The aim of this work is to discuss some selected applications of square wave voltammetry published in the last five years. The applications focused here cover several electroanalytical fields such as: determination of pesticides; molecules with biological activity; metals and other environmental pollutants. Special attention is given to the work developed in the Grupo de Materiais Eletroquímicos e Métodos Eletroanalíticos - IQSC - USP concerning the utilization of square wave voltammetry, with different kinds of electrodes, for the determination of pesticides in natural waters and active principles in pharmaceutical formulations. The new methodology is simple, fast and sensitive when compared with the traditional ones such as chromatography and spectrophotometry. The satisfactory results obtained provide alternative procedures for the quality control of drugs and the monitoring of pesticides in natural environments.

A eletrorredução do Dipiridamol (DIP) foi estudada em solução tampão fosfato 0,10 mol L-1 (pH 3,0) em microeletrodo de platina coberto com mercúrio eletrodepositado (Hg-ME), empregando as técnicas de voltametria cíclica, de varredura linear e polarografia. A similaridade entre o perfil voltamétrico obtido com Hg-ME e as ondas polarográficas sigmoidais com correntes limitadas por difusão é demonstrada. Experimentos com eletrodo de gota pendente de mercúrio (HMDE) foram realizados em paralelo para confirmar os resultados obtidos com Hg-ME, os quais indicaram que a reação de redução ocorre em duas etapas irreversíveis com o consumo de dois elétrons e dois prótons por etapa. A corrente limite de difusão, referente à primeira etapa de redução, permitiu estimar o coeficiente de difusão do DIP como sendo igual a 2,04 x 10-5 cm² s-1.

The electroreduction of Dipyridamole (DIP) was studied in 0.10 mol L-1 phosphate buffer solution (pH 3.0) on a mercury coated platinum microelectrode (Hg-ME), employing cyclic, linear sweep voltammetry and polarography techniques. The similarity between Hg-ME voltammetric profile and the sigmoidal polarographic waves both with a diffusion limited current is showed. Experiments with a hanging mercury drop electrode (HMDE) were performed in parallel to confirm the results obtained with Hg-ME, which indicated that the reduction occurs in two irreversible steps involving two electrons and two protons each step. The limiting diffusion current, concerning the first step, allows estimating the diffusion coefficient for DIP as being equal to 2.04 x 10-5 cm² s-1.