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Potentiometric Sensor for L ‐Ascorbic Acid Based on EVA Membrane Doped with Copper(II)
Author(s) -
Fernandes Julio C. B.,
Kubota Lauro T.,
Neto Graciliano de Oliveira
Publication year - 1999
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199906)11:7<475::aid-elan475>3.0.co;2-w
Subject(s) - ascorbic acid , potentiometric titration , copper , membrane , chemistry , potentiometric sensor , electrode , redox , inorganic chemistry , analytical chemistry (journal) , nuclear chemistry , chromatography , organic chemistry , biochemistry , food science
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 Cu 2+ 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 5.6×10 –6 and 3.7×10 –4 mol L –1 , when 0.1 mol L –1 KH 2 PO 4 buffer at pH 5.0 and 25.0°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.