Determination of Iodide via Direct Fluorescence Quenching at Nitrogen-Doped Carbon Quantum Dot Fluorophores

The development of analytical methods for rapidly, sensitively, and selectively detecting iodide (I ^- ) in aqueous media is critically important because I ^- is closely related to human health because of a number of diseases caused by the deficiency and radioactivity of I ^- . In this work, we describe N-doped carbon quantum dots as the fluorophores for the direct determination of I ^- fluorescence, achieving a detection limit of 10 μM with an analytical linear range up to 2.0 mM. The experimental results also demonstrate that the N-doped carbon quantum dot fluorophores possess high selectivity for I ^- detection. The presence of nitrogen functional groups results in a positively charged carbon quantum dot surface, which is advantageous for the detection of I ^- fluorescence because of the strong electrostatic interaction between carbon quantum dots and I ^- . This work demonstrates the possibility of developing carbon quantum dot fluorophore-based fluorescence methods for the determination of other anions.