Fig. 5
Representative detection and validation of polyethylene terephthalate (PET) fiber-based fragment in FFPE human colon tissue using LDIR and OPTIR spectroscopy. (a) Chemical image (recorded at wavenumber 1660 cm− 1) of sample 3 provides an overview of the entire cross-section (LDIR, 3 μm resolution). Subsequent chemical imaging of a defined area with higher spatial resolution (LDIR, 1 μm resolution) results in a clear visualization of the fiber. The calculated ratio image (wavenumber 1730/1660 cm− 1) strongly indicates that the PET fiber is embedded within the tissue matrix. (b) The chemical image overlay (1660 cm− 1 and 1730 cm− 1) reveals the distinct spatial distribution of the fiber, tissue material, and areas where the fiber is fully embedded. Full spectral analysis at each point is presented in the spectral fingerprint region (OPTIR, 500 nm resolution).
