Studies concerning the biomonitoring of the degree of environmental pollution using a urea-sensitive enzymatic sensor

Abstract

The biosensor, which determines the variation of the pH as a consequence of the hydrolysis process of urea, is composed of a biological receiver (the urease) and a potentiometric sensor (a metallic pH electrode, tungsten). Keeping in mind that the sensitivity of the sensor changes depending with the inhibitor concentration for urease (which is present in the water or in the soil), this could be used to determine the degree of pollution of the surface waters and of the soil. In this way it would be possible to establish the quantities of the urea utilized as chemical fertilizer.

In the present work, we present the investigation of the inhibition effect of the ions Pb²⁺, Fe²⁺, Sn²⁺, Zn²⁺ and Hg²⁺ toward the urea-sensitive biosensor. The determinations with samples of surface waters and soils in the presence of 10⁻¹ M urea and one-minute contact time has demonstrated the possibility of monitoring the concentrations of these ions in the following domains: 10⁻²–10⁻⁶ M Fe²⁺; 10⁻²–10⁻⁶ M Zn²⁺; 10⁻⁴–10⁻⁶ M Pb²⁺. These limiting values are found if the cation is individually present. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:27–30, 2000