Discriminating detection of dissolved ferrous and ferric ions using copper nanocluster-based fluorescent probe.

Discrimination and detection of specific metal ions that belong to the same metallic element with different valence states in a complex matrix is challenging. In the present work, a fluorescence method using polyvinylpyrrolidone stabilized copper nanocluster (CuNCs@PVP) as a probe for discriminating detection of ferrous (Fe) and ferric (Fe) ions was developed. The CuNCs@PVP exhibited an excellent selective response to Fe ions in contrast to Fe ions and other metal ions when the pH value of solution was less than 4.0. Furthermore, the fluorescence of the CuNCs@PVP could be more sensitively quenched by Fe ions by virtue of Fenton reaction. The different response of CuNCs@PVP towards Fe and Fe ions under different conditions offered the potential for the discriminating detection of Fe and Fe ions. Based on detailed optimization of detection conditions, an excellent linear relationship between the fluorescence quenching efficiency (F/F) of the CuNCs@PVP and the concentration of Fe ions over the range of 0.4-20.0 μM and of Fe ions in the range of 0.01-0.4 μM were obtained, respectively. The detection limits for the Fe and Fe ions were 0.14 μM and 0.008 μM, respectively. The developed probe showed good selectivity and presented an alternative strategy for discriminating detection of Fe and Fe ions in complex samples.