Quantifying the uncertainty and errors between common analytical methods for measuring airborne microplastics

In recent years airborne microplastics have emerged as a ubiquitous pollutant worldwide, with negative implications for ecosystems, climate and human health. The differing sampling and analysis techniques used amongst micro- and nanoplastic research groups limits our understanding of the global distribution of airborne microplastics and nanoplastics. We present plans and progress for an ongoing coordinated inter-laboratory experiment, designed to elucidate strengths and weaknesses of individual analysis methods. Daily active pumped air samples were collected in a controlled manner at a remote site in Canterbury, New Zealand, alongside weekly deposition samples. All samples were divided evenly, using specific contamination controls, into four sample sets for interlaboratory method comparisons, and distributed to participating research groups in New Zealand, Germany and the UK. Samples will be analysed using common microplastic analysis techniques: micro-Fourier transform infrared spectroscopy (µFTIR), micro-Raman spectroscopy (µRaman), fluorescence microscopy, pyrolysis – gas chromatography/mass spectrometry (Py-GC/MS), and thermal desorption – proton transfer reaction – mass spectrometry (TD-PTR-MS). The results will allow quantification of the relative uncertainties and biases associated with each individual method, and inform how future airborne microplastics studies performed with different analytical methods should be interpreted.