LACCASE ELECTRODE FOR THE CONTINUOUS-FLOW DETERMINATION OF PHENOLIC-COMPOUNDS

Laccase (p-diphenol, O2 oxido-reductase, E.C. 1. 10. 3.2) from Botryti s cinerea was immobilized in a gelatin support on an O2 sensing electr ode. The enzyme was copolymerized with the inert protein using glutara ldehyde (1.25 % w/w) on the hydrophobic selective gas membrane of a pO 2 sensor and this was covered with a Nuclepore polycarbonate microporo us film (0.03 mum). The enzyme electrode was used in a continuous-flow system to measure the concentration of a wide range of phenolic subst rates. The measuring time of each sample was about 1.5 min including r esponse and rinsing times. The electrode response was set for hydroqui none up to 0.8 mM with high reproducibility and less than 5 % error. T he electrode response for hydroquinone concentration of 0.25 mM was st able with repeated use for at least 800 assays without significant los s of activity.