Selective Fluorescence Staining of Microplastic in Water Utilizing Nile Red/surfactant Combination

To observe and quantify microplastics (MPs) in an aqueous environment, separation of MPs from water (e.g., filtration), drying, and staining them with a fluorescent dye by using a solvent is a common procedure. In this study, the tedious procedures were tried to be avoided, through selectively and in situ fluorescence staining of MPs in water by the combination of a dye and a surfactant. A non-polar fluorescent dye such as Nile red was adsorbed to MPs in the presence of Tergitol MIN FOAM 1x and penetrated the polymer matrix by thermal treatment, exhibiting stable fluorescence behavior. The effect of different staining parameters, including temperature, time, dye/surfactant ratio, dye/MP ratio, and MP concentration, were investigated to find better staining conditions. Fluorescence quenching of non-adsorbed dyes in aqueous solution was successfully achieved by the addition of aniline, which allowed selective fluorescence staining of MPs in water possibly for rapid detection and monitoring of MPs.

Automated summary

In this study, selective fluorescence staining of microplastics in water was successfully achieved through the combination of a dye and a surfactant, avoiding tedious separation, drying, and staining procedures. This method provides a potential approach for rapid detection and monitoring of microplastics.