Screen-printed enzyme electrodes for the detection of marker analytes during winemaking Original Research Article

Biosensors for malic acid and glucose have been developed, using screen-printed electrodes and two different classes of enzymes: NAD(P)+-dependent dehydrogenases and oxidases. The active surface of the electrodes was modified using Meldola Blue (malic acid) and Prussian Blue (glucose) and in this way sensitive, low cost and reliable NAD(P)H and H2O2 probes were obtained. Fixed potential amperometry was used for the detection of substrates in small volumes of sample (50 μl). Immobilization of the enzymes in a polyethylenimine–glutaraldehyde cross-linking membrane allowed sensors to be obtained with sufficient operational stability. The detection limits were of 10−5 M for malic acid and 10−6 M for glucose. The sensors were applied in the analysis of different samples of wine.