Progresses in treatment processes and quantification strategies of micro- and nanoplastics

Plastics are the choice for package of products, medical implants, and other applications. But the transformation of plastics into minuscule particles, known as micro- and nanoplastics (MNPs, microplastics’ size <5 ​mm and nanoplastics’ size <1 ​μm), through physical action or chemical degradation, led to their widespread presence in virtually every ecosystem, and there are concerns about their impact on the environment and human health. Therefore, establishing standardized lines for maximum concentrations of MNPs in a system is essential to ensure the coexistence of MNPs with nature as well as humans. However, the complexity and diversity of MNPs in terms of size, polymer type, and density make the identification and quantification of MNPs a significant challenge. This review introduces representative treatment processes for purification or extraction of MNPs from environmental samples, and the advanced methods for quantitative analysis of MNPs. Special attention is paid to techniques related to the quantitative analysis of MNPs, and the advantages and limitations of these methods are discussed. Moreover, the necessity of establishing harmonized and standardized methods for the quantitative analysis of MNPs in investigating standardized lines of maximum concentrations of MNPs in the systems is envisioned, and the challenges and urgent issues with concerns for the future are discussed and summarized.