Automated Impedance Measurements in Electrochemical Cells

In this paper a system is described for impedance measurements in electrochemical cells, integrated by a fast potentiostat, signal generator, digital transient recorder and a computer interface. The treatment of the signal is made by obtaining the correlation between the response cell signal with the in-phase and in-quadrature signals, as is made in the frequency response analysis systems, but the quadrature component being numerically generated. This allows one to obtain the d.c. ®rst and second harmonic cell responses in a single experiment, as well as the a.c. phase selective response by programming the reference signal phase angle. The results obtained with a dummy cell showed the validity of the procedure since the deviation of the measured results from the theoretical data is low. The C/E curve of the interface 1 M KCI/Hg at 258C is concordant with that previously reported in the literature. Moreover, the system has been tested with the reduction of Cd(II) ion. # 1999 Elsevier Science Ltd. All rights reserved.