E. Akyilmaz et E. Dinckaya, A new enzyme electrode based on ascorbate oxidase immobilized in gelatin for specific determination of L-ascorbic acid, TALANTA, 50(1), 1999, pp. 87-93
A biosensor for the specific determination of L-ascorbic acid in fruit juic
es and vitamin C tablets was developed using ascorbate oxidase (EC 1.10.3.3
) from cucumber (Cucumis sativus L.) in combination with a dissolved oxygen
probe. Ascorbate oxidase immobilized with gelatin using glutaraldehyde and
fixed on pretreated teflon membrane served as an enzyme electrode. The pho
sphate buffer (50 mM, pH 7.5) and 35 degrees C were established as providin
g the optimum conditions. The biosensor response depends linearly on L-asco
rbic acid concentration between 5.0 x 10(-5) and 1.2 x 10(-3) M with a resp
onse time 45 s. The biosensor is stable for more than 2 months, while more
than 200 assays were performed. The results obtained for fruit juices and t
ablets were compared with DCIP (2,6 dichlorophenolindophenol) method. (C) 1
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