# Methods of Analyzing Microsized Plastics in the Environment
## 1 Introduction
This review focuses on summarizing the technologies developed and currently used for the sampling, extraction, purification, and detection of microplastics in real environmental samples and anticipating the direction of future technologies (Figure 1, Table 1). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Analysis** & **Definition** & **Advantage** & **Disadvantage** & **References** \\ \hline Microscopy & \begin{tabular}{c} Analyze substances using a \\ microscope. Optical \\ microscopes to electron \\ microscopes such as SEM \\ and TEM are widely used. \\ \end{tabular} & \begin{tabular}{c} Able to directly observe \\ the surface \\ Simple sample \\ preparation \\ \end{tabular} & \begin{tabular}{c} Takes the longest time \\ to determine \\ Depending on the \\ researcher, the result \\ judgment may vary, \\ resulting in low accuracy \\ \end{tabular} & \begin{tabular}{c} \\ [24; 25] \\ \end{tabular} \\ \hline Spectroscopy & \begin{tabular}{c} Analyze the surface of a \\ material using \\ optical technology \\ \end{tabular} & \begin{tabular}{c} Multiple samples can \\ be analyzed at once, \\ and the method \\ \end{tabular} & \begin{tabular}{c} Difficult to discriminate \\ large amounts of samples \\ Takes a long time \\ to identify \\ \end{tabular} & \begin{tabular}{c} [26; 27] \\ \end{tabular} \\ \hline Thermal analysis & \begin{tabular}{c} Analysis using heat based \\ on the unique physical and \\ chemical properties of \\ each substance \\ \end{tabular} & \begin{tabular}{c} A large number of \\ samples can be \\ identified at once \\ Existing data library \\ can be used for analysis \\ \end{tabular} & Samples are \\ \hline Emerging Technology & \begin{tabular}{c} Analyze using a new \\ technology that is \\ attracting attention instead \\ of the previously described \\ analysis methods \\ \end{tabular} & \
\begin{tabular}{c} Development in the \\ direction of \\ complementing the \\ shortcomings of \\ existing technologies \\ \end{tabular} &
\begin{tabular}{c} \\ [30; 31] \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of technically analyzing results. Methods for identifying plastics using various techniques such as microscopy, spectroscopy and thermal analysis have been continuously developed (Figure 1, Table 1). Each technology has different characteristics as well as advantages/disadvantages. Microscopy enables the most intuitive identification of results through visual confirmation. Sample preparation is simple but time consuming, and is less accurate than other methods [24; 25]. Spectroscopy uses optical principles to analyze the surface of a sample. Multiple samples can be identified at once, and data libraries for each material that have been  
Figure 1: Four major approaches to analyze microplastics in the environment. Microscopic observation allows the size, shape, and chemical composition of target microplastics to be directly probed. Thermal and spectroscopic analyses allow researchers to understand target plastics’ chemical and physical signatures. Emerging technologies, including a simple dye staining method, help to expedite the simultaneous, high-throughput capture of microplastics without using expensive analytical instruments. In Figure, dunes (a), foresbore (b), photographs (d1, e1, f1), Nile Red staining (d2, e2, f2) and the analysis process by Image J program (d3, e3, f3) can be checked. Reprinted with permission from the reference [32; 33; 34; 35]. Copyright 2018, 2019, 2020 American Chemical Society. Additionally, copyright 2019 John Wiley and Sons. previously accumulated can be used for analysis. In addition, the sample is preserved after analysis, and quantitative analysis such as oxidation of each particle is possible [26]. However, compared to thermal analysis, it is difficult to identify a large number of samples at once [33]. Thermal analysis has the advantage of being able to discriminate larger amounts of samples than the aforementioned microscopy and spectroscopy [28].