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|Type:||Artigo de evento|
|Title:||Potentiometric Biosensor For L-ascorbic Acid Based On Ascorbate Oxidase Of Natural Source Immobilized On Ethylene-vinylacetate Membrane|
|Abstract:||The development of a potentiometric biosensor for L-ascorbic acid based on ascorbate oxidase is described. The enzyme was extracted of the epicarp of Cucumis sativus L. fruit and immobilized in a graphite/epoxy electrode by occlusion in a poly(ethylene-co-vinyl acetate) matrix (EVA 40%m/m). The electrode showed a sub-Nerntian response (slope of 50.3±0.6mV), between 8.0x10-6 and 4.5x10-4moll-1 for ascorbate, when 0.1moll-1 KH2PO4 buffer at pH 5.0 and 25.0°C was employed. The biosensor was continuously tested, during 15 days (about 300 analyses), and no decrease in the response was observed, for vitamin C determination in pharmaceuticals samples, without any previous treatment. The biosensor was stable for at least 1 month when stored in a refrigerator. The relative standard deviation was about 4% compared to the spectrophotometric method. The response time was about 5min at room temperature. Copyright (C) 1999 Elsevier Science B.V.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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