Microplastics have become an issue of increasing concern in recent years due to their ubiquitous presence in the environment and the risk of injuries or ingestions by organisms at all trophic levels. The purpose of the current research is to develop a method to identify nano- and micro-plastics via fluorescence labeling. The fluorescent dye, Nile red, has a well characterized solvatochromatic shift in both excitation and emission spectra. A fundamental premise of our study is that Nile red will exhibit a similar shift as function of the dielectric constant of plastics. We measured the dielectric constants of eight common plastics; dielectric constants shifted from 2.04 F/m for Teflon to 3.45 F/m for Nylon which correlates to the polarity of the functional groups. The solvatochromatic shift of Nile red emission adsorbed on to the surfaces of the plastics linearly scales with dielectric constant (R<sup>2</sup>=0.8928). We are currently in the process of acquiring micro-reflectance UV-Vis spectra to determine if there is a solvatochromatic shift in the excitation spectra of Nile red. Based on these results, we are exploring possibility of a flow-through cell method of detection to distinguish between plastic types.

Rapid detection and identification of microplastics using Nile red

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