Chronoamperometric determination of d-lactate using screen-printed enzyme electrodes Original Research Article

A reagentless biosensor for d-lactate was developed using the screen-printing technology. In a simple design, d-lactate dehydrogenase and NAD+ were deposited onto the surface of a carbon electrode, modified with an insoluble salt of Meldola’s Blue. The detection of d-lactate was performed by chronoamperometry and took advantage of the constant potential oxidation of NADH, formed in the reaction catalysed by d-lactate dehydrogenase. The total of 150 s were necessary for a measurement and linear detection of d-lactate was achieved over the range 0.1–1 mM. Twenty-five microliter sample volumes were required for the assays. The choice of a properly applied potential together with the use of polyethyleneimine–Nafion in the sensing layer allowed to minimise the interferences for the detection of d-lactate in real samples of wine.