Multiwalled Carbon Nanotube Chemically Modified GoldElectrode for Inorganic As Speciation and Bi(III) Determination

A chemically modified gold electrode has been conveniently
prepared by binding multiwalled carbon nanotubes
(MWCNTs) to which thiol functions have been tethered.
The electrode has been characterized by atomic force
microscopy and oxidative desorption experiments and
gives excellent results for trace determination of As(III)
and Bi(III) in natural and high-salinity waters, overcoming
the limitation typical of solid electrodes. A mechanism for
As(III) preconcentration at the electrode is proposed and
supported by results obtained by two similar chemically
modified electrodes (CMEs), the first one prepared with
single-walled carbon nanotubes and the second one with
a monolayer of (biphenyl)dimethanethiol. The performance
obtained with the MWCNTs-CME largely overcomes
that obtained by using other devices.