# Simply Applicable Method for Microplastics Determination in Environmental Samples
## 1 Introduction
Studies using Py-GC-MS for MPs identification and quantification identified characteristic series of n-alkanes, n-alkenes, and n-alkadienes, with the following fragment ions selected for quantification in environmental matrices: \(m/z\) 55 for tridecane homologue [10], \(m/z\) 85 for n-alkanes (eicosane) [19; 20], and eicosane with \(m/z\) 83 [20]. For conclusive identification of PE in environmental matrices with TED-GC-MS 1,12-ridecadiene, 1,13-tetradecadiene, 1,14-pentadekadien and 1,15-hexadecadiene, and alkene-alkadiene pairs from C\({}_{11}\) to C\({}_{16}\) were chosen [7; 31]. The protocols for monitoring MPs are recognized by the ASTM standards, only for the initial step of analytical procedure. In fact, the adopted standards recognize only the sampling and preparation of water samples with a high, medium, and low content of suspended substances [32]. Standards for the identification of MPs with Py-GC-MS [33], infrared and Raman spectroscopy [34], on the other hand, are still under development. Polymers are too diverse (Table 1) to allow their direct identification regardless of the dimension, or type. In addition to their chemical diversity, during the production of plastic products, different additives are added (for example antioxidants, flame retardants, and plasticizers) [35]. The headspace-solid phase microextraction GC-MS (HS-SPME-GC-MS) technique has already been successfully applied to the characterization of polymers and the identification of VOCs from expanded PS [37; 38], and on its basis the method for the identification of the most common polymers in MPs was developed. The aim of our research was to develop a simpler identification method for MPs in complex soil matrices based on conventional sample preparation techniques. To make this method feasible, the SPME technique was coupled to simple instrumentation commonly found worldwide in environmental laboratories (GC-MS, also with lower sensitivity). This \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Polymer Type** & **Abbreviation** & **Formula** & **Density 1 [g/cm3]** & **Melting Point 1 [\({}^{\circ}\)C]** & **Glass Transition** \\  & & & **[g/cm3]** & **[\({}^{\circ}\)C]** & **Temperature 1 [\({}^{\circ}\)C]** \\ \hline Polyethylene & LDPE & (C\({}_{2}\)H\({}_{4}\))n & 0.90–0.92 & & \\ (low and high density) & HDPE & (C\({}_{2}\)H\({}_{4}\))n & 0.95–0.96 & 141 & \(-\)123—20 \\ Polypropylene & PP & (C\({}_{3}\)H\({}_{6}\))n & 0.85–0.88 & 179 & \(-\)15—3 \\ Polyethylene & PET & (C\({}_{10}\)H\({}_{8}\)O\({}_{4}\))n & 1.33–1.48 & 264 & 65–77 \\ Polystyrene & PS & (C\({}_{6}\)H\({}_{8}\))n & 1.04–1.10 & 242–276 & 91–128 \\ Polyvinyl chloride & PVC & (C\({}_{2}\)H\({}_{3}\)Cl)n & 1.38–1.40 & 220–305 & 71–107 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics of the most common polymer types of microplastics (MPs) found in the environmental samples. was compared to instrumentation not necessarily routinely available to every laboratory, like the Py-GC-MS and the TED-GC-MS [19; 39]. This paper proposed the use of HS-SPME-GC-MS, previously employed for monitoring technological processes, to identify the five most common types of MPs (polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), and polyethylene terephthalate (PET)) found in environmental samples (alluvial soil, organic compost, and algae biomass), specifically soil and water, according to their dimension (1-5 mm and 1 mm-100 \(\upmu\)m).