Cyanide Detection using Azo-acylhydrazone in Aqueous Media with High Sensitivity and Selectivity

The cyanide anion (CN−) is known to be an extremely toxic anion and can directly lead to the death of human beings in several minutes because it strongly binds cytochrome-c, thereby disrupting the mitochondrial electron-transport chain and causing a decreased oxidative metabolism and oxygen utilization. A colorimetric sensor L1 bearing azosalicylic aldehyde of benzoyl hydrazone was designed and synthesized. The binding property of the sensor L1 with anions such as F−, Cl−, Br−, I−, CH3COO−, H2PO4−, HSO4−, ClO4−, CN− and SCN−, was examined by UV-vis and 1H NMR spectra. The result showed that sensor L1 has behaved good selectivity and high sensitivity for CN− in DMSO/H2O (5:5, v/v) binary solutions. When CN− was added to the solution containing L1, a dramatic color change from colorless to red was observed, while the other anions did not cause noticeable changes. And the detection limits were 1.0×10−5 mol•L-1 and 3.7×10−8 mol•L-1 of CN− from visual color changes and UV-vis spectrum changes respectively. Furthermore, test strips based on sensor L1 were fabricated, and sensor L1 could be served as practical colorimetric sensor to detect CN− for “in-the-field” measurement. In addition, test strips based on L1 were fabricated, which could serve as a practical colorimetric sensor to detect CN− in field measurements or in test kits.