On October 21, 2022, Laurens Mandemaker and Florian Meirer from Utrecht University published a review in the peer-reviewed scientific journal Angewandte Chemie investigating the different micro-spectroscopic techniques available specifically for the detection of nanoplastics (NPs). Being able to accurately detect and characterize micro- and nanoplastics (MNPs) is a crucial first step in assessing human exposure to MNPs and their potential impacts on early life health.
The researchers explain that detecting and characterizing NPs comes with many significant analytical challenges. NPs are too small for light-based microscopes using ultraviolet, visible, or infrared light to image them, and the particle number-to-mass ratio increases significantly within such small size ranges (NPs are most commonly defined as less than 1 μm in diameter), meaning that even for relatively large particle numbers, mass characterization techniques such as GC-MS and LC-MS approach their limit of detection. To complicate the situation further, NPs primarily consist of carbon, hydrogen, and oxygen, which makes them very similar to the organic matter that surrounds them in environmental or tissue samples and subsequently limits the use of imaging methods based on element contrast.
To address these challenges and carry out an effective analysis of NPs, the authors argue that future studies should make use of both particle imaging as well as correlative or direct chemical characterization (such as mass characterization techniques). Their study reviews in depth the analytical benefits and limitations of a range of available techniques for NP characterization including electron, fourier transform infrared, fluorescence, scanning probe, and Raman microscopy, as well as for Raman spectroscopy and correlative approaches. To carry out the multi-pronged analyses needed to properly detect and characterize NPs, the authors explain that further research is needed to develop standardized technical protocols as well as smart solutions for sample preparation. However, they are confident these will be developed in the coming years..
“This review is a fundamental first step within AURORA to help analytical chemists prioritize and improve techniques needed to correctly measure nanoplastics in humans and subsequently understand their potential impacts on health,” comments the first author of the study, Laurens Mandemaker. “It’s both very challenging and rewarding to be involved in the effort to measure these plastic pollutants in places where no one has been able to measure before.”
The study was carried out with funding from the AURORA and POLYRISK projects within the CUSP research cluster as well as from an NWO Groot project. Both authors are partners within AURORA, and this publication is a result of the AURORA work package on the in-depth characterization of MNPs.
Mandemaker, L. and Meirer, F. (October 24, 2022). “Spectro-Microscopic Techniques for Studying Nanoplastics in the Environment and in Organisms.” Angewandte Chemie