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

Abstract

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 (Fe3+) and ferric (Fe2+) ions was developed. The CuNCs@PVP exhibited an excellent selective response to Fe3+ ions in contrast to Fe2+ 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 Fe2+ ions by virtue of Fenton reaction. The different response of CuNCs@PVP towards Fe3+ and Fe2+ ions under different conditions offered the potential for the discriminating detection of Fe3+ and Fe2+ ions. Based on detailed optimization of detection conditions, an excellent linear relationship between the fluorescence quenching efficiency (F/F0) of the CuNCs@PVP and the concentration of Fe3+ ions over the range of 0.4–20.0 μM and of Fe2+ ions in the range of 0.01–0.4 μM were obtained, respectively. The detection limits for the Fe3+ and Fe2+ 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 Fe3+ and Fe2+ ions in complex samples.