HoLDI mass spectrometry for rapid, solventless detection of airborne nanoplastics and co-occurring aerosol organics

Nanoplastics are increasingly recognized as an atmospheric contaminant with potential implications for exposure and climate-relevant aerosol processes, yet routine detection in real-world air remains limited by laborious sample preparation, contamination risk, and poor cross-study comparability. Here we present a practical analytical workflow built around a 3D-printed hollow laser desorption/ionization (HoLDI) target that adapts MALDI time-of-flight mass spectrometry for direct, solventless analysis of particles collected on common aerosol substrates. We integrate HoLDI-MS with size-resolved aerosol sampling (cascade impactor) and real-time particle sizing (SMPS/OPS), complemented by electron microscopy and EDS for morphology and elemental context. Indoor air measurements reveal polymer signatures consistent with polyethylene, polyethylene glycol, and polydimethylsiloxanes, with higher relative signal intensities in the microscale size fractions than in the submicron range, indicating a size-dependent distribution and/or detection efficiency in complex indoor matrices. In outdoor air, HoLDI-MS captures polycyclic aromatic hydrocarbon patterns with relatively stronger signals in the nanoscale fractions, underscoring the capability to concurrently track plastic-related polymers and non-plastic organic aerosol constituents across size modes. HoLDI provides an accessible, rapidly deployable pathway toward harmonized, size-resolved chemical fingerprints of airborne nano/microplastics and co-occurring aerosols, helping close critical observational gaps needed for exposure assessment and atmospheric process studies.