Prussian Blue- and lactate oxidase-based amperometric biosensor for lactic acid

The properties of amperometric lactate biosensors based on Prussian Blue (PB) and lactate oxidases (LOX) of different origin (from Pediococcus sp. and Enterococcus sp. RL1) immobilised in Nafion were investigated by flow injection analysis. The operating potential was −50 mV (versus Ag/AgCl, 0.1 M KCl). A linear range in the dependence of current response upon the concentration of lactic acid was up to 0.8 mM. The detection limit of electrodes containing a high amount (6 U) of enzyme was below 1 μM. Operational stability could be maintained by exposing the electrodes to low (20 μM) concentrations of lactic acid.