Enzyme biosensor for determination of organophosphates

A potentiometric enzyme biosensor for the direct measurement of organophosp hate pesticides was developed. The basic element of this enzyme biosensor w as a pH electrode modified with an immobilized organophosphorus hydrolase l ayer formed by cross-linking OPH with bovine serum albumin and glutaraldehy de: Organophosphorus hydrolase catalyzes the hydrolysis of organophosporus pesticides to release protons, the concentration of which is proportional t o the amount of hydrolyzed substrate. The organophosphate enzyme biosensor had a response time of less than 3 min, a useful operating range of 0.002-0 .4 mM for paraoxon and parathion, and a long-term stability of over a month when stored in pH 8.5, 1 mM HEPES + 100 mM NaCl buffer at 4 degrees C. The effects of various parameters, buffer concentration, pH, temperature and e nzyme loading are described. (C) 1998 John Wiley & Sons, Inc.