A MELET- and IFE-based UV-visible luminescent ratiometric probe for quantization of mercury(II) and nitrofurantoin in environmental sewage.

A novel fluorimetric ratiometric probe of green and eco-friendily nitrogen-enriched, oxygen-doped carbon nanodots (Cnanodots) was prepared for the quantitative analysis of mercury(II) (Hg) and nitrofurantoin (Nit) in the environmental sewage. The Cnanodots exhibits dual-emission peaks respectively at 345 and 445 nm under 285 nm excitation, with excitation-independent properties. Unexpectedly, this Cnanodots displays two obvious ratiometric responses to Hg and Nit through decreasing the signal at 345 nm and remaining invariable at 445 nm. Experimental results confirm that the highly sensitive analysis of Hg and Nit are achieved respectively based on matching energy-level electron transfer and inner filter effect mechanisms. The fluorescence (FL) ratiometric intensity of [FL/FL] expresses a good linear relationship with the concentration of Hg in the scope of 0.01-20 μM, while the logarithm of [Log(FL-FL)] on the quenching degree of the probe by Nit also shows a good linear correlation within the range of 0.01-100 μM. The detection limits were calculated to be 4.14 nM for Hg, and 7.84 nM for Nit. Moreover, recovery experiments of Cnanodots for Hg and Nit sensing in real sewage samples obtained satisfactory results, comfirming the feasibility of practical application.