# Simply Applicable Method for Microplastics Determination in Environmental Samples
## 1 Introduction  
Industrial development has accelerated the manufacture and the disposal of plastic materials. Currently, the increased use of single use plastics, for convenience or hygiene (e.g., pandemic), is only a stone in the mosaic of plastic pollution, still it represents a significant contributor to microplastic (MP) pollution. Since the turn of the century there has been a steady rise in scientific interest in MPs in environmental research, though most of it focuses on the MPs in the marine environment. While the impacts of marine MPs have gained scientific and significant media and public attention, there is a paucity of research conducted on the terrestrial environment. This is despite the claim of researchers that MPs are also accumulating on land, especially in agricultural areas. The number of publications concerning MP pollution in soils has risen, however, as the topic has gained scientific attention over the last five years. During this time, it has been found that the mass of MPs in soils may be as much as four times greater when compared to the marine environment [1; 2; 3]. There is currently a gap in the knowledge of MP pollution in terrestrial systems because of a lack of standardized methods, which are available for the quantification of MPs in soils. Therefore, an exact and effective analysis method for assaying MPs in soil samples is needed [3] and steps toward a simple, widely available, and reliable method for the most abundant polymer types [4]; polyethylene terephthalate--PET, polystyrene--PS, polyvinyl chloride--PVC, polypropylene--PP, and polyethylene--PE (high density) would be of great interest to the scientific community. There are numerous routes of entry for MP pollution into the soil environment. Landfills from urban and industrial centers, irrigation with wastewater, lake water flooding,littering roads and illegal waste dumping, and vinyl much used in agricultural activities, for example, can introduce MPs, which settle on the surface and penetrate subsoils [5]. The collection of soil samples to test for the representative MPs concentration in the final product is the most important step and can be easily influenced by intrinsic factors (due to heterogeneity of MPs and soil types, depth, and soil-layer and accurate representation of soil status: overall, average, etc.). The soil samples should be chemically and physically pretreated (dried, sieved, floated, filtered, extracted, and digested) [3; 6]. Finally, MPs can be identified using non-destructive and destructive methods. Visual methods, such as scanning electron microscope (SEM) are usually combined with spectroscopic techniques to confirm the presence of MPs. Micro-Fourier transformed infrared (m-FT-IR) and Raman spectroscopy are commonly used methods. Destructive methods rely on thermal analytical methods, such as thermogravimetry (TGA), which measure weight loss. Gaseous products may then be analyzed with thermal desorption gas chromatography mass spectrometry (TED-GC-MS) [7; 8]; or pyrolysis followed by identification of MPs' degradation products employing gas chromatography-mass spectrometry (Py-GC-MS) [9; 10; 11; 12; 13]. Identification of MPs using destructive methods has been widely exploited for the identification of PET, PS, PVC, PP, and PE. However, each polymer type has specific thermal degradation pathways and products. PET is polyester with ethylene glycol and dimethyl terephthalate or terephthalatic acid as monomer units, which is mainly used in the production of food packaging and beverage bottles. The mechanisms of PET thermal decomposition have been reported to be intramolecular backbiting and chain scission leading to cyclic oligomers, vinyl ester, and acid end-groups. PET thermal decomposition was found to be accelerated in the presence of oxygen and chain scission was found to occur more commonly at 280 \({}^{\circ}\)C in the presence of water [14; 15].