Analytical Application Of The Membrane-stabilized Enzyme-modified Interface Between Two Immiscible Electrolyte Solutions

An amperometric urea biosensor based on facilitated transfer of urease-generatedrnammonium ion by a neutral carrier (ionophore) dibenzo-18-crown-6 across the polarizablernmembrane-stabilized interface between water and nitrobenzene is described and discussed.rnThe enzyme urease employed for the investigation was immobilized on the sensor surfacernby physical entrapment as a gel between dialysis membranes. The current response of thernanlperometric sensor was found to be directly proportional to the concentration of urea inrnthe sample solution. In addition, correction for residual current due to interfering (residual)rnsubstances is relatively easy. The sensor gave a linear response to urea in the concentrationrnrange 5 x 10" to 5 x 10.3 M. The response time of the sensor was I min. The sensitivityrnappeared to be dependent on the conditions of immobilization of the enzyme. The effect ofrnthe thickness of the enzyme layer on the sensor response has been discussed. The life timernof the sensor was more than 3 weeks when stored in the buffer solution at roomrntemperature

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