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

The growing concern over microplastic pollution has led to increasedfocus on environmental nanoplastics, which are smaller, more dynamic,and present unique challenges in both quantification and riskassessment. Nanoplastics exhibit high variability in size, shape,chemical composition, and surface chemistry, complicating theirdetection and quantification through conventional analytical techniquesdeveloped for nanomaterial analysis. One of the key challenges innanoplastic research is the lack of realistic, environmentally relevanttest materials that accurately mimic the characteristics of nanoplasticsfound in natural environments. In this study, we generatedpolystyrene-based nanoplastics from fragmented plastic items and usethem to produce controlled test materials for evaluating and comparinganalytical techniques under well-defined conditions. Specifically, weinvestigated the potential of microvolume UV-visible (UV-vis)spectroscopy as a practical and non-destructive technique for thequantification in stock suspensions, aiming to expand the analyticaltoolkit for environmental nanoplastic research. UV-vis spectroscopy wascompared with established mass-based techniques, pyrolysis gaschromatography-mass spectrometry and thermogravimetric analysis, as wellas nanoparticle tracking analysis, a number-based method. Thecomparative analysis demonstrated that UV-vis spectroscopy provides arapid, accessible, and effective mean of quantifying nanoplastics,especially when sample volumes are limited. Despite some underestimationof nanoplastic concentrations relative to mass-based techniques, UV-vismeasurement results were consistent in terms of order of magnitude,showing reliable trends across different methods. This study underscoresthe potential of UV-vis spectroscopy as a valuable tool for quantifyingrealistic nanoplastic test materials and supporting the development offuture applications in environmental nanoplastic research.