METHYLPHENAZONIUM-MODIFIED ENZYME SENSOR-BASED ON POLYMER THICK-FILMS FOR SUBNANOMOLAR DETECTION OF PHENOLS

A methylphenazonium-zeolite-modified enzyme sensor based on a planar, screen-printed, two-electrode arrangement is described for the subnanomolar detection of phenols. Using tyrosinase (EC 1.14.18.1), a novel polyurethane hydrogel was applied for immobilization and stabilization of the enzyme, which forms a self-adhering layer on the active surface of the strip sensor. Performance and characteristics of the sensor were evaluated with regard to response time, detection limit, selectivity, and dependences on temperature and pH as well as operating and storage stabilities. The sensor shows marked sensitivity to eight phenolic compounds usually present in industrial waste waters. The detection limit for phenol was obtained with 0.25 nM. Comparing sensor responses with DIN and EPA standard methods for the chemical analyses of both synthetic and real sample matrices, the results indicate the feasibility of the strip sensor for sensitive determination of phenols in field analysis.