The application of Bismuth modified cheap and disposable screen printed carbon electrode
(BiSPCE) for voltammetric studies of metal–thiol rich peptides complexation was evaluated
considering systems consisting of cadmium as a metal and GSH and PC2 as thiol peptides.
Comparison of the performance of BiSPCE with the commonly used glassy carbon electrode
(BiFE) was made. The information obtained about the complexation sequence using the former
electrode was quite consistent with previous studies made on GSH and Cd systems using the
conventional mercury electrodes due to the absence of signal splitting, the good sensitivity and
the wider linearity range. In contrast with the conventional mercury electrodes, the anodic
signals associated with bismuth electrode material were observed to be weakened and all the
available signals were well resolved which shows the suitability of Bismuth based electrode for
metal- thiol complexation studies. MCR-ALS could not be applied due to the continuous shift
of the peak potentials, loss of linearity of the species and anomalous shape of the complex signal
formed between Cd and GSH. Therefore, the complexation sequence between GSH and Cd2+
was evaluated qualitatively. However, a relatively well defined shape and intense
voltammograms were observed for Cd-PC2 system and consequently, MCR-ALS was applied
after correction of the continuous peak potential shift for the complex signals. The peak intensity
associated with complex signal was dominated by the intense signal of the free metal reduction
in acidic and fairly basic medium. However a relatively intense signal of the complexes was
obtained at pH 7.5 in borate buffer solution. In addition extensive Bi complexation was observed
from ESI-MS experiment which proves the suitability of ex situ mode of Bi film preparation for
thiol- metal complexation studies by voltammetric titration technique
