An Amperometric Urea Biosensor Based on a Polyaniline−Perfluorosulfonated Ionomer Composite Electrode

A new procedure for urea determination was developed. By cross-linking urease onto a polyaniline−Nafion composite electrode which sensed the ammonium ion effectively, a very sensitive urea biosensor was formed. The effects of applied potential, pH of buffer solutions, flow rate of carrier, and possible interferences on the response of urea biosensor were studied. With the developed urea biosensor, a detection limit as low as 0.5 μM and a response time as short as 40 s were obtained in an flow injection analysis system. A relative standard deviation of 2.2% ( n = 15) was obtained for the successive analysis of a 0.03 mM standard urea solution. Applicability of the urea biosensor for urea analysis was demonstrated by the analysis of NIST standard reference material and urine samples.