INTERFERENCE-BASED AMYGDALIN SENSOR WITH EMULSIN AND PEROXIDASE

An interference-based biosensor for amygdalin, a cyanogenic glycoside, is developed. Horseradish peroxidase (HRP) is adsorbed on a pyrolytic graphite (PG) electrode and then emulsin is cross-linked with glutara ldehyde on the electrode surface. The prepared bienzyme electrode is p oised at - 300 mV versus Ag/AgCl for 40 s to reduce dissolved O-2 to H 2O2 at the PG surface. Then the potential is stepped to 0 mV, at which the accumulated H2O2 is reduced and the 0, reduction does not proceed . Since the H2O2 reduction is catalyzed by HRP, the transient cathodic current is inhibited by cyanide, which is liberated from amygdalin by emulsin. Therefore, the transient current is a function of the amygda lin concentration. This sensor responds to 10(-6)-10(-3) M amygdalin. Sensors for more concentrated amygdalin is prepared by using thinner e mulsin films. This bienzyme electrode functions even in two-electrode mode. (C) 1998 Elsevier Science S.A. All rights reserved.