Highly selective fluorometric detection of para-nitrophenol from its isomers by nitrogen-doped graphene quantum dots

Nitrogen-doped graphene quantum dots (N-GQDs) with blue fluorescence and excellent water-solubility and an average diameter of approximately 21 nm have been prepared via hydrothermal treatment of ammonium fluoroborate and trisodium citrate, with the average size in diameter about 21 nm. It was found that paranitrophenol (4-NP) could dramatically quench the fluorescence of N-GQDs via static quenching because the good linearity of the Stern-Volmer equation (k(q) >> 2.0 x 10(10) L/(mol.s)) and the change in lifetime before and after the addition of 4-NP, which are different from that of its isomers and other analogs or metal ions. A fast and direct fluorimetric method with N-GQDs probe has thereby been developed for detecting 4-NP at concentrations from 0 to 20 mu M, with a limit of detection of 0.29 mu M. Furthermore, this proposed fluorimetric method was successfully applied to analyze 4-NP in real water samples, showing the feasible detection of trace 4-NP in complicated environmental water samples. The developed N-GQDs-based fluorimetric method is expected to be applied to the highly selective determination of 4-NP from its isomers, other analogs and general metal ions.

Automated summary

Nitrogen-doped graphene quantum dots (N-GQDs) with blue fluorescence and excellent water-solubility were prepared, and a fluorimetric method using N-GQDs probe for detecting 4-NP was developed successfully, showing the feasible detection of trace 4-NP in complicated environmental water samples and expected to be applied for highly selective determination of 4-NP.