Voltammetric Behavior of Cadmium(II) At N-P-Chlorophenylcinnamohydroxamic Acid Modified Carbon Paste Electrode
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Date
2000-06
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Addis Ababa Universty
Abstract
A sensitive voltammetric method has been developed for the determination of
cadmium(ll) utilizing a carbon paste electrode modified with N-p-chlorophenylcinnamohydroxamic
acid. The analyte was accumulated at the modified electrode
surface (via complexation) under open circuit and precisely controlled convective
condition. It was then quantified electrochemically by differential pulse anodic
stripping voltammetry in a different non-deaerated electrolyte solution following
medium exchange. Detailed experiments were conducted to establish the optimal
carbon paste composition, pH and concentration of accumulation and stripping
solutions, preconcentration time, bulk cadmium(li) concentration, and instrumental
parameters.Two good linearities were obtained between the voltammetric current and
cadmium concentration employing different preconcentration times. One is acquired
in the concentration range 2.00 x 10'7 - 3.20 x 10’6 MCd(ll) (r=0.999) and the other
from 4.00 x 10‘8 to 1.60 x 10'7 M Cd(ll) (r=0.999) with 1 min and 2 min
preconcentration time, respectively. The detection limit was found to be 9.80 x 10'9
M(1.1 ppb) Cd(ll) with 2 min preconcentration time. For a series of six determinations
of Cd(ll) at 1 x 10‘6 M and 8 x 1CT8 M levels relative standard deviations of 2.6% and
5.5%, respectively, were achieved. Electrochemical cleaning was used to regenerate
the surface rapidly and reproducibility; and this allows the use of a single modified
electrode surface in multiple analytical determinations over several weeks. Many
common metal ions had little or no effect on the determination of cadmium(ll). The
method was verified by the determination of trace cadmium(ll) in municipal and
mineral waters.
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Cadmium(II) At N-P-Chlorophenylcinnamohydroxamic Acid