Microplastics analysis: can we carry out a polymeric characterisation of atmospheric aerosol using direct inlet Py-GC/MS?

Microplastics are emerging pollutants of great concern since they are widely distributed in the environment. While the occurrence of microplastics was studied in marine and freshwaters, sediments, soil, and different classes of organisms, the atmosphere was somewhat understudied, although it can be the most significant transport pathway from mid to high latitudes. This work is one of the first studies testing the possible application of pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) for detecting polymers in atmospheric aerosol. It explored the possibility of a direct inlet analysis of sampling filters, proposing for the first time the calculation of an "aerosol organic baseline" for estimating the level of interferences to specific polymer tracers due to the organic matter content of atmospheric aerosol. The direct inlet analysis was tested for environmental samples and commercial dust, using the micro-FTIR analytical technique as a reference. Polyethylene (PE), polypropylene (PP), and polystyrene were detected in atmospheric aerosol samples; PE, PP, and Nylon 6 (polyamide 6, PA6) were detected in the commercial dust. The first results obtained on the atmospheric aerosol allow for highlighting the technique's potential and drawing insights from the difficulties encountered. Results suggest that the direct analysis of the sampling filters can be employed as an exploratory technique due to its fast response, even if further research is needed to obtain a comprehensive polymeric characterisation of atmospheric aerosol.