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Type: Artigo de periódico
Title: Potentiometric sensor for L-ascorbic acid based on EVA membrane doped with copper(II)
Author: Fernandes, JCB
Kubota, LT
Neto, GDO
Abstract: The development of a new potentiometric sensor for L-ascorbic acid based on the redox properties of copper(II) ions incorporated in a EVA membrane was carried out. The poly(ethylene-co-vinyl acetate) matrix (EVA 40 % wt.) was doped with CU2+ ions and dispersed on the surface of a graphite/epoxy electrode. The electrode displayed a Nernstian response (slope between 55 and 60 mV/decade), in the ascorbate concentration between 5.6 x 10(-6) and 3.7 x 10(-4) mol L-1, when 0.1 mol L-1 KH2PO4 buffer at pH 5.0 and 25.0 degrees C was employed. The sensor stability was assessed, allowing 280 determinations without significant decrease in the response. The relative standard deviation for vitamin C determination in pharmaceuticals samples by the proposed method was about 10%. Considering these deviations, the results obtained for both the methods (spectrophotometric and potentiometric) were similar.
Subject: L-abscorbic acid
potentiometric sensor
copper(II) ions
EVA membrane
pharmaceutical analysis
modified electrode
Country: Alemanha
Editor: Wiley-v C H Verlag Gmbh
Rights: fechado
Date Issue: 1999
Appears in Collections:Unicamp - Artigos e Outros Documentos

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