Avaliação do uso da espectroeletroquimica na determinação simultanea de metais empregando metodos quimiometricos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

This work describes the construction of a spectroelectrochemical cell with an optical path of 1 mm and a platinum minigrating as an optically transparent electrode. The cell was characterised by means of electrochemical and spectroelectrochemical experiments, using a 5.0 mmol L potassium ferrocyanate solution. After this characterisation, the spectroelectrochemical properties of xylenol orange complexes with Ni(II), Co(II), Fe(III) and Cu(II) were investigated. Fe(III) and Cu(II) complexes showed spectroelectrochemical activities from 0.6 to -0.4 V. Based on these results, differen approaches for determination of iron and copper were evaluted, by employing spectroelectrochemical data, and univariate and multivariate calibrations. Multivariate calibration models based on PLS, PLS unfold and N-PLS chemometric methods were constructed, by employing spectroelectrochemical data obtained with copper and iron complexex with xylenol orange, in the metal concentration range from 5.0 to 20.0 mg L. These models were employed to determine iron in pharmaceutical products and copper in brass. The results were compared with those obtained by employing the univariate method. The comparative study among the chemometric methods mentioned above showed that PLS unfold provides the best results, with average error of prediction lower than 5%. Multivariate calibration models for the simultaneous determination of iron and copper in synthetic mixtures were also constructed, in the metal concentration range from 5.0 to 10.0 mg L. These results also showed that the calibration models based on PLS unfold provided the lowest average errors of prediction (<6%).

ASSUNTO(S)

eletrodos compostos complexos eletrodos de vidro

ACESSO AO ARTIGO

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