Nanoplastic Analysis with Nanoelectromechanical System Fourier Transform Infrared Spectroscopy: NEMS-FTIR

Abstract: This paper presents a photothermal infrared (IR) spectroscopy technique based on a nanoelectromechanical system, which is coupled to a commercial Fourier transform infrared spectrometer (NEMS--FTIR) as a promising solution for the chemical characterization and quantification of nanoplastics. Polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) nanoparticles with nominal diameters of 100, 54, and 262~nm, respectively, were analyzed by NEMS--FTIR with limits of detection (LoD) of 353~pg for PS, 102~pg for PP, and 355~pg for PVC. The PS mass deposited on the NEMS chips was estimated from the measured absorptance values and the attenuation coefficient of PS. The wide spectral range of the FTIR allowed the identification of individual polymer nanoparticles from a mixture. The potential of NEMS--FTIR for the analysis of real--world samples was evaluated by confirming the presence of polyamide (PA) particles released from commercial tea bags during brewing. Accelerated aging of the tea bags under elevated temperature and UV radiation showed continuous release of PA particles over time.