Inhibition of Rhodamine B-Ferricyanide Chemiluminescence by Gold Nanoparticles and Sensitive Determination of Hazardous Cyanide

We describe a new turn off-on chemiluminescence (CL) method for the sensitive and selective determination of cyanide based on the inhibiting effect of gold nanoparticles (AuNPs) on rhodamine B (RohB)-ferricyanide (Fe(CN)6(3-)) reaction. Free RohB can generate strong chemiluminescence emission when oxidized with Fe(CN)6(3-), but undergoes an intense extinction in the presence of AuNPs. Energy transfer and collisions between RohB molecules and AuNPs are probably the reason for this decreasing effect. Furthermore, it was found that CL intensity gradually recovered in the presence of cyanide due to its interaction with the AuNPs. The relation between the decreased CL intensity and cyanide concentration was exploited to develop a method for the determination of cyanide in the 16.7 - 1333 nmol L(-1) concentration range, with a detection limit of 13.6 nmol L(-1). In comparison with other nanoparticle-based methods, the presented assay shows good sensitivity and reliability for the determination of cyanide. The method was satisfactorily applied to the determination of cyanide in environmental and biological samples.