For an appropriate risk assessment of microplastics in the environment and food, it is essential to know the levels of microplastic contamination. Extensive research has been carried out in the field of microplastic detection in recent years. While common methods such as Raman spectroscopy and pyrolysis GCMS are time consuming and require trained personnel and expensive equipment, there is a need for an inexpensive and easy to use method. Staining microplastics with the Nile red (NR) fluorescent dye has great potential to meet these criteria because the only requirement is a device for fluorescence imaging [1, 2]. In our work, we tested NR and newly developed derivatives to achieve greater selectivity for plastic particles and more intense fluorescence. In addition, the influence of the use of different solvents and water at different pH values in the dyeing process was examined by analyzing the fluorescence spectra of solid samples of colored microplastics and natural particles. Finally, a standardized method was developed method developed from the knowledge acquired and tested on sea salt and wastewater. The results will be presented in our talk.