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|Título:||FIA potentiometric system based on periodate polymeric membrane sensors for the assessment of ascorbic acid in commercial drinks|
|Autor:||Guerreiro, J. Rafaela L.|
Kamel, Ayman H.
Sales, M. Goreti F.
Flow injection analysis (FIA)
|Relatório da Série N.º:||Food Chemistry; Vol. 120, Issue 3|
|Resumo:||Ascorbic acid is found in many food samples. Its clinical and technological importance demands an easyto- use, rapid, robust and inexpensive method of analysis. For this purpose, this work proposes a new flow procedure based on the oxidation of ascorbic acid by periodate. A new potentiometric periodate sensor was constructed to monitor this reaction. The selective membranes were of PVC with porphyrin-based sensing systems and a lipophilic cation as additive. The sensor displayed a near-Nernstian response for periodate over 1.0x10-2–6.0x10-6 M, with an anionic slope of 73.9 ± 0.9 mV decade-1. It was pH independent in acidic media and presented good selectivity features towards several inorganic anions. The flow set-up operated in double-channel, carrying a 5.0x10-4 M IO- 4 solution and a suitable buffer; these were mixed in a 50-cm reaction coil. The overall flow rate was 7 ml min-1 and the injection volume 70 µl. Under these conditions, a linear behaviour against concentration was observed for 17.7–194.0 µg ml-1, presenting slopes of 0.169 mV (mg/l)-1, a reproducibility of ±1.1 mV (n = 5), and a sampling rate of ~96 samples h-1. The proposed method was applied to the analysis of beverages and pharmaceuticals.|
|Versão do Editor:||http://www.sciencedirect.com/science/article/pii/S0308814609013077|
|Aparece nas colecções:||ISEP – GRAQ – Artigos|
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|ART_JGuerreiro_2010_GRAQ.pdf||96,21 kB||Adobe PDF||Ver/Abrir|
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