Fabrication of ferrocenyl glutathione modified electrode and its application for detection of cadmium ions

1′-cysteaminecarbonyl-1-glutathionecarbonyl-ferrocene (Fc-GSH) was synthesized from ferrocene dicarboxylic acid and reduced glutathione (GSH) with 4 steps. IR and 1 H-NMR were used to characterize the products. Then Fc-GSH was immobilized on the surface of gold electrode. Cyclic votammetry (CV) was adopted to investigate the electrochemical properties of this Fc-GSH modified electrode in the absence and presence of Cd 2+ aqueous solutions. The peak oxidation potential ( E a ) and reduction potential ( E c ) of Fc-GSH modified electrode were observed at E a = 0.74 V and E c = 0.64 V (vs Ag/AgCl) before the accumulation of Cd 2+ . This redox process is a monoelectron chemical reaction. The anodic shift is about 80 mV in the presence of 20 nmol/L of Cd 2+ aqueous solution. Moreover, this shift is in proportion to the concentration of Cd 2+ when the concentration of Cd 2+ is lower than 20 nmol/L. So the modified electrode can be used as probes to detect cadmium ions with the limit of 0.1 nmol/L by cyclic voltammetry.