A novel amperometric bienzymatic biosensor has been developed based on the incorporation of Lactate Oxidase (LOx) and Horseradish Peroxidase (HRP) into a carbon nanotube/polysulfone membrane by the phase inversion technique onto screen-printed electrodes (SPEs). In order to improve the sensitivity and reduce the working potential, experimental conditions have been optimized and ferrocene has also been incorporated into the membrane as a redox mediator of the enzymatic reactions, which allows the reduction of H2O 2 at -100 mV. Measurements were carried out in phosphate buffer solution at pH 7.5 and under batch conditions. The biosensor response time to l-lactate was only 20 s and showed a good reproducibility (RSD 2.7%). Moreover, the detection limit was 0.05 mg L-1 of l-lactate with a linear interval range from 0.1 mg L-1 to 5 mg L-1. Finally, the biosensor has been applied to the determination of l-lactic acid in different wine and beer samples. Then, the results obtained with the biosensor were compared with the ones obtained using, as a reference method, a commercial kit based on spectrophotometric measurements, obtaining an excellent agreement between the results, validating our approach. © 2012 The Royal Society of Chemistry.
|Publication status||Published - 21 Aug 2012|