Measuring micro- and nanoplastics in agricultural soils by py-GC/MS-IRMS

Plastic materials and their associated additives have emerged as critical environmental concerns, particularly within agricultural systems. These materials not only affect soil properties but also pose potential risks of absorption by plants, thereby facilitating the trophic transfer of contaminants. The measurement of nanoplastic particles (NPs) presents challenges due to their small size and low concentrations. While techniques such as micro-Fourier transform infrared spectroscopy (µFTIR) and micro-RAMAN are commonly used for identifying microparticles, they lack the capability to quantify NPs (<1µm). Many analytical techniques have limited detection limits, which makes it difficult to accurately measure low concentrations of nanoplastic particles (NPs), such as those present in plants. An alternative approach involves labelling or doping micro- and nanoplastics (MNPs) or their additives, enabling their screening and characterization in laboratory environments. This strategy, particularly when combined with stable isotopes, allows for tracing the biological fate of MNPs and their additives in plants and organisms. While this method is currently impractical for field trials due to its cost and analytical challenges, it can be only practically applicable in controlled laboratory experiments. Here we tested extraction methods for determining MNPs by pyrolysis associated with gas chromatography coupled to mass spectrometry and isotope ratio mass spectrometry (py-GC/MS-IRMS) using polymers labelled with stable isotopes (¹³C). Detection methods for additives are being refined to identify potential markers for tracking the dynamics of MNPs in the environment. Compound-specific stable isotope analysis (CSIA) can provide valuable information on the fate of polymers, polymer additives and the characterisation of the products of plastic decomposition. The poster will present a preliminary comparative evaluation and optimization of extraction and detection methods for MNPs using py-GC/MS-IRMS, focusing on the application of stable isotope-labelled polymers (¹³C). Key findings will demonstrate the challenges and potential of these methodologies for quantifying and characterizing MNPs in laboratory trials.