Sensitive determination of Cd(II) by square wave anodic stripping voltammetry with in situ bismuth-modified multiwalled carbon nanotubes doped carbon paste electrodes

This paper presents a new electrochemical method for the determination of Cd(II) using a bismuth-modified multiwalled carbon nanotubes doped carbon paste electrode (Bi/MCNTs-CPE). Because of good electrical conductivity of MCNTs and excellent electroanalytical performance of bismuth film, the new electrode significantly enhances the sensitivity for the detection of Cd(II) and exhibits superior performance in comparison to the bare carbon paste electrode, the bismuth-modified carbon paste electrode, and the multiwalled carbon nanotubes doped carbon paste electrode. Many parameters such as mass ratio of carbon paste and MCNTs, pH of measure solution, concentration of Bi(III), preconcentration time, preconcentration potential, and operational parameters of square wave anodic stripping voltammetry were investigated. Under optimum conditions, the linear regression equation of Cd(II) was ip = 4.458c − 11.73 (ip: μA, c: μg L−1, R = 0.9983) from 1.0 to 60 μg L−1 with a detection limit of 0.3 μg L−1. Finally, the Bi/MCNTs-CPE was successfully applied to the determination of Cd(II) in tap water sample with satisfactory results.

► Bismuth-modified carbon nanotube doped carbon paste electrode was easily fabricated.
► Advantage of bismuth film and doped carbon nanotubes was effectively combined.
► The optimum mass ratio of carbon paste to carbon nanotubes is 6.6.
► The novel electrode significantly enhances signal for detection of Cd(II).