Laccase electrode for the continuous-flow determination of phenolic compounds

Summary Laccase (p-diphenol, O₂ oxido-reductase, E.C. 1.10.3.2) from Botrytis cinerea was immobilized in a gelatin support on an O₂ sensing electrode. The enzyme was copolymerized with the inert protein using glutaraldehyde (1.25 % w/w) on the hydrophobic selective gas membrane of a pO₂ sensor and this was covered with a Nuclepore polycarbonate microporous film (0.03 m). The enzyme electrode was used in a continuous-flow system to measure the concentration of a wide range of phenolic substrates. The measuring time of each sample was about 1.5 min including response and rinsing times. The electrode response was set for hydroquinone up to 0.8 mM with high reproducibility and less than 5 % error.The electrode response for hydroquinone concentration of 0.25 mM was stable with repeated use for at least 800 assays without significant loss of activity.