A dual-modal fluorometric and colorimetric nanoprobe based on graphitic carbon nitrite quantum dots and Fe (II)-bathophenanthroline complex for detection of nitrite in sausage and water.

A fluorometric and colorimetric dual-mode sensing platform based on graphitic carbon nitrite quantum dots (g-CNQDs) and Fe (II)-bathophenanthroline complex (BPS-Fe2+) was designed to the sensitive detection of nitrite (NO2-) in sausage and water. In this system, the fluorescence of g-CNQDs was quenched by BPS-Fe2+ complex due to the inner filter effect (IFE). When NO2- was present, Fe2+ was oxidized by nitrite to form BPS-Fe3+ complex with BPS, leading to the recovery of the fluorescence from g-CNQDs. Therefore, we constructed a "turn-off-on" fluorescence probe for detection of NO2-. Moreover, with the increase of NO2- concentration, the color of the solution changed from red to colorless, so the UV-vis measurements and on-site visual detection were realized. The method is capable of detecting NO2- in the concentration range of 2.32-34.8 μM with good selectivity and high sensitivity. In addition, the method has the potential to determine NO2- in water samples and sausage samples.