Identification of microplastics using 4-dimethylamino-4′-nitrostilbene solvatochromic fluorescence

In this work, we introduce the use of 4-dimethylamino-4 '-nitrostilbene (DANS) fluorescent dye for applications in the detection and analysis of microplastics, an impendent source of pollution made of synthetic organic polymers with a size varying from less than 5 mm to nanometer scale. The use of this dye revealed itself as a versatile, fast and sensitive tool for readily discriminate microplastics in water environment. The experimental evidences herein presented demonstrate that DANS efficiently absorbs into a variety of polymers constituting microplastics, and its solvatochromic properties lead to a positive shift of the fluorescence emission spectrum according to the polarity of the polymers. Therefore, under UV illumination, microplastics glow a specific emission spectrum from blue to red that allows for a straightforward polymer identification. In addition, we show that DANS staining gives access to different detection and analysis strategies based on fluorescence microscopy, from simple epifluorescence fragments visualization, to confocal microscopy and phasor approach for plastic components quantification.

Automated summary

The study introduces a new fluorescent dye DANS for the detection and analysis of microplastics. Experimental evidence shows that DANS efficiently absorbs into various polymers and its solvatochromic properties can distinguish different types of polymers. DANS staining allows for different strategies of detection and analysis, from simple epifluorescence fragments visualization to confocal microscopy and phasor approach for quantification of plastic components.