Micro- and Nanoplastics in Alpine Snow: A New Method for Chemical Identification and (Semi)Quantification in the Nanogram Range

We present a new method for chemical
characterization of micro-
and nanoplastics based on thermal desorption–proton transfer
reaction–mass spectrometry. The detection limit for polystyrene
(PS) obtained is <1 ng of the compound present in a sample, which
results in 100 times better sensitivity than those of previously reported
by other methods. This allows us to use small volumes of samples (1
mL) and to carry out experiments without a preconcentration step.
Unique features in the high-resolution mass spectrum of different
plastic polymers make this approach suitable for fingerprinting, even
when the samples contain mixtures of other organic compounds. Accordingly,
we got a positive fingerprint of PS when just 10 ng of the polymer
was present within the dissolved organic matter of snow. Multiple
types of microplastics (polyethylene terephthalate (PET), polyvinyl
chloride, and polypropylene carbonate), were identified in a snowpit
from the Austrian Alps; however, only PET was detected in the nanometer
range for both snowpit and surface snow samples. This is in accordance
with other publications showing that the dominant form of airborne
microplastics is PET fibers. The presence of nanoplastics in high-altitude
snow indicates airborne transport of plastic pollution with environmental
and health consequences yet to be understood.