Improvement of an enzyme electrode by poly(vinyl alcohol) coating for amperometric measurement of phenol

A poly(vinyl alcohol) film cross-linked with glutaraldehyde (PVA–GA) was introduced to the surface of a tyrosinase-based carbon paste electrode. The coated PVA–GA film was beneficial in terms of increasing the stability and reproducibility of the enzyme electrode. The electrode showed a sensitive current response to the reduction of the o-quinone, which was the oxidation product of phenol, by the tyrosinase, in the presence of oxygen. The effects of the PVA and PVA–GA coating, the pH, and the GA:PVA ratio on the current response were investigated. The sensitivity of the PVA–GA–Tyr electrode was 130.56 μA/mM (1.8 μA/μM cm2) and the linear range of phenol was 0.5–100 μM. At a higher concentration of phenol (>100 μM), the current response showed the Michaelis–Menten behavior. Using the PVA–GA–Tyr electrode, a two-electrode system was tested as a prototype sensor for portable applications.