Analytical Approaches for Analyzing Microplastics Using Pyrolysis Gas Chromatography Mass Spectrometry and Accelerated Solvent Extraction

Wastewater treatment plant (WWTP) biosolids act as major sinks for microplastics, yet robust mass-based quantification of polymer composition in these complex matrices remains analytically challenging. This study applies an integrated accelerated solvent extraction (ASE) and pyrolysis–gas chromatography–mass spectrometry (Py-GCMS) workflow to quantify polymer mass concentrations in biosolids from two municipal wastewater treatment plants (WWTP1 and WWTP2). Polymer-specific calibration curves were developed and validated across multiple analytical days to assess linearity, reproducibility, and quantitative reliability. Five polymers – polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), and polymethyl methacrylate (PMMA) – were consistently detected and quantified in all biosolid samples. Across both WWTPs, PE dominated total polymer mass, followed by PVC, with PP and PS present at intermediate concentrations and PMMA occurring at the lowest levels. WWTP1 exhibited higher concentrations for all quantified polymers compared to WWTP2, although the relative ranking of polymer abundance was consistent between plants. Replicate agreement was strong, indicating good analytical precision and method robustness. These results demonstrate that ASE when combined with Py-GCMS can provide a reproducible and sensitive mass-based approach for characterizing polymer burdens in biosolids. The observed dominance of PE and PVC highlights the disproportionate contribution of high-production, fragmentation-prone plastics to wastewater-derived solids. The method offers a complementary perspective to particle-count-based techniques and provides critical insight into the true polymer mass loads associated with land-applied biosolids.