Desenvolvimento de um sistema multieletrodo para medidas voltametricas : voltametria multiplexada com uso de transformada de Hadamard

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

A multielectrode system for voltammetric analysis has been developed making use of the advantages related to the use of solid-statc ultramicroelectrodes (UMEs). The instrument is capable of dealing with 31 UMEs in two different forms: in the first one, it is possible to obtain a voltammetric curve using only 1 UME or groups of UMEs at the same potential; in the second form, every UMEs work at different potential values. The control and data acquisition functions are performed through a PC/AT-286 microcomputer running a software written in Quick-Basic 4.5. The electrochemical cell, with a two electrodes configuration, has the counterelectrode connec- ted to a single current-to-voltage converter. Current signals were converted to digital using a 12 bits analog-to-digital converter. The excitation potential was applied to the electrodes using two 8 bits digital-to-analog converter conected to the extremities of a voltage divider formed by 30 resistors of 1 kW. Two arrays of UMEs, using a mercury film deposit onto the surface of a 55 mm diameter copper wire, were constructed in order evaluate the instrumento The potential difference applied to the electrodes can assume the shape of a linear ramp or triangular function as well as differential or normal pulse. A new methodology, using multiplexed currents, was also developed This method make use of Hadamard transfonn resulting in a better signal/ noise ratio for the measured currents.

ASSUNTO(S)

voltametria ultramicroeletrodos

ACESSO AO ARTIGO

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