Determination of malic acid in real samples by using enzyme immobilized reactors and amperometric detection
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Data
2004-07-01
Autores
Manzoli, A.
Tomita, LSN
Fertonani, F. L.
de Oliveira-Neto, G.
Mascini, M.
Yamanaka, H.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Taylor & Francis Inc
Resumo
The malate dehydrogenase (MDH) and ascorbate oxidase were immobilized independently, onto silanized controlled porous silica and packed in a tygon tube. The reactors were inserted in the flow system, and the malic acid was determined by measurement of NADH produced by enzymatic reaction. The NADH was reoxidized in a wall jet cell that consisted of spectrographic graphite, Ag/AgCl, KCl(sat), and steel needle as work, reference, and counter electrodes, respectively. The current intensities were measured at 390 mV. The malate calibration curve shows a linear range from 5.0 x 10(-6) to 1.0 x 10(-4) molL(-1), the lifetime was 40 analyses, after that a decrease of 20% on the response is observed. Three different citric juices were analyzed and a good correlation between the proposed method and spectrophotometric commercial kit were obtained.
Descrição
Palavras-chave
citrus juice, malic acid, malate dehydrogenase, ascorbic acid
Como citar
Analytical Letters. Philadelphia: Taylor & Francis Inc., v. 37, n. 9, p. 1823-1832, 2004.