THE LIQUID-LIQUID MICRO-INTERFACE FOR THE AMPEROMETRIC DETECTION OF UREA

The detection of the ammonium ion produced by the enzymatic action of urease on urea is investigated electrochemically by means of facilitat ed ion transfer reactions at liquid-liquid micro-interfaces. The ureas e was used either in a dissolved form (free in aqueous solution) or im mobilized onto the surface of an ammonia gas permeable membrane. The s ensing structure utilizing the ammonia gas permeable membrane allowed the detection of urea from 200 mu M to 4mM. Thick film technology was utilized in conjunction with UV excimer laser photoablation techniques to fabricate a microelectrode strip sensor for the ammonium ion.