Advances in analysis of microplastics in drinking water treatment plants. Fluorescence techniques using iDye Pink

Recently, the increasing amount of plastic waste has raised concerns about microplastics in aquatic environments. In this study, microplastics between 0.1 and 5 mm in samples from different points of three Drinking Water Treatment Plants (DWTP) were separated, quantified, and identified. Staining methods were used in combination with microscopic and spectroscopic techniques. On the one hand, the Rose Bengal dye was used to discriminate between natural and synthetic particles. On the other hand, Nile Red and iDye Pink reagents have been evaluated for staining microplastics, providing them with fluorescence. The nature of the particles is determined by comparison with a series of patterns by means of an epifluorescence microscope. In addition, "Micro Fourier Transform Spectrophotometer " and "Raman Spectroscopy" were used to identify the nature of the particles more accurately. Concerning the results, polyester was the most common material by fluorescence identification, and it was confirmed with Raman spectroscopy. Since most of the particles observed were microfibres, Raman proved to be a better identification technique than μ-FTIR, which could only identify large fragments. In addition, the global elimination of microplastics (MPs) resulted notable in the three DWTPs, being 81.47% for A, 88.98% for B, and 82.27% for C, thus guaranteeing a higher quality of drinking water.