Immobilization of lactate oxidase in a poly(vinyl alcohol) matrix on platinized graphite electrodes by chemical cross-linking with isocyanate

A new method for development of an electrochemical sensor based on lactate oxidase is dedbed. Platinized spectroscopic-grade graphite electrodes were modified by chemically cross-linking l-lactate oxidase from Pediococcus species into a poly(vinyl alcohol) network through reaction with a tri-isocyanate. The immobilized enzyme exhibits high activity and long-term stability. The sensor provides a linear response to l-lactate over a concentration range of 2 × 10 −5−4 × 10 −3 M and a sensitivity of 1.71 μA.1. mmole −1. The response time of the sensor is 10–45 sec and the detection limit is 10μ M. Stable response to the substrate was obtained over a period of 3 months. The new sensor was also used for the analysis of some dairy products without any special pretreatment.