Extraction and identification of a wide range of microplastic polymers in soil and compost

Prosenc, Franja (author), Leban, Pia (author), Šunta, Urška (author), Bavcon Kralj, Mojca (author)

Microplastic pollution is globally widespread; however, the presence of microplastics in soil systems is poorly understood, due to the complexity of soils and a lack of standardised extraction methods. Two commonly used extraction methods were optimised and compared for the extraction of low-density (polyethylene (PE)) and high-density microplastics (polyethylene (PET)), olive-oil-based extraction, and density separation with zinc chloride (ZnCl2). Comparable recoveries in a low-organic-matter matrix (soil; most >98%) were observed, but in a high-organic-matter matrix (compost), density separation yielded higher recoveries (98 ± 4% vs. 80 ± 11%). Density separation was further tested for the extraction of five microplastic polymers spiked at different concentrations. Recoveries were >93% for both soil and compost, with no differences between matrices and individual polymers. Reduction in levels of organic matter in compost was tested before and after extraction, as well as combined. Double oxidation (Fenton’s reagent and 1 M NaOH) exhibited the highest reduction in organic matter. Extracted microplastic polymers were further identified via headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS). This method has shown the potential for descriptive quantification of microplastic polymers. A linear relationship between the number of particles and the signal response was demonstrated for PET, polystyrene (PS), polyvinyl chloride (PVC), and PE (R$^2$ > 0.98 in alluvial soil, and R$^2$ > 0.80 in compost). The extraction and identification methods were demonstrated on an environmental sample of municipal biowaste compost, with the recovery of 36 ± 9 microplastic particles per 10 g of compost, and the detection of PS and PP.

• Language: English
• Keywords: microplastic extraction, oil extraction, density separation, GC–MS, mass spectrometry, plastic polymers, polyethylene terephthalate, polyethylene, mass spectrometry identification, terrestrial environments
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: ZF - Faculty of Health Sciences
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: 16 str.
• Numbering: Vol. 13, iss. 23, art. 4069
• PID: 20.500.12556/RUL-133742
• UDC: 543.51:691.175
• ISSN on article: 2073-4360
• DOI: 10.3390/polym13234069
• COBISS.SI-ID: 89126147
• Publication date in RUL: 13.12.2021

Record is a part of a journal

• Title: Polymers
• Shortened title: Polymers
• Publisher: MDPI
• ISSN: 2073-4360
• COBISS.SI-ID: 517951257

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 01.12.2021

Secondary language

• Language: Slovenian
• Keywords: ekstrakcija mikroplastike, pridobivanje olja, ločevanje gostote, GC–MS, masna spektrometrija, plastični polimeri, polietilen tereftalat, polietilen