Linamarin sensors:  interference-based sensing of linamarin using linamarase and peroxidase

An interference-based linamarin sensor is developed. Horseradish peroxidase (HRP) is adsorbed on a pyrolytic graphite (PG) electrode, and then linamarase from cassava is cross-linked with glutaraldehyde on the electrode surface. The prepared bienzyme electrode is poised at -300 mV vs Ag/AgCl for 40 s to reduce dissolved O(2) to H(2)O(2) at the PG surface. The potential is then stepped to 0 mV, at which point the accumulated H(2)O(2) is reduced, though the O(2) reduction does not proceed. Since the H(2)O(2) reduction is catalyzed by HRP, the transient cathodic current is inhibited by cyanide, which is liberated from linamarin by linamarase. Therefore, the transient current is a function of the linamarin concentration. This sensor responds to 1 × 10(-5)-5 × 10(-3) M linamarin and can estimate a linamarin concentration of a cassava extract.