Challenges and solutions in the analysis of micro- and nanoplastics down to 500 nm with automated Raman microspectroscopy: suitable filters, accuracy in the detection, identification, and quantification

Microplastics (1 µm–5 mm) and nanoplastics (90% correct material identification. Validation with 500 nm polystyrene beads yielded 67 ± 10% recovery relative to theoretical values. Analysis of potable water samples showed predominantly non-plastic particles, with only 0.36 ± 0.13% in the 0.5–10 µm range identified as plastics, 18% of them <1 µm. Further method development, particularly for sample preparation, will be required for broader application to water and food samples. For interest only in particles ≥1 µm, filters with pore size closer 1 µm (e.g., silicon) are recommended. Overall, automated Raman microspectroscopy can quantitatively analyze MNPs down to 500 nm, supporting improved plastic exposure risk assessment.