1. Introduction
The simultaneous determination of several elements
at trace or low level concentration in real
matrices is one of the main aims of new analytical
procedures. Good selectivity and high sensitivity are
required. The principle obstacle in increasing the
sensitivity of polarographic methods of analysis is
the problem of separation of the charging current
and the faradaic current. This problem could be easily
overcome using square-wave voltammetry (SWV),
which was ®rst reported by Barker and Jenkins
[1,2] at the dropping mercury electrode. Although
the ®rst applications were limited by the lack of good
commercial instrumentation, results indicate that
square-wave polarography is becoming an electrochemical
method with a great potential [3±5]. Modern
square-wave voltammetry is a complex but powerful
technique that requires microcomputer and a microprocessor.
Most of the recent new instruments can
ful®ll these conditions and therefore, the technique has
become a common and powerful one in determining
many organic or inorganic substances [6±9].