Simultaneous determination of species by Differential Alternative Pulses Voltammetry

A new voltammetric technique providing high resolution – Differential Alternative Pulses Voltammetry (DAPV) based on the nonlinearity of I/E characteristic of the electrochemical systems was developed, suitable for simultaneous determination of species without their preliminary separation. Superimposition of couples of single rectangular pulses separated by a constant delay time and having same amplitude and opposite polarity, combined with appropriate signal processing yields first derivative of peak shaped curve. The DAPV faradaic current response equation for reversible electrochemical reactions was theoretically derived, graphically presented and experimentally tested. DAPV was applied for determination of species having very near E1/2 potentials: Pb2+/Tl+ and In3+/Cd2+ under increasing concentration ratios. The experimental results compared with those obtained by Differential Pulse Polarography (DPP) and Second Harmonic Alternating Current Polarography show superiority of DAPV resolution power which is combined with high sensitivity, similar to that providing by DPP, employing a simple electronic equipment.