Quantitative evaluation of true-to-life nanoplastics using UV-visible spectroscopy and comparative analytical techniques

Abstract

The growing concern over microplastic pollution has led to increased focus on environmental nanoplastics, which are smaller, more dynamic, and present unique challenges in both quantification and risk assessment. Nanoplastics exhibit high variability in size, shape, chemical composition, and surface chemistry, complicating their detection and quantification through conventional analytical techniques developed for nanomaterial analysis. One of the key challenges in nanoplastic research is the lack of realistic, environmentally relevant test materials that accurately mimic the characteristics of nanoplastics found in natural environments. In this study, we generated polystyrene-based nanoplastics from fragmented plastic items and use them to produce controlled test materials for evaluating and comparing analytical techniques under well-defined conditions. Specifically, we investigated the potential of microvolume UV-visible (UV-vis) spectroscopy as a practical and non-destructive technique for the quantification in stock suspensions, aiming to expand the analytical toolkit for environmental nanoplastic research. UV-vis spectroscopy was compared with established mass-based techniques, pyrolysis gas chromatography-mass spectrometry and thermogravimetric analysis, as well as nanoparticle tracking analysis, a number-based method. The comparative analysis demonstrated that UV-vis spectroscopy provides a rapid, accessible, and effective mean of quantifying nanoplastics, especially when sample volumes are limited. Despite some underestimation of nanoplastic concentrations relative to mass-based techniques, UV-vis measurement results were consistent in terms of order of magnitude, showing reliable trends across different methods. This study underscores the potential of UV-vis spectroscopy as a valuable tool for quantifying realistic nanoplastic test materials and supporting the development of future applications in environmental nanoplastic research.