Electrospray ionization (ESI) is one of the most widely used ionization methods in commercial mass spectrometry. However, it is challenging to effectively ionize most nonpolar plastics. In this study, a low-cost, rapid, free of complex sample preparation, and capable of generating easily interpretable characteristic peaks method for MP identification was developed. It integrates cheap pyrolysis modules with conventional electrospray ionization mass spectrometry (PESI-MS) and operates with a minimal sample input of μm-scale in size and μg-scale in mass. It presents a limit of detection (LOD) of 0.1 μg and achieves a linear quantitative range of 0.2-1 μg with a coefficient of determination (R2) of 0.99, supporting accurate quantitative analysis of target MPs. Within 2.4 s, the polymer vapor generated during atmospheric pyrolysis at an optimal temperature of 400 °C was effectively ionized to provide characteristic backbone information. The method was initially applied to representative MPs, including polyolefins (polyethylene PE, polypropylene PP), polyacrylate (poly(methyl methacrylate) PMMA), polyesters (polyethylene terephthalate PET, polylactide PLA), nylon (polyamide 6, PA6), and polyformaldehyde (POM). Principal component analysis (PCA) of the PESI-MS data revealed distinct spectral features for each MP type. In addition, Pearson product-moment correlation coefficient (PPMC) analysis elucidates both similarities and differences among the polymers and enables precise identification of MPs. Finally, the combined application of PESI-MS and PPMC analysis was used to comprehensively analyze nonplastic, plastic, and real-life samples, thereby validating the effectiveness of this approach in identifying environmental MPs.
He et al. (Mon,) studied this question.