Chromium(III)-doped carbon dots: fluorometric detection of p-nitrophenol via inner filter effect quenching

We report on the synthesis of chromium(III)-doped carbon dots (Cr-CDs) by one-pot hydrothermal pathway using tris(2, 4-pentanedionato) chromium(III) and polyethyleneimine as precursors. The Cr-CDs have a graphene-analogous structure and display blue-green fluorescence with excitation/emission maxima at 350/466 nm, a 20% quantum yield, and excitation-independent emissions. Their cytotoxicity is low. The Cr-CDs were used as a fluorescence probe for p-nitrophenol (p-NP). The assay has a linear working range that extends from 0.8~150 μM and a 0.27 μM lower detection limit. The assay was applied to the detecting of p-NP in spiked human urine, and conceivably may be extended to a method for the determination of parathion.