POTENTIOMETRIC BIOSENSOR FOR LYSINE ANALYSIS BASED ON A CHEMICALLY IMMOBILIZED LYSINE OXIDASE MEMBRANE

An enzymatic lysine electrode is developed for the potentiometric anal ysis of lysine (Lys). This lysine biosensor consists of a chemically i mmobilized lysine oxidase membrane attached to an all-solid-state ammo nium electrode. In this system, the enzymatic degradation of lysine pr oduces ammonia, which is then detected with the ammonium electrode. Th e influence of immobilization conditions on the potentiometric respons e and the lifetime of the electrode was studied. Under optimal conditi ons, the relationship between the potentiometric response and the log [Lys] was linear between 3x10(-5) and 10(-3) M, the sensitivity was 50 mV/decade, the repeatability 1.4%, and the response time t(95%) was 1 5 s. (C) 1998 Elsevier Science B.V, All rights reserved.