Supplementary file 1_Profiling autofluorescence signatures of microplastics from commercial plastic products by flow cytometry and multivariate analysis.docx

Polymer differentiation depended on multichannel autofluorescence signatures rather than fluorescence intensity alone, with differentiation driven by fluorescence detection channels exhibiting the greatest variance among polymer types. Significant differences were observed among polymer types (p < 0.001). Side scatter consistently provided greater differentiation than forward scatter, whereas scatter-based normalisation significantly reduced differentiation (p < 0.001).

Complementary spectroscopic analyses identified a calcium carbonate filler in white polyvinyl chloride, a phthalate-type plasticiser in clear polyvinyl chloride, and a copper phthalocyanine pigment in black high-density polyethylene. Collectively, these findings demonstrate the potential of autofluorescence-based multichannel flow cytometry for microplastic differentiation while providing a foundation for future studies involving more complex and environmentally representative samples.</p>