A physical chemistry lens on environmental nanoplastics analysis challenges. Part II: Detection techniques - principles, limitations and future directions.

Abstract

Nanoplastics (NPs) have become a prominent environmental pollutant, garnering increasing scientific and public attention due to their possible effects on ecosystems and human health. However, their detection remains a major analytical challenge due to their small size, diverse polymeric compositions, and unique surface properties facilitating strong interactions with complex environmental matrices. To date, no single technique can provide complete information on their identity, morphology, and concentration, and many existing methods fail when adapted from microplastics workflows. This review aims to provides a comparative evaluation of current detection approaches for NPs, with a special focuson the physical principles underpinning each technique and how these principles affect their performance at the nanoscale. Spectroscopic (e.g. FTIR, Raman, XPS), mass-based (e.g. pyrolysis–GC–MS, MALDI-TOF), imaging (e.g. SEM, TEM, fluorescence microscopy), and population-level (e.g. DLS, NTA, flow cytometry) methods are discussed in terms of what they measure, how they work, and why their applicability to NPs may be limited. Rather than presenting techniques as black boxes, this review explains their working principle in the context of NPs research needs, offering a tangible way to understand what each method can—and cannot—reveal about NPs in terms of polymer classification and surface chemistry, quantification, morphological analysis, size distribution, and concentration. The merits and drawbacks of each technique are assessed, emphasizing their complementary roles in addressing the challenges of NP analysis. The originality of this review lies in its principle-based evaluation of detection methods, a comparative synthesis table that informs multimodal workflows, and a standards-oriented roadmap. This roadmap connects the current MP framework to the future requirements of NP research — harmonised methods, cross-laboratory comparability, and reliable data to underpin future monitoring and remediation efforts.