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Due to the complex nature of the sediment, MPs in the samples must be extracted from sample matrices. The density separation is widely applied to extract MPs from sediment samples. The sediment is dried prior to mixing with a concentrated salt solution. After a period of agitation, MPs and light particles float to the surface or stay suspended, whereas heavy particles settle down (Klein et al. 2018). Many studies extract MPs by using sodium chloride (NaCl) solution since this is inexpensive and environmentally friendly (Alam et al. 2019; Campanale et al. 2020; Free et al. 2014; Mani et al. 2015). However, the density of NaCl solution (~1.2 g/cm³) cannot extract some polymers such as Polyvinyl chloride (PVC), Polyethylene terephthalate (PET), polycarbonate, and polyurethane. Therefore, sodium iodide (NaI), sodium zinc chloride (ZnCl₂), and sodium polytungstate (Na₂WO₄) are viable choices (Ballent et al. 2016; Ta and Babel 2019; Yin et al. 2020). Conversely, MPs in water samples are easily filtered and separated during the sampling step (Dris et al. 2018).