The cover of Analytical Chemistry (April 21, 2020, Volume 92, Number 8) visualizes a novel method for nanoplastic particle analysis. It depicts the coupling of Raman microscopy and field-flow fractionation (FFF), enabled by optical tweezers. The illustration shows nanoplastic particles flowing through a channel where they are optically trapped by laser light, separated, and characterized spectroscopically. In the foreground, an accompanying spectrum demonstrates how different plastic types can be identified by their distinct Raman signatures.

The image highlights this innovative approach to visualize and precisely analyze invisible nanoplastic fragments in complex mixtures—a crucial advancement for environmental research and material characterization.