Development of a thermoanalytical method for the analysis of microplastics in atmospheric depositions

Microplastics are an increasingly concerning type of environmental contaminant that can reach all environmental compartments, from the soil to the oceans to the atmosphere. Atmospheric MPs are particularly dangerous as they can easily reach other ecosystems through the phenomenon of atmospheric deposition and enter the respiratory systems of animals and humans, causing a variety of health issues. In the absence of standardised methods to quantify them, various techniques have emerged. Py-GC-MS is one of the most promising and the main one capable of providing their results in terms of mass and not number of particles. In this study, an analytical method based on Py-GC-MS was developed and used to detect and estimate the presence of seven polymers in total atmospheric depositions: PS, PET, PC, PA (nylon-6), PE, PVC, and SBR. Samples were obtained through the exposure of passive collectors and pretreated with evaporation, Fenton process, and filtration before being sent to the Py-GC-MS. The presence of OM proved capable of producing considerable interferences during the analysis, but the attempts made to avoid, or at least reduce, it (washing the samples with hexane and double pyrolysis) had little effect. The characterization of the OM revealed that the bulk of this contamination was caused by lignocellulosic biomass’ derivatives and fatty acids.