A fluorescence sensor array based on triple-color emission S,N-co-doped graphene quantum dots for metal ions discrimination

In recent years, metal ion pollution poses serious threats to human health and ecosystems, so there is a pressing need to develop rapid methods for simultaneous detection of multiple metal ions. Herein, we developed a fluorescent array sensor based on triple-color emission S,N-GQDs (sulfur and nitrogen co-doped graphene quantum dots) for the rapid discrimination and quantitative analysis of 10 metal ions in environmental samples. The triple-color fluorescence emission of S,N-GQDs exhibited distinct responses to different metal ions, which were effectively captured by linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA), thereby facilitating the differentiation of both metal ions and their mixtures. The aforementioned 10 metal ions have been successfully discriminated over a broad concentration range (0–300 μM). Moreover, quantification of metal ions was achieved at a low concentration of 2.03 μM for Mn²⁺, 0.50 μM for Fe³⁺, 0.11 μM for Cu²⁺, 3.92 μM for Zn²⁺, 0.55 μM for Pb²⁺, 1.14 μM for Ni²⁺, 2.10 μM for Cd²⁺, 0.29 μM for Ag⁺, 1.14 μM for Co²⁺ and 0.96 μM for Ba²⁺. Moreover, the sensor array demonstrated excellent recovery rates for metal ions in water samples (tap water and lake water), indicating great application prospects in environmental water monitoring.