Development And Application Research Of Pyrolysis-mass Spectrometery Microplastic Detection Technology

Microplastics(MPs),defined as plastic particles(<5mm),have become a major global environmental issue.MPs can exist for hundreds of years in the environment,and cause extensive harm to marine organisms as well as the ecological environment.MPs enter the human body through the food chain,resulting in human health risks.Nanoplastics(NPs),generally defined as microplastic(<1?m),have received more attention due to their smaller size and worse toxicity than MPs.NPs even can enter the internal recycle of the human body and generate extensive toxicity at the cellular and molecular levels.Thus,they have been studied separately from MPs.As an emerging marine pollutant,the distribution,migration,source,fate,and ecotoxicology of MPs in the marine environment are urgent to study,and the accurate and efficient detection techniques and methods have been considered as an important foundation for MPs research.However,traditional microplastics detection techniques mainly rely on spectroscopic method,which have some limitations and deficiencies,especially for NPs.This study intended to develop a portable pyrolysis-mass spectrometry(Pyr-MS)microplastics detection device,build qualitative and quantitative analysis methods,providing a tool support for MPs research.To verify the practicability,marine MPs pollutions and sources were studied based on the proposed technology and methods.The abundance evaluation models of MPs/NPs in the aging injection plastic bottles were studied,providing a reference for the research of MPs/NPs in the environment.(1)Develop the Pyr-MS technology,provide a new tool for MPs research.As for the lack of MPs pyrolyzer,a miniaturized and low power consumption resistance heating-pyrolyzer was designed.As for NPs are unable to detect separately and need trace analysis,thereby,an electromagnetic heating-pyrolysis device was developed.Pyrolyzers were coupled to portable MS by filtration and distributary,and the pyrolysis products directly entered the MS for analysis.A portable Pyr-MS device was developed,which realized the rapid analysis of MPs and NPs.This technique is not limited by the surface morphology and size of MPs samples,making up the lack of spectroscopy technology.(2)Based on the developed Pyr-MS equipment,the qualitative and quantitative analysis methods of microplastics were built,providing a new method for MPs.The peak area of the characteristic ions of polymers was found to be proportional(fingerprint),which could be used for identification.The fingerprints of several common plastics were established to verify their reliability;the standard curves for quantitative analysis of MPs were drawn,providing mass information of MPs,realizing simultaneous qualitative and quantitative analysis.The influence of environmental factors on Pyr-MS was studied,including matrix interference,ultraviolet light aging and additives;results showed their impact coud be negligible.Based on the developed electromagnetic heating-pyrolysis mass spectrometry(Eh-Pyr-MS),the trace detection method of NPs was constructed.The separation and extraction of NPs was avoided through direct pyrolysis analysis of heat-resistant filter papers.The sensitivity of nano PS particles reached 85.7ng.The analysis method of mixed plastics was also studied based on the fingerprint information and quantitative calibrations of polymers,that indicated the potential of Pyr-MS in the detection of mixed plastics.(3)Based on the developed Pyr-MS device and method,marine MPs pollution was studied.Given the shortcomings of current beach MPs flotation methods,a disodium hydrogen phosphate flotation method based on auxiliary heating was proposed,which possessed the requirements of high-density,low-cost and eco-friendly.Seven kinds of polymers with different densities were used in disodium hydrogen phosphate and sodium chloride recovery experiments;resulted showed disodium hydrogen phosphate had better recovery.Microplastics in the beach and nearshore surface seawater were collected and analyzed by Pyr-MS device and method.To test the reliability of the identification and quantification of Pyr-MS,FT-IR and balance were used for comparison.The shape,abundance and type of MPs were counted and analyzed.The abundance of MPs in the beach was up to 6665 item/kg,and the average abundance in the surface seawater was up to 5.9±3.5 item/m~3,which indicated that the pollution level and the ecological risk were high.It was found that a great deal of plastic fishing gear used in the coastal aquaculture has become an important source of offshore MPs pollution of Weihai.(4)Based on the Eh-Pyr-MS device,MPs/NPs in the aging infusion bottles were analyzed.An analytical method of MPs/NPs in the saline infusion bottles(SIBs)was established.The MPs/NPs were found to be derived from the surface of aging plastics through the Eh-Py-MS and microscope observation.The quality and quantity concentration evaluation models in SIBs were built,which further verified the reliability of this method,and provided a useful reference for MPs/NPs research.This study revealed the potential risks of MPs/NPs pollution in the medical infusion productions due to improper storage or other reasons,that needs more attention.The developed Pyr-MS technique would provide a new tool for MPs research,making up spectroscopy technology dificiencies such as the limit of the surface morphology and the inability of NPs.The quantitative methods based on the mass concentration were provided for assessing MPs/NPs,which could be a supplement for the current number counting.