Madalena C. C. Areias
Federal University of Pernambuco
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Featured researches published by Madalena C. C. Areias.
Talanta | 2005
Ivanildo Luiz de Mattos; Madalena C. C. Areias
A highly selective, fast and stable biosensor for determination of glucose in soluble coffee has been developed. The biosensor electrode consist of a thin film of ferric hexacyanoferrate (Prussian Blue or PB) electrodeposited on the glassy carbon electrode (GCE) (to provide a catalytic surface for the detection of hydrogen peroxide) glucose oxidase immobilized on top of the electrode and a Nafion((R)) polymer layer. The stability of the PB film and the biosensor was evaluated by injecting standard-solution (50muM H(2)O(2) and 0.5mM glucose) during 4h in a flow-injection system with the electrodes polarized at -50mV versus Ag/AgCl. The system is able to handle about 60 samples per hour and is very stable and suitable for industrial control. Determination of glucose in the range 2.5 and 15% (w/v) in phosphate buffer with precision (r.s.d.<1.5%) has been achieved and is in agreement with the conventional procedures. Linear calibration in the range of 0.15 and 2.50mM with detection limits of ca. 0.03mM has been obtained. The morphology of the enzyme glucose oxidase on the modified electrode has been analyzed by scanning electron microscopy (SEM) measurements.
Green Chemistry | 2011
Ronny F. M. de Souza; Madalena C. C. Areias; Lothar W. Bieber; Marcelo Navarro
Mixtures of carbonyl compounds and allyl halides, adsorbed on a graphite powder cathode, were reduced under aqueous anolyte to give high yields of homoallylic alcohols. Catalytic amounts of silver or tetrabutylammonium tetrafluoroborate improved the yields significantly. Inexpensive allyl chloride gave superior results when compared to allyl bromide.
Journal of Electroanalytical Chemistry | 2003
Madalena C. C. Areias; Lothar W. Bieber; Marcelo Navarro; Flamarion B. Diniz
Abstract The first report of an electrochemical Reformatsky reaction in aqueous medium and in the absence of metal is presented. Ethyl bromoisobutyrate ( 1 ) and benzaldehyde ( 2 ) were electrolyzed in a divided cell at a potential of −1.2 V versus Ag/AgCl, corresponding to the reduction wave of 1 . Several types of carbon cathodes and a platinum anode were used in a 0.1 M KBr solution in either water+methanol (5:1) or water. The Reformatsky adduct ethyl 2,2-dimethyl-3-hydroxy-3-phenyl propionate ( 5 ) was obtained with yields up to 46% (relative to consumed 2 ) together with varying amounts of ethyl isobutyrate ( 3 ) and diethyl 2,2,3,3-tetramethylsuccinate ( 4 ). The probable mechanism starts with a radical species generated from 1 which adds to benzaldehyde giving a radical intermediate, which is further reduced to the final product 5 . A radical chain through bromine abstraction from 1 is also possible. No products resulting from reduction of benzaldehyde were observed. On zinc electrodes, in an undivided cell, an organometallic reaction producing the same coupling product 5 becomes more important. The results represent a strong additional support for a radical mechanism postulated in previous work for the Zn-promoted chemical Reformatsky reaction in water.
RSC Advances | 2013
Ronny F. M. de Souza; Madalena C. C. Areias; Lothar W. Bieber; Marcelo Navarro
A green electrochemical heterocoupling procedure has been developed. Prenyl halides and benzaldehyde adsorbed on a graphite powder cathode were reduced in a cavity cell using aqueous anolyte, providing isomer mixtures of prenylated alcohols. High α-regioselectivity was observed using graphite with 3% TBABF4, while high γ-regioselectivity was obtained using 2% silver-doped graphite.
Journal of The Chilean Chemical Society | 2009
Ivanildo Luiz de Mattos; Marcos Caroli; Madalena C. C. Areias; Marcelo Navarro
A suitable flow-injection method for the analysis of commercial solutions of hydrogen peroxide is described. A Nafion-coated glassy carbon electrode, modified by deposition of copper hexacyanoferrate (CuCHF), is employed as an amperometric sensor. The method allows the analysis of 45 samples per hour, with peroxide concentrations in the range of 1.25 -10.0 mM, with relative standard deviations smaller than 1%.
Journal of Electroanalytical Chemistry | 2004
Diogo S. Santana; Givaldo O. Melo; Márcio V.F. Lima; Jorge R.R. Daniel; Madalena C. C. Areias; Marcelo Navarro
Electrochimica Acta | 2008
Madalena C. C. Areias; Marcelo Navarro; Lothar W. Bieber; Flamarion B. Diniz; Eric Léonel; Christine Cachet-Vivier; Jean-Yves Nedelec
Analyst | 2016
Madalena C. C. Areias; Kenichi Shimizu; Richard G. Compton
Electrochimica Acta | 2010
Ronny F. M. de Souza; Carlos A. de Souza; Madalena C. C. Areias; Christine Cachet-Vivier; Michel Laurent; Rachid Barhdadi; Eric Léonel; Marcelo Navarro; Lothar W. Bieber
Electroanalysis | 2016
Madalena C. C. Areias; Kenichi Shimizu; Richard G. Compton