A robust gold nanocluster-peroxyoxalate chemiluminescence system for highly sensitive detection of cyanide in environmental water

Detection of cyanide (CN-) ion is of essential importance due to its high toxicity to human life. Herein, we developed a gold nanoclusters (AuNCs)-peroxyoxalate chemiluminescence (CL) system for ultrasensitive detection of CN- in environmental water samples. Bis (2,4,5-trichloro-6-carbopentoxyphenyl) oxalate (CPPO)-hydrogen peroxide (H2O2) CL reaction was utilized to produce high energy intermediates, namely energy donors, and AuNCs served as the acceptors to harvest the energy via CL resonance energy transfer (CRET) process. Besides, it was demonstrated that AuNCs also could act as a catalyst to enhance the generation of the high energy intermediate; and the AuNCs also had an aggregation induced emission (AIE) effect in the organic solvent that was used in CPPO-based CL system. In the presence of CN-, AuNCs can be etched by CN- due to the Elsner complexation reaction between CN- and AuNCs, and thus both of the quantum yield and catalytic activity decreased remarkably. As a result, significant quenching of CPPO-AuNCs CL was observed. The CL intensity decreased linearly in the concentration range of 2.5–125 μg/L CN-, and the detection limit was calculated to be 0.55 μg/L, 10-fold lower than that obtained by the fluorescent sensing of AuNCs. The relative standard deviation was 4.3% for seven parallel measurements of 100 μg/L CN-. It also exhibited high selectivity and favorable anti-interference capability. The sensing system was used for detection of CN- in five standard water samples, and the analytical results were in good agreement with the certified values. Overall, the simple and sensitive CL sensing platform offers a promising tool for convenient detection of CN- in environmental water samples.