Viscosity and binder composition effects on tyrosinase-based carbon paste electrode for detection of phenol and catechol

The systematic study of the effect of binder viscosity on the sensitivity o f a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxan e) chemical composition were used to represent a wide range of viscosities (10-60 000 mPa s(-1) at 25 degreesC) while minimizing polarity effects. The highest response for both phenol and catechol was achieved using a silicon oil binder of intermediate viscosity (100 mPa s(-1)). The binder viscosity showed no appreciable effect on the direct oxidation of phenol and catecho l using a plain CPE, suggesting the involvement of diffusion kinetics in th e binder matrix for the enzyme-based CPE. The effect of the relative binder concentration in the carbon paste was measured over the range of 30-70%. O ptimal results were obtained using 40% silicon oil. For comparison of the v iscosity effects observed with the carbon paste electrode (CPE) containing silicon oil, other low and high viscosity mineral oils and paraffin waxes w ere also examined. (C) 2001 Elsevier Science B.V. All rights reserved.