Biosensor for phenol based on the direct electron transfer blocking of peroxidase immobilising on silica-titanium

Horseradish peroxidase (HRP) was immobilised on silica gel modified with ti tanium oxide. This material was employed to prepare modified carbon paste e lectrode. The direct electron transfer of the hydrogen peroxide reduction b y HRP was blocked when immobilised on silica-titanium, This biosensor prese nted a very sensitive response for phenol (1 mu mol l(-1)) at an applied po tential of 0 mV vs SCE. The best condition was achieved in phosphate buffer pH 6.8, ratio of hydrogen peroxide/phenol higher than 0.35. The biosensor showed a linear response range between 10 and 50 mu mol l(-1) of phenol, ad justed by the equation j=-32.8+16.3 [phenol], for n=5 with a correlation co efficient of 0.9995. The response time of the biosensor was about 3 s. (C) 1999 Elsevier Science B.V. All rights reserved.