During the last years, microplastics in the environment came to the fore in environmental science research. For an appropriate risk assessment, it is essential to know the levels of microplastic contamination in the environment. In the field of microplastic detection, extensive research has been carried out in recent years. While common methods such as Raman spectroscopy and pyrolysis GC-MS are time-consuming and require trained staff and expensive equipment, there is the need for a cheap and easily applicable method. Staining microplastics with the fluorescent dye Nile red (NR) has a high potential to fulfill these criteria. In our work, we tested Nile red and newly developed derivatives, with the aim of achieving greater selectivity for plastic particles and more intense fluorescence. In addition, the influence of using different solvents and water at different pH values in the dyeing process was investigated by analyzing solid sample fluorescence spectra of dyed microplastics and natural particles. Finally, the method developed from the acquired knowledge was tested for sea salt.
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The research projects of Wasser 3.0 (www.wasserdreinull.de) are conducted by sponsors and donors. Wasser 3.0 gGmbH is a non-profit company with strong focus on responsible research, education and communication. The enterprise abcr GmbH (www.abcr.de) from Karlsruhe (GERMANY) is directly involved in the project as an industrial partner. The authors acknowledge special support from Dr. Elena Sergeeva, Dr. Truong Giang Do, Dr. Vitalii Petryk, and Dr. Sergey Sergeev from abcr service lab for the fruitful discussion about fluorescent dyes and their application. Michael Sturm additionally thanks the “Deutsche Bundesstiftung Umwelt” (DBU) for the grant of a PhD scholarship (Az. 20018/549).
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Sturm, M.T., Horn, H. & Schuhen, K. The potential of fluorescent dyes—comparative study of Nile red and three derivatives for the detection of microplastics. Anal Bioanal Chem 413, 1059–1071 (2021). https://doi.org/10.1007/s00216-020-03066-w