Fabrication of a new multi-walled carbon nanotube paste electrode for stripping voltammetric determination of Ag(i)

A new modified carbon paste electrode based on multi-walled carbon nanotubes and a synthesized Schiff base of N , N ′-bis(2-hydroxybenzylidene)-2,2′(aminophenylthio) ethane, acting as a chelating agent for Ag( i ) ions, is described. The electroanalytical procedure for the determination of Ag( i ) was comprised of two steps: the chemical accumulation of the analyte under open-circuit conditions followed by replacing the medium with a 0.1 M HCl solution where the accumulated Ag( i ) was reduced for 20 s in −0.7 V. The potential was then scanned from −0.2 to +0.2 V to obtain the voltammetric peak. The effective parameters in the sensor response were examined. Under optimized operational conditions, a linear response range from 0.5-200 ng mL −1 was obtained. The detection limit for silver determination was 0.092 ng mL −1 . For 7 successive determinations of 15.0 and 60.0 ng mL −1 of Ag( i ), relative standard deviations of 2.2% and 1.2% were obtained, respectively. The procedure was applied in determining Ag( i ) in X-ray photographic films and water samples. Open circuit accumulation of Ag( i ) onto the surface of a modified carbon paste electrode and determination by differential pulse stripping voltammetry.