Detection of cyanide and sulfide ions by different mechanisms using a fluorescent chemical sensor containing a fluorophore and a potential ligand for metal complexes

Abstract

Here, we present a fluorescent chemical sensor for the simultaneous detection of CN⁻ and S²⁻ ions, which are highly toxic to humans and the environment. When the BPMA-Flu–Cu²⁺ complex comprising BPMA-Flu, a fluorophore combined with Cu²⁺, was used, the fluorescence was turned off. However, the fluorescence was turned on again by the addition of CN⁻ and S²⁻ ions. BPMA-Flu is a unique compound containing both a fluorophore and a ligand coordinated to a metal ion. This strategy using the proposed BPMA-Flu–Cu²⁺-based fluorescent chemical sensor facilitated quantitative analysis of CN⁻ and S²⁻ ions with high selectivity and sensitivity, despite varying detection mechanisms. The detection limit was as low as 290 nM and 74 nM for CN⁻ and S²⁻ ions, respectively. The sensor was selective and excluded other anions at concentrations 10-fold higher than those of CN⁻ and S²⁻ ions. The recovery rates did not exceed 10% of the original values for the detection of CN⁻ ions in rainwater and tap water. These results indicate acceptable accuracy and precision for practical applications.