A Novel Application of Fluorine Doped Carbon Dots Combining Vortex-Assisted Liquid-Liquid Microextraction for Determination of 4-Nitrophenol with Spectrofluorimetric Method

A simple and fast vortex-assisted liquid–liquid microextraction (VA-LLME) combining with fluorescent carbon dots have been developed for the determination 4-nitrophenol (4-NP). The high fluorescent quantum yield (58.9%) fluorine doped carbon dots (F-CDs) were synthesized using tetrafluoroterephthalic acid as a fluorine source and using citric acid as a fluorine source and using ethylenediamine as a nitrogen source via a one-step hydrothermal method. F-CDs fluorescence was effectively quenched by 4-NP due to inner filter effect (IFE) and the strong interactions between functional groups (-COOH,-OH, -NH2 and -F groups) of the F-CDs and 4-NP. In VALLME method, n-octanol was employed as extraction solvent, and vortex-mix was exploited as a gentle mix method to reduce emulsification time and improve the extraction efficiency. The detection limits, the quantification limit and relative standard deviation for the 4-NP were found as 15 nM, 50 nM and 3.5%, respectively. Moreover, the obtained F-CDs can be employed as fluorescent probe to detect 4-NP in real environmental water samples.