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Square-wave voltammetry

Square-wave voltammetry (SWV) is one of the four major voltammetric techniques provided by modern computer-controlled electroanalytical instruments, such as Autolab and µAutolab (both EcoChemie, Utrecht), BAS 100 A (Bioanalytical Systems) and PAR Model 384 B (Princeton Applied Research). The other three important techniques are single scan and cyclic staircase, pulse and differential pulse voltammetry (see Chap. II.2). All four are either directly applied or after a preconcentration to record the stripping process. The application of SWV boomed in the last decade, firstly because of the widespread use of the instruments mentioned above, secondly because of a well-developed theory, and finally, and most importantly, because of its high sensitivity to surface-confined electrode reactions. Adsorptive stripping SWV is the best electroanalytical method for the determination of electro active organic molecules that are adsorbed on the electrode surface. The theory and application of SWV are described in several reviews, and here only a brief account of the recent developments will be given. Contemporary SWV originates from the Kalousek commutator and Barker’s square-wave polarography. The Kalousek commutator switched the potential between a slowly varying ramp and a certain constant value in order to study reversibility of electrode reactions . Barker employed a low-amplitude symmetrical square wave superimposed on a ramp, and recorded the difference in currents measured at the ends of two successive half cycles, with the objective to discriminate the capacitive current. SWV was developed by combining the high-amplitude, high-frequency square wave with the fast staircase waveform, and by using computer-controlled instruments instead of analog hardware.

square-wave voltammetry

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