited detection flux for samples with complex backgrounds such as blood, water bodies rich in organic matters and the like. (2) The fluorescence interference problem is remarkable in that proteins, pigments and additives (especially red pigments) contained in the plastic in the biological matrix can generate strong fluorescence background, so that the baseline of a Raman spectrum is remarkably raised, and even the characteristic peak of a polymer is completely covered, so that the spectrum library is failed to match or misjudged. Studies have shown that interference with pigments is difficult to eliminate even after oxidation treatment. (3) The limitation of diffraction limit is that the spatial resolution of the traditional confocal raman spectrum is limited by the optical diffraction limit (typically 300-500 nm), and for submicron-order (especially <300 nm) plastic particles, the signal intensity is drastically reduced and the detection difficulty is significantly increased. (4) The spectrum masking of the biological matrix is that when micro-nano plastic enters a biological system, a layer of biomolecules is quickly adsorbed on the surface to form a protein crown, so that the surface property of particles is changed, a new interference peak is introduced into a Raman spectrum, background noise is increased, and the original spectrum characteristics of the polymer are masked. Meanwhile, new functional groups are added on the surface of the polymer in the bioconversion process, so that the spectral fingerprint of the polymer is further changed. Limitations of nano-hyperspectral imaging techniques include: (1) The spectrum identification capability is insufficient, the hyperspectral imaging mainly relies on the spectrum information of visible light-near infrared wave bands to identify substances, the spectrum resolution is far lower than that of Raman spectrum, and the distinguishing capability of different polymer components is limited. In complex matrices, interference of non-plastic particles such as biomacromolecules, minerals and th