AMPEROMETRIC LYSINE BIOPROBES ANALYSIS IN FEEDS

Amperometric enzyme electrode probes have been constructed for the spe cific determination of L-lysine and used in batch and flow analysis. T he enzyme lysine oxidase was immobilized on a preactivated polymer sup port which was placed on a platinum electrode. Additional blocking mem branes conferred high stability, reproducibility and avoided electroch emical and enzyme interfaces. Parameters including pH, temperature, st orage and operational times were optimized. Lysine was determined in t he range 10(-6) - 2.10(-3) M with a detection limit of 5 x 10(-7) M. T he Michaelis constant was 2 x 10(-3) M. This value was approximately t wo order of magnitudes higher than that reported in literature for the free enzyme. The response time of the probe was about 2 min in batch and flow analysis and 30 sec in flow injection analysis (FIA). The res ulting probes were stable for more than three months with more than 30 0 analyses performed. The determination of lysine was carried out by b oth flow-through analysis and FIA. Analysis in feeds was carried out b y acid hydrolysis to liberate lysine; then the solution was analyzed b y the bioprobe and HPLC procedures. Results by the two methods correla ted well.